An electric core and a preparation method and application thereof

Abstract

The application discloses a battery cell and a preparation method and application thereof. The battery cell comprises an anode pole piece and a plurality of gel electrolytes, and the plurality of gel electrolytes are distributed on the surface of the anode pole piece in different regions. The application contains a plurality of electrolytes in one battery cell through the characteristics of the gel electrolyte. Specifically, the plurality of gel electrolytes are distributed on the surface of the anode pole piece in different regions or in a laminated manner. The region of different electrolytes in the pole piece can be adjusted according to the dynamics and thermodynamics of different electrolytes, the lithium precipitation problem caused by dynamics or thermodynamics at different positions of the battery cell is improved, and the battery cell has the characteristics of good cycle performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of batteries, and particularly relates to a battery cell and a preparation method and application thereof. BACKGROUND

[0002] A lithium ion battery generally comprises a positive electrode, a negative electrode, a separator and an electrolyte. As an important component of a lithium ion battery, the electrolyte not only determines the migration rate of lithium ions in a liquid phase, but also participates in the formation of an SEI film and plays a key role in the performance of the SEI film. Therefore, the charging performance of a battery can be adjusted by improving the composition of the electrolyte. Currently, a single battery usually contains only one electrolyte on the market. As people have higher and higher requirements for the charging performance of the battery, the charging window adjustment is limited, the lithium precipitation is more likely to occur, and the cycle performance of the battery is relatively poor. + In the liquid phase, also participates in the formation of the SEI film, and plays a key role in the performance of the SEI film. Therefore, the charging performance of a battery can be adjusted by improving the composition of the electrolyte. Currently, a single battery usually contains only one electrolyte on the market. As people have higher and higher requirements for the charging performance of the battery, the charging window adjustment is limited, the lithium precipitation is more likely to occur, and the cycle performance of the battery is relatively poor. SUMMARY

[0003] The application aims to at least solve one of the technical problems existing in the prior art. To this end, the application provides a battery cell, which has good cycle performance.

[0004] The application also provides a preparation method of the battery cell.

[0005] The application also provides a secondary battery.

[0006] The application also provides an electric device.

[0007] The application also provides an application of the battery cell.

[0008] In a first aspect, the application provides a battery cell, which comprises an anode sheet and a plurality of gel electrolytes, and the plurality of gel electrolytes are distributed in regions on the surface of the anode sheet.

[0009] According to the battery cell of the application, at least the following advantages are achieved:

[0010] The application contains a plurality of electrolytes in one battery cell by the characteristics of the gel electrolyte, specifically, a plurality of gel electrolytes are distributed in regions or stacked on the surface of the anode sheet, the regions of different electrolytes in the sheet can be adjusted according to the dynamics and thermodynamics of different electrolytes, the lithium precipitation problem caused by dynamics or thermodynamics at different positions of the battery cell is improved, and the battery cell has good cycle performance. The battery cell in the application is applied to a battery, and the obtained battery has good cycle performance and high safety performance.

[0011] In some embodiments of the application, the battery cell further comprises a cathode sheet, and the gel electrolyte is located between the anode sheet and the cathode sheet.

[0012] In some embodiments of the present application, the battery cell further comprises a first separator, and the gel electrolyte is located between the anode electrode and the first separator.

[0013] In some embodiments of the present application, the battery cell further comprises a second separator, and the second separator is located on the side of the cathode electrode away from the anode electrode.

[0014] In some embodiments of the present application, the plurality of gel electrolytes are distributed in different regions on the surface of the anode electrode.

[0015] The plurality of gel electrolytes distributed in different regions on the surface of the anode electrode include, but are not limited to, parallel distribution, cross distribution, etc.

[0016] In some preferred embodiments of the present application, the surface of the anode electrode comprises a long film surface and a short film surface.

[0017] In some embodiments of the present application, the battery cell comprises n gel electrolytes, n≥2, and n is an integer.

[0018] In some embodiments of the present application, the gel electrolyte comprises gel electrolyte I and gel electrolyte II.

