CN1214480C - Lithium ion secondary battery and its manufacture - Google Patents

Abstract

The present invention aims to provide a secondary lithium ion battery which ensures ionic conductance and adhesion strength and has the advantages of small size, compactness, no use of a firm external can, thinness, arbitrary shape, high charge and discharge efficiency, stabilization and practicality, and a manufacture method thereof. The battery of the present invention has a multilayer lamination body (12), and the multilayer lamination body (12) is formed by that an adhesive resin layer (8) which is composed of an electrolyte phase (9), a macromolecular gel phase (10)containing an electrolyte and a macromolecular solid phase (11) joints a positive electrode (1) and a negative electrode (3) to a separator (3) containing a Li-iron non-aqueous electrolyte.

Description

Lithium ion secondary battery and manufacturing method thereof

technical field

The present invention relates to a lithium ion secondary battery in which a positive electrode and a negative electrode face each other by sandwiching a separator holding an electrolyte, and particularly relates to a thin lithium ion secondary battery having excellent charge and discharge characteristics.

Background technique

There is a strong demand for miniaturization and weight reduction of portable electronic devices, and the realization of these requires higher voltage, higher energy density, higher load resistance, and safety assurance. Various battery developments and improvements are currently underway. Lithium-ion batteries are secondary batteries that can achieve high voltage, high energy density, and high load resistance among existing batteries, and are the most promising batteries that can meet the above requirements.

A lithium ion secondary battery has, as its main components, a positive electrode, a negative electrode, and an ion conductive layer sandwiched between the two electrodes. In the lithium-ion secondary battery that has been practically used now, the positive electrode is made by mixing active material powder such as lithium-cobalt composite oxide with electronic conductor powder and binder resin, and then coating it on the aluminum collector. For the plate-shaped positive electrode and negative electrode, a carbon-based active material powder is mixed with a binder resin and coated on a copper current collector to form a plate-shaped negative electrode. In addition, as the ion conductive layer, a porous film such as polyethylene or polypropylene is impregnated with a non-aqueous solvent containing lithium ions.

Lithium-ion secondary batteries that are currently in practical use use a strong outer can made of stainless steel or the like, and pressurize to maintain the electrical connection between the positive electrode-ion conductive layer-negative electrode. As a method of bringing the positive electrode and the negative electrode into close contact, a method of using a strong case made of metal or the like is employed. However, the above-mentioned exterior can increases the weight of the lithium ion secondary battery, making it difficult to reduce the size and weight of the lithium ion secondary battery, and also makes it difficult to form an arbitrary shape due to the rigidity of the exterior can.

In order to reduce the size and weight of lithium-ion secondary batteries and to achieve arbitrary shapes, it is necessary to join the positive electrode and the ion-conducting layer, and the negative electrode and the ion-conducting layer, and maintain this state without applying pressure from the outside.

Regarding the method in this regard, in U.S. Patent No. 5,437,692, it is disclosed that a polymer with lithium ion conductivity is used as an ion-conducting layer, and a bonding layer containing a lithium compound is used to bond the positive electrode and the negative electrode to the above-mentioned conductive layer. method. In addition, WO95/15589 discloses a method of forming a plastic ion-conducting layer first, and then using the plastic ion-conducting layer to join positive and negative electrodes.

However, if the method disclosed in the above-mentioned U.S. Patent No. 5,437,692 is used, sufficient strength cannot be obtained, and the battery cannot be made thin enough. In addition, the ionic conduction resistance between the ion-conducting layer and the positive electrode and the negative electrode is also high, and the charge-discharge Battery characteristics, such as battery characteristics, also have practical problems. In addition, according to the above-mentioned WO95/15589, since the plastic ion-conducting layer is bonded, there is a problem that sufficient strength cannot be obtained, and the battery cannot be made thin enough.

Contents of the invention

The present invention is made in order to solve the above-mentioned problems, and the object is to provide a battery structure in which the positive electrode and the negative electrode are adhered to the ion-conducting layer (hereinafter referred to as a separator) with an adhesive resin, and the battery structure can be ensured. Sufficient bonding strength between the electrodes and the separator can be ensured, and the ion conduction resistance between the positive electrode and the negative electrode and the separator can be ensured to be similar to that of a battery using a conventional external can.

The present invention provides a lithium ion secondary battery, which is characterized in that: it has a multi-layer laminate, and the laminate is composed of a mixed phase composed of an electrolyte solution phase, a polymer gel phase containing the electrolyte solution, and a polymer solid phase. The adhesive resin layer connects the positive electrode and the negative electrode to the separator holding the electrolyte, wherein the polymer gel phase is insoluble in the electrolyte and does not react in the lithium-ion secondary battery. In the case of the gel phase;

The polymer solid phase does not dissolve in the electrolyte, does not react in the lithium ion secondary battery, and becomes a solid phase in the presence of the electrolyte.

