阅读说明：本技术 电池及其制备方法 (Battery and preparation method thereof ) 是由 杨丽美 刘晓梅 于 2018-05-24 设计创作，主要内容包括：本发明提供了一种电池及其制备方法,所述电池包括电芯以及电解液,所述电芯包括正极极片、负极极片以及隔离膜。在所述电池中,所述正极膜片和/或所述负极膜片表面设置有凸起点,其中,设置在所述正极膜片表面的凸起点的高度为T<Sub>c</Sub>,设置在所述负极膜片表面的凸起点的高度为T<Sub>a</Sub>,所述正极膜片在电池荷电状态为100％SOC时的厚度增加量为H<Sub>c</Sub>,所述负极膜片在电池荷电状态为100％SOC时的厚度增加量为H<Sub>a</Sub>,且0.3≤(T<Sub>c</Sub>+T<Sub>a</Sub>)/(H<Sub>c</Sub>+H<Sub>a</Sub>)≤1。本发明可有效减少电池在整个寿命周期中的膨胀力,使电池兼具高安全性和长循环寿命的特点。(The invention provides a battery and a preparation method thereof, wherein the battery comprises a battery cell and electrolyte, and the battery cell comprises a positive pole piece, a negative pole piece and a separation film. In the battery, the surface of the positive membrane and/or the negative membrane is provided with a convex point, wherein the height of the convex point arranged on the surface of the positive membrane is T c The height of the convex point arranged on the surface of the negative electrode diaphragm is T a The thickness increment of the positive diaphragm at the state of charge of the battery of 100 percent SOC is H c The thickness increment of the negative diaphragm at the state of charge of the battery of 100 percent SOC is H a And 0.3 ≦ (T) c +T a )/(H c +H a ) Less than or equal to 1. The invention can effectively reduce the expansion force of the battery in the whole life cycle, and the battery has the characteristics of high safety and long cycle life.)

1. a kind of battery, including battery core and electrolyte, the battery core include:

Anode pole piece including plus plate current-collecting body and is set to plus plate current-collecting body surface and including the cathode film of positive active material Piece；

Cathode pole piece including negative current collector and is set to negative current collector surface and including the negative electrode film of negative electrode active material Piece；And

Isolation film is arranged between anode pole piece and cathode pole piece；

It is characterized in that,

In the battery, the anode diaphragm and/or the cathode membrane surface are provided with raised points, wherein are arranged in institute The height for stating the raised points of positive membrane surface is T_c, the height that the raised points on the cathode membrane surface are arranged in is T_a, described Thickness increment of the positive diaphragm when battery charge state is 100%SOC is H_c, the cathode membrane is in battery charge state Thickness increment when for 100%SOC is H_a, and 0.3≤(T_c+T_a)/(H_c+H_a)≤1。

2. battery according to claim 1, which is characterized in that 0.4≤(T_c+T_a)/(H_c+H_a)≤0.8, it is preferable that 0.6≤ (T_c+T_a)/(H_c+H_a)≤0.8。

3. battery according to claim 1, which is characterized in that the raised points are distributed in the cathode film in array format Piece and/or the cathode membrane surface.

4. battery according to claim 1, which is characterized in that the raised points are excellent in various rules or irregular shape Selection of land, the raised points are in rounded shape, semicircle shape, square shape, oblong-shaped or trapezoidal shape.

5. battery according to claim 1, which is characterized in that the raised points are arranged in the positive membrane surface, In the positive membrane surface, the projected area of the raised points is the 10%~60% of the positive diaphragm gross area.

6. battery according to claim 1, which is characterized in that the raised points are arranged at the cathode membrane surface, On the cathode membrane surface, the projected area of the raised points is the 10%~60% of the cathode membrane gross area.

7. battery according to claim 1, which is characterized in that the raised points are provided only on the positive membrane surface.