[0019] In some preferred embodiments of the present application, the gel electrolyte I comprises gel factor I and lithium salt I.

[0020] In some more preferred embodiments of the present application, the gel factor I comprises gel monomer I, crosslinking agent I and initiator I.

[0021] In some more preferred embodiments of the present application, the gel monomer I comprises cyano acrylate. Preferably, the gel monomer I comprises cyano acrylate.

[0022] In some more preferred embodiments of the present application, the mass fraction of the gel monomer I in the gel electrolyte I is 5-10%.

[0023] In some more preferred embodiments of the present application, the crosslinking agent I comprises acrylate. Preferably, the crosslinking agent I comprises acrylate.

[0024] In some more preferred embodiments of the present application, the mass fraction of the crosslinking agent I in the gel electrolyte I is 1-5%.

[0025] In some more preferred embodiments of the present application, the initiator I comprises one of dibenzoyl peroxide, acetyl peroxide, di-t-butyl peroxide, azobisisobutyronitrile or azobisisoheptyl nitrile.

[0026] In some more preferable embodiments of the present application, the mass fraction of the initiator I in the gel electrolyte I is 1-5%.

[0027] In some more preferable embodiments of the present application, the mass fraction of the gelling agent I in the gel electrolyte I is 7-20%.

[0028] In some more preferable embodiments of the present application, the lithium salt I comprises at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4) or lithium bis-trifluoromethanesulfonimide (LiTFSI).

[0029] Through the above embodiments, the lithium salt I has high conductivity and good stability, which can better improve the performance of the gel electrolyte I, and further improve the performance of the battery cell.

[0030] In some more preferable embodiments of the present application, the mass fraction of the lithium salt I in the gel electrolyte I is 5-15%.

[0031] Through the above embodiments, the gel electrolyte I has excellent kinetic performance.

[0032] In some preferable embodiments of the present application, the gel electrolyte I comprises an electrolyte solvent I.

[0033] In some more preferable embodiments of the present application, the electrolyte solvent I comprises at least one of a carbonate compound I or an ester solvent I.

[0034] In some more preferable embodiments of the present application, the carbonate compound I comprises at least one of ethylene carbonate (EC) or propylene carbonate (PC).

[0035] In some more preferable embodiments of the present application, the viscosity of the ester solvent I at 25°C is 0.2-0.6 mPa·s.

[0036] Through the above embodiments, the addition of the low-viscosity solvent, the ester solvent I, can reduce the internal impedance of the battery cell and accelerate the Li + ion transfer rate, thereby increasing the kinetic performance and high-low temperature performance of the battery cell, etc.

[0037] In some more preferable embodiments of the present application, the ester solvent I comprises at least one of ethyl propionate (EA), propyl acetate (EP) or propyl propionate (PP).

[0038] In some more preferable embodiments of the present application, the mass fraction of the carbonate compound I in the gel electrolyte I is 50-75%.

[0039] In some more preferable embodiments of the present application, the mass fraction of the ester solvent I in the gel electrolyte I is 15-28%.

[0040] In some preferable embodiments of the present application, the gel electrolyte I further comprises an additive I.

[0041] In some more preferable embodiments of the present application, the additive I comprises at least one of an ester compound I or a cyanogen additive I.

[0042] In some more preferable embodiments of the present application, the ester compound I comprises vinylene carbonate.

[0043] In some more preferable embodiments of the present application, the cyanogen additive I comprises at least one of ammonium nitrodiamide (AND), ethylene glycol monobutyl ether (EGBE) or hexanetricarbonitrile (HTCN).

[0044] In some more preferable embodiments of the present application, the mass fraction of the additive I in the gel electrolyte I is 3-8%.

[0045] In some preferable embodiments of the present application, the gel electrolyte I comprises 7-20% of the gel factor I, 5-15% of the lithium salt I, 3-8% of the additive I, and the rest is the electrolyte solvent I, based on the total mass of the gel electrolyte I.