In the above-mentioned lithium ion secondary battery of the present invention, the positive electrode and the negative electrode are arranged alternately between a plurality of cut separators.

In the lithium ion secondary battery of the present invention, the positive electrode and the negative electrode are arranged alternately between wound separators.

In the above-mentioned lithium ion secondary battery of the present invention, the positive electrode and the negative electrode are arranged alternately between the folded separators.

In the above-mentioned lithium ion secondary battery of the present invention, the polymer gel phase and the polymer solid phase contain the same or different polymer materials, and the average molecular weight of the polymer material contained in the polymer gel phase and the polymer material The polymer materials contained in the solid phase have different average molecular weights.

In the above-mentioned lithium ion secondary battery of the present invention, the polymer gel phase and the polymer solid phase may contain polyvinylidene fluoride, and the average molecular weight of the polyvinylidene fluoride contained in the polymer gel phase and the above-mentioned polymer gel phase may be The polyvinylidene fluoride contained in the solid phase has different average molecular weights.

In the above-mentioned lithium ion secondary battery of the present invention, it is also possible that the polymer gel phase and the polymer solid phase contain polyvinyl alcohol, and the average molecular weight of the polyvinyl alcohol contained in the above-mentioned polymer gel phase and the above-mentioned polymer solid phase The average molecular weight of the polyvinyl alcohol contained differs.

According to the lithium ion secondary battery of the present invention, the average molecular weight of the polymer material contained in the polymer gel phase is smaller than the average molecular weight of the polymer material contained in the polymer solid phase.

According to the lithium ion secondary battery of the present invention, the polymer gel phase and the polymer solid phase contain the same kind of polymer material.

According to the lithium ion secondary battery of the present invention, the polymer gel phase and the polymer solid phase contain polyvinylidene fluoride, and the average molecular weight of the polyvinylidene fluoride contained in the polymer gel phase is smaller than that contained in the polymer solid phase. The average molecular weight of polyvinylidene fluoride.

According to the lithium-ion secondary battery of the present invention, it is possible to ensure that the positive electrode and the negative electrode are connected by using a bonding resin layer composed of a mixed phase between a polymer gel phase containing an electrolyte, a polymer solid phase, and a polymer liquid phase. Bonding strength and ionic conductivity with the separator, and can ensure bonding strength and high ionic conductivity. Therefore, even if a laminated battery having a laminated body of multiple layers is used, a practical lithium ion secondary battery having a compact size, high performance, and a large battery capacity can be obtained without the need for a strong outer can.

The present invention provides a method for manufacturing a lithium ion secondary battery having a multilayer laminate in which a positive electrode and a negative electrode are bonded to a separator holding an electrolytic solution, which is characterized by comprising the following steps : A separator in which a plurality of polymer materials with different average molecular weights are dissolved in a solvent is coated on the opposite side of the separator to form a separator in which the positive electrode and the negative electrode are alternately bonded to each other through the adhesive resin layer. After that, the battery body is immersed in the electrolyte solution, so that the above-mentioned adhesive resin layer becomes a mixed phase of the polymer gel phase containing the electrolyte solution, the polymer solid phase and the electrolyte solution layer. As mentioned above, by impregnating the electrolyte solution in the adhesive resin layer and making it a mixed-phase method of the polymer gel phase containing the electrolyte solution, the polymer solid phase and the electrolyte solution layer, it is possible to ensure that the positive electrode and the The bonding strength and ionic conductivity between the negative electrode and the separator, and by superimposing a single laminate, it is possible to manufacture a small and compact one that does not require a strong outer can, thin, arbitrary shape, high charge and discharge efficiency, and stable And practical lithium-ion secondary batteries.

Description of drawings

1, FIG. 2 and FIG. 3 are schematic sectional views of main parts showing an embodiment of the lithium ion secondary battery of the present invention, which has a structure of a single laminated body having multiple layers. FIG. 4 is a schematic cross-sectional view illustrating the structure of the single laminate in FIGS. 1 , 2 and 3 . Fig. 5 shows an example of an overcharge (200% charge) test result. Fig. 6 shows an example of the results of the overdischarge test. In FIGS. 5 and 6 , (A) shows charging characteristics, and (B) shows discharging characteristics.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

An embodiment of the lithium ion secondary battery of the present invention is shown in the main part sectional pattern diagram of Fig. 1, Fig. 2 and Fig. 3, and Fig. 4 (a) and (b) are to illustrate Fig. 1, Fig. 2 and Fig. 3 4 (b) is a partial enlarged view of the adhesive resin layer of FIG. 4 (a).