8. a kind of preparation method of battery, is used to prepare battery of any of claims 1-7, which is characterized in that packet Include step:

(1) anode sizing agent including positive active material is coated on plus plate current-collecting body, obtains positive pole after dry, cold pressing Negative electrode slurry including negative electrode active material is coated on negative current collector by piece, obtains cathode pole piece after dry, cold pressing, Described in anode pole piece the original depth of positive diaphragm be H₁, the original depth of cathode membrane is H in the cathode pole piece₂；

(2) anode pole piece, cathode pole piece and isolation film, electrolyte that step (1) prepares are assembled into battery case, are obtained To battery to be tested, it is 100%SOC that the battery to be tested, which is charged to state-of-charge, is disassembled after power-off, positive at this time Diaphragm with a thickness of H₁', cathode membrane with a thickness of H₂', then the thickness increment H of positive diaphragm_c=H₁′-H₁, cathode membrane Thickness increment H_a=H₂′-H₂；

(3) using having the anode pole piece and/or cathode pole piece of raised point structure prepared to roller to step (1) to carry out roll-in Compacting, to form raised points in positive diaphragm and/or cathode membrane surface, wherein the convex of the positive membrane surface is set The height of starting point is T_c, the height that the raised points on the cathode membrane surface are arranged in is T_a, and 0.3≤(T_c+T_a)/(H_c+H_a) ≤ 1, then obtained anode pole piece, cathode pole piece and isolation film, electrolyte are assembled into battery case to get electricity is arrived again Pond.

9. the preparation method of battery according to claim 8, which is characterized in that in step (1), the anode diaphragm Original depth H₁For 0.1mm~0.4mm.

10. the preparation method of battery according to claim 8, which is characterized in that in step (1), the cathode membrane Original depth H₂For 0.07mm~0.3mm.

Technical field

The present invention relates to battery technology fields more particularly to a kind of battery and preparation method thereof.

Background technique

As the core realm of new-energy automobile industry development, power battery is always the focus of extensive concern, but with The continuous application of new-energy automobile, requirement of the people to power battery energy density are higher and higher.In order to promote power electric Pond energy density, the method taken extensively at present be promoted positive and negative anodes compacted density, promoted collector unit area on painting Cloth weight etc., to obtain compression of the battery core on internal space.But in actual application due to core material physics itself Active force changes or due to battery core inside side reaction product accumulation etc., will cause battery core expansive force and be continuously increased.Such as When capacity attenuation is to 80%, battery core expansive force increases sharply to 35000N under 60 DEG C of cycling conditions, gives power battery module structure band Carry out security risk.Especially when battery core expansive force is more than the endurance of power battery module end plate, power battery module is whole Destructurized, power battery module hierarchical structure unstability will lead to new-energy automobile security performance degradation.

In order to solve the problems, such as battery core expansive force, expansion space is reserved when power battery module level generally uses battery core to assemble Or the schemes such as paster material for increasing absorbable expansion power between adjacent battery core.But it is empty to increase reserved expansion in battery core assembling Between to packaging technology bring larger difficulty, and battery core and the consistency in battery core gap are also relatively difficult to guarantee；Increase between adjacent battery core Although the paster material of absorbable expansion power is added to solve the problems, such as to a certain extent, generally increase in cost more obvious.

Summary of the invention

In view of the problems in the background art, the purpose of the present invention is to provide a kind of battery and preparation method thereof, The characteristics of expansive force of the battery in entire life cycle can be effectively reduced, battery is made to have both high security and long circulation life.