[0046] In some preferable embodiments of the present application, the gel electrolyte I comprises 5-10% of the gel monomer I, 1-5% of the crosslinking agent I, 1-5% of the initiator I, 5-15% of the lithium salt I, 3-8% of the additive I, and the rest is the electrolyte solvent I, based on the total mass of the gel electrolyte I.

[0047] In some preferable embodiments of the present application, the gel electrolyte I comprises 5-10% of the gel monomer I, 1-5% of the crosslinking agent I, 1-5% of the initiator I, 5-15% of the lithium salt I, 3-8% of the additive I, 50-75% of the carbonate compound I and 15-28% of the ester solvent I, based on the total mass of the gel electrolyte I.

[0048] In some preferable embodiments of the present application, the gel electrolyte II comprises a gel factor II and a lithium salt II.

[0049] In some more preferable embodiments of the present application, the gel factor II comprises a gel monomer II, a crosslinking agent II and an initiator II.

[0050] In some more preferable embodiments of the present application, the gel monomer II comprises a cyano acrylate substance. Preferably, the gel monomer II comprises a cyano acrylate.

[0051] In some more preferable embodiments of the present application, the mass fraction of the gel monomer II in the gel electrolyte II is 5-10%.

[0052] In some more preferable embodiments of the present application, the crosslinking agent II comprises an acrylate substance. Preferably, the crosslinking agent II comprises an acrylate.

[0053] In some more preferable embodiments of the present application, the mass fraction of the crosslinking agent II in the gel electrolyte II is 1-5%.

[0054] In some more preferable embodiments of the present application, the initiator II comprises one of dibenzoyl peroxide, acetyl peroxide, di-t-butyl peroxide, azobisisobutyronitrile or azobisisoheptyl nitrile.

[0055] In some more preferable embodiments of the present application, the mass fraction of the initiator II in the gel electrolyte II is 1-5%.

[0056] In some more preferable embodiments of the present application, the mass fraction of the gel factor II in the gel electrolyte II is 7-20%.

[0057] In some more preferable embodiments of the present application, the lithium salt II comprises at least one of lithium hexafluorophosphate (LiPF6), lithium bis-trifluoromethanesulfonylimide (LiTFSI) or lithium difluorophosphate (LiPO2F2).

[0058] Through the above embodiments, lithium hexafluorophosphate (LiPF6) has high conductivity and good stability, lithium bis-trifluoromethanesulfonylimide (LiTFSI) has good solubility and low-temperature performance, and lithium difluorophosphate (LiPO2F2) has better cycle performance and high-temperature storage performance, which can better improve the performance of the gel electrolyte I and further improve the performance of the battery cell.

[0059] In some more preferable embodiments of the present application, the mass fraction of the lithium salt I in the gel electrolyte I is 5-20%.

[0060] Through the above embodiments, the gel electrolyte II has better comprehensive performance, especially good high-pressure resistance and safety performance.

[0061] In some preferable embodiments of the present application, the gel electrolyte II further comprises an electrolyte solvent II.

[0062] In some more preferable embodiments of the present application, the electrolyte solvent II comprises at least one of carbonic ester compound II or ester solvent II.

[0063] In some more preferable embodiments of the present application, the carbonic ester compound II comprises at least one of ethylene carbonate (EC), propylene carbonate (PC) or diethyl carbonate (DEC).

[0064] In some more preferable embodiments of the present application, the ester solvent II has a viscosity of 0.15-1.5 mPa·s at 25°C.

[0065] By the above embodiments, the addition of the low-viscosity solvent, the ester solvent II, can reduce the internal impedance of the battery cell and accelerate the Li + ion transfer rate, thus increasing the kinetic performance and high-low temperature performance of the battery cell, etc.

[0066] In some more preferable embodiments of the present application, the ester solvent II comprises propyl propionate (PP).

[0067] Propyl propionate (PP) is a solvent that takes into account the high-low temperature performance.

[0068] In some more preferable embodiments of the present application, in the gel electrolyte II, the mass fraction of the carbonic ester compound II is 40-65%.

[0069] In some more preferable embodiments of the present application, in the gel electrolyte II, the mass fraction of the ester solvent II is not higher than 30%.