In Fig. 1 to Fig. 4, laminated body 12 is made up of following parts: on the positive electrode current collector 2 that is made of metal such as aluminum foil, the positive electrode 1 that is made of positive electrode active material layer 3 is molded, and is made of copper etc. The negative electrode 4 made of the negative electrode active material layer 6 is molded on the negative electrode current collector 5 made of metal, and the separator 7 of the electrolyte solution containing lithium ions is kept, and the separator 7 is connected to the positive electrode 1 and the separator 7 is connected to the negative electrode 4. The adhesive resin layer 8 for bonding.

Fig. 1 is a structure in which positive electrodes 1 and negative electrodes 4 are alternately arranged between a plurality of cut-off separators 7, and Fig. 2 and Fig. 3 are a structure in which positive electrodes are alternately arranged between wound separators 7 1 and negative electrode 4 configurations. Although not shown in the drawings, a structure in which positive electrodes 1 and negative electrodes 4 are alternately arranged between folded separators 7 is also possible.

As shown in Figure 4 (b), the adhesive resin layer 8 is made of a polymer solid phase 11, a polymer gel phase 10 containing an electrolytic solution, and is held in a polymer solid phase 11 or a polymer gel phase 10. The electrolytic solution phase 9 in the fine pores is composed of mixed phases.

Using the polymer solid phase 11 of the adhesive resin layer 8, one side of the facing surface of the separator 7 is firmly bonded to the positive electrode 1, and the other facing surface of the separator 7 is firmly bonded to the negative electrode 4. The electrolytic solution phase 9 can obtain high ionic conductivity, and the polymer gel phase 10 is used to control the reduction of the bonding (bonding) strength caused by the phase melting between the polymer solid phase 11 and the electrolytic solution phase 9, while maintaining High ionic conductivity makes the ionic conductivity between the separator 7 and the positive electrode 1 and the negative electrode 4 extremely high.

In order to form the polymer solid phase 11 and the polymer gel phase 10 on the adhesive resin 8, an adhesive obtained by dissolving polymer materials having different average molecular weights in a solvent is used.

That is, as a binder, a polymer material (low-molecular-weight polymer) that will be swelled by the electrolyte solution and a polymer material (high-molecular-weight polymer) that will not be swelled (high-molecular-weight polymer) are uniformly dissolved in a suitable solvent. Adhesive, after the positive electrode 1 and the negative electrode 4 are bonded to the separator 7 with the adhesive and the adhesive is fully dried, the electrolyte is immersed in the adhesive at a specified temperature to form a The adhesive resin phase 8 is composed of a polymer solid phase 11 containing a high molecular weight polymer, a gel phase 10 containing a low molecular weight polymer, and an electrolyte solution phase 9 .

The aforementioned polymer materials having different average molecular weights may be of the same type or of different types. In the case of different types of polymer materials, although the gel phase and the solid phase can be formed even if the average molecular weight is the same by this combination, in this case, ideally, the average molecular weights are different. The reason is that even if different types of polymer materials have similar molecular weights, the gel state will change over time due to the formation of the so-called 'topological complexation (entanglement)' in the solution system, and the battery characteristics will change. Changes are also possible.

As a polymer material for forming the adhesive resin phase 8, at least it must not dissolve in the electrolytic solution, and must not react in the lithium ion secondary battery. Furthermore, it is necessary to become a gel phase and a solid phase in the presence of an electrolytic solution, and any polymer material can be used as long as it satisfies this condition. In addition, even if it is the same type of polymer material, it will depend on the type of solvent of the electrolytic solution or the temperature history when manufacturing the lithium-ion secondary battery, and two forms of gel phase or solid phase can be obtained, but as in the present invention Polymer materials that can become a gel phase under certain conditions, for example, acrylate polymers such as poly(methyl methacrylate), poly(acrylonitrile), low molecular weight polyvinylidene fluoride, and their combinations with other Copolymers between high molecular compounds, low molecular weight polyvinyl alcohol and their copolymers with other high molecular compounds, or mixtures with low molecular weight polyvinyl alcohol as the main component, etc. In addition, as a polymer material that can become a solid phase under the conditions of the present invention, high molecular weight polyvinylidene fluoride, poly(tetrafluoroethylene) or their copolymers with other polymer compounds, high molecular weight Polyvinyl alcohol and their copolymers with other polymer compounds, or mixtures with high molecular weight polyvinyl alcohol as the main component, etc.

As the positive electrode active material used in the positive electrode active material layer 3, for example, composite oxides between lithium and transition metals such as cobalt, manganese, nickel, lithium-containing chalcogenides, or their composite compounds, in addition Composite compounds having various additive elements in the above-mentioned composite oxides, lithium-containing chalcogen compounds, or composite compounds thereof can be used. In addition, as the negative electrode active material used in the negative electrode active material layer 6 , carbon materials and the like can be used as long as lithium ions can be taken in and out.

