CN112289981B - A kind of bipolar electrode and method of making battery - Google Patents

Abstract

The invention discloses a bipolar electrode and a method for manufacturing a battery. A slurry composed of a positive electrode active material is coated on one side of a bipolar current collector, and a slurry composed of a negative electrode active material is coated on an auxiliary current collector. On one side of the bipolar current collector, after drying and rolling separately, a conductive adhesive is coated on the other side of the bipolar current collector, and the auxiliary current collector is combined with the conductive adhesive to form a bipolar electrode. In this method of making bipolar electrodes, the positive and negative active materials are rolled separately, and the rolled positive and negative active materials are bonded together by a conductive adhesive, which avoids the waste of overpressure and volumetric energy density, and also The continuity of electrode fabrication can be achieved.

Description

A kind of bipolar electrode and method of making battery

technical field

The invention relates to the field of lithium batteries, in particular to a bipolar electrode and a method for manufacturing the battery.

Background technique

The same type of active material is coated on both sides of the current collector, and the slurry mixing and compaction of the same active material have similar requirements and properties, so using the same solvent in the coating process, the deformation force and solvent influence during the evaporation process can be Acceptable; the consistency of the compaction density and the requirements of the compaction and the material itself during the rolling process also minimizes the impact on the deformation of the pole piece, but in the bipolar electrode, the upper and lower sides are different types of active materials, The types of solvents used in the slurry coating process are different, and it is easy to interact with each other during coating and baking. Especially during rolling, due to the inconsistent rolling coefficients, rolling on the side with the larger rolling coefficient is likely to cause overpressure. , Rolling on the side with the smaller rolling coefficient is likely to cause waste of volumetric energy density.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for manufacturing a bipolar electrode and a battery, which avoids waste of overvoltage and volumetric energy density, and can also realize the continuity of electrode manufacturing.

The technical scheme of the present invention is:

A method for making bipolar electrodes, which specifically includes the following steps:

(1), the slurry that the positive electrode active material is formed is coated on one side of the bipolar current collector, and is dried and rolled to form;

(2), coating the slurry composed of the negative electrode active material on one side of the auxiliary current collector, and drying and roll forming; the auxiliary current collector has a porous structure, and the slurry composed of the negative electrode active material Protruding into the hole of the auxiliary current collector;

(3) Coating a conductive adhesive layer on the other side of the bipolar current collector, and bonding the other side of the auxiliary current collector with the conductive adhesive layer to form a bipolar electrode.

The bipolar current collector is selected from a single bipolar current collector composed of a single metal substance, a composite bipolar current collector composed of different metal substances or different metals and non-metallic substances.

The single bipolar current collector is made of metal Al or stainless steel, the composite bipolar current collector composed of different metal substances is composed of aluminum-copper or aluminum-nickel metal, and the different metals and non-metals are The composite bipolar current collector composed of substances is composed of metal aluminum copper and conductive resin.

When the bipolar current collector is a single bipolar current collector, the slurry composed of the positive electrode active material is coated on either side of the bipolar current collector; the bipolar current collector is a composite bipolar current collector When using a bipolar current collector, the slurry composed of the positive electrode active material is coated on one side of the bipolar current collector with high pressure resistance.

The auxiliary current collector is composed of non-conductive material or conductive metal mesh, and the non-conductive material is selected from polypropylene PP, polyethylene PE, polyethylene terephthalate PET or polyimide PI.

The rolling compaction density after the slurry composed of the positive active material is coated on the bipolar current collector is greater than the rolling compaction density after the slurry composed of the negative active material is coated on the auxiliary current collector.

The area of the side of the auxiliary current collector is smaller than the area of the side of the bipolar current collector, and the coating area of the slurry composed of the positive active material and the slurry composed of the negative active material is smaller than the area of the side of the auxiliary current collector; the described The coating area of the conductive adhesive layer is smaller than the area of the side of the bipolar current collector and larger than the area of the side of the auxiliary current collector.

The edge of the auxiliary current collector and the other side of the slurry formed by the bipolar current collector not coated with the positive active material are in contact with each other through welding.

A method for making a battery from bipolar electrodes, wherein a plurality of bipolar electrodes and a plurality of separators are superimposed at intervals to form a winding core, the stacking directions of the plurality of bipolar electrodes are the same, and the plurality of bipolar electrodes are stacked together. The current collector is sealed and connected with the co-directional ends of a plurality of separators to form a sealing layer, and then the winding core is placed in the battery casing, and the battery is made after liquid injection, chemical formation, secondary sealing and volume separation.