[0070] In some more preferable embodiments of the present application, in the gel electrolyte II, the mass fraction of the ester solvent II is 18-30%.

[0071] In some more preferable embodiments of the present application, in the gel electrolyte II, the mass fraction of the ester solvent II is 20-30%.

[0072] In some preferable embodiments of the present application, the gel electrolyte II further comprises an additive II.

[0073] In some more preferable embodiments of the present application, the additive II comprises at least one of ester compound II or cyanide additive II.

[0074] In some more preferable embodiments of the present application, the ester compound II comprises vinylene carbonate.

[0075] In some more preferable embodiments of the present application, the cyan additive II comprises at least one of ammonium dinitramide (AND), succinonitrile (SN), hexanetristriazide (HTCN) or LDY242. Among them, LDY242 is a positive complex additive.

[0076] The cyan additive II improves the battery hot box test effect.

[0077] In some more preferable embodiments of the present application, the mass fraction of the additive II in the gel electrolyte II is 5-8%.

[0078] In some preferable embodiments of the present application, in the gel electrolyte II, based on the total mass of the gel electrolyte II, 7-20% of the gel factor II, 5-20% of the lithium salt II, 5-8% of the additive II, and the balance of the electrolyte solvent II are included.

[0079] In some preferable embodiments of the present application, in the gel electrolyte II, based on the total mass of the gel electrolyte II, 5-10% of the gel monomer II, 1-5% of the crosslinking agent II, 1-5% of the initiator II, 5-20% of the lithium salt II, 5-8% of the additive II, 40-65% of the carbonate compound II and 18-30% of the ester solvent II are included.

[0080] In some preferable embodiments of the present application, in the gel electrolyte II, based on the total mass of the gel electrolyte II, 5-10% of the gel monomer II, 1-5% of the crosslinking agent II, 1-5% of the initiator II, 5-20% of the lithium salt II, 5-8% of the additive II, 40-65% of the carbonate compound II and 18-30% of the ester solvent II are included.

[0081] In some preferable embodiments of the present application, the gel electrolyte I and the gel electrolyte II are distributed in different regions on the surface of the anode electrode sheet, and the gel electrolyte I and the gel electrolyte II are in contact.

[0082] In some preferable embodiments of the present application, the edge of the surface of the anode electrode sheet is provided with the gel electrolyte I.

[0083] In some preferable embodiments of the present application, the middle of the surface of the anode electrode sheet is provided with the gel electrolyte II.

[0084] In some preferable embodiments of the present application, the surface of the anode electrode sheet has a plurality of gel electrolyte I regions separated by gel electrolyte II regions.

[0085] In some preferable embodiments of the present application, the gel electrolyte I is distributed on the edge of the surface of the anode electrode sheet, and the gel electrolyte II is distributed on the middle of the surface of the anode electrode sheet.

[0086] In view of the fact that lithium precipitation of the battery cell is in a regional manner, such as easy lithium precipitation at the edge of the electrode sheet (including lithium precipitation at the head and tail of the electrode sheet), the present application adopts regional distribution of gel electrolyte I and gel electrolyte II, and distributes gel electrolyte I at the edge of the battery cell to improve the situation of lithium precipitation at the edge or lithium precipitation at the head and tail of the electrode sheet, so that the battery cell is less likely to precipitate lithium.

[0087] In some preferred embodiments of the present application, the gel electrolyte I is distributed on both ends of the surface of the anode electrode sheet along the length direction of the anode electrode sheet.

[0088] In some preferred embodiments of the present application, the gel electrolyte I is distributed on both ends of the surface of the anode electrode sheet along the width direction of the anode electrode sheet.

[0089] In some preferred embodiments of the present application, the gel electrolyte I, the gel electrolyte II and the gel electrolyte I are sequentially distributed on the surface of the anode electrode sheet in a transverse manner.

[0090] In some preferred embodiments of the present application, the gel electrolyte I, the gel electrolyte II and the gel electrolyte I are sequentially distributed on the surface of the anode electrode sheet in a longitudinal manner.

