CN105958124B - Lithium ion battery and preparation method thereof - Google Patents

Lithium ion battery and preparation method thereof Download PDF

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Publication number
CN105958124B
CN105958124B CN201610580100.5A CN201610580100A CN105958124B CN 105958124 B CN105958124 B CN 105958124B CN 201610580100 A CN201610580100 A CN 201610580100A CN 105958124 B CN105958124 B CN 105958124B
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anode
cathode
pole piece
coating
current collector
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CN105958124A (en
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赵伟
陶涛
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Ningde Amperex Technology Ltd
Dongguan Amperex Technology Ltd
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Ningde Amperex Technology Ltd
Dongguan Amperex Technology Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

本申请涉及二次电池领域，具体讲，涉及一种锂离子电池及其制备方法。本申请的锂离子电池包括由阴极极片、阳极极片和设置于阴极极片和阳极极片之间的隔膜卷绕而成的扁平状电芯，阳极极片在电芯的拐角处涂覆有阳极材料A1，在电芯的平面层处涂覆有阳极材料B1，阳极材料A1的克容量高于阳极材料B1；和/或，阴极极片在电芯的拐角处涂覆有阴极材料A2，在电芯的平面层处涂覆有阴极材料B2，阴极材料A2的克容量低于阴极材料B2。本申请通过使电池内圈阴极包阳极的区域保持较高的正负极容量比，改善电池拐角处界面性能，解决拐角处析锂的问题，提高电池的低温放电性能和改善电池循环析锂。

The present application relates to the field of secondary batteries, and specifically, to a lithium-ion battery and a method for preparing the same. The lithium-ion battery of the present application includes a flat battery cell wound with a cathode electrode sheet, an anode electrode sheet, and a separator disposed between the cathode electrode sheet and the anode electrode sheet, wherein the anode electrode sheet is coated with an anode material A1 at the corner of the battery cell, and an anode material B1 is coated at the flat layer of the battery cell, and the gram capacity of the anode material A1 is higher than that of the anode material B1 ; and/or, the cathode electrode sheet is coated with a cathode material A2 at the corner of the battery cell, and a cathode material B2 is coated at the flat layer of the battery cell, and the gram capacity of the cathode material A2 is lower than that of the cathode material B2 . The present application improves the interface performance at the battery corner by maintaining a high positive-negative electrode capacity ratio in the area where the cathode encloses the anode in the inner circle of the battery, solves the problem of lithium deposition at the corner, improves the low-temperature discharge performance of the battery, and improves the lithium deposition during battery cycle.

Description

Lithium ion battery and preparation method thereof
Technical Field
The application relates to the field of secondary batteries, in particular to a lithium ion battery and a preparation method thereof.
Background
The lithium ion battery has the advantages of high energy density, high cycle performance, high voltage, low self-discharge, light weight and the like, is widely applied to various portable electronic products such as notebook computers, digital cameras, mobile phones, watches and the like, and particularly products designed and manufactured by Apple represent essence of modern human technology to lead the trend of the times. With the wide application of various portable electronic products, people have higher and higher requirements on the performance of lithium ion batteries, especially on the energy density, the cycle performance and the like of the lithium ion batteries.
During the circulation process of the battery, lithium ions can be inserted and extracted between a cathode and an anode of the battery, when the lithium ions migrate from the cathode to the anode, due to the limitation of a winding structure of the battery, the cathode at the turning position of an inner ring wraps the area of the anode, the capacity ratio of the cathode and the anode of the battery is insufficient, the excessive lithium ions of the cathode are inserted into the anode, the anode does not have enough capacity to be capable of inserting the lithium ions, the excessive lithium ions are separated out in the area of the inner ring wrapped by the cathode, and the lithium separation of the anode can seriously reduce the circulation performance of the battery.
The current common process adopted by the lithium ion battery is a winding structure design, firstly, slurry which is uniformly stirred is coated on a cathode and anode current collector at a certain speed, the current common coating process mainly comprises transfer coating and extrusion coating (slot die), the length of a cathode and anode diaphragm is coated on the surface of the current collector through the two processes, and then slitting is carried out. And after the pole piece blank area after slitting is welded with the pole lug, the pole piece blank area and the isolating film are sequentially arranged to be wound, and the bare cell and the aluminum-plastic film are packaged, injected and formed after winding is finished.
In terms of battery design, in order to prevent the battery from generating lithium precipitation in the use process, the capacity ratio of the cathode and the anode of the battery needs to be more than a certain value in general design so as to ensure that the battery does not generate obvious lithium precipitation in the normal use process, thereby causing the battery to lose efficacy. If the designed cathode-anode capacity ratio is too large, lithium precipitation of the battery in the use process can be avoided, but the thickness of a battery cell is thicker, and the energy density of the battery is seriously reduced.
In view of this, the present application is specifically made.
