KR20240173388A - Battery Pack - Google Patents

Abstract

The present invention provides a battery pack comprising: a pack housing including a bottom frame, a side frame, and a cover to form an accommodation space therein, wherein the cover and the bottom frame are spaced apart in a first direction; at least one cell stack accommodated in the accommodation space, wherein a plurality of cooling plates and a plurality of battery cells are stacked in a second direction perpendicular to the first direction; wherein each cell stack is formed by alternately stacking each cooling plate and at least one battery cell in the second direction, and an air gap is formed between the at least one battery cell and the bottom frame so that gas generated from each battery cell can flow.

Description

Battery Pack

The present invention relates to a battery pack including a cell stack in which a plurality of battery cells are stacked, and more particularly, to a battery pack capable of performing gas discharge through a bottom frame of a pack housing.

Secondary batteries, unlike primary batteries, can be charged and discharged, and can be applied to various fields such as digital cameras, mobile phones, laptops, hybrid cars, and electric cars. Secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-hydrogen batteries, and lithium secondary batteries.

Secondary batteries can be manufactured as pouch-type battery cells or can-type battery cells. A pouch-type battery cell has a structure in which an electrode assembly is accommodated inside a flexible pouch. A can-type battery cell has a structure in which an electrode assembly is accommodated inside a rigid casing and can be composed of a cylindrical battery cell or a square battery cell.

A plurality of battery cells are electrically connected and used. At this time, the plurality of battery cells are arranged inside a module housing to form a cell stack in a stacked form to form a battery module. A plurality of battery modules can be arranged inside a pack housing to form a battery pack.

Recently, a configuration has been proposed in which the cell stack is placed directly in a pack housing, etc. However, unlike can-type battery cells, the external packaging material (pouch) of pouch-type battery cells is formed of a flexible material and is vulnerable to external impact, so it is difficult to ensure safety when a cell stack composed of pouch-type battery cells is directly installed in a pack housing.

In particular, conventional battery packs use the lower part of the pack housing as a cooling path, but in this case, there is a problem of reduced rigidity of the lower part of the pack housing.

The present invention (disclosure) aims, in one aspect, at providing a battery pack capable of smoothly discharging gas generated from a battery cell.

In addition, the present invention aims to provide a battery pack capable of increasing the rigidity of the battery pack as one aspect.

And, as one aspect, the present invention aims to provide a battery pack capable of increasing cooling efficiency.

In one aspect to achieve at least some of the above objects, the present invention provides a battery pack, comprising: a pack housing including a bottom frame, a side frame, and a cover to form an accommodation space therein, wherein the cover and the bottom frame are spaced apart in a first direction; at least one cell stack accommodated in the accommodation space, wherein a plurality of cooling plates and a plurality of battery cells are stacked in a second direction perpendicular to the first direction; wherein each cell stack is formed by alternately stacking each cooling plate and at least one battery cell in the second direction, and an air gap is formed between the at least one battery cell and the bottom frame so that gas generated from each battery cell can flow.

In embodiments, the bottom surface of the cooling plate may have a shape extending in the first direction toward the bottom frame from the lowest side of the battery cell.

In embodiments, the air gap may have a height of 1 mm or more and 20 mm or less in the first direction.

In embodiments, the battery cell may be fixed to the adjacent cooling plate and the adjacent battery cell by an adhesive member. Accordingly, the cell stack may be arranged in the pack housing in a state in which a plurality of battery cells and a plurality of cooling plates are combined. The adhesive member may include at least one of a thermally conductive adhesive having a thermal conductivity of 0.3 W/(m K) or more, a thermally conductive grease, a thermally conductive epoxy, and a heat-dissipating pad.

In embodiments, the thickness of the adhesive material may be 0.5 mm or more and 3 mm or less.

In embodiments, the floor frame may include at least one gas discharge hole communicating with the air gap to discharge gas in the air gap, and a gas path through which gas introduced through each gas discharge hole flows. The floor frame may include a first plate having the gas discharge hole formed therein, and a second plate forming the gas path between the first plate and the second plate.

In embodiments, the first plate may have a greater thickness than the second plate.

In embodiments, the floor frame may include a venting unit that discharges gas flowing through the gas passage to the outside of the pack housing.

In embodiments, a filler member may be arranged between the upper surface of the cell stack and the cover to fill at least a portion of the space between the upper surface of the cell stack and the cover. The filler member may secure the cell stack and the cover.

In embodiments, the filling material may include a thermally conductive adhesive having a thermal conductivity of 0.3 W/(m K) or greater.

In embodiments, the cooling plate may include a porous structure or a flow space through which a cooling medium flows.

In embodiments, the bottom frame may have a support member disposed thereon that supports a portion of a lowermost side of at least one battery cell.

In embodiments, the battery cell may include a pouch-shaped secondary battery or a square secondary battery.

In embodiments, the battery cell includes a cell body portion in which an electrode assembly is accommodated, a sealing portion arranged on at least a portion of a periphery of the cell body portion to seal the electrode assembly, and an electrode lead electrically connected to the electrode assembly, wherein the sealing portion includes a first sealing portion formed in an area where the electrode lead is exposed to the outside and a second sealing portion formed in an area where the electrode lead is not arranged, and the cell stack can be arranged such that the second sealing portion faces the bottom frame.

In embodiments, the air gap may be formed between the lower surface of the cell body and the floor frame, or between the second sealing portion and the floor frame. The height between the lower surface of the cell body and the floor frame may have a value of 1 mm or more and 20 mm or less, or the height between the second sealing portion and the floor frame may have a value of 1 mm or more and 15 mm or less.

In embodiments, the battery cell includes a casing that accommodates the electrode assembly and a gas exhaust valve disposed on a lower surface of the casing, and the air gap can be formed between the lower surface of the casing and the bottom frame.