As the positive electrode current collector 2 and the negative electrode current collector 5, any metal that is stable in the lithium-ion secondary battery can be used. It is desirable to use aluminum as the positive electrode current collector 2, and it is desirable to use aluminum as the negative electrode current collector. copper. The shape of the current collectors 2 and 5, foil, mesh, metal mesh, etc., can be used, but in order to obtain the bonding strength with the active material and to facilitate the impregnation of the electrolyte solution after bonding, a mesh A shape with a large surface area such as a metal mesh or a metal mesh is ideal.

As a material used for the separator, any membrane can be used as long as it is impregnated with an electrolyte solution such as an insulating porous membrane, net, non-woven fabric, etc. and can obtain sufficient strength. It is preferable to use a porous membrane made of polypropylene, polyethylene, or the like from the viewpoint of ensuring safety. In the case of using a fluorine-based resin, it may be necessary to perform surface treatment with plasma or the like in order to secure adhesiveness.

As the electrolytic solution, ether solvents such as dimethoxyethane, diethoxyethane, dimethyl ether, and diethyl ether, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, etc., can be used. LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiC(CF ₃ SO ₂ ) ₃ , LiN(C ₂ F ₅ SO ₂ ) ₂ and other electrolyte electrolytes.

Hereinafter, examples of the lithium ion secondary battery of the present invention will be described in detail, but it goes without saying that the present invention is not limited to these examples.

Example 1

(production of positive electrode)

The positive active material paste prepared by dispersing 87 parts by weight of LiCoO ₂ , 8 parts by weight of graphite powder, and 5 parts by weight of polyvinylidene fluoride into N-methylpyrrolidone (hereinafter referred to as NMP) was used with a scraper blade ( Doctor Blade) coating thickness of about 300 microns to form a positive electrode active material film. An aluminum mesh with a thickness of 30 micrometers to be the positive electrode current collector 2 was placed on the top thereof, and a positive electrode active material paste adjusted to a thickness of 300 micrometers was applied again on the top thereof by the doctor blade method. After being left in a dryer at 60° C. for 60 minutes, it became semi-dry to form a laminate of the positive electrode current collector 2 and the positive electrode active material. The positive electrode 1 in which the positive electrode active material layer 3 was formed was produced by rolling the laminated body to a thickness of 400 μm. After immersing the positive electrode 1 in the electrolytic solution, the peel strength between the positive electrode active material layer and the positive electrode current collector was measured, and the value of the strength was 20 to 25 gf/cm.

(production of negative electrode)

Disperse 90 parts by weight of mesophase carbon particles (Mesophase Microbead Carbon) (product name MCMB, produced by Osaka Gas), and 5 parts by weight of polyvinylidene fluoride into NMP to prepare the negative electrode active material paste. It was applied to a thickness of 300 micrometers to form a negative electrode active material thin film. A copper mesh with a thickness of 20 micrometers to be a negative electrode current collector was placed on the upper part, and a negative electrode active material paste adjusted to a thickness of 300 micrometers was coated on the upper part again by the doctor blade method. After being left in a dryer at 60° C. for 60 minutes, it became semi-dry to form a laminate of the negative electrode current collector 5 and the negative electrode active material. The negative electrode 4 in which the negative electrode active material layer 6 was formed was produced by rolling the laminated body to a thickness of 400 μm.

After the negative electrode 4 was soaked in the electrolytic solution, the peel strength between the negative electrode active material layer 6 and the negative electrode current collector 5 was measured, and the value of the strength was 5 to 10 gf/cm.

(adhesive adjustment)

With the average molecular weight (Mw) being 3.0 parts by weight of poly(methyl methacrylate) (produced by Aldric company) of 350000, the average molecular weight (Ww) is 2.0 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and 95 parts by weight The composition ratio of NMP of 2 parts is mixed, and it is fully stirred to make it into a uniform solution to make a viscous adhesive.

(production of batteries)

The adjusted adhesive was applied to one surface of each of two porous polypropylene sheets (Selga-do #2400 manufactured by Hekistoserani-s) used as the separator 7 . Then, before the adhesive was dried, the above-mentioned positive electrode 1 that had been produced was sandwiched between the separators 7 so as to be tightly adhered, and dried at 60° C. for 2 hours. By evaporating NMP from the binder, it becomes a porous film having continuous pores.

Punch the spacer 7 that sandwiches the positive electrode 1 (or negative electrode) into a specified size, and apply the adjusted adhesive to one side of the stamped spacer 7, and paste the spacer 7 that has been stamped into a specified size. Negative electrode 4 (or positive electrode) of the size, and then apply the adjusted adhesive to one side of another separator 7 that has been punched into a specified size, and apply the other separator 7 on the coated surface Paste it on the surface of the previously pasted negative electrode 4 (or positive electrode). This process was repeated to form a battery body having a multilayered electrode laminate, which was dried under pressure to produce a battery body with a flat laminated structure as shown in FIG. 1 .

Connect the current collectors connected to the respective ends of the flat-plate laminated structure battery body by spot welding the positive electrodes and the negative electrodes, so that the above-mentioned plate-shaped laminated structure battery bodies are electrically connected in parallel. connect.