In order to achieve the above object, in the first aspect of the present invention, the present invention provides a kind of batteries comprising battery core with And electrolyte, the battery core include anode pole piece, cathode pole piece and isolation film, the anode pole piece include plus plate current-collecting body with And being set to plus plate current-collecting body surface and the positive diaphragm including positive active material, the cathode pole piece includes negative current collector And it is set to negative current collector surface and the cathode membrane including negative electrode active material, the isolation film is arranged in anode pole piece Between cathode pole piece.In the battery, the anode diaphragm and/or the cathode membrane surface are provided with raised points, In, the height that the raised points of the positive membrane surface are arranged in is T_c, the raised points on the cathode membrane surface are set Height is T_a, thickness increment of the anode diaphragm when battery charge state is 100%SOC is H_c, the cathode membrane exists Thickness increment when battery charge state is 100%SOC is H_a, and 0.3≤(T_c+T_a)/(H_c+H_a)≤1。

In the second aspect of the present invention, the present invention provides a kind of preparation methods of battery, are used to prepare the present invention first Battery described in aspect is done comprising steps of the anode sizing agent including positive active material is coated on plus plate current-collecting body by (1) Anode pole piece is obtained after dry, cold pressing, the negative electrode slurry including negative electrode active material is coated on negative current collector, it is dry, cold Cathode pole piece is obtained after pressure, wherein the original depth of positive diaphragm is H in the anode pole piece₁, cathode in the cathode pole piece The original depth of diaphragm is H₂；(2) anode pole piece, cathode pole piece and isolation film, the electrolyte prepared step (1) assembles Enter in battery case, obtain battery to be tested, it is 100%SOC that the battery to be tested, which is charged to state-of-charge, is powered off laggard Row dismantling, at this time positive diaphragm with a thickness of H₁', cathode membrane with a thickness of H₂', then the thickness increment H of positive diaphragm_c= H₁′-H₁, the thickness increment H of cathode membrane_a=H₂′-H₂；(3) using being prepared to step (1) to roller with raised point structure Good anode pole piece and/or cathode pole piece carries out roll-in compacting, to form protrusion in positive diaphragm and/or cathode membrane surface Point, wherein the height that the raised points of the positive membrane surface are arranged in is T_c, the protrusion on the cathode membrane surface is set The height of point is T_a, and 0.3≤(T_c+T_a)/(H_c+H_a)≤1, then again by obtained anode pole piece, cathode pole piece and isolation Film, electrolyte are assembled into battery case to arrive battery.

Compared with the existing technology, the present invention include at least it is as described below the utility model has the advantages that

The present invention is to solve the problems, such as cell expansion from battery core design angle, in positive diaphragm and/or cathode membrane Raised points are arranged in surface, and the height of raised points is designed according to the thickness increase degree of respective electrode diaphragm, and be positive cathode pole piece Volume expansion advance reservation during cycle charge-discharge goes out space, reduces expansive force of the battery in entire life cycle, drop It is low because of cell expansion bring mould group load pressure, reduce the security risk of power battery module structure.

Battery of the invention has both the characteristics of high security and long circulation life.

Battery structure of the invention is simple, it is possible to reduce production cost improves production efficiency.

Detailed description of the invention

Fig. 1 is the structural schematic diagram of an embodiment of anode pole piece of the invention.

Fig. 2 is the enlarged drawing of part A in Fig. 1.

Fig. 3 is the structural schematic diagram of an embodiment of cathode pole piece of the invention.

Fig. 4 is the enlarged drawing of part B in Fig. 3.

Fig. 5 is the structural schematic diagram of an embodiment of battery core of the invention.

Fig. 6 is the structural schematic diagram of another embodiment of battery core of the invention.

Fig. 7 is the structural schematic diagram of the another embodiment of battery core of the invention.

Wherein, the reference numerals are as follows:

1 anode pole piece

11 plus plate current-collecting bodies

12 positive diaphragms

2 cathode pole pieces

21 negative current collectors

22 cathode membranes

3 isolation films

T raised points

Specific embodiment

The following detailed description of battery according to the present invention and preparation method thereof.