In the embodiments, the receiving space is divided into a plurality of partition spaces by partition walls, and each cell stack can be placed in each partition space.

In another aspect, the present invention provides a battery pack, comprising: a pack housing including a bottom frame, a side frame, and a cover to form an accommodation space therein, the cover and the bottom frame being arranged spaced apart in a first direction; and at least one cell stack accommodated in the accommodation space, the cell stack including a plurality of cooling plates and a plurality of battery cells stacked in a second direction perpendicular to the first direction, wherein each cell stack is configured such that the at least one battery cell is arranged in the pack housing spaced apart from the bottom frame in the first direction.

According to one embodiment of the present invention having such a configuration, the effect of smoothly discharging gas generated from a battery cell to the outside of the pack housing can be obtained.

In addition, according to one embodiment of the present invention, it is possible to obtain an effect of increasing the rigidity of the battery pack. In particular, since the rigidity of the lower part of the pack housing is increased, it is possible to obtain an effect of applying the battery pack not only to a cell-to-pack (CTP) structure but also to a cell-to-chassis (CTC) structure and a cell-to-body (CTB) structure.

And, according to one embodiment of the present invention, the effect of increasing the cooling efficiency of the battery pack can be obtained.

Figure 1 is an exploded perspective view of a battery pack according to one embodiment of the present invention.
Figure 2 is a perspective view of the battery assembly illustrated in Figure 1.
Figure 3 is an exploded perspective view of the battery assembly illustrated in Figure 2.
Figure 4 is a perspective view showing an example of a battery cell used in the present invention.
Fig. 5 is a cross-sectional view of a cell stack along line I-I' of Fig. 2.
Figure 6 is an enlarged view of part “A” of Figure 5.
Figures 7 and 8 are cross-sectional views each showing a modified example of the cell stack illustrated in Figure 6.
Fig. 9 is a cross-sectional view showing a modified example of the cell stack shown in Fig. 6.
Fig. 10 is a cross-sectional view of a battery pack along line II-II' of Fig. 1.
Fig. 11 is a cross-sectional view showing a modified example of Fig. 10.
Fig. 12 is a cross-sectional view taken along line III-III' of Fig. 1.
Figure 13 is an exploded perspective view of a battery pack according to another embodiment of the present invention.
Fig. 14 is a cross-sectional view taken along line IV-IV' of Fig. 13.
FIG. 15 is a perspective view showing another example of a battery cell provided in the cell stack of the present invention.

Before going into the detailed description of the present invention, it should be noted that the terms or words used in this specification and claims described below should not be interpreted as being limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of the present invention based on the principle that the inventor can appropriately define the concept of the term in order to describe his own invention in the best way. Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, and it should be understood that there may be various equivalents and modified examples that can replace them at the time of filing this application.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. At this time, it should be noted that the same components in the attached drawings are indicated by the same symbols as much as possible. In addition, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect the actual size.

Figure 1 is an exploded perspective view of a battery pack (100) according to one embodiment of the present invention.

Referring to FIG. 1, a battery pack (100) according to one embodiment of the present invention may include a pack housing (160) and at least one cell stack (110). The cell stack (110) may be accommodated in the pack housing (160). At this time, the cell stack (110) may be accommodated in the pack housing (160) after forming a battery assembly (105). The battery assembly (105) will be described with reference to FIGS. 2 and 3.

The pack housing (160) can form a space that accommodates at least one cell stack (110). An accommodation space (165) can be formed inside the pack housing (160). The pack housing (160) can include a bottom frame (170), a side frame (161), and a cover (163). The pack housing (160) can be arranged such that the cover (163) and the bottom frame (170) are spaced apart from each other in a first direction (Z), and an accommodation space (165) can be formed between the cover (163) and the bottom frame (170).

The floor frame (170) may be configured to support the lower portion of the cell stack (110). The floor frame (170) may include at least one gas discharge hole (173). At least one gas discharge hole (173) may be formed on a support surface (170a) of the floor frame (170). Each gas discharge hole (173) may discharge gas discharged from the cell stack (110) to the outside of the floor frame (170). A plurality of gas discharge holes (173) may be formed on the support surface (170a) of the floor frame (170). The plurality of gas discharge holes (173) may be arranged spaced apart from each other and may have a circular shape. However, the shape and arrangement structure of the gas discharge holes (173) are not limited to the structure illustrated in FIG. 1. For example, the gas discharge holes (173) may also have a polygonal shape such as a slit shape, an oval shape, or a square shape.

The gas introduced into the gas discharge hole (173) may flow through the gas path (174 of FIG. 10) formed in the bottom frame (170) and then be discharged to the outside of the pack housing (160) through at least one venting unit (175). At least one venting unit (175) may be arranged in the pack housing (160). At least one venting unit (175) may be arranged in the bottom frame (170), but the arrangement position and number of the venting units (175) may be variously changed. The venting unit (175) may be formed as an open hole. Alternatively, the venting unit (175) may also include a venting valve that opens when the pressure of the gas is higher than the set pressure.

The side frame (161) may have a shape extending in the first direction (Z) from the edge of the floor frame (170). In FIG. 1, the side frame (161) is illustrated as having a plate shape, but the shape or structure of the side frame (161) may be variously changed. For example, the side frame (161) may have a shape in which a plurality of plates are joined to each other to increase rigidity. The side frame (161) may be formed integrally with the floor frame (170), but is not limited thereto. For example, the side frame (161) may be manufactured separately from the floor frame (170) and then joined by a known joining method such as welding.

The cover (163) can be coupled to the upper part of the side frame (161). For example, the cover (163) can be coupled to the side frame (161) by bolt fastening. However, the coupling method of the cover (163) and the side frame (161) is not limited thereto. The cover (163) can cover the receiving space (165) formed by the bottom frame (170) and the side frame (161). In Fig. 1, the cover (163) is illustrated as having a plate shape, but the shape or structure of the cover (163) can be changed in various ways.