The bottom surface and the top surface of the winding core are respectively the two sides of the bipolar current collector, that is, the bipolar electrodes on the top layer and the bottom layer of the winding core are the bipolar collectors only coated with the slurry composed of the positive active material. Fluid A, the bonding composite structure B of the bipolar current collector coated only with the conductive adhesive layer and the auxiliary current collector coated with the slurry composed of the negative electrode active material, and the bipolar current collector A is not coated with One side of the slurry composed of the positive active material and one side of the bipolar current collector without the conductive adhesive layer in the bonding composite structure B are the bottom surface and the top surface of the winding core, and the bottom surface and the top surface of the winding core are respectively. They are respectively connected with the conductive segments partially protruding out of the battery case.

Advantages of the present invention:

In the present invention, the slurry composed of the positive active material is coated on one side of the bipolar current collector, and the slurry composed of the negative active material is coated on one side of the auxiliary current collector. The other side of the polar current collector is coated with a conductive adhesive, and the auxiliary current collector and the conductive adhesive are combined with a bipolar electrode. In this method of making bipolar electrodes, the positive and negative active materials are rolled separately, and the rolled positive and negative active materials are bonded together by a conductive adhesive, which avoids the waste of overpressure and volumetric energy density, and also The continuity of electrode fabrication can be achieved.

Description of drawings

FIG. 1 is a schematic structural diagram of a bipolar electrode in Example 1 of the present invention.

FIG. 2 is a schematic structural diagram of a bipolar battery in Example 1 of the present invention.

3 is a schematic structural diagram of a bipolar battery in Example 2 of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

Referring to Figure 1, a method for manufacturing a bipolar electrode specifically includes the following steps:

(1) The copper-aluminum composite tape is used as the bipolar current collector, the thickness of the positive electrode conductive layer 11 aluminum is 10um, the thickness of the negative electrode conductive layer 12 copper is 4.5um, and the positive electrode is coated on the Al side surface of the bipolar current collector. NCM slurry 13 with an active substance mass percentage content of 96% and a solid content of 73% was dried at 100° C. and then rolled, with a compacted density of 3.4 g/cm ³ ;

(2), using a copper mesh as the auxiliary current collector 14, coating one side of the auxiliary current collector 14 with a graphite slurry 15 with a negative active material mass percentage of 95% and a solid content of 53%, and then drying at 100 ° C After drying, roll pressing, the compacted density is 1.7g/cm ³ ;

(3), coat the conductive adhesive layer 16 on the Cu side surface of the bipolar current collector negative electrode conductive layer 12, and then the bipolar current collector and the auxiliary current collector 14 of the graphite slurry are fed into the roller and dried , so that the other side of the auxiliary current collector 14 is bonded with the conductive adhesive layer 16 to form a bipolar electrode, and the edge of the auxiliary current collector 14 and the Cu side surface of the bipolar current collector are in contact with each other by welding.

The area of the side of the auxiliary current collector 14 is smaller than the area of the side of the bipolar current collector, the coating area of the NCM slurry 13 and the graphite slurry 15 is smaller than the area of the side of the auxiliary current collector; the coating area of the conductive adhesive layer 16 is less than The area of the side of the bipolar current collector is larger than the area of the side of the auxiliary current collector 14 .

Referring to FIG. 2, a plurality of bipolar electrodes and a plurality of separators 21 are stacked to form a winding core, and the stacking directions of the plurality of bipolar electrodes are the same, that is, the bipolar current collectors of each bipolar electrode are located in the corresponding Below the auxiliary current collector 14, the co-directional ends of the plurality of bipolar current collectors (the positive electrode conductive layer 11 and the negative electrode conductive layer 12) and the separator 21 are sealed by an insulating sealing device, and then a sealing layer is formed by hot pressing. 22. After placing the winding core in the battery casing 23, a battery is made after liquid injection, chemical formation, two sealing, and volume separation; wherein, the bottom surface and the top surface of the winding core are the two sides of the bipolar current collector respectively. , that is, the bipolar electrodes on the top and bottom layers of the core are respectively the bipolar current collector A coated with NCM slurry 13, the bipolar current collector only coated with conductive adhesive layer 16, and the bipolar current collector coated with only the conductive adhesive layer 16. Bonded composite structure B of auxiliary current collector of graphite slurry 15, bipolar current collector A is not coated with one side of NCM slurry 13, and bipolar current collector in bonded composite structure B is not coated with conductive adhesive One side of the agent layer 16 is the bottom surface and the top surface of the winding core, respectively, and the bottom surface and the top surface of the winding core are respectively connected with the conductive segments 24 partially extending out of the battery case.