At room temperature, the battery body of the flat-pack laminated structure was soaked into a mixed solvent of ethylene carbonate and dimethyl carbonate (the molar ratio was 1:1) with LiPF ₆ dissolved in a concentration of 1.0 mol/dm ³ . Inject the electrolyte into the solution.

Next, the peel strengths of the positive electrode active material layer 3 and the separator 7, the negative electrode active material layer 6 and the separator 7 were measured (using the measurement method specified by JIS K6854), and the strengths were 25 to 30 gf/cm, 15 to 20 gf/cm, respectively. cm.

The lithium-ion secondary battery is completed by encapsulating the flat laminated battery body after the electrolyte is injected with an aluminum laminated film, hot-melt bonding it, and sealing it.

Example 2

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and a battery body having a flat laminated structure as shown in FIG. 1 was fabricated.

(adhesive adjustment)

With the average molecular weight (Mw) being 3.0 parts by weight of poly(acrylonitrile) (produced by Aldric company) of 86200, the average molecular weight (Ww) is 2.0 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and the NMP of 95 parts by weight The composition ratio is mixed, and it is fully stirred to make it into a uniform solution to make a viscous adhesive.

Example 3

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and a battery body having a flat laminated structure as shown in FIG. 1 was fabricated.

(adhesive adjustment)

With average molecular weight (Mw) being 2.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 180000, average molecular weight (Ww) is 2.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and the NMP of 95 parts by weight Mix it according to the composition ratio, stir it sufficiently to make it into a uniform solution, and make a viscous adhesive.

Example 4

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and a battery body having a flat laminated structure as shown in FIG. 1 was manufactured.

(adhesive adjustment)

With average molecular weight (Mw) being 3.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 180000, average molecular weight (Ww) is 3.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and the NMP of 93 parts by weight Mix it according to the composition ratio, stir it sufficiently to make it into a uniform solution, and make a viscous adhesive.

Example 5

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and a battery body having a flat laminated structure as shown in FIG. 1 was fabricated.

(adhesive adjustment)

With average molecular weight (Mw) being 5.0 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 180000, average molecular weight (Ww) is 5.0 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and 90 parts by weight of NMP Mix it according to the composition ratio, stir it sufficiently to make it into a uniform solution, and make a viscous adhesive.

Example 6

The adjustment of the adhesive and the electrolytic solution in the production of the battery in the above-mentioned Example 1 were changed as follows, and the rest were processed in the same manner as in Example 1 to produce a battery body having a flat laminated structure as shown in FIG. 1 .

(adhesive adjustment)

With average molecular weight (Mw) being 2.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 180000, average molecular weight (Ww) is 2.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and the NMP of 95 parts by weight Mix it according to the composition ratio, stir it sufficiently to make it into a uniform solution, and make a viscous adhesive.

(electrolyte)

Dissolve LiPF ₆ (Tokyo Chemical Co. ^, Ltd. Production).

Example 7

Only the adjustment of the adhesive in the above-mentioned Example 6 was changed as follows, and a battery body having a flat laminated structure as shown in FIG. 1 was manufactured.

(adhesive adjustment)

With average molecular weight (Mw) being 3.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 180000, average molecular weight (Ww) is 3.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and the NMP of 93 parts by weight Mix it according to the composition ratio, stir it sufficiently to make it into a uniform solution, and make a viscous adhesive.

Example 8

Only the adjustment of the adhesive in the above-mentioned Example 6 was changed as follows, and a battery body having a flat laminated structure as shown in FIG. 1 was manufactured.

(adhesive adjustment)

With average molecular weight (Mw) being 5.0 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 180000, average molecular weight (Ww) is 5.0 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and 90 parts by weight of NMP Mix it according to the composition ratio, stir it sufficiently to make it into a uniform solution, and make a viscous adhesive.

Example 9

The adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, the injection temperature of the electrolyte solution in the manufacture of the battery was changed to 70° C., and the rest were processed in the same way as in Example 1 to produce a flat laminate as shown in FIG. 1 . The battery body is constructed in layers.

(adhesive adjustment)

With average molecular weight (Mw) being 2.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 180000, average molecular weight (Ww) is 2.5 parts by weight of polyvinylidene fluoride (produced by Aldric company) of 534000, and the NMP of 95 parts by weight Mix it according to the composition ratio, stir it sufficiently to make it into a uniform solution, and make a viscous adhesive.

Example 10

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and the rest were processed in the same manner as in Example 1 to produce a battery body having a flat laminated structure as shown in FIG. 1 .

(adhesive adjustment)

With the average molecular weight (Mw) being 2.5 parts by weight of polyvinyl alcohol (produced by ナカライ chemical company) of 22000, the composition of 2.5 parts by weight of polyvinyl alcohol (produced by Aldric company) with an average molecular weight (Ww) of 186000, and 95 parts by weight of NMP Ratio to make it mixed, fully stirred to make it into a uniform solution, made of viscous adhesive.

