CN-121983676-A - Lithium ion battery preparation method and lithium ion battery

Abstract

The application provides a preparation method of a lithium ion battery and the lithium ion battery, and relates to the field of battery preparation, wherein the preparation method of the lithium ion battery comprises the steps of batching, coating, rolling, die cutting, laminating, baking, liquid injection, formation and capacity division, wherein during coating, positive electrode slurry is coated on a first positive electrode plate on one side, positive electrode slurry is coated on a second positive electrode plate on both sides, negative electrode slurry is coated on a negative electrode plate on both sides, during lamination, the first positive electrode plate is coated on the first positive electrode plate, the negative electrode plate and the second positive electrode plate are alternately stacked in the middle, during stacking of the last pair of positive electrode plates, the negative electrode plate is firstly placed, then the first positive electrode plate is coated on the lower side to complete lamination, and in the lamination process, a diaphragm is separated in a Z shape. The application reduces the material cost and improves the energy density of the battery core.

Inventors

• QIN YINGYING
• LIU KEWEI
• XIA XINDE

Assignees

• 广州鹏辉能源科技股份有限公司

Dates

Publication Date

20260505

Application Date

20260209

Claims (10)

1. 1. The preparation method of the lithium ion battery is characterized by comprising the steps of batching, coating, rolling, die cutting, laminating, baking, liquid injection, formation and capacity division, wherein during coating, positive electrode slurry is coated on a first positive electrode plate on one side, positive electrode slurry is coated on a second positive electrode plate on two sides, negative electrode slurry is coated on a negative electrode plate on two sides, during lamination, the first positive electrode plate is coated on the upper side, the negative electrode plate and the second positive electrode plate are alternately stacked in the middle, during stacking of the last pair of the positive electrode plates, the negative electrode plate is firstly placed, then the first positive electrode plate is coated on the lower side to finish lamination, and during lamination, the diaphragm is separated in a Z shape.
2. 2. The method of manufacturing a lithium-ion battery according to claim 1, wherein after die cutting, a predetermined number of the first positive electrode sheets are taken out and placed upside down such that the coated faces of the set of first positive electrode sheets placed upside down are opposite to the coated faces of the other set of first positive electrode sheets.
3. 3. The method of manufacturing a lithium-ion battery according to claim 2, wherein two sets of the first positive electrode sheet, the negative electrode sheet, and the second positive electrode sheet are placed in a lamination machine in groups.
4. 4. The lithium ion battery is characterized in that the lithium ion battery preparation method according to any one of claims 1 to 3 is adopted, an electric core of the lithium ion battery comprises a plurality of pole pieces which are stacked, the pole pieces comprise a first positive pole piece, a negative pole piece and a second positive pole piece, the first positive pole piece is provided with a positive pole coating surface, the negative pole piece is provided with two negative pole coating surfaces, the second positive pole piece is provided with two positive pole coating surfaces, the first pole piece of the electric core is the first positive pole piece, the middle pole piece is formed by alternately stacking the negative pole piece and the second positive pole piece, the last pair of pole pieces are the negative pole piece and the first positive pole piece in sequence, the positive pole coating surface of the first pole piece faces the middle pole piece, and the positive pole coating surface of the last pole piece faces the middle pole piece.
5. 5. The lithium-ion battery of claim 4, wherein the first positive electrode sheet is further provided with an uncoated surface, the uncoated surface is positioned on the back side of the positive electrode coated surface, and both ends of the battery cell are uncoated surfaces.
6. 6. The lithium ion battery of claim 4 or 5, wherein the first positive electrode sheet is coated on one side with a positive electrode slurry, the second positive electrode sheet is coated on both sides with the positive electrode slurry, and the positive electrode slurry comprises a positive electrode active material, a conductive agent, and a positive electrode binder.
7. 7. The lithium-ion battery of claim 6, wherein the first positive electrode sheet and the second positive electrode sheet are made of an aluminum foil material.
8. 8. The lithium ion battery of claim 4 or 5, wherein the negative electrode sheet is double-coated with a negative electrode slurry comprising a negative electrode active material, a conductive agent, and a negative electrode binder.
9. 9. The lithium-ion battery of claim 8, wherein the negative electrode sheet is made of a copper foil material.
10. 10. The lithium-ion battery of claim 4 or 5, wherein the cell further comprises a separator disposed in a zig-zag configuration, adjacent pole pieces being separated by the separator.