Disclosure of Invention
The first invention of the present application aims to provide a lithium ion battery and a preparation method thereof.
The second invention of the present application aims to provide a preparation method of the lithium ion battery.
The purpose of the application is achieved, and the technical scheme is as follows:
the application relates to a lithium ion battery, include by cathode pole piece, anode pole piece and set up in cathode pole piece with the flat form electricity core that diaphragm between the anode pole piece was convoluteed and is formed, anode pole piece is in the corner coating of electricity core has anode material A1The planar layer of the battery core is coated with an anode material B1The anode material A1Has a higher gram capacity than the anode material B1(ii) a And/or the cathode pole piece is coated with a cathode material A at the corner of the battery cell2Coating the planar layer of the battery core with a cathode material B2The cathode material A2Has a lower gram capacity than that of the cathode material B2。
Preferably, the anode material A1Specific gram volume of the anode material B1The gram volume of the catalyst is 1-100 mAh/g, preferably 5-20 mAh/g.
Preferably, the cathode material A2Specific gram capacity of the cathode material B2The gram volume of the glass is 1 to 100mAh/g, preferably 5 to 20 mAh/g.
Preferably, the anode material B1The gram capacity of the anode material A is 300-400 mAh/g1The gram volume of the glass is 301-500 mAh/g.
Preferably, the cathode material A2The gram capacity is 140-230 mAh/g, and the cathode material B2The gram volume of the glass is 141-330 mAh/g.
Preferably, the coating weight of the cathode pole piece at the corner is less than the coating weight at the planar layer.
Preferably, the coating weight of the anode pole piece at the corner is greater than the coating weight at the planar layer.
Preferably, the anode material A1Is coated withThe length of the area is 1-30 mm; and/or the cathode material A2The length of the coated area is 1-30 mm.
Preferably, the anode material A1The coated region and the anode material B1The gap between the coated areas is 0-2 mm; and/or, the cathode material A2The coated region and the anode material B2The gap between the coated regions is 0 to 2 mm.
Preferably, the anode material A1Anode material B1The graphite particles are respectively and independently selected from at least one of natural graphite, artificial graphite, soft carbon, hard carbon, mesocarbon microbeads, tin-based oxides, tin-based composite oxides, silicon-carbon alloys and lithium titanate; and/or, the cathode material A2Cathode material B2Each independently selected from LiCoO2、LiNiO2、LiMnO2、LiFePO4、LixNiyCozMnO2At least one of, 0<x<1，0<y<1，0<z<1。
The application also relates to a preparation method of the lithium ion battery, which is characterized in that the coating of the pole piece in the preparation method is selected from at least one of the following modes:
(1) coating a cathode material on the current collector of the cathode pole piece in a whole piece; coating anode material A on the area corresponding to the corner on the current collector of the anode pole piece1Coating an anode material B on the area corresponding to the planar layer on the current collector of the anode pole piece1(ii) a Or
(2) Coating an anode material on the current collector of the anode pole piece in a whole piece; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the area corresponding to the planar layer on the current collector of the cathode pole piece2(ii) a Or
(3) Coating anode material A on the area corresponding to the corner on the current collector of the anode pole piece1At a placeCoating an anode material B on the area corresponding to the planar layer on the current collector of the anode pole piece1(ii) a Coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the area corresponding to the planar layer on the current collector of the cathode pole piece2(ii) a Or
(4) Coating cathode material on the current collector of the cathode pole piece in a whole piece, wherein the coating weight of the cathode pole piece at the corner is less than that of the planar layer; coating anode material A on the area corresponding to the corner on the current collector of the anode pole piece1Coating an anode material B on the area corresponding to the planar layer on the current collector of the anode pole piece1(ii) a Or
(5) Coating anode material on the current collector of the anode pole piece in a whole piece mode, wherein the coating weight of the anode pole piece at the corner is larger than that of the anode pole piece at the plane layer; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the area corresponding to the planar layer on the current collector of the cathode pole piece2(ii) a Or
(6) Coating anode material A on the area corresponding to the corner on the current collector of the anode pole piece1Coating an anode material B on the area corresponding to the planar layer on the current collector of the anode pole piece1And the coating weight of the anode pole piece at the corner is larger than that of the plane layer; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the area corresponding to the planar layer on the current collector of the cathode pole piece2(ii) a Or
(7) Coating anode material A on the area corresponding to the corner on the current collector of the anode pole piece1Coating an anode material B on the area corresponding to the planar layer on the current collector of the anode pole piece1(ii) a Coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2At the cathode pole pieceCoating cathode material B on the current collector corresponding to the area of the plane layer2And the coating weight of the cathode pole piece at the corner is less than the coating weight at the planar layer; or
(8) Coating anode material A on the area corresponding to the corner on the current collector of the anode pole piece1Coating an anode material B on the area corresponding to the planar layer on the current collector of the anode pole piece1And the coating weight of the anode pole piece at the corner is larger than that of the plane layer; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the area corresponding to the planar layer on the current collector of the cathode pole piece2And the coating weight of the cathode pole piece at the corner is less than that of the plane layer.