[0091] In some preferred embodiments of the present application, the gel electrolyte I, the gel electrolyte II and the gel electrolyte I are sequentially distributed on the surface of the anode electrode sheet in a transverse manner; or, the gel electrolyte I, the gel electrolyte II and the gel electrolyte I are sequentially distributed on the surface of the anode electrode sheet in a longitudinal manner.

[0092] In some preferred embodiments of the present application, the gel electrolyte I, the gel electrolyte II and the gel electrolyte I are sequentially distributed on the surface of the anode electrode sheet along the length direction of the anode electrode sheet; or, the gel electrolyte I, the gel electrolyte II and the gel electrolyte I are sequentially distributed on the surface of the anode electrode sheet along the width direction of the anode electrode sheet.

[0093] In some preferred embodiments of the present application, the area ratio of the sequentially distributed gel electrolyte I, gel electrolyte II and gel electrolyte I is (0.8-1.2):(2.8-3.2):(0.8-1.2).

[0094] Through the above-mentioned embodiments, the area ratio of the sequentially distributed gel electrolyte is also a factor affecting the performance of the battery cell, and the area ratio of (0.8-1.2):(2.8-3.2):(0.8-1.2) is adopted in the present application to further improve the situation of lithium precipitation at the edge of the battery cell (including lithium precipitation at the head and tail of the electrode sheet).

[0095] In the second aspect of the present application, a preparation method of a battery cell is provided, which comprises the following steps: regionally coating a plurality of kinds of gel electrolyte on the surface of the anode electrode sheet.

[0096] In some embodiments of the present application, the preparation method comprises the following steps:

[0097] S1, preparing a gel electrolyte I; preparing a gel electrolyte II;

[0098] S2, spraying the gel electrolyte I and the gel electrolyte II on the surface of the anode electrode sheet in different regions.

[0099] In a third aspect of the present application, a secondary battery is provided, comprising the above-mentioned battery cell.

[0100] In some embodiments of the present application, the secondary battery comprises at least one of a lithium ion battery or a sodium ion battery.

[0101] In a fourth aspect of the present application, an electric device is provided, comprising the above-mentioned secondary battery.

[0102] In a fifth aspect of the present application, the above-mentioned battery cell is applied in the preparation of a battery or an electric device. BRIEF DESCRIPTION OF DRAWINGS

[0103] The present application will be further described below in conjunction with the drawings and examples, in which:

[0104] Figure 1 FIG. 1 is a distribution diagram of the gel electrolyte I and the gel electrolyte II in Example 1 of the present application;

[0105] Figure 2 FIG. 2 is a distribution diagram of the gel electrolyte I and the gel electrolyte II in Example 2 of the present application;

[0106] Figure 3 FIG. 3 is a cycle performance test result diagram of the battery cell in Example 1 and Comparative Example 1 of the present application;

[0107] Figure 4 FIG. 4 is a Swelling test result diagram of the battery cell in Example 1 and Comparative Example 1 of the present application during the cycle process;

[0108] Figure 5 FIG. 5 is a picture of the interface disassembly of the battery cell in Comparative Example 1 of the present application after 1200 cycles;

[0109] Figure 6 FIG. 6 is a picture of the interface disassembly of the battery cell in Example 1 of the present application after 1200 cycles;

[0110] Figure 7 FIG. 7 is a distribution diagram of the gel electrolyte I and the gel electrolyte II in Example 3 of the present application.

[0111] FIG. 8 is a distribution diagram of the gel electrolyte I and the gel electrolyte II in Example 4 of the present application. DETAILED DESCRIPTION

[0112] The concept and the technical effects of the present application will be described clearly and completely in combination with the embodiments, so as to fully understand the purposes, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0113] The experimental methods not specified in the following embodiments are generally according to the conventional conditions or according to the suggested conditions of the manufacturers; the raw materials, reagents and the like used, if not specifically stated, are all raw materials and reagents that can be obtained by commercial means.