Illustrate battery according to a first aspect of the present invention first comprising battery core and electrolyte.Wherein, referring to figs. 1 to Fig. 7, the battery core include: anode pole piece 1, including plus plate current-collecting body 11 and are set to 11 surface of plus plate current-collecting body and including just The positive diaphragm 12 of pole active material；Cathode pole piece 2, including negative current collector 21 and be set to 21 surface of negative current collector and Cathode membrane 22 including negative electrode active material；And isolation film 3, it is arranged between anode pole piece 1 and cathode pole piece 2.Institute It states in battery, positive diaphragm 12 and/or 22 surface of cathode membrane are provided with raised points T.Wherein, it is arranged on positive 12 surface of diaphragm Raised points T height be T_c, the height that the raised points T on 22 surface of cathode membrane is arranged in is T_a, positive diaphragm 12 is in battery lotus Thickness increment when electricity condition is 100%SOC (i.e. first time full charge) is H_c, cathode membrane 22 is in battery charge state Thickness increment when 100%SOC (i.e. first time full charge) is H_a, and the battery meets: 0.3≤(T_c+T_a)/(H_c+H_a) ≤1。

The present invention solves the problems, such as cell expansion from battery core design angle, in positive diaphragm and/or cathode membrane table Raised points, and the height of the thickness increase degree design raised points according to respective electrode diaphragm in first time full charge is arranged in face It spends, the volume expansion advance reservation during the cathode pole piece cycle charge-discharge that is positive goes out space, reduces battery in entire week in service life Interim expansive force reduces because cell expansion bring mould group bears pressure, reduces the security risk of power battery module structure.

In battery core design of the invention, the raised points of proper height are set in positive diaphragm and/or cathode membrane surface, Battery can have both the characteristics of high security and long circulation life.Raised point height is insufficient, cannot mention in battery charge and discharge process The volume expansion of positive and negative anodes pole piece is accommodated for enough spaces, cell expansion power is still very high, the cycle performance and peace of battery Full performance all will be very poor；Raised points excessive height, although adequate space can be provided in battery charge and discharge process to accommodate just The volume expansion of cathode pole piece, but electrolyte relative deficiency, the electrolyte of positive and negative anodes pole piece are caused in excessive volume expansion space Wellability is deteriorated, and battery polarization increases in charging process, and transmission path of the ion in charge and discharge process is also longer, therefore meeting Seriously affect the service life cycle of battery.Preferably, 0.4≤(T_c+T_a)/(H_c+H_a)≤0.8；It is highly preferred that 0.6≤(T_c+ T_a)/(H_c+H_a)≤0.8。

In battery described in first aspect present invention, the height T of the raised points T on positive 12 surface of diaphragm is set_cWith The height T of the raised points T on 22 surface of cathode membrane is set_aSpecific value be not particularly limited, as long as meeting the two With with (H_c+H_a) the ratio between 0.3~1.

In a specific embodiment, it can be provided only on positive 12 surface of diaphragm referring to Fig. 5, raised points T, at this time negative electrode film The height T of the raised points T on 22 surface of piece_aIt is zero, in this way, the battery meets: 0.3≤T_c/(H_c+H_a)≤1；Preferably, 0.4 ≤T_c/(H_c+H_a)≤0.8；It is highly preferred that 0.6≤T_c/(H_c+H_a)≤0.8。

In another specific embodiment, it can be provided only on 22 surface of cathode membrane referring to Fig. 6, raised points T, it is positive at this time The height T of the raised points T on 12 surface of diaphragm_cIt is zero, in this way, the battery meets: 0.3≤T_a/(H_c+H_a)≤1；Preferably, 0.4≤T_a/(H_c+H_a)≤0.8；It is highly preferred that 0.6≤T_a/(H_c+H_a)≤0.8。

In still another embodiment, referring to Fig. 7, the surface of positive diaphragm 12 and cathode membrane 22 is provided with protrusion Point T, T_aAnd T_cIt is all larger than zero, in this way, the battery meets: 0.3≤(T_c+T_a)/(H_c+H_a)≤1；Preferably, 0.4≤(T_c+ T_a)/(H_c+H_a)≤0.8；It is highly preferred that 0.6≤(T_c+T_a)/(H_c+H_a)≤0.8。

Preferably, raised points T is provided only on positive 12 surface of diaphragm.This is because usually cathode pole piece caking property compared with Low, cathode membrane, which is easy to fall off, to lose powder.