The technical scheme of the application has at least the following beneficial effects:
according to the lithium ion battery, different materials are coated on the current collector, so that the higher positive-negative capacity ratio is kept in the areas of the corners and the planes of the battery, particularly the areas of the inner ring cathode package anode of the battery, the interface performance of the corners of the battery is improved, the problem of lithium precipitation at the corners is solved, the low-temperature discharge performance of the battery is improved, and the lithium precipitation of the battery in a circulating manner is improved.
This application coats through adopting different materials, and the regional anode material that adopts high gram capacity of corner or the cathode material of low gram capacity are favorable to among the cathode pole piece especially the negative pole of corner to wrap the positive pole interface play and better imbed lithium ion, improve the gram capacity performance of the negative pole of battery, improve the energy density of battery.
Description of the drawings:
FIG. 1 is a schematic cross-sectional view of a uniform coating of a cathode plate;
FIG. 2 is a schematic cross-sectional view of a gap coating of a cathode plate;
FIG. 3 is a schematic cross-sectional view of a uniform coating of the anode sheet;
FIG. 4 is a schematic cross-sectional view of gap coating of an anode sheet;
fig. 5 is a schematic diagram of a wound cell after gap coating of a cathode plate and uniform coating of an anode plate;
wherein:
1-cathode pole piece;
11-a cathode membrane;
12-a cathode current collector;
13-cathode diaphragm at corner;
14-cathode membrane at planar layer;
15-a cathode tab;
2-anode pole piece;
21-an anode membrane;
22-an anode current collector;
23-anode membrane at planar layer;
24-anode diaphragm at corner;
25-an anode tab;
3-a separator;
4-the anode at the cell corner wraps the cathode membrane area;
5-the cathode at the cell corners wraps around the anode membrane area.
In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and the detailed description. It should be understood that the detailed description and specific examples, while indicating the present application, are given by way of illustration only and not by way of limitation.
Detailed Description
The application relates to a lithium ion battery, which comprises a cathode pole piece, an anode pole piece and a flat battery core wound by a diaphragm arranged between the cathode pole piece and the anode pole piece,
the cathode pole piece comprises a cathode current collector and cathode diaphragms coated on two sides of the cathode current collector, and the anode pole piece comprises an anode current collector and anode diaphragms coated on two sides of the anode current collector;
the anode pole piece is coated with an anode material A at the corner of the battery cell1Coating the planar layer of the battery core with an anode material B1Anode material A1Gram volume of>Anode material B1(ii) gram capacity of;
and/or the cathode pole piece is coated with a cathode material A at the corner of the cell2Coating the planar layer of the battery core with a cathode material B2Cathode material A2Gram volume of<Cathode material B2The gram volume of (c).
The flat layer and the corner are defined by a point where the slope of the tangent line of the arc of the flat battery at the corner is 0.
As an improvement of the lithium ion battery of the present application, an anode material A1Gram volume ratio of (A) anode material (B)1The gram volume of the catalyst is 1-100 mAh/g, preferably 5-20 mAh/g. If the anode material A is used1Specific capacity and anode material B1If the difference of the gram capacities is too small, the improvement of lithium separation at corners is not obvious. The phase difference is too large, resulting in an increase in the cost of the battery.
As an improvement of the lithium ion battery of the present application, a cathode material A2Specific gram volume of cathode material B2The gram volume of the glass is 1 to 100mAh/g, preferably 5 to 20 mAh/g. If the cathode material A2Specific capacity and cathode material B2Has a too small difference in gram capacity, pairThe improvement in corner lithium extraction was not significant. The battery capacity is affected by the excessive difference, and the energy density of the battery is greatly reduced.
As an improvement of the lithium ion battery of the present application, an anode material B1The gram volume of the anode material is 300-400 mAh/g, and the anode material A1The gram volume of the glass is 301-500 mAh/g.
As an improvement of the lithium ion battery of the present application, a cathode material A2A gram capacity of 140-230 mAh/g, a cathode material B2The gram volume of the glass is 141-330 mAh/g.
As an improvement of the lithium ion battery of the present application, the coating weight of the cathode sheet at the corners is less than the coating weight at the planar layers.
As an improvement of the lithium ion battery of the present application, the coating weight of the anode plate at the corners is greater than the coating weight at the planar layers.
Wherein,
capacity of battery (coating weight of cathode x gram capacity of cathode x solid content of active material of cathode film x area of cathode film)
Therefore, the coating weight is the amount of the cathode and anode materials which can be coated with different coating weights to exert different battery capacities according to the gram capacities of the cathode and anode materials in the process of manufacturing the battery, and can be mainly controlled by the coating thickness.