The pack housing (160) may include a partition wall (167) that divides the receiving space (165) into a plurality of divided spaces. A cell stack (110) may be placed in each divided space. Each cell stack (110) may be placed in a divided space after being assembled into a battery assembly.

Meanwhile, the pack housing (160) according to the embodiment may have a structure mounted on the chassis or body of the vehicle, but is not limited thereto. For example, in the case of a cell-to-chassis (CTC) structure in which a plurality of cell laminates (110) are directly mounted on the chassis of the vehicle, or a cell-to-body (CTB) structure in which a plurality of cell laminates (110) are directly mounted on the body of the vehicle, the pack housing (160) may also constitute a part of the chassis or body of the vehicle.

The pack housing (160) may be made of a material having high thermal conductivity, such as metal. For example, the pack housing (160) may include aluminum or an aluminum alloy. Alternatively, the pack housing (160) may include steel or a steel alloy to ensure rigidity.

FIG. 2 is a perspective view of the battery assembly (105) illustrated in FIG. 1, and FIG. 3 is an exploded perspective view of the battery assembly (105) illustrated in FIG. 2.

Referring to FIGS. 2 and 3, the battery assembly (105) may include a cell stack (110) in which a plurality of battery cells (120) are stacked, and a busbar assembly (150).

The cell stack (110) may include a plurality of cooling plates (130) and a plurality of battery cells (120). The plurality of cooling plates (130) and the plurality of battery cells (120) may be stacked in a second direction (X) perpendicular to the first direction (Z). The cell stack (110) may be formed by alternately stacking cooling plates (130) and at least one battery cell (120) in the second direction (X). One or a plurality of battery cells (120) may be arranged between adjacent cooling plates (130).

The cell stack (110) may have a state in which the cooling plate (130) is exposed to the outside. The cooling plate (130) may be arranged on both sides of the cell stack (110) based on the second direction (X). The cooling plate (130) arranged at the outermost side of the cell stack (110) may protect the battery cell (120) from the outside.

The adhesive member (140) can fix the battery cell (120) and the cooling plate (130) or the adjacent battery cells (120) to each other. Each battery cell (120) can be fixed to the adjacent cooling plate (130) and the adjacent battery cell (120) by the adhesive member (140). Accordingly, the cell stack (110) can form a state in which a plurality of battery cells (120) and a plurality of cooling plates (130) are combined. The cell stack (110) can be placed in the receiving space (165) of the pack housing (160) in a state in which a plurality of battery cells (120) and a plurality of cooling plates (130) are combined.

The adhesive member (140) may include a thermally conductive material so as to transfer heat generated from the battery cell (120) to the cooling plate (130). In order to improve heat transfer performance, the adhesive member (140) may include a material having a thermal conductivity of 0.3 W/(m K) or more. Due to the high thermal conductivity of the adhesive member (140), heat generated from the battery cell (120) may be easily transferred to the cooling plate (130) through the adhesive member (140). The adhesive member (140) may be configured to include at least one of a thermally conductive adhesive, a thermally conductive grease, a thermally conductive epoxy, and a heat-dissipating pad so as to ensure good heat transfer. As an example, the adhesive member (140) may be applied in a liquid or gel state between the battery cell (120) and the cooling plate (130) or between adjacent battery cells (120), or may be placed in the form of a pad. The type, material, and placement method of the adhesive member (140) may be changed in various ways according to known technology.

The thickness of the adhesive member (140) may be 0.5 mm or more and 3 mm or less. If the thickness of the adhesive member (140) exceeds 3 mm, it may act as thermal resistance when cooling the battery cell (120) and may also reduce the energy density of the battery pack. Therefore, the thickness of the adhesive member (140) may have a value of 3 mm or less in order to reduce the thermal resistance and improve the energy density of the battery pack. In addition, if the thickness of the adhesive member (140) is small, less than 0.5 mm, when the adhesive member (140) is applied in a liquid or gel state, an area where the adhesive is not applied may occur or the amount of the adhesive applied may not be uniform. In addition, if the thickness of the adhesive member (140) is thin, the adhesive performance between the battery cell (120) and the cooling plate (130) and/or the adhesive performance between the battery cell (120) and the adjacent battery cell (120) may be reduced. Therefore, the thickness of the adhesive member (140) may be 0.5 mm or more in consideration of stable placement and/or adhesive performance of the adhesive member (140).

The busbar assembly (150) may include at least one busbar (151) having electrical conductivity and an electrically insulating support plate. The at least one busbar (151) may electrically connect electrode leads (125) of battery cells (120) to implement a series and/or parallel connection structure between the battery cells (120). The support plate may be arranged between the busbar (151) and the battery cell (120) to support the busbar (151). An outer plate may be arranged on a portion facing the busbar (151) to protect the busbar (151).

Fig. 4 is a perspective view illustrating an example of a battery cell (120) used in the present invention. Referring to Fig. 4, the battery cell (120) may include, as an example, a pouched type secondary battery.

The battery cell (120) may include a cell body portion (122) in which an electrode assembly (127) is accommodated, a sealing portion (123) arranged on at least a portion of the periphery of the cell body portion (122) to seal the electrode assembly (127), and an electrode lead (125) electrically connected to the electrode assembly (127).

The battery cell (120) may be configured in a form in which an electrode assembly (127) is accommodated in a pouch (121) forming an outer casing. The electrode assembly (127) includes a plurality of electrode plates and electrode tabs and is accommodated in the pouch (121). Here, the electrode plates are configured of a positive electrode plate and a negative electrode plate, and the electrode assembly (127) may be configured in a form in which the positive and negative electrode plates are laminated with a separator interposed therebetween so that wide surfaces of the positive and negative electrode plates face each other. The plurality of positive and negative electrode plates are each provided with electrode tabs, and the electrode tabs may be connected to electrode leads (125) of the same polarity by contacting each other with the same polarity.