In battery described in first aspect present invention, the raised points T on positive 12 surface of diaphragm can be in material composition Positive diaphragm 12 is consistent, and the raised points T on 22 surface of cathode membrane can be consistent with cathode membrane 22 in material composition.Preferably, Can after pole piece cold pressing process, before winding (or lamination) forms battery core process, by using have raised point structure to roller pair Anode pole piece and/or cathode pole piece carry out roll-in compacting, to form protrusion in positive diaphragm 12 and/or 22 surface of cathode membrane Point T.In this way, production cost can not only be reduced, and high production efficiency.

In battery described in first aspect present invention, it is preferable that raised points T can be distributed in positive diaphragm in array format 12 and/or 22 surface of cathode membrane.

In battery described in first aspect present invention, raised points T can be in various rules or irregular shape, it is preferable that Raised points T can in rounded shape, semicircle shape, square shape, oblong-shaped or trapezoidal shape.

In battery described in first aspect present invention, it is preferable that the In at positive 12 surface of diaphragm is arranged in raised points T Positive 12 surface of diaphragm, the projected area of raised points T are the 10%~60% of 12 gross area of positive diaphragm.

In battery described in first aspect present invention, it is preferable that the In at 22 surface of cathode membrane is arranged in raised points T 22 surface of cathode membrane, the projected area of raised points T are the 10%~60% of 22 gross area of cathode membrane.

In battery described in first aspect present invention, positive diaphragm 12 may be provided at one of them of plus plate current-collecting body 11 On surface, also it can be set on upper and lower two surfaces of plus plate current-collecting body 11.The type of positive active material is not exposed to tool The limitation of body can be selected according to actual needs.By taking lithium ion battery as an example, the positive active material can be selected from lithium transition Metal oxide, lithium transition-metal oxide add in other transition metal or nontransition metal or nonmetallic obtained compound One or more.Preferably, the positive active material can be selected from lithium and cobalt oxides (LiCoO₂), lithium nickel oxide (LiNiO₂), lithium manganese oxide (LiMnO₂), Li, Ni, Mn oxide (LiNi_xMn_2-xO₄, 0≤x≤2), lithium nickel cobalt manganese oxide One or more of (NCM series), lithium nickel cobalt aluminum oxide (NCA series), the li-contained phosphate of olivine structural, olivine The li-contained phosphate of structure can also be coated further by carbon coating layer.The li-contained phosphate material of olivine structural is in charge and discharge Crystal volume in journey is almost unchanged, can farthest reduce the volume expansion because of charge and discharge bring anode pole piece.It is excellent Selection of land, the li-contained phosphate primary particle partial size of olivine structural are 100nm~1 μm.Carbon-coated olivine structural contains lithium The intergranular electric conductivity of positive active material can not only be effectively ensured in phosphate, it can also be ensured that positive diaphragm and anode collect Electric conductivity between fluid；Meanwhile the presence of carbon coating layer can also reduce positive active material and issue in electrolyte effect The probability of raw transition metal (such as Fe element) dissolution, prevents resulting side reaction product from depositing and causing cell expansion power Increase；The thickness of carbon coating layer preferably can be 5nm~13nm.

The general formula of the li-contained phosphate of olivine structural can be LiFe_1-x-yMn_xM’_yPO₄, 0≤x≤1,0≤y≤0.1,0≤ X+y≤1, M ' selected from the other transition metal elements or one or more of non-transition metal elements in addition to Fe, Mn, M ' is preferred It is one or more of in Cr, Mg, Ti, Al, Zn, W, Nb, Zr.It is further preferred that the phosphoric acid containing lithium of the olivine structural Salt is selected from LiFePO4 (LiFePO₄), lithium manganese phosphate (LiMnPO₄), iron manganese phosphate for lithium (LiFe_1-aMn_aPO₄, 0 < a < 1) in It is one or more of.