As an improvement of the lithium ion battery, the difference value between the coating weight of the cathode pole piece at the corner and the coating weight at the plane layer is 0.1-1.5 mg/cm2(ii) a If the coating weight difference of the cathode pole piece is too small, the improvement of lithium precipitation at the corner is not obvious. The battery capacity is affected by the excessive difference, and the energy density of the battery is greatly reduced.
As an improvement of the lithium ion battery, the difference value between the coating weight of the anode plate at the corner and the coating weight at the plane layer is 0.1-1.5 mg/cm2. If the difference between the coating weights of the anode plates is too small, if the difference between the gram capacities is too smallToo small, the improvement in corner lithium extraction is not significant. Too much difference affects the battery capacity.
As an improvement of the lithium ion battery of the present application, an anode material A1Anode material B1Each independently is at least one selected from natural graphite, artificial graphite, soft carbon, hard carbon, mesocarbon microbeads, tin-based oxides, tin-based composite oxides, silicon-carbon alloys and lithium titanate.
Wherein A is1、B1Any one of the above materials can be selected, and only requirement A is satisfied1Gram volume>B1The capacity is reduced; specifically, A1Optionally one of silicon-carbon alloy and tin-base, B1One of artificial graphite and soft carbon may be selected.
As an improvement of the lithium ion battery of the present application, a cathode material A2Cathode material B2Each independently selected from LiCoO2、LiNiO2、LiMnO2、LiFePO4、LixNiyCozMnO2At least one of, 0<x<1，0<y<1，0<z<1。
Wherein A is2、B2Any one of the above materials can be selected, and only requirement A is satisfied2Gram volume<B2The gram volume of the product is obtained; specifically, A2LiCoO can be selected2、LiNiO2、LiMnO2One of (1), B2LiFePO can be selected4、LixNiyCozMnO2One kind of (1).
As an improvement of the lithium ion battery, the thickness of the flat battery core is 1-10 mm.
As an improvement of the lithium ion battery of the present application, an anode material A1The length of the coated area is 1-30 mm; and/or, cathode material A2The length of the coated area is 1-30 mm.
As one of the lithium ion batteries of the present applicationThe improvement is anode material A1Coated region and anode material B1The gap between the coated areas is 0-2 mm; and/or, cathode material A2Coated region and anode material B2The gap between the coated regions is 0 to 2 mm. The optimum process conditions are seamless coating and the gap between the two coating zones is minimized to avoid loss of energy density.
As an improvement of the lithium ion battery of the present application, the lithium ion battery further comprises a cathode tab and an anode tab, and the positions of the cathode and the anode tab are provided with: the cathode tab and the anode tab are respectively positioned on the inner ring and the outer ring of the battery, and the cathode tab and the anode tab are respectively positioned on the outer ring and the inner ring of the battery.
As an improvement of the lithium ion battery, the thickness of the cathode and anode tabs is 0.05-0.5 mm.
As an improvement of the lithium ion battery, the thickness of the current collector of the cathode and the anode is 0.004-0.05 mm.
As an improvement of the lithium ion battery, the thickness of the isolating membrane is 0.004-0.05 mm.
The application also relates to a preparation method of the lithium ion battery, which comprises the steps of coating, drying, cold pressing, welding a tab, packaging and injecting liquid after winding with an isolation film and the like, wherein the coating mode of the pole piece is selected from the following steps:
(1) coating a cathode material on the current collector of the cathode pole piece in a whole piece; coating anode material A on the corresponding area of the corner on the current collector of the anode pole piece1Coating anode material B on the current collector of the anode pole piece in the area corresponding to the planar layer1(ii) a Or
(2) Coating an anode material on the current collector of the anode piece in a whole piece; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the current collector of the cathode pole piece in the area corresponding to the planar layer2(ii) a Or
(3) Coating anode material A on the corresponding area of the corner on the current collector of the anode pole piece1Coating anode material B on the current collector of the anode pole piece in the area corresponding to the planar layer1(ii) a Coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the current collector of the cathode pole piece in the area corresponding to the planar layer2(ii) a Or
(4) Coating cathode materials on a current collector of the cathode pole piece in a whole piece manner, wherein the coating weight of the cathode pole piece at the corner is less than that of the planar layer; coating anode material A on the corresponding area of the corner on the current collector of the anode pole piece1Coating anode material B on the current collector of the anode pole piece in the area corresponding to the planar layer1(ii) a Or
(5) Coating anode materials on a current collector of the anode piece in a whole piece manner, wherein the coating weight of the anode piece at the corner is greater than that of the planar layer; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the current collector of the cathode pole piece in the area corresponding to the planar layer2(ii) a Or
(6) Coating anode material A on the corresponding area of the corner on the current collector of the anode pole piece1Coating anode material B on the current collector of the anode pole piece in the area corresponding to the planar layer1And the coating weight of the anode pole piece at the corner is greater than that of the plane layer; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the current collector of the cathode pole piece in the area corresponding to the planar layer2(ii) a Or
(7) Coating anode material A on the corresponding area of the corner on the current collector of the anode pole piece1Coating anode material B on the current collector of the anode pole piece in the area corresponding to the planar layer1(ii) a Coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the current collector of the cathode pole piece in the area corresponding to the planar layer2And the coating weight of the cathode pole piece at the corner is less than the coating weight at the plane layer; or
(8) Coating anode material A on the corresponding area of the corner on the current collector of the anode pole piece1Coating anode material B on the current collector of the anode pole piece in the area corresponding to the planar layer1And the coating weight of the anode pole piece at the corner is greater than that of the plane layer; coating cathode material A on the corresponding area of the corner on the current collector of the cathode pole piece2Coating cathode material B on the current collector of the cathode pole piece in the area corresponding to the planar layer2And the coating weight of the cathode pole piece at the corner is less than that of the plane layer.