The pouch (121) may include a cell body portion (122) and a sealing portion (123). The cell body portion (122) is formed in a container shape and provides a space in which an electrode assembly (127) and an electrolyte are accommodated inside.

The sealing portion (123) is a portion where a part of the pouch (121) is joined to seal the perimeter of the cell body portion (122). The sealing portion (123) is formed in a flange shape that extends outward from the cell body portion (122) formed in the shape of a container, and is arranged along at least a part of the perimeter of the cell body portion (122). A heat-melting method may be used for joining the pouch (121) to form the sealing portion (123), but is not limited thereto.

In addition, in this embodiment, the sealing portion (123) may include a first sealing portion (123a) formed in an area where the electrode lead (125) is exposed to the outside, and a second sealing portion (123b) formed in an area where the electrode lead (125) is not placed. A part of the electrode lead (125) may be exposed to the outside of the pouch (121). At a location where the electrode lead (125) is pulled out, the electrode lead (125) may have at least one surface covered by an insulating film (126). The insulating film (126) increases the sealing degree of the first sealing portion (123a) and at the same time secures an electrical insulation state between the electrode lead (125) and the pouch (121).

As an example, the pouch (121) may be formed from a single casing. That is, one or two storage portions may be formed by forming them on a single casing, and then the casing may be folded so that the storage portions form one space (i.e., cell body portion (122)) to complete the pouch (121).

As an example, the cell body part (122) may be formed in a square shape. The sealing part (123) may be formed at a portion of the perimeter of the cell body part (122) where the outer material overlaps. However, there is no need to form the sealing part (123) on the surface (129) where the outer material folds. Therefore, in the embodiment illustrated in FIG. 4, the sealing part (123) may be formed on the outer surface of the cell body part (122), but may be provided on only three surfaces of the cell body part (122). That is, in the embodiment illustrated in FIG. 4, the sealing part (123) may not be arranged on any surface (129) of the outer surface of the cell body part (122).

As an example, the electrode leads (125) may be arranged on opposite sides of the longitudinal direction (Y) of the battery cell (120). An electrode lead (125) of a first polarity (e.g., a positive electrode) may be arranged on one longitudinal side of the battery cell (120), and an electrode lead (125) of a second polarity (e.g., a negative electrode) may be arranged on the other longitudinal side. The two electrode leads (125) may be arranged in sealing portions (123) formed on different sides. Accordingly, in the embodiment illustrated in FIG. 4, the sealing portion (123) may include two first sealing portions (123a) in which the electrode leads (125) are arranged, and one second sealing portion (123b) in which the electrode leads (125) are not arranged. The second sealing portion (123b) may be formed on the lower surface of the pouch (121). When the second sealing portion (123b) is positioned toward the lower side in the first direction (Z), the lowermost side (128) of the battery cell (120) can be formed by the second sealing portion (123b).

Meanwhile, the pouch (121) used in the embodiment of the present invention is not limited to a three-sided sealing structure in which a single sheet of outer material is folded to form a sealing portion (123) on three sides as shown in Fig. 4. For example, it is also possible to have a four-sided sealing structure in which two sheets of outer material are folded to form a cell body portion (122) and sealing portions (123) are formed on all four sides around the cell body portion (122).

In addition, in order to increase the bonding reliability of the sealing portion (123) and minimize the volume occupied by the sealing portion (123), the battery cell (120) of the present embodiment may be formed in a form in which the sealing portion (123) is folded at least once. At least one tape (T) may be attached to the second sealing portion (123b) to prevent the second sealing portion (123b) from unfolding due to the spring back phenomenon.

The battery cell (120) configured in this manner may be configured as a known secondary battery, such as a lithium ion (Li-ion) battery or a nickel metal hydride (Ni-MH) battery that can be charged and discharged.

Meanwhile, in FIG. 4, a pouch-type secondary battery is described as an example of a battery cell (120), but the embodiment of the present invention does not exclude the use of a square secondary battery (see FIG. 15) as a battery cell (120).

FIG. 5 is a cross-sectional view of a cell stack (110) along line I-I' of FIG. 2, and FIG. 6 is an enlarged view of portion "A" of FIG. 5.

Referring to FIGS. 5 and 6, the cell stack (110) may include a plurality of cooling plates (130) and a plurality of battery cells (120) stacked in a second direction (X).

The cell stack (110) may have a shape in which cooling plates (130) and at least one battery cell (120) are alternately stacked in the second direction (X). For example, at least one battery cell (120) may be placed between cooling plates (130).

The cooling plate (130) may be placed on the outside of the cell stack (110). The cooling plate (130) placed on the outside of the cell stack (110) may protect the battery cell (120) placed on the inside of the cell stack (110) from the outside.

The battery cell (120) may be fixed by an adjacent cooling plate (130) and/or an adjacent battery cell (120) and an adhesive member (140). In addition, the cooling plate (130) may be fixed by an adjacent battery cell (120) and an adhesive member (140). That is, the adhesive member (140) may be placed between the cooling plate (130) and the battery cell (120), or between the battery cell (120) and an adjacent battery cell (120). The adhesive member (140) may have an adhesive force that can maintain the battery cell (120) in a fixed state. The cell stack (110) may be placed in an accommodation space (165 of FIG. 1) of a pack housing (160 of FIG. 1) in a state in which a plurality of battery cells (120) and a plurality of cooling plates (130) are combined.

The adhesive member (140) may include a thermally conductive material. Accordingly, heat generated from the battery cell (120) may be transferred to the cooling plate (130) through the adhesive member (140). In addition, when a plurality of battery cells (120) are arranged between two cooling plates (130), heat generated from a battery cell (120) that is arranged relatively far from the cooling plate (130) may be transferred to the cooling plate (130) after passing through the battery cell (120) that is relatively close to the cooling plate (130) through the adhesive member (140). When two battery cells (120) are arranged between two cooling plates (130), heat generated from each battery cell (120) may be transferred to the cooling plate (130) that is arranged adjacent to each battery cell (120).