[0114] Example 1

[0115] The present embodiment discloses a battery cell, and the preparation process thereof comprises:

[0116] (I) Preparation of gel electrolyte:

[0117] 1) Preparation of gel electrolyte I: the gel electrolyte I is prepared by the methods of rectification, dehydration and alcohol removal, and detection, wherein the gel electrolyte I comprises electrolyte solvent I, lithium salt I, gel factor I, and additive I: wherein, according to the mass fraction, the electrolyte solvent I comprises 25.8% of EC, 30.0% of PC, 10.3% of EP, and 8.6% of PP (the viscosity of the mixture of EP and PP is 0.2-0.6 mPa·s at 25℃); the additive I is: 2.6% of AND, 0.4% of EGBE, and 1.7% of HTCN; the lithium salt I comprises 8.6% of LiPF6, 1.3% of LiBF4, and 0.4% of LiTFSI; the gel factor I comprises 5.2% of gel monomer I, 2.6% of crosslinking agent I, and 2.5% of initiator I, the gel monomer I is n-butyl cyanoacrylate, the crosslinking agent I is butyl acrylate, and the initiator I is dibenzoyl peroxide (acetyl peroxide, di-tert-butyl peroxide, azobisisobutyronitrile or azobisisoheptyl nitrile can also be used);

[0118] The electrolyte solvent I, the lithium salt I, the additive I, and the gel factor I are mixed to obtain the gel electrolyte I.

[0119] 2) Preparation of the gel electrolyte II: the gel electrolyte II is prepared by the method of rectification, dehydration and alcohol removal, and detection, wherein the gel electrolyte II includes electrolyte solvent II, lithium salt II, gel factor II, and additive II, wherein, by mass fraction, the electrolyte solvent II includes 7.7% of EC, 17% of PC, 23% of DEC, and 23% of PP (the viscosity of PP is 0.15-1.5 mPa·s, 25°C); the additive II is 2.6% of AND, 0.9% of SN (butanedinitrile), and 1.7% of HTCN (1,3,6-hexanetristriazine); the lithium salt II includes 12.8% of LiPF6, 0.9% of LiTFSI, and 0.4% of LiPO2F2; the gel factor II is 5.1% of gel monomer II, 2.6% of crosslinking agent II, and 2.3% of initiator II, the gel monomer II is n-butyl cyanoacrylate, the crosslinking agent II is butyl acrylate, and the initiator II is dibenzoyl peroxide (acetyl peroxide, di-tert-butyl peroxide, azobisisobutyronitrile, or azobisisoheptyl nitrile can also be used);

[0120] The electrolyte solvent II, the lithium salt II, the additive II, and the gel factor II are mixed to obtain the gel electrolyte II.

[0121] (II) The anode sheet (the anode active ingredient is graphite) after rolling and slitting is sprayed with the gel electrolyte I and the gel electrolyte II in the manner of Figure 1 The gel electrolyte I and the gel electrolyte II are distributed at both ends of the surface of the anode sheet in the length direction of the surface of the anode sheet: the gel electrolyte I is coated at the head / tail position of the anode sheet, and the gel electrolyte II is coated at the middle position, wherein the area ratio of the gel electrolyte I, the gel electrolyte II, and the gel electrolyte I distributed in the length direction of the anode sheet is 1:3:1. After the gel electrolyte is coated, the cathode sheet (the cathode active ingredient is lithium cobaltate) after slitting, a separator are wound, rubber-coated, top side edge sealed, baked, formed, double-sealed, divided, aged, OCV, and appearance detected to obtain the battery cell.

[0122] Example 2

[0123] The difference between the battery cell of the present example and the battery cell of Example 1 is only that the distribution of the gel electrolyte I and the gel electrolyte II is different, and in the present example, the anode sheet after rolling and slitting is sprayed with the gel electrolyte I and the gel electrolyte II in the manner of Figure 2 The gel electrolyte I and the gel electrolyte II are distributed at both ends of the surface of the anode sheet in the length direction of the surface of the anode sheet: the gel electrolyte I is coated at the head / tail position of the anode sheet, and the gel electrolyte II is coated at the middle position, wherein the area ratio of the gel electrolyte I, the gel electrolyte II, and the gel electrolyte I distributed in the length direction of the anode sheet is 1:3:1.