In the present application, the coating of the same gram capacity of active material on the current collector is a uniform coating. The current collector is coated with one gram of active material in the corresponding area at the corner or the plane layer, a strip distribution is formed on the current collector, and then the rest area is coated with another gram of active material, wherein the coating mode is gap coating.
Also, different coating weights of the slurry can be applied by gap coating.
Preparation example
Preparing a cathode plate 1:
1. uniform coating: a schematic cross-sectional view of cathode sheet coating as shown in fig. 1, a slurry of a cathode material is uniformly stirred and coated on a cathode current collector 12 by transfer to form a cathode membrane 11.
2. Gap coating of different gram volumes: the cross-sectional view of the cathode plate coating is shown in FIG. 2, and the cathode material A is uniformly stirred2Coating the slurry on the corresponding area of the corner of the current collector 12 to form a membrane 13, and uniformly stirring the cathode material B2Is coated on the current collector 12 in the corresponding area of the plane layerForming the membrane 14; forming a cathode pole piece 1 after gap coating;
3. gap coating with different weights: coating the slurry of the cathode material which is uniformly stirred on the current collector 12, wherein the coating weight of the cathode pole piece at the corner is less than that of the planar layer;
preparation of Anode sheet 2：
1. Gap coating of different gram volumes: the cross-sectional view of the anode piece coating is shown in FIG. 3, and the anode material B which is uniformly stirred is1The slurry is applied to the area corresponding to the planar layer on the anode current collector 22 to form an anode membrane 23, and the anode material A is uniformly stirred1Coating the slurry on the corresponding area of the upper corner of the anode current collector 22 to form an anode diaphragm 24 and form the anode pole piece 2 after gap coating;
2. gap coating with different weights: coating the anode current collector 22 with the uniformly stirred slurry of the anode material, wherein the coating weight of the anode piece at the corner is greater than that of the planar layer;
3. uniform coating: as shown in fig. 4, a cross-sectional view of the anode sheet coating, a slurry of the anode material stirred uniformly is applied onto an anode current collector 22 by transfer to form an anode membrane 21.
Preparing an electric core:
before welding, an aluminum sheet with the width of 5mm and the thickness of 0.1mm is welded on the cathode current collector 12 at the innermost ring to serve as a cathode tab 15, a nickel sheet with the width of 5mm and the thickness of 0.1 is welded on the anode current collector 22 at the innermost ring to serve as an anode tab 25, and when winding starts, the cathode tab and the anode tab are both positioned in an inner ring structure of a battery cell. The lithium ion battery is formed by sequentially laminating a cathode pole piece 1, a separation film 3 and an anode pole piece 2 and then winding the laminated layers along the same direction. And packaging the wound battery core and the aluminum plastic film, injecting liquid, melting, cutting off the air bag, and forming to obtain the finished battery core.
Wherein, the schematic diagram of the winding structure after the cathode plate 1 is coated in the gap and the anode plate 2 is coated uniformly is shown in fig. 5.
Example 1
The embodiment relates to a lithium ion battery, which comprises a cathode pole piece and an anode pole piece.
According to the preparation method of the preparation example, the cathode plate and the anode plate shown in table 1 are prepared, and the battery cell is prepared.
Table 1: gram volume of coating of cathode and anode pole piece
According to the preparation method of the preparation example, the cathode plate and the anode plate shown in table 2 were prepared, and the battery cell was prepared.
Table 2: gram capacity and weight of coating of cathode and anode pole piece
Examples of the experiments
(1) Phenomenon of lithium separation
10 batteries were selected from the batteries of examples 1 to 5 and comparative examples 1 to 2, respectively, and subjected to cycle testing, after 100 cycles, the batteries were disassembled, the lithium analysis conditions at the corners 4 and 5 of the anode plate were observed, and the number of the batteries in which lithium analysis occurred in the anode plate was counted, and the obtained results are shown in table 3.