In order to improve heat transfer performance, the adhesive member (140) may include a material having a thermal conductivity of 0.3 W/(m K) or more. The adhesive member (140) may be configured to include at least one of a thermal adhesive, a thermal grease, a thermally conductive epoxy, and a heat dissipation pad. As an example, the adhesive member (140) may be applied in a liquid or gel state between the battery cell (120) and the cooling plate (130) or between adjacent battery cells (120), or may be arranged in a pad form. The type, material, and arrangement method of the adhesive member (140) may be variously changed according to the known technology.

The number of battery cells (120) arranged between cooling plates (130) can be changed in various ways in consideration of the cooling performance of the battery cells (120), the force with which the adhesive member (140) fixes the battery cells (120), and the energy density of the cell stack (110). For example, in order to improve the cooling performance of the battery cells (120), it is necessary to increase the number of cooling plates (130). For example, the cooling plates (130) can be arranged every two battery cells (120).

The battery cell (120) provided in the cell stack (110) may have a sealing portion (123) formed on the lower surface (122a) of the cell body portion (122). A second sealing portion (123b) may be arranged on the lower surface (122a) of the cell body portion (122). When the battery cell (120) has a three-sided sealing structure, the sealing portion (123) may not be arranged on the upper surface (129) of the battery cell (120). In the cell stack (110), the upper surface (129) of the battery cell (120) and the upper surface (132) of the cooling plate (130) may form the same plane. However, the cell stack (110) may also have a shape in which either the upper surface (129) of the battery cell (120) or the upper surface (132) of the cooling plate (130) protrudes more.

If the battery cell (120) is made of a pouch-type secondary battery, the sealing portion of the battery cell (120) may be opened or deformed when the internal pressure of the battery cell (120) increases in an event situation. Gas discharge from the battery cell (120) in an event situation can typically occur through the sealing portion of the battery cell (120).

The bottom surface (131) of the cooling plate (130) may be supported by the support surface (170a of FIG. 1 and FIG. 10) of the bottom frame (170 of FIG. 1 and FIG. 10). The bottom surface (131) of the cooling plate (130) may have a shape that extends to the bottom of the battery cell (120). When the bottom surface (131) of the cooling plate (130) is placed on the bottom frame (170), an air gap (115) may be formed between at least one battery cell (120) and the bottom frame (170). The air gap (115) provides a space in which gas generated from each battery cell (120) can flow. The air gap (115) may be formed as an open space in which the gas can flow. The air gap (115) may be formed at the bottom of the cell stack (110). When the second sealing portion (123b) is placed at the bottom of the cell stack (110) so that the second sealing portion (123b) faces the air gap (115), gas generated in an event situation can be discharged to the air gap (115).

The bottom surface (131) of the cooling plate (130) may have a shape that extends in the first direction (Z) toward the bottom frame (170 in FIG. 1) more than the cell body portion (122) of the battery cell (120). The air gap (115) may be formed as a space between the plane formed by the bottom surface (131) of the cooling plate (130) and the lower surface (122a) of the cell body portion (122).

The height of the air gap (115) may be defined as the height of an open space through which gas can flow. The maximum height (H) of the air gap (115) may correspond to the length by which the bottom surface (131) of the cooling plate (130) protrudes beyond the lower surface (122a) of the cell body portion (122). As an example, the maximum height (H) of the air gap (115) may have a value of 1 mm or more and 20 mm or less. If the maximum height (H) of the air gap (115) is less than 1 mm, it becomes difficult for the gas to flow, and if it exceeds 20 mm, the energy density of the cell stack (110) may be greatly reduced.

The bottom surface (131) of the cooling plate (130) may have a shape that extends in the first direction (Z) toward the bottom frame (170 of FIG. 1 and FIG. 10) from the bottommost side (128) of the battery cell (120). When the second sealing portion (123b) is arranged at the bottom of the battery cell (120), the bottommost side (128) of the battery cell (120) may correspond to the second sealing portion (123b). The air gap (115) may also be formed in the space between the bottom surface (131) of the cooling plate (130) and the bottommost side (128) of the battery cell (120). As an example, the height (H1) between the bottom surface (131) of the cooling plate (130) and the bottommost side (128) of the battery cell (120) may have a value of 1 mm or more and 15 mm or less.

In this way, the air gap (115) may be formed between the lower surface of the cell body and the support surface (170a of FIG. 1 and FIG. 10) of the bottom frame (170), or may be formed between the lowermost side (128) of the battery cell (120) (e.g., the second sealing portion) and the support surface (170a) of the bottom frame (170).

Figures 7 and 8 are cross-sectional views each showing a modified example of the cell stack illustrated in Figure 6.

As shown in FIG. 7, the cooling plate (130) may have a porous structure in which a plurality of internal spaces (133) are formed. When the cooling plate (130) has a porous structure, the internal surface area of the cooling plate (130) may increase. Accordingly, the cooling performance through the cooling plate (130) may be improved. The cooling plate (130) may be manufactured by an extrusion process. The internal spaces (133) may have a shape extending along the longitudinal direction of the cooling plate (130). When an extrusion process is used, a plurality of internal spaces (133) may be easily formed inside the cooling plate (130).

As shown in FIG. 8, the cooling plate (130) may include a flow space (134) in which a cooling medium (coolant) may flow therein. Accordingly, heat transferred from the battery cell (120) to the cooling plate (130) may be transferred to the cooling medium flowing in the flow space (134), thereby cooling the battery cell (120). The cooling medium may include not only a gas such as air, but also a liquid such as coolant.

The cooling plate (130) illustrated in Fig. 8 shows a shape in which one flow space (134) is formed inside, but the shape and number of the flow spaces (134) can be changed in various ways. For example, the flow space (134) can also have a shape or arrangement similar to the internal space (133) illustrated in Fig. 7.