[0124] Example 3

[0125] The embodiment discloses a battery cell, which is different from the embodiment 1 only in that the distribution of the gel electrolyte I and the gel electrolyte II is different, in the embodiment, the gel electrolyte I and the gel electrolyte II are sprayed on the anode sheet after rolling and slitting in the form of region division (the gel electrolyte I is distributed on the edge of the surface of the anode sheet, and the gel electrolyte II is coated in the middle part). Figure 7 The area ratio of the gel electrolyte I and the gel electrolyte II distributed on the anode sheet is 1:2.5.

[0126] Comparative example 1

[0127] The comparative example discloses a battery cell, which is different from the embodiment 1 only in that the electrolyte in the comparative example only includes the gel electrolyte II, and specifically, the preparation process of the battery cell in the comparative example includes:

[0128] The anode sheet, the diaphragm after rolling and slitting are wound, the top side edge is sealed, and the gel electrolyte II is injected after baking before liquid injection (the preparation and composition of the gel electrolyte II are the same as those in the embodiment 1, and the gel electrolyte II is detected, filled, and stored in the warehouse as a finished product). After the battery is injected, baking, formation, second sealing, capacity grading, aging, OCV and appearance detection are performed to obtain the battery cell.

[0129] Test example

[0130] The lithium cobaltate material obtained in the embodiment and the comparative example is subjected to performance testing, and specifically includes:

[0131] 1. The cycle performance of the battery cell prepared in the embodiment 1 and the comparative example 1 is tested, and the test result is shown in Table 1. Figure 3 The cycle performance test procedure is as follows: 14.1 A constant current charging to 4.25 V, 12 A constant current charging to 4.35 V, 8 A constant current constant voltage charging to 4.5 V, 0.05 C cutoff; 0.7 C constant current discharging to 3.0 V, and cycling for 1500 times.

[0132] 2. The cycle process swelling of the battery cell prepared in the embodiment 1 and the comparative example 1 is tested, and the test result is shown in Table 2. Figure 4 The specific test procedure includes the following steps: every 50 cycles, after full charging, the thickness of the battery cell is tested by using a flat plate thickness gauge, and the pressure of the flat plate thickness gauge is 500 g.

[0133] 3. The interface condition of the battery cell prepared in the comparative example 1 and the embodiment 1 after 1200 cycles (the test procedure is the same as that described in part 1 of the test example) is tested, and the battery interface disassembly photos are shown in Figs. 1 and 2, respectively. Figure 5 Figure 6

[0134] ​​The battery cell cycle performance test data shows that the battery cell using only one electrolyte formulation (Comparative Example 1) has worse cycle performance than the battery cell using two electrolyte formulations. Furthermore, as the number of cycles increases, the thickness of the battery cell made in Comparative Example 1 suddenly and drastically increases around 800 cycles, indicating that lithium plating has occurred at this point. The battery cell made in Example 1 does not exhibit this phenomenon, and the interface of Example 1 is significantly better than that of Comparative Example 1.

[0135] Both gel electrolytes I and II are made through intermolecular hydrophilic-hydrophobic interactions of their components. The main differences between the two gel electrolytes include variations in the type and content of the electrolyte solvent, additives, and lithium salt, resulting in different focuses for improving the battery cell. Specifically, gel electrolyte I exhibits superior kinetic performance compared to gel electrolyte II. This is primarily because gel electrolyte I uses solvents with lower viscosity, such as EP and PP, with a viscosity range of 0.2-0.6 mPa·s (25℃). Adding low-viscosity solvents reduces the internal impedance of the battery cell and accelerates Li-ion exchange. + The rate of change increases the kinetic performance and high / low temperature performance of the battery cell. Gel electrolyte II, compared to gel electrolyte I, uses fewer types of low-viscosity solvents, with a low-viscosity solvent range of 0.5-1.5 mPa·s (25℃). Gel electrolyte II has superior overall performance, especially in high voltage resistance and safety. (See attached...) Figure 1 and 2 As shown, a gel electrolyte I with good kinetic properties is sprayed or scraped onto both ends / both sides of the cathode or anode electrode to prevent lithium deposition at the electrode edges (the edges along the length of the electrode) and the beginning and end (the edges along the width of the electrode). A gel electrolyte II with superior overall performance is sprayed onto one end of the cathode or anode to prevent lithium deposition in the middle of the electrode due to insufficient wetting. Examples 1-3 all effectively improve lithium deposition in the cell, thereby improving cycle performance.