Table 3: detection result of lithium separation phenomenon
(2) Capacity and volumetric energy density
The batteries provided in examples 1 to 5 and comparative examples 1 to 2 were subjected to a capacity test and a volumetric energy density test, and the results are shown in Table 4.
The capacity test is carried out in an environment at 25 ℃, the capacity is 0.2C discharge capacity, and the volume energy density is capacity multiplied by plateau voltage/volume.
Table 4: capacity and volumetric energy density measurements
Group of Average capacity/mAh Average thickness/mm Average volumetric energy density/Wh/L
Battery cell 1 2140 4.47 545
Battery cell 2 2170 4.48 552
Battery cell 3 2190 4.47 557
Battery cell 4 2155 4.47 548
Battery cell 5 2120 4.48 539
Battery cell 6 2130 4.49 540
Battery cell 7 2120 4.47 520
Comparative example cell 1 2100 4.47 530
Comparative example cell 2 2120 4.48 540
(3) Cycle performance
10 batteries were selected from the batteries of examples 1 to 5 and comparative examples 1 to 2, respectively, and subjected to cycle performance test:
the test conditions were: charging to 4.35V at 45 deg.C under constant current of 0.7C, charging to 0.05C under constant voltage of 4.35V, discharging to 3.0V under constant current of 1.0C, recording initial capacity, repeating the above steps 500 times, and discharging to 3.0V under 0.2C after 50 cycles. The test results are shown in table 5.
Table 5: results of cycle performance testing
Group of 100 times (twice) 200 times (one time) 300 times (twice) 400 times (one time) 500 times (times) 600 times (one time) 700 times
Battery cell 1 2087 2033 1973 1950 1926 2087 2033
Battery cell 2 2129 2077 2007 1979 1955 2129 2077
Battery cell 3 2155 2091 2030 2002 1978 2155 2091
Battery cell 4 2103 2049 1983 1942 1918 2103 2049
Battery cell 5 2063 2008 1940 1916 1880 2063 2008
Battery cell 6 2061 2021 1960 1937 1910 2061 2021
Battery cell 7 2055 2011 1943 1921 1908 2055 2011
Comparative example cell 1 2001 1932 1873 1785 1743 2001 1932
Comparative example cell 2 2042 1997 1936 1885 1842 2042 1997
As can be seen from tables 4 and 5, compared with the battery prepared by the conventional coating process, the lithium battery of the present application can improve the energy density of the battery by coating the anode material and/or the cathode material with different gram capacities, and the battery cell still has a higher capacity retention rate after 500 cycles.
The above-described embodiments have been described in detail, and those skilled in the art to which the present invention pertains may make variations and modifications. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present application should fall within the scope of the claims of the present application. In addition, although specific terms are used herein, they are used in a descriptive sense only and not for purposes of limitation.

Claims (11)

1.一种锂离子电池，包括由阴极极片、阳极极片和设置于所述阴极极片和所述阳极极片之间的隔膜卷绕而成的扁平状电芯，其特征在于，所述阳极极片在所述电芯的拐角处涂覆有阳极材料A1，在所述电芯的平面层处涂覆有阳极材料B1，所述阳极材料A1的克容量高于所述阳极材料B1；和/或，所述阴极极片在所述电芯的拐角处涂覆有阴极材料A2，在所述电芯的平面层处涂覆有阴极材料B2，所述阴极材料A2的克容量低于所述阴极材料B2。1. A lithium-ion battery, comprising a flat electric core wound by a cathode pole piece, an anode pole piece and a diaphragm that is arranged between the cathode pole piece and the described anode pole piece, it is characterized in that, The anode sheet is coated with anode material A 1 at the corner of the cell, and anode material B 1 is coated at the plane layer of the cell, and the gram capacity of the anode material A 1 is higher than that of the Anode material B 1 ; and/or, the cathode pole piece is coated with cathode material A 2 at the corner of the electric core, and is coated with cathode material B 2 at the plane layer of the electric core, and the cathode Material A2 has a lower grammability than the cathode material B2 . 2.根据权利要求1所述的锂离子电池，其特征在于，所述阳极材料A1的克容量比所述阳极材料B1的克容量高1～100mAh/g。2. The lithium ion battery according to claim 1, characterized in that the gram capacity of the anode material A1 is 1˜100 mAh/g higher than the gram capacity of the anode material B1 . 3.根据权利要求1所述的锂离子电池，其特征在于，所述阴极材料A2的克容量比所述阴极材料B2的克容量低1～100mAh/g。