Fig. 9 is a cross-sectional view illustrating a modified example of the cell stack illustrated in Fig. 6.

The number of battery cells (120) arranged between the cooling plates (130) can be changed in various ways in consideration of the cooling performance of the battery cells (120), the force with which the adhesive member (140) fixes the battery cells (120), and the energy density of the cell stack (110). In order to increase the energy density of the cell stack (110), the number of battery cells (120) arranged between the cooling plates (130) can be increased, but in this case, the cooling of the battery cells (120) may not be sufficient. In particular, when the number of battery cells (120) arranged between the cooling plates (130) increases, a difference in cooling performance occurs between battery cells (120) arranged far from the cooling plates (130) and battery cells (120) arranged close to the cooling plates (130), which may increase the temperature deviation of the battery cells (120). In consideration of this, the number of battery cells (120) arranged between the cooling plates (130) may be configured to be 1 to 10. In addition, the number of battery cells (120) arranged between the cooling plates (130) may be 1 to 8, 1 to 6, or 1 to 4. For example, as shown in FIG. 9, 4 battery cells (120) may be arranged between the cooling plates (130). However, the number of battery cells (120) arranged between the cooling plates (130) is not limited to the above-described number, and may exceed 10. Meanwhile, heat generated in battery cells (120) arranged far from the cooling plates (130) may also be discharged to the outside through a heat-conductive charging member (180 in FIG. 1).

FIG. 10 is a cross-sectional view of a battery pack (100) along line II-II' of FIG. 1, and FIG. 11 is a cross-sectional view illustrating a modified example of FIG. 10.

Referring to FIGS. 10 and 11, the battery pack (100) can accommodate a plurality of battery assemblies (105) in the accommodation space (165) of the pack housing (160). Each battery assemblies (105) includes a cell stack (110), and each cell stack (110) can have a shape in which a plurality of cooling plates (130) and a plurality of battery cells (120) are stacked in a second direction (X). The battery cells (120) can be fixed to adjacent cooling plates (130) and/or adjacent battery cells (120) by an adhesive member (140). The pack housing (160) can include a side frame (161), a cover (163), and a bottom frame (170). The pack housing (160) may include a partition wall (167) that divides a plurality of receiving spaces (165), and a battery assembly (105) may be placed in each receiving space (165).

Each cell stack (110) may be arranged in the pack housing (160) with at least one battery cell (120) spaced apart from the bottom frame (170) in the first direction (Z). Each cell stack (110) may be accommodated in the receiving space (165) and supported by the support surface (170a) of the bottom frame (170). The cooling plate (130) may be in contact with the support surface (170a) of the bottom frame (170) and supported by the support surface (170a). An air gap (115) may be formed between the cell stack (110) and the bottom frame (170). The air gap (115) may be formed between the support surface (170a) of the bottom frame (170) and the lower surface of the battery cell (120). Gas generated from each battery cell (120) may flow through the air gap (115).

The floor frame (170) may include a gas discharge hole (173) and a gas path (174). The gas discharge hole (173) may be formed in the floor frame (170) so as to be in communication with the air gap (115). The gas discharge hole (173) may be in communication with the air gap (115) to discharge gas in the air gap (115). Gas introduced through each gas discharge hole (173) may flow through the gas path (174). The gas flowing through the gas path (174) may be discharged to the outside of the pack housing (160) through at least one venting unit (175 of FIG. 1 and FIG. 12).

The floor frame (170) may include a first plate (171) and a second plate (172). The first plate (171) may be positioned opposite the air gap (115), and a gas discharge hole (173) may be formed in the first plate (171). The second plate (172) may be coupled to the first plate (171). A gas path (174) may be formed between the first plate (171) and the second plate (172). The second plate (172) may be coupled to the first plate (171) in a direction opposite to the air gap (115).

The floor frame (170) may have a sufficient thickness not only to support the battery cells (120) in the pack housing (160), but also to increase the overall rigidity of the pack housing (160). At least a portion of the floor frame (170) may include a stainless steel (SUS) material so as to have sufficient rigidity. When the floor frame (170) includes a stainless steel (SUS) material, the phenomenon in which the floor frame (170) is easily melted or deformed due to high-temperature gas can be reduced. However, the material of the floor frame (170) is not limited to stainless steel (SUS), and various changes may be made in consideration of securing rigidity and heat resistance.

When the floor frame (170) includes a first plate (171) and a second plate (172), the first plate (171) that directly supports the cell stack (110) may have a greater thickness than the second plate (172) to secure rigidity. Since the second plate (172) is attached to the first plate (171) to form a gas path (174), it may have a smaller thickness than the first plate (171). For example, the first plate (171) may have a thickness of 2 to 10 mm, and the second plate (172) may have a thickness of 0.2 to 0.8 times the thickness of the first plate (171).

The second plate (172) may include a first portion (172a) spaced apart from the first plate (171) to form a gas passage (174), and a second portion (172b) attached to the first plate (171). The second portion (172b) of the second plate (172) may be joined to the first plate (171) by a known joining means such as welding.

The first part (172a) of the second plate (172) forms a gas path (174). The receiving space (165) of the pack housing (160) can be divided into a plurality of divided spaces by a partition wall (167). At least one gas path (174) can be connected to each divided space divided by the partition wall (167). The gas path (174) connected to each divided space can be separated from the gas path (174) connected to the adjacent divided space. That is, the gas path (174) through which gas generated in the divided space arranged on one side of the partition wall (167) flows can have a structure that is separated from the gas path (174) through which gas generated in the adjacent divided space flows. Accordingly, gas generated from a battery cell (120) of one cell stack (110) can be discharged to the outside without passing through a gas path (174) connected to an adjacent receiving space (divided space) (165).