[0136] Considering that lithium plating in battery cells occurs in different regions, such as the edges of electrodes where lithium plating is more likely to occur (including the head and tail of electrodes), this invention uses gel electrolyte I and gel electrolyte II distributed in different regions. Gel electrolyte I is distributed at the edges of the battery cell to improve the situation of edge lithium plating or head and tail lithium plating, making the battery cell less prone to lithium plating.

[0137] In summary, this invention incorporates multiple electrolytes (2 to n) with different formulations into a single battery cell. For example, electrolyte 1 and electrolyte 2 have different formulations. They are mixed separately in a gel to form gel electrolyte I and gel electrolyte II. These are then coated in different areas of the electrode where lithium plating is prone to occur, thereby improving the lithium plating performance.

[0138] It should be noted that, unless otherwise specified, "room temperature" or "normal temperature" in this article refers to approximately 25°C; and the word "approximately" in numerical values ​​in this article means an error of ±2%.

[0139] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application. Furthermore, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A battery cell, characterized in that, The battery cell includes an anode plate and several types of gel electrolytes, which are distributed in different regions on the surface of the anode plate. The gel electrolytes include gel electrolyte I and gel electrolyte II. The kinetic performance of gel electrolyte I is better than that of gel electrolyte II, while gel electrolyte II has better high voltage resistance and safety performance. The gel electrolyte I and gel electrolyte II are distributed in separate regions on the surface of the anode plate, and the gel electrolyte I and gel electrolyte II are in contact with each other; The gel electrolyte I is disposed at both ends or both sides of the anode plate, and the gel electrolyte II is disposed in the middle of the anode plate.

2. The battery cell according to claim 1, characterized in that, The gel electrolyte I includes electrolyte solvent I, which includes ester solvent I.

3. The battery cell according to claim 2, characterized in that, The viscosity of the ester solvent I at 25°C is 0.2-0.6 mPa·s.

4. The battery cell according to claim 1, characterized in that, The gel electrolyte I includes electrolyte solvent I, which includes carbonate compound I.

5. The battery cell according to claim 4, characterized in that, The carbonate compound I includes at least one of ethylene carbonate or propylene carbonate.

6. The battery cell according to claim 1, characterized in that, The gel electrolyte II includes electrolyte solvent II, which includes ester solvent II.

7. The battery cell according to claim 6, characterized in that, The viscosity of the ester solvent II at 25°C is 0.15-1.5 mPa·s.

8. The battery cell according to claim 1, characterized in that, The gel electrolyte II includes electrolyte solvent II, which includes carbonate compound II.

9. The battery cell according to claim 8, characterized in that, The carbonate compound II includes at least one of ethylene carbonate, propylene carbonate, or diethyl carbonate.

10. The battery cell according to claim 1, characterized in that, Gel electrolyte I, gel electrolyte II, and gel electrolyte I are sequentially and laterally distributed on the surface of the anode electrode. Alternatively, gel electrolyte I, gel electrolyte II, and gel electrolyte I are sequentially and longitudinally distributed on the surface of the anode electrode.

11. A method for preparing a battery cell according to any one of claims 1-10, characterized in that, The process includes the following steps: coating several types of gel electrolytes onto the surface of the anode electrode in different areas.

12. A secondary battery, characterized in that, Includes the battery cell as described in any one of claims 1-10.

13. The use of the battery cell as described in any one of claims 1-10 in the manufacture of batteries or electrical devices.

Images