3. The lithium ion battery according to claim 1, characterized in that the gram capacity of the cathode material A2 is 1˜100 mAh/g lower than the gram capacity of the cathode material B2 . 4.根据权利要求1所述的锂离子电池，其特征在于，所述阳极材料B1的克容量为300～400mAh/g，所述阳极材料A1的克容量为301～500mAh/g。4. The lithium ion battery according to claim 1, characterized in that, the gram capacity of the anode material B1 is 300-400mAh/g, and the gram capacity of the anode material A1 is 301-500mAh/g. 5.根据权利要求1所述的锂离子电池，其特征在于，所述阴极材料A2克容量为140～230mAh/g，所述阴极材料B2的克容量为141～330mAh/g。5. The lithium-ion battery according to claim 1, characterized in that, the gram capacity of the cathode material A2 is 140-230mAh/g, and the gram capacity of the cathode material B2 is 141-330mAh/g. 6.根据权利要求1所述的锂离子电池，其特征在于，所述阴极极片在所述拐角处的涂布重量小于所述平面层处的涂布重量。6 . The lithium-ion battery according to claim 1 , wherein the coating weight of the cathode sheet at the corner is smaller than the coating weight at the planar layer. 7.根据权利要求1所述的锂离子电池，其特征在于，所述阳极极片在所述拐角处的涂布重量大于所述平面层处的涂布重量。7. The lithium ion battery according to claim 1, characterized in that, the coating weight of the anode pole piece at the corner is greater than the coating weight at the planar layer. 8.根据权利要求1所述的锂离子电池，其特征在于，所述阳极材料A1所涂布区域的长度为1～30mm；和/或，所述阴极材料A2所涂布区域的长度为1～30mm。8. The lithium ion battery according to claim 1, characterized in that, the length of the area coated with the anode material A1 is 1 to 30 mm; and/or, the length of the area coated with the cathode material A2 1 to 30 mm. 9.根据权利要求1所述的锂离子电池，其特征在于，所述阳极材料A1所涂布区域与所述阳极材料B1所涂布区域之间的间隙为0～2mm；和/或，所述阴极材料A2所涂布区域与所述阳极材料B2所涂布区域之间的间隙为0～2mm。9. The lithium ion battery according to claim 1, characterized in that, the gap between the area coated with the anode material A1 and the area coated with the anode material B1 is 0-2mm; and/or , the gap between the area coated with the cathode material A 2 and the area coated with the anode material B 2 is 0-2 mm. 10.根据权利要求1所述的锂离子电池，其特征在于，所述阳极材料A1、阳极材料B1各自独立的分别选自天然石墨、人造石墨、软碳、硬碳、中间相炭微球、锡基氧化物、锡基复合氧化物、硅碳合金和钛酸锂中的至少一种；和/或，所述阴极材料A2、阴极材料B2各自独立的分别选自LiCoO2、LiNiO2、LiMnO2、LiFePO4、LixNiyCozMnO2的至少一种，0<x<1，0<y<1，0<z<1。10. The lithium ion battery according to claim 1, wherein the anode material A 1 and the anode material B 1 are each independently selected from natural graphite, artificial graphite, soft carbon, hard carbon, mesocarbon At least one of balls, tin-based oxides, tin-based composite oxides, silicon-carbon alloys, and lithium titanate; and/or, the cathode material A 2 and the cathode material B 2 are each independently selected from LiCoO 2 , At least one of LiNiO 2 , LiMnO 2 , LiFePO 4 , Li x Ni y Co z MnO 2 , 0<x<1, 0<y<1, 0<z<1. 11.一种如权利要求1～10所述任一权利要求所述的锂离子电池的制备方法，其特征在于，所述制备方法中极片的涂布选自以下方式中的至少一种：11. A method for preparing a lithium-ion battery according to any one of claims 1 to 10, wherein the coating of the pole piece in the preparation method is selected from at least one of the following methods: (1)在所述阴极极片的集流体上整片涂覆阴极材料；在所述阳极极片的集流体上拐角处所对应的区域涂覆阳极材料A1，在所述阳极极片的集流体上平面层所对应的区域涂覆阳极材料B1；或(1) Coating the cathode material on the current collector of the cathode pole piece; coating the anode material A 1 on the area corresponding to the corner on the current collector of the anode pole piece, and coating the anode material A 1 on the collector of the anode pole piece The area corresponding to the plane layer on the fluid is coated with anode material B 1 ; or (2)在所述阳极极片的集流体上整片涂覆阳极材料；在所述阴极极片的集流体上拐角处所对应的区域涂覆阴极材料A2，在所述阴极极片的集流体上平面层处所对应的区域涂覆阴极材料B2；或(2) Coating the anode material on the current collector of the anode pole piece; coating the cathode material A 2 on the area corresponding to the corner on the current collector of the cathode pole piece, and coating the cathode material A 2 on the current collector of the cathode pole piece The region corresponding to the upper plane layer of the fluid is coated with cathode material B 2 ; or (3)在所述阳极极片的集流体上拐角处所对应的区域涂覆阳极材料A1，在所述阳极极片的集流体上平面层所对应的区域涂覆阳极材料B1；在所述阴极极片的集流体上拐角处所对应的区域涂覆阴极材料A2，在所述阴极极片的集流体上平面层处所对应的区域涂覆阴极材料B2；或(3) Coating the anode material A 1 on the area corresponding to the corner on the current collector of the anode pole