Description

Lithium ion battery preparation method and lithium ion battery Technical Field The application relates to the field of battery preparation, in particular to a lithium ion battery preparation method and a lithium ion battery. Background Lithium batteries are widely used in the fields of consumer electronics, electric automobiles, energy storage systems and the like as high-efficiency and light energy storage equipment. In the manufacturing process of lithium batteries, the structural design of the battery cell has an important influence on the battery performance. The common lamination type battery cell adopts a mode of alternately stacking a plurality of layers of positive and negative plates, wherein the positive plate is usually made of lithium transition metal oxide materials, and the negative plate is made of graphite or silicon-based materials. The alternate structural design aims to ensure uniform migration of lithium ions between the anode and the cathode during charge and discharge. Currently, the lamination process of industry standard generally adopts a three-layer basic unit structure of 'negative electrode-positive electrode-negative electrode' (N-P-N), and in actual production, the multi-layer lamination is realized by repeating the unit. However, the inventor notices that a common phenomenon exists in the existing production process, namely, no matter how the number of lamination layers is increased, the final formed battery cell always takes a negative electrode sheet as an initial layer and a termination layer, namely, a five-layer structure or other odd-layer structure of 'negative electrode-positive electrode-negative electrode' is formed, so that the two final electrode sheets are both negative electrode sheets. This will lead to problems with material costs and energy density constraints. Because a negative electrode plate is additionally used in the battery structure, the cost of raw materials (including copper foil, negative electrode active materials (such as graphite) and binders and the like) related to the negative electrode plate is generally higher than that of aluminum foil and positive electrode materials adopted by the positive electrode plate, and the material cost of the single battery is obviously increased. In a mass production scenario, such material redundancy would create a considerable cost burden for the factor accumulation effect. On the premise that the battery capacity is determined by the positive/negative electrode capacity, the redundant negative electrode plate does not participate in capacity contribution (only serves as a current loop carrier), but the total weight and the volume of the battery cell are increased. Based on the defined formula (energy to weight or volume ratio) of energy density (Wh/kg or Wh/L), this structural redundancy will directly result in a simultaneous decrease in the weight and volume energy densities of the cells. Disclosure of Invention The application aims to provide a lithium ion battery preparation method and a lithium ion battery, which can obviously reduce the material cost and improve the energy density of a battery core. In a first aspect, the invention provides a preparation method of a lithium ion battery, the preparation method of the lithium ion battery comprises the steps of batching, coating, rolling, die cutting, lamination, baking, liquid injection, formation and capacity division, wherein during coating, positive electrode slurry is coated on a first positive electrode plate on one side, positive electrode slurry is coated on a second positive electrode plate on both sides, negative electrode slurry is coated on a negative electrode plate on both sides, during lamination, the first positive electrode plate is firstly coated on the upper side, the negative electrode plate and the second positive electrode plate are alternately stacked in the middle, during stacking of the last pair of positive electrode plates, the negative electrode plate is firstly placed, then the first positive electrode plate is coated on the lower side to finish lamination, and during lamination, a diaphragm is separated in a Z shape. In an alternative embodiment, after die cutting, a preset number of first positive plates are taken out and placed upside down, so that the coated surfaces of the first positive plates of the group placed upside down are opposite to the coated surfaces of the other first positive plates. In an alternative embodiment, two sets of the first positive electrode sheet, the negative electrode sheet, and the second positive electrode sheet are placed in a lamination machine in groups. In a second aspect, the present invention provides a lithium ion battery, where the battery cell of the lithium ion battery is manufactured by using the manufacturing method of the lithium ion battery in the foregoing embodiment, the battery cell of the lithium ion battery includes a plurality of electrode plates stacked together, the electr