Example 2

Referring to Figure 3, a method for manufacturing a bipolar electrode specifically includes the following steps:

(1) The porous vapor-deposited composite current collector that is conducted by the conductive filling layer is used as a bipolar current collector, wherein 0.5um of conductive carbon black 17 conducts 500nm copper (negative electrode conductive layer 12) and 700nm aluminum (positive electrode conductive layer 11) ), between the negative electrode conductive layer 12 and the positive electrode conductive layer 11 is a porous support layer 18, and the Al side surface of the bipolar current collector is coated with a positive electrode active material mass percentage of 96% and a solid content of 73% NCM slurry 13 , and then dried at 100°C and then rolled, with a compacted density of 3.4g/cm ³ ;

(2), using a copper mesh as the auxiliary current collector 14, coating one side of the auxiliary current collector 14 with a graphite slurry 15 with a negative active material mass percentage of 95% and a solid content of 53%, and then drying at 100 ° C After drying, roll pressing, the compacted density is 1.7g/cm ³ ;

(3), coat the conductive adhesive layer 16 on the Cu side surface of the bipolar current collector negative electrode conductive layer 12, and then the bipolar current collector and the auxiliary current collector 14 of the graphite slurry are fed into the roller and dried , so that the other side of the auxiliary current collector 14 is bonded with the conductive adhesive layer 16 to form a bipolar electrode.

The preparation method of the battery is the same as that of Example 1, the difference is only that after the interval is superimposed, the porous support layers 18 of the plurality of bipolar current collectors and the ends of the diaphragm 21 in the same direction are sealed by an insulating sealing device, and then hot-pressed. The sealing layer 22 is formed in the manner.

Example 3

Referring to Figure 1, a method for manufacturing a bipolar electrode specifically includes the following steps:

(1) The copper-aluminum composite tape is used as the bipolar current collector, the thickness of the positive electrode conductive layer 11 aluminum is 10um, the thickness of the negative electrode conductive layer 12 copper is 4.5um, and the positive electrode is coated on the Al side surface of the bipolar current collector. NCM slurry 13 with an active substance mass percentage content of 96% and a solid content of 73% was dried at 100° C. and then rolled, with a compacted density of 3.4 g/cm ³ ;

(2) Using porous PET as the auxiliary current collector 14, coating one side of the auxiliary current collector 14 with a graphite slurry 15 with a negative active material mass percentage of 95% and a solid content of 53%, and then baked at 100°C After drying, roll pressing, the compacted density is 1.7g/cm ³ ;

(3), coat the conductive adhesive layer 16 on the Cu side surface of the bipolar current collector negative electrode conductive layer 12, and then the bipolar current collector and the auxiliary current collector 14 of the graphite slurry are fed into the roller and dried , so that the other side of the auxiliary current collector 14 is bonded with the conductive adhesive layer 16 to form a bipolar electrode, and the edge of the auxiliary current collector 14 and the Cu side surface of the bipolar current collector are in contact with each other by welding.

The preparation method of the battery is the same as that in Example 1.

Comparative Example 1

A method for making bipolar electrodes, which specifically includes the following steps:

(1) The copper-aluminum composite tape is used as the bipolar current collector, the thickness of copper is 4.5um, the thickness of aluminum is 10um, and the mass percentage of active material coated on the Cu side surface of the bipolar current collector is 95% , Graphite slurry with a solid content of 53%, dried at 100°C and then rolled, with a compacted density of 1.7g/cm ³ ;

(2), using aluminum mesh as the auxiliary current collector, coating one side of the auxiliary current collector with NCM slurry with an active material mass percentage of 96% and a solid content of 73%, drying at 100 ° C and rolling, Compacted density 3.4g/cm ³ ;

(3) Coat the conductive adhesive layer on the Al side surface of the bipolar current collector, and then the bipolar current collector and the auxiliary current collector coated with the NCM slurry are fed into the roller and dried, thereby making the auxiliary current collector One side of the uncoated NCM slurry is bonded with the conductive adhesive layer to form a bipolar electrode.

The preparation method of the battery is the same as that in Example 1.

Comparative Example 2

A method for making bipolar electrodes, which specifically includes the following steps:

(1) The copper-aluminum composite tape is used as the bipolar current collector, the thickness of copper is 4.5um, the thickness of aluminum is 10um, and the mass percentage of active material coated on the Cu side surface of the bipolar current collector is 95% , Graphite slurry with a solid content of 53%, dried at 100°C and then rolled, with a compacted density of 1.7g/cm ³ ;

(2) Coat the Al side surface of the bipolar current collector with NCM slurry with an active material mass percentage of 96% and a solid content of 73%, drying at 100°C and then rolling, with a compacted density of 3.4g /cm ³ , bipolar electrodes were prepared.