piece, and coating the anode material B 1 on the area corresponding to the plane layer on the current collector of the anode pole piece; The area corresponding to the upper corner of the current collector of the cathode electrode sheet is coated with cathode material A 2 , and the area corresponding to the upper plane layer of the current collector of the cathode electrode sheet is coated with cathode material B 2 ; or (4)在所述阴极极片的集流体上整片涂覆阴极材料，且所述阴极极片在所述拐角处的涂布重量小于所述平面层处的涂布重量；在所述阳极极片的集流体上拐角处所对应的区域涂覆阳极材料A1，在所述阳极极片的集流体上平面层所对应的区域涂覆阳极材料B1；或(4) On the current collector of the cathode pole piece, the cathode material is coated on the whole piece, and the coating weight of the cathode pole piece at the corner is less than the coating weight at the plane layer; The area corresponding to the corner on the current collector of the pole piece is coated with anode material A 1 , and the area corresponding to the plane layer on the current collector of the anode pole piece is coated with anode material B 1 ; or (5)在所述阳极极片的集流体上整片涂覆阳极材料，且所述阳极极片在所述拐角处的涂布重量大于所述平面层处的涂布重量；在所述阴极极片的集流体上拐角处所对应的区域涂覆阴极材料A2，在所述阴极极片的集流体上平面层处所对应的区域涂覆阴极材料B2；或(5) Coating anode material on the current collector of the anode pole piece, and the coating weight of the anode pole piece at the corner is greater than the coating weight at the plane layer; The area corresponding to the upper corner of the current collector of the pole piece is coated with cathode material A 2 , and the area corresponding to the upper plane layer of the current collector of the cathode pole piece is coated with cathode material B 2 ; or (6)在所述阳极极片的集流体上拐角处所对应的区域涂覆阳极材料A1，在所述阳极极片的集流体上平面层所对应的区域涂覆阳极材料B1，且所述阳极极片在所述拐角处的涂布重量大于所述平面层处的涂布重量；在所述阴极极片的集流体上拐角处所对应的区域涂覆阴极材料A2，在所述阴极极片的集流体上平面层处所对应的区域涂覆阴极材料B2；或(6) Coating the anode material A 1 on the area corresponding to the corner on the current collector of the anode pole piece, and coating the anode material B 1 on the area corresponding to the plane layer on the current collector of the anode pole piece, and the The coating weight of the anode sheet at the corner is greater than the coating weight at the planar layer; the area corresponding to the corner on the current collector of the cathode sheet is coated with cathode material A 2 , and the The area corresponding to the plane layer on the current collector of the pole piece is coated with cathode material B 2 ; or (7)在所述阳极极片的集流体上拐角处所对应的区域涂覆阳极材料A1，在所述阳极极片的集流体上平面层所对应的区域涂覆阳极材料B1；在所述阴极极片的集流体上拐角处所对应的区域涂覆阴极材料A2，在所述阴极极片的集流体上平面层处所对应的区域涂覆阴极材料B2，且所述阴极极片在所述拐角处的涂布重量小于在所述平面层处的涂布重量；或(7) Coating the anode material A 1 in the area corresponding to the corner on the current collector of the anode pole piece, and coating the anode material B 1 in the area corresponding to the plane layer on the current collector of the anode pole piece; The area corresponding to the upper corner of the current collector of the cathode sheet is coated with cathode material A 2 , and the area corresponding to the upper plane layer of the current collector of the cathode sheet is coated with cathode material B 2 , and the cathode sheet is in the coat weight at the corner is less than the coat weight at the planar layer; or (8)在所述阳极极片的集流体上拐角处所对应的区域涂覆阳极材料A1，在所述阳极极片的集流体上平面层所对应的区域涂覆阳极材料B1，且所述阳极极片在所述拐角处的涂布重量大于所述平面层处的涂布重量；在所述阴极极片的集流体上拐角处所对应的区域涂覆阴极材料A2，在所述阴极极片的集流体上平面层处所对应的区域涂覆阴极材料B2，且所述阴极极片在所述拐角处的涂布重量小于所述平面层处的涂布重量。(8) Coating the anode material A 1 on the area corresponding to the corner on the current collector of the anode pole piece, and coating the anode material B 1 on the area corresponding to the plane layer on the current collector of the anode pole piece, and the The coating weight of the anode sheet at the corner is greater than the coating weight at the planar layer; the area corresponding to the corner on the current collector of the cathode sheet is coated with cathode material A 2 , and the The area corresponding to the planar layer on the current collector of the electrode sheet is coated with cathode material B 2 , and the coating weight of the cathode sheet at the corner is smaller than the coating weight of the planar layer.
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