Example 11

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and the rest were processed in the same manner as in Example 1 to produce a battery body having a flat laminated structure as shown in FIG. 1 .

(adhesive adjustment)

With the average molecular weight (Mw) being 1.5 parts by weight of polyvinylidene fluoride of 180000, the average molecular weight (Mw) being 1.5 parts by weight of polyvinyl alcohol of 22000, the average molecular weight (Ww) being 2.5 parts by weight of polyvinylidene fluoride of 534000, and 94.5 parts by weight The composition ratio of NMP of 2 parts is mixed, and it is fully stirred to make it into a uniform solution to make a viscous adhesive.

Example 12

Using the positive electrode and negative electrode shown in Example 1 above, and the adhesive shown in Examples 1 to 11 above, a lithium ion secondary battery having a battery body with a flat laminated structure as shown in FIG. 2 was produced.

(production of batteries)

Apply an adhesive to each single side of each of two strip-shaped separators 7 made of polypropylene sheet (produced by Hekisto, trade name セヘキスト, trade name セヘキスト, trade name セヘキスト) ) was sandwiched between the coated surfaces and pasted closely, and then placed in a dryer at 60° C. for 2 hours to evaporate NMP.

On one side of the strip-shaped separator 7 that sandwiches the negative electrode 4 (or positive electrode) and is bonded in the middle, an adhesive is applied, and one end of the separator 7 is bent by a predetermined amount, and the positive electrode 1 (or positive electrode) Negative electrode) sandwiched in the middle of the crease and overlapped to pass into the laminator. Next, apply an adhesive to the other side of the strip-shaped separator, and paste another positive electrode 1 (or negative electrode) at a position opposite to the positive electrode 1 (or negative electrode) sandwiched at the crease. , the separator 7 is rolled into an oblong shape, and the process of winding the separator 7 while pasting another positive electrode 1 (or negative electrode) is repeated to form a battery body with a multilayer battery laminate, and the battery body is added to the battery body. The crimping was carried out and dried to produce a flat roll-type battery body with a laminated structure as shown in FIG. 2 .

The battery bodies of the flat-shaped laminated structure were electrically connected in parallel by spot-welding the collector tabs respectively connected to the respective ends of the flat-shaped laminated structure battery bodies.

After immersing the battery body with a flat laminated structure into an electrolyte solution in which LiPF ₆ is dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate (molar ratio 1:1) at a concentration of 1.0 mol/dm ³ After being filled, it was sealed in a bag made of aluminum laminated film by hot-melt bonding to make a battery.

In this embodiment, although the example of winding the separator 7 is shown, it is also possible to fold the separator in which the strip-shaped negative electrode 4 (or positive electrode 1) has been joined between the separators 7, and repeat it while folding. The process of folding the separator while affixing the positive electrode 1 (or negative electrode).

Example 13

Using the positive electrode and negative electrode shown in Example 1 above, and the adhesives shown in Examples 1 to 11 above, a lithium ion secondary battery having a battery body with a flat laminated structure as shown in FIG. 3 was produced. The difference from the above-mentioned Example 2 is that the separator, the positive electrode, and the negative electrode are wound at the same time.

(production of batteries)

The strip-shaped negative electrode 4 (or positive electrode) is disposed between two strip-shaped separators 7 made of polypropylene sheet (produced by ヘキスト, trade name セヘキスト-ド#2400), and the strip-shaped positive electrode 1 (or Negative electrode) is disposed outside one separator 7 so as to protrude by a certain amount. On the surface of the inside of each separator 7 and the outer surface of the configuration positive pole 1 (or negative pole) separator 7, smear adhesive, make positive pole 1 (or negative pole) and 2 pieces of spacer 7 and negative pole 4 (or positive pole) ) are overlapped and passed into the laminator, and then, on the surface of the outer side of the other side of the spacer 7, an adhesive is applied, and the protruding positive electrode 1 (or negative electrode) is bent and pasted on the coated surface The separator 7 stacked so that the folded positive electrode 1 (or negative electrode) is wrapped inside is wound into an elongated shape to form a battery body having a multilayer electrode laminate, and the battery is dried while heating. The body is made into a flat roll-type laminated structure battery body.

The battery bodies of the flat-shaped laminated structure were electrically connected in parallel by spot-welding the collector tabs respectively connected to the respective ends of the flat-shaped laminated structure battery bodies.

After immersing the battery body with a flat laminated structure into an electrolyte solution in which LiPF ₆ is dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate (molar ratio 1:1) at a concentration of 1.0 mol/dm ³ After being filled, it was sealed in a bag made of aluminum laminated film by hot-melt bonding to make a battery.