The preparation method of the battery is the same as that in Example 1.

The bipolar electrodes prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1.

The experimental result contrast of table 1 embodiment and comparative example

From the comparison of Examples 1-3, it can be seen that increasing the welding step after compounding can effectively increase the peel strength of the active material, while the non-conductive auxiliary current collector has higher peeling due to its large area and perforation rate; In Comparative Example 1, due to the large compaction (compacted density of 3.4 g/cm ³ ), the problem of tape breakage of the aluminum mesh is prone to occur; in Comparative Example 2, it can be seen that direct rolling will cause negative electrode overpressure (compacted density of 3.4 g/cm 3 ). ³ ) Lithium precipitation occurs.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (9)

1. A method for manufacturing a bipolar electrode is characterized in that: the method specifically comprises the following steps:

(1) coating slurry consisting of positive active substances on one side surface of the bipolar current collector, and drying, rolling and molding;

(2) coating slurry consisting of negative active materials on one side surface of the auxiliary current collector, and drying, rolling and molding; the auxiliary current collector is of a porous structure, and slurry formed by the negative active material extends into the holes of the auxiliary current collector;

(3) coating a conductive adhesive layer on the other side surface of the bipolar current collector, and bonding the other side surface of the auxiliary current collector with the conductive adhesive layer to form a bipolar electrode;

the rolling compaction density of the slurry formed by the positive electrode active material after being coated on the bipolar current collector is larger than that of the slurry formed by the negative electrode active material after being coated on the auxiliary current collector.

2. The method of claim 1, wherein: the bipolar current collector is a single bipolar current collector consisting of a single metal substance, or a composite bipolar current collector consisting of different metal substances or different metals and nonmetal substances.

3. The method of claim 2, wherein: the single bipolar current collector is made of metal Al or stainless steel, the composite bipolar current collector made of different metal substances is made of aluminum copper or aluminum nickel metal, and the composite bipolar current collector made of different metals and non-metal substances is made of metal aluminum copper and conductive resin.

4. The method of claim 2, wherein: when the bipolar current collector is a single bipolar current collector, slurry formed by positive active materials is coated on any side surface of the bipolar current collector; when the bipolar current collector is a composite bipolar current collector, slurry formed by the positive active material is coated on one side surface of the bipolar current collector with high pressure resistance.

5. The method of claim 1, wherein: the auxiliary current collector is made of a non-conductive material or a conductive metal mesh, and the non-conductive material is selected from polypropylene (PP), Polyethylene (PE), polyethylene terephthalate (PET) or Polyimide (PI).

6. The method of claim 1, wherein: the area of the side surface of the auxiliary current collector is smaller than that of the side surface of the bipolar current collector, and the coating areas of the slurry formed by the positive electrode active material and the slurry formed by the negative electrode active material are smaller than those of the side surface of the auxiliary current collector; the coating area of the conductive adhesive layer is smaller than the area of the side face of the bipolar current collector and larger than the area of the side face of the auxiliary current collector.

7. The method of claim 1, wherein: the edge of the auxiliary current collector is in reinforced contact with the other side face of the bipolar current collector, which is not coated with the slurry formed by the positive active material, through welding.

8. The method of claim 1, wherein the bipolar electrode is formed as a battery, and the method further comprises: the bipolar electrodes and the partition plates are overlapped at intervals to form a roll core, the overlapping directions of the bipolar electrodes are the same, the bipolar current collectors and the end parts of the partition plates in the same direction are hermetically connected to form a sealing layer, and then the roll core is placed in a battery shell and then subjected to liquid injection, formation, secondary sealing and capacity grading to form the battery.

9. The method for manufacturing a battery according to claim 8, wherein: the bottom surface and the top surface of the winding core are respectively two side surfaces of a bipolar current collector, namely, bipolar electrodes on the bottom layer and the top layer of the winding core are respectively a bipolar current collector A only coated with slurry formed by positive active substances, a bipolar current collector only coated with a conductive adhesive layer and an adhesive composite structure B coated with an auxiliary current collector formed by negative active substances, one side surface of the bipolar current collector A not coated with the slurry formed by the positive active substances and one side surface of the bipolar current collector in the adhesive composite structure B not coated with the conductive adhesive layer are respectively the bottom surface and the top surface of the winding core, and the bottom surface and the top surface of the winding core are respectively connected with conductive terminals partially extending out of a battery shell.

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