In battery described in first aspect present invention, positive diaphragm 12 may also include conductive agent and binder.Bonding The type of agent and conductive agent is not exposed to specific limitation, can be selected according to actual needs.Preferably, the binder It can be selected from Kynoar, polytetrafluoroethylene (PTFE), vinylidene-tetrafluoroethylene-propylene terpolymer, vinylidene-hexafluoro third One or more of alkene-tetrafluoroethylene terpolymer, tetrafluoraoethylene-hexafluoropropylene copolymer, fluorinated acrylate resin. Preferably, the conductive agent can be selected from conductive black, superconduction carbon black, electrically conductive graphite, acetylene black, Ketjen black, graphene, carbon nanometer One or more of pipe.

In battery described in first aspect present invention, cathode membrane 22 may be provided at one of them of negative current collector 21 On surface, also it can be set on upper and lower two surfaces of negative current collector 21.The type of negative electrode active material is not exposed to tool The limitation of body can be selected according to actual needs.By taking lithium ion battery as an example, the negative electrode active material can be selected from graphite, One or more of soft carbon, hard carbon, carbon fiber, carbonaceous mesophase spherules, silica-base material, tin-based material, lithium titanate.Wherein, stone Ink can be selected from one or more of artificial graphite, natural graphite, and silica-base material can be selected from elemental silicon, silicon oxide compound, silicon-carbon One or more of compound, silicon alloy, tin-based material can be selected from one of simple substance tin, tin oxygen compound, tin alloy or It is several.Negative electrode active material preferably can be artificial graphite, and the artificial graphite is more preferably non-needle coke offspring, this The particle expansion of kind artificial graphite tends to isotropism, can effectively reduce the expansion of cathode pole piece in a thickness direction, to have Effect reduces cell expansion power.Preferably, the degree of graphitization of the artificial graphite is 91%~95%.

In battery described in first aspect present invention, cathode membrane 22 may also include binder and conductive agent.Bonding The type of agent and conductive agent is not limited specifically, can be selected according to actual needs.Preferably, the binder It can be selected from one or more of SBR emulsion (SBR), sodium carboxymethylcellulose (CMC).Preferably, the conductive agent can Selected from one or more of conductive black, superconduction carbon black, electrically conductive graphite, acetylene black, Ketjen black, graphene, carbon nanotube.

In battery described in first aspect present invention, the type of plus plate current-collecting body is not exposed to specific limitation, can root It is selected according to actual demand.Preferably, plus plate current-collecting body can be aluminium foil or surface is composite base material or the surface setting of aluminium layer There is the aluminium foil of layer of charcoal.

In battery described in first aspect present invention, the type of negative current collector is not exposed to specific limitation, can root It is selected according to actual demand.Preferably, negative current collector can be copper foil or surface is composite base material or the surface setting of layers of copper There is the copper foil of layer of charcoal.

In battery described in first aspect present invention, isolation film 3 can be PE or PP material, and the thickness of isolation film 3 can be 7 μm~20 μm, the porosity of isolation film 3 can be 35%~45%.It not only ensure that the mechanical manufacturability of isolation film in this way, and And ensure that the good imbibition ability of battery and good chemical property, it reduces because side reaction product accumulation bring battery is swollen Expansive force increases.

In battery described in first aspect present invention, electrolyte may include lithium salts, organic solvent and optional addition Agent.