Comparative example 1

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and a lithium ion secondary battery was produced.

(adhesive adjustment)

Mix with 5.0 parts by weight of poly(methyl methacrylate) (manufactured by ALdrich) with an average molecular weight (Mw) of 350,000, and a composition ratio of 95 parts by weight of NMP, stir sufficiently to become a uniform solution, and make a viscous of adhesives.

Comparative example 2

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and a lithium ion secondary battery was produced.

(adhesive adjustment)

Mix with 5.0 parts by weight of poly(acrylonitrile) (manufactured by ALdrich) with an average molecular weight (Mw) of 86200, and 95 parts by weight of NMP, stir well enough to become a uniform solution, and make a viscous adhesive agent.

Comparative example 3

Only the adjustment of the adhesive in the above-mentioned Example 1 was changed as follows, and a lithium ion secondary battery was produced.

(adhesive adjustment)

Mix 5.0 parts by weight of polyvinylidene fluoride (manufactured by ALdrich) with an average molecular weight (Mw) of 180,000, and 95 parts by weight of NMP, and stir sufficiently to become a uniform solution to form a viscous adhesive .

Comparative example 4

Only the adjustment of the adhesive in Example 1 above was changed as follows, and a lithium ion secondary battery having a battery body with a flat laminated structure as shown in FIG. 1 was fabricated.

(adhesive adjustment)

Mix with 7.0 parts by weight of polyvinylidene fluoride (manufactured by ALdrich) with an average molecular weight (Mw) of 534,000, and 93 parts by weight of NMP, and stir sufficiently to become a uniform solution to form a viscous adhesive .

Comparative example 5

Using the same adhesive as in Examples 6 and 9 above, the electrolyte injection temperature in the battery production of Example 1 was changed to 100°C, and the rest were processed in the same manner as in Example 1 to produce a flat panel as shown in Figure 1. A lithium-ion secondary battery with a battery body with a laminated structure.

The characteristics of the lithium ion secondary batteries obtained in Examples 1 to 11 and Comparative Examples 1 to 5 were evaluated. Table 1 shows the resistance of the unit cells of the various batteries of the above-mentioned Examples 1 to 11 and Comparative Examples 1 to 5 together with the adhesive strength (peel strength) of the positive electrode active material and the separator and the negative electrode active material and the separator. measurement results. Fig. 5 shows the test results of overcharge (200% charge), and Fig. 6 shows the results of overdischarge tests, in which (A) represents the charging characteristics, and (B) represents the discharging characteristics. All of the figures show the lithium ion secondary batteries of Examples 6 to 8 above, but similar results can be obtained also in other Examples.

Table 1 Peel strength (gf/cm) Battery resistance (Ω) Positive / Separator Negative pole/separator Example 1 17 12 twenty four Example 2 15 14 twenty three Example 3 20 13 twenty one Example 4 twenty two 33 25 Example 5 twenty one 52 30 Example 6 25 15 20 Example 7 twenty four 29 twenty two Example 8 28 44 28 Example 9 26 16 20 Example 10 20 12 twenty one Example 11 twenty three 14 27 Comparative example 1 0 (unable to measure) 0 (unable to measure) Can't measure Comparative example 2 0 (unable to measure) 0 (unable to measure) Can't measure Comparative example 3 0 (unable to measure) 0 (unable to measure) Can't measure Comparative example 4 52 61 150 Comparative Example 5 0 (unable to measure) 0 (unable to measure) Can't measure

As can be seen from the results in Table 1 above, in the lithium ion secondary batteries of Comparative Examples 1 to 3, the peel strength was close to 0, and the value could not be measured. Since any of the adhesives used in Comparative Examples 1 to 3 is an adhesive composed of an electrolyte solution and a polymer gel phase containing the electrolyte solution due to swelling of the electrolyte solution, it is considered to be ionically conductive. The ratio is high, but the adhesive strength cannot be ensured, and the electrical resistance is high due to peeling between electrodes, making measurement difficult.

In addition, although the lithium ion secondary battery of Comparative Example 4 exhibited a large peel strength value, its cell resistance was high due to its low ion conductivity.

In the lithium ion secondary battery of Comparative Example 5, the peel strength was close to 0 and was an unmeasurable value, and the resistance of the battery was also large and unmeasurable. Although the composition of the adhesive used in Comparative Example 5 is the same as in Examples 6 and 9, since the injection temperature of the electrolyte is as high as 100°C, the polymer that does not swell at low temperatures will also swell. As a result, similar to Comparative Examples 1 to 3, although the ionic conductivity was considered to be high, the adhesive strength could not be ensured.

On the other hand, the lithium ion secondary batteries of Examples 1 to 11 had a battery resistance of 20 to 30Ω, a peel strength of 12 to 52 gf/cm, and both ionic conductivity and adhesive strength were secured. In Examples 1 to 11, it has become a mixed phase of the polymer gel phase containing the electrolyte and the polymer solid phase, and the ionic conductivity is ensured by the polymer gel phase containing the electrolyte, and the polymer solid phase is ensured. Bond strength.