At least one gas path (174) may be connected to each receiving space (165). For example, as illustrated in FIG. 10, one gas path (174) may be connected to each receiving space (165). Alternatively, as illustrated in FIG. 11, multiple gas paths (174) may be connected to each receiving space (165). When multiple gas paths (174) are connected to one receiving space (165), the second part of the second plate (172) may be joined to the first plate (171) at a location where the gas discharge hole (173) is not formed.

Conventional battery packs use the lower part of the pack housing as a cooling path, but in this case, there is a problem that the rigidity of the lower part of the pack housing is reduced. However, according to an embodiment, the rigidity of the pack housing (160) can be increased by arranging the cooling plate (130) on the side of the battery cell instead of arranging the cooling path at the lower part of the pack housing. That is, according to the embodiment, the bottom frame (170) of the pack housing (160) has a sufficient thickness and does not have a cooling path, so that the rigidity of the bottom frame (170) can be increased. It is possible to increase the thickness of the first plate (171) that supports the cell stack (110) and the second plate (172) only have a thickness that can form a gas path (174).

Between the upper surface of the cell stack (110) and the cover (163), a filling member (180) may be arranged to fill at least a portion of the space between the upper surface of the cell stack (110) and the cover (163). The filling member (180) may prevent gas and/or flame generated from the battery cell (120) from flowing into the space between the upper surface of the cell stack (110) and the cover (163). Accordingly, the gas and/or flame generated from the battery cell (120) may be discharged through the air gap (115) formed between the cell stack (110) and the bottom frame (170) and then discharged to the outside of the battery pack (100) through the gas discharge hole (173) and the gas path (174).

The charging member (180) may have an adhesive force that fixes the cell stack (110) and the cover (163). The charging member (180) may function to maintain the cell stack (110) in a fixed state inside the pack housing (160). The battery cell (120) may be maintained in a fixed state with an adjacent battery cell (120) and/or a cooling plate (130) by the adhesive member (140) in the second direction (X), and the upper surface of the battery cell (120) may be fixed to the cover (163). Accordingly, even when an air gap (115) is formed between the lower surface of the battery cell (120) and the bottom frame (170), the battery cell (120) may be maintained in a stably fixed state inside the pack housing (160).

The charging member (180) may include a material having a thermal conductivity of 0.3 W/(m K) or more. Heat generated from the battery cell (120) may be transferred to the cover (163) through the charging member (180) and may be released to the outside through the cover (163) made of a thermally conductive material such as metal. In order to improve heat transfer performance, the charging member (180) may include a material having a thermal conductivity of 0.3 W/(m K) or more. The charging member (180) may be configured to include at least one of a thermally conductive adhesive, a thermally conductive grease, a thermally conductive epoxy, and a heat dissipation pad. As an example, the charging member (180) may be applied in a liquid or gel state between the battery cell (120) and the cover (163), or may be placed in the form of a pad. The type, material, and arrangement method of the charging member (180) can be changed in various ways according to the known technology.

Fig. 12 is a cross-sectional view taken along line III-III' of Fig. 1.

Referring to FIG. 12, the bottom frame (170) may include a first plate (171) and a second plate (172). The first plate (171) may be provided with a gas discharge hole (173) communicating with the receiving space (165) of the pack housing (160), and a gas path (174) may be arranged between the first plate (171) and the second plate (172). The gas path (174) may be connected to at least one venting unit (175). Accordingly, gas discharged from the cell stack (110) may pass through the gas discharge hole (173) and the gas path (174) and then be discharged to the outside of the pack housing (160) through the venting unit (175). The venting unit (175) may also be formed of an open hole. Alternatively, the venting unit (175) may include a venting valve that opens when the gas pressure is higher than the set pressure.

Next, a battery pack (100) according to another embodiment of the present invention will be described with reference to FIGS. 13 and 14.

FIG. 13 is an exploded perspective view of a battery pack (100) according to another embodiment of the present invention, and FIG. 14 is a cross-sectional view taken along line IV-IV' of FIG. 13.

As shown in FIGS. 13 and 14, the battery pack (100a) may have the same configuration as the battery pack (100) described with reference to FIGS. 1 to 12, except that it includes a support member (176).

The battery pack (100a) illustrated in FIGS. 13 and 14 may have a support member (176) positioned on the bottom frame (170) to support a portion of at least one battery cell (120) on the lowermost side (128 in FIG. 5).

The battery cell (120) is fixed to an adjacent battery cell (120) or an adjacent cooling plate (130) by an adhesive member (140), and the cooling plate (130) may be supported by the bottom frame (170). However, in the cell stack (110), the battery cell (120) is spaced apart from the bottom frame (170) at a portion where an air gap (115) is formed. Therefore, a phenomenon in which at least one battery cell (120) sags in the direction of gravity (downward direction) due to the weight of the battery cell (120) may occur. In order to prevent the sagging of the battery cell (120), a support member (176) may be arranged on the bottom frame (170). The support member (176) may support a portion of the lowest side (128 of FIG. 5) of at least one battery cell (120).

The support member (176) may have a shape protruding from the floor frame (170). The support member (176) may be arranged in a part of the space between the cell stack (110) and the floor frame (170). In order to facilitate the flow of gas discharged from the battery cell (120), the support member (176) may be configured with a plurality of protrusions spaced apart from each other on the floor frame (170). The support member (176) may have a structure in which a plurality of protrusions spaced apart from each other are arranged in a plurality of rows. Accordingly, the gas discharged from the battery cell (120) may flow through the air gap (115) through the space between the support members (176) and then be discharged to the outside through the gas discharge hole (173) and the gas path (174).

Meanwhile, in the embodiments illustrated in FIGS. 1 to 3, 5, and 10 to 14, the cell stack (110) has been described as including a pouch-type secondary battery. However, as another embodiment, the battery cell (120) included in the cell stack (110) may include a square secondary battery instead of a pouch-type secondary battery.