The lithium salts can be organic lithium salt, can also be inorganic lithium salt.Preferably, the lithium salts can be selected from lithium hexafluoro phosphate, LiBF4, lithium perchlorate, hexafluoroarsenate lithium, tetrafluoro oxalic acid lithium phosphate, LiN (SO₂R_F)₂、LiN(SO₂F)(SO₂R_F), double three One or more of fluoromethane sulfimide, bis- (fluorine sulphonyl) imine lithiums, di-oxalate lithium borate, difluorine oxalic acid boracic acid lithium, In, substituent R_FFor C_nF_2n+1, n be 1~10 integer.It is further preferred that the lithium salts is lithium hexafluoro phosphate.Lithium salt It can be 0.6mol/L~1.2mol/L.

The organic solvent may include chain ester and cyclic ester.Chain ester can be selected from dimethyl carbonate, diethyl carbonate, carbon Sour methyl ethyl ester, methyl propyl carbonate, methyl formate, Ethyl formate, methyl acetate, ethyl acetate, propyl propionate, ethyl butyrate, third One or more of acetoacetic ester, propyl butyrate；Cyclic ester can be selected from ethylene carbonate, propene carbonate, butylene, Asia One or more of sulfuric acid vinyl ester, propylene sulfite, gamma-butyrolacton, tetrahydrofuran.In addition, the organic solvent is also It may include different classes of ionic liquid etc..

Additive can be vinylene carbonate, can guarantee the stabilization of SEI film film forming, reduce because of side reaction product zone of illuviation The cell expansion power come increases, and content can be the 1.5%~2.5% of electrolyte total weight.

In battery described in first aspect present invention, the battery further includes battery case, battery case can be used aluminium, Steel or plastic material, the thickness of battery case can be 0.4 μm~1.0 μm.The effect of battery case mainly guarantees to have certain Rigidity reduce cell expansion to generate certain binding force to the expansion of internal battery core in cell expansion and externally act on Power.Battery core can reserve certain spatial margin after entering shell, can be pre- in advance to battery expansion of battery core in charge and discharge process Slot milling reduces battery integrally external expansive force.Wherein, spatial margin may be set to 9%~11%.

Secondly the preparation method of the battery of explanation according to a second aspect of the present invention, is used to prepare described in first aspect present invention Battery, comprising steps of

(1) anode sizing agent including positive active material is coated on plus plate current-collecting body, obtains anode after dry, cold pressing Negative electrode slurry including negative electrode active material is coated on negative current collector by pole piece, obtains cathode pole piece after dry, cold pressing, Wherein the original depth of positive diaphragm is H in the anode pole piece₁, the original depth of cathode membrane is H in the cathode pole piece₂；

(2) anode pole piece, cathode pole piece and isolation film, electrolyte that step (1) prepares are assembled into battery case In, battery to be tested is obtained, it is 100%SOC that the battery to be tested, which is charged to state-of-charge, it is disassembled after power-off, this When anode diaphragm with a thickness of H₁', cathode membrane with a thickness of H₂', then the thickness increment H of positive diaphragm_c=H₁′-H₁, cathode The thickness increment H of diaphragm_a=H₂′-H₂；

(3) using having the anode pole piece and/or cathode pole piece of raised point structure prepared to roller to step (1) to carry out Roll-in compacting, to form raised points in positive diaphragm and/or cathode membrane surface, wherein setting is in the positive membrane surface Raised points height be T_c, the height that the raised points on the cathode membrane surface are arranged in is T_a, and 0.3≤(T_c+T_a)/(H_c+ H_a)≤1, then again by obtained anode pole piece, cathode pole piece and isolation film, electrolyte be assembled into battery case to get To battery.

In the preparation method of battery, the original depth H of the anode diaphragm₁For 0.1mm~0.4mm.

In the preparation method of battery, the original depth H of the cathode membrane₂For 0.07mm~0.3mm.

Below with reference to embodiment, the application is further described.It should be understood that these embodiments be merely to illustrate the application without For limiting scope of the present application.The example that battery is lithium ion battery is only shown in embodiment, but the application is without being limited thereto.