In addition, if the temperature rises abnormally due to some reason during the use of the battery, the polymer solid phase will swell due to the electrolyte, and as a result, the current will be cut off due to the peeling between the electrode and the separator, thereby ensuring From a safety point of view it is ideal.

Furthermore, as shown in Figure 5, the discharge characteristics (curve (B)) after overcharging (curve (A)) show good characteristics, and, as shown in Figure 6, after overdischarging (curve (B)) The charging characteristics of (curve (A)) also showed good characteristics.

Possibility of industrial use

A secondary battery that can be used as a portable electronic device such as a portable personal computer and a handy phone can realize miniaturization, weight reduction, and arbitrary shape while improving the performance of the battery.

Claims (12)

1. lithium rechargeable battery is characterized in that:

Possess multilayer laminate, this laminated body use by the electrolysis liquid phase, contain electrolyte high-molecular gel mutually and the adhesive resin layer that constitutes of the mixed phase of macromolecule solid phase, positive pole and negative pole are joined on the barrier film that maintains electrolyte,

Wherein, described high-molecular gel is not dissolved in electrolyte mutually, does not react in lithium rechargeable battery, becomes gel phase under the situation that electrolyte exists;

Described macromolecule solid phase is not dissolved in electrolyte, does not react in lithium rechargeable battery, becomes solid phase under the situation that electrolyte exists.

2. the described lithium rechargeable battery of claim 1 is characterized in that: described positive pole and negative pole alternatively are configured in and cut off between a plurality of barrier films that come.

3. the described lithium rechargeable battery of claim 1, it is characterized in that: described positive pole and negative pole alternatively are configured between the barrier film that winds up.

4. the described lithium rechargeable battery of claim 1, it is characterized in that: described positive pole and negative pole alternatively are configured between the barrier film of folding up.

5. the described lithium rechargeable battery of claim 1, it is characterized in that: high-molecular gel mutually and the macromolecule solid phase contain the macromolecular material of of the same race or xenogenesis, the mean molecule quantity of the macromolecular material that the mean molecule quantity of the macromolecular material that above-mentioned high-molecular gel is mutually contained and above-mentioned macromolecule solid phase are contained is different.

6. the described lithium rechargeable battery of claim 1, it is characterized in that: high-molecular gel mutually and the macromolecule solid phase contain Kynoar, the mean molecule quantity of the Kynoar that the mean molecule quantity of the Kynoar that above-mentioned high-molecular gel is mutually contained and above-mentioned macromolecule solid phase are contained is different.

7. the described lithium rechargeable battery of claim 1, it is characterized in that: high-molecular gel mutually and the macromolecule solid phase contain polyvinyl alcohol, the mean molecule quantity of the polyvinyl alcohol that the mean molecule quantity of the polyvinyl alcohol that above-mentioned high-molecular gel is mutually contained and above-mentioned macromolecule solid phase are contained is different.

8. the described lithium rechargeable battery of claim 1, it is characterized in that: the mean molecule quantity of the macromolecular material that above-mentioned high-molecular gel is mutually contained is less than the mean molecule quantity of the contained macromolecular material of above-mentioned macromolecule solid phase.

9. the described lithium rechargeable battery of claim 8 is characterized in that: above-mentioned high-molecular gel mutually and above-mentioned macromolecule solid phase comprise the macromolecular material of identical type.

10. the described lithium rechargeable battery of claim 1, it is characterized in that: high-molecular gel phase and macromolecule solid phase contain Kynoar, and the mean molecule quantity of the Kynoar that above-mentioned high-molecular gel is mutually contained is less than the mean molecule quantity of the contained Kynoar of above-mentioned macromolecule solid phase.

11. the manufacture method of a lithium rechargeable battery, described lithium rechargeable battery has the laminated body that makes positive pole and negative pole join the multilayer on the barrier film that maintains electrolyte to, it is characterized in that comprising the following steps: that coating is dissolved into the bonding agent that constitutes in the solvent by the different multiple macromolecular material of mean molecule quantity on the relative face of barrier film, having formed by the adhesive resin layer makes positive pole and negative pole alternatively join cell body between the barrier film of multilayer to, this cell body be impregnated in the electrolyte, above-mentioned adhesive resin layer is become to containing the high-molecular gel phase of electrolyte, the mixed phase of macromolecule solid phase and electrolyte layer.

12. the manufacture method of the described lithium rechargeable battery of claim 11, it is characterized in that: described dipping operation comprises the step of a heating battery body, so that in described adhesive resin layer, make macromolecular material form the high-molecular gel phase, and make macromolecular material form the macromolecule solid phase with big mean molecule quantity with less mean molecule quantity.

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