FIG. 15 is a perspective view showing another example of a battery cell (120a) provided in the cell stack (110) of the present invention.

A battery cell (120a) composed of a square secondary battery may include an electrode assembly (122a) and a casing (121a) containing an electrolyte therein, and a plurality of electrode terminals (electrode leads) (125a) exposed to the outside of the casing (121a). The casing (121a) may have a shape extending in the longitudinal direction. An electrode terminal (125a) may be positioned at at least one of the longitudinal ends of the casing (121a). As illustrated in FIG. 15, the battery cell (120a) may have a structure in which two electrode terminals (125a) are arranged to face opposite directions. However, the arrangement positions and numbers of the electrode terminals (125a) may be variously changed.

The battery cell (120a) may include a gas discharge valve (124a) that discharges gas generated inside the casing (121a) to the outside of the casing (121a). The gas discharge valve (124a) may be arranged on the lower surface of the casing (121a).

The battery cell (120a) illustrated in FIG. 15 may constitute the cell stack (110) illustrated in FIGS. 1 to 3, FIG. 5, and FIGS. 10 to 14. In this case, the lower surface of the battery cell (120a) may be arranged spaced apart from the support surface (170a of FIG. 1) of the bottom frame (170 of FIG. 1). That is, an air gap (115 of FIG. 5) may be formed between the battery cell (120a) and the bottom frame (170) so that gas generated from each battery cell (120a) may flow. The air gap (115) may be formed between the lower surface of the casing (121a) and the support surface (170a) of the bottom frame (170).

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and it will be apparent to those skilled in the art that various modifications and variations are possible within a scope that does not depart from the technical spirit of the present invention described in the claims.

For example, the above-described embodiments may be implemented by deleting some of the components, and the embodiments may be implemented in combination with each other.

100... Battery Pack 105... Battery Assembly
110... cell stack 115... air gap
120, 120a... Battery cell 130... Cooling plate
140... Adhesive 150... Busbar assembly
160... Pack Housing 170... Floor Frame
180... No charging

Claims (19)

A pack housing comprising a bottom frame, a side frame and a cover to form an accommodation space therein, wherein the cover and the bottom frame are spaced apart from each other in a first direction;
At least one cell stack accommodated in the above-described accommodation space, wherein a plurality of cooling plates and a plurality of battery cells are stacked in a second direction perpendicular to the first direction;
Including,
Each cell stack is formed by alternately stacking each cooling plate and at least one battery cell in the second direction,
A battery pack in which an air gap is formed between at least one battery cell and the bottom frame to allow gas generated from each battery cell to flow. In the first paragraph,
A battery pack in which the bottom surface of the cooling plate has a shape extending in the first direction toward the bottom frame from the lowest side of the battery cell. In the first paragraph,
A battery pack wherein the air gap has a height of 1 mm or more and 20 mm or less in the first direction. In the first paragraph,
A battery pack in which the above battery cells are fixed to adjacent cooling plates and adjacent battery cells by adhesive members. In paragraph 4,
A battery pack wherein the adhesive material includes at least one of a thermally conductive adhesive, a thermally conductive grease, a thermally conductive epoxy, and a heat-dissipating pad having a thermal conductivity of 0.3 W/(m K) or more. In paragraph 4,
A battery pack wherein the thickness of the above adhesive material is 0.5 mm or more and 3 mm or less. In the first paragraph,
A battery pack in which the floor frame is connected to the air gap and includes at least one gas discharge hole for discharging gas in the air gap, and a gas path through which gas introduced through each gas discharge hole flows. In Article 7,
A battery pack wherein the bottom frame includes a first plate having the gas discharge hole formed therein, and a second plate forming the gas path between the first plate and the second plate. In Article 8,
A battery pack wherein the first plate has a greater thickness than the second plate. In Article 7,
A battery pack wherein the above floor frame includes a venting unit that discharges gas flowing through the gas passage to the outside of the pack housing. In the first paragraph,
A battery pack in which a filling material is arranged between the upper surface of the cell stack and the cover, filling at least a portion of the space between the upper surface of the cell stack and the cover. In Article 11,
The above charging member is a battery pack that fixes the cell stack and the cover. In the first paragraph,
A battery pack wherein the cooling plate includes a porous structure or a flow space through which a cooling medium flows. In the first paragraph,
A battery pack in which a support member is arranged on the bottom frame to support a portion of the lowermost side of at least one battery cell. In the first paragraph,
The above battery cell includes a cell body portion in which an electrode assembly is accommodated, a sealing portion arranged on at least a portion of the periphery of the cell body portion to seal the electrode assembly, and an electrode lead electrically connected to the electrode assembly.
The above sealing portion includes a first sealing portion formed in an area where the electrode lead is exposed to the outside, and a second sealing portion formed in an area where the electrode lead is not placed.
A battery pack in which the above cell stack is arranged such that the second sealing portion faces the bottom frame. In Article 15,
A battery pack wherein the air gap is formed between the lower surface of the cell body and the bottom frame, or between the second sealing portion and the bottom frame. In the first paragraph,
The above battery cell includes a casing that accommodates an electrode assembly and a gas discharge valve arranged on a lower surface of the casing.
A battery pack in which the air gap is formed between the lower surface of the casing and the bottom frame. In the first paragraph,
The above-mentioned accommodation space is divided into multiple partitions by bulkheads.
A battery pack in which each cell stack is placed in its own partition space.
A pack housing comprising a bottom frame, a side frame and a cover to form an accommodation space inside, wherein the cover and the bottom frame are spaced apart in a first direction; and
At least one cell stack accommodated in the above-described accommodation space, wherein a plurality of cooling plates and a plurality of battery cells are stacked in a second direction perpendicular to the first direction;
Including,
A battery pack wherein each cell stack is configured such that at least one battery cell is arranged in the pack housing spaced apart from the bottom frame in the first direction.

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