CN220382154U - Secondary battery and electronic device - Google Patents
Secondary battery and electronic device Download PDFInfo
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- CN220382154U CN220382154U CN202321391222.1U CN202321391222U CN220382154U CN 220382154 U CN220382154 U CN 220382154U CN 202321391222 U CN202321391222 U CN 202321391222U CN 220382154 U CN220382154 U CN 220382154U
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- active material
- material layer
- secondary battery
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- 239000006183 anode active material Substances 0.000 claims description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 19
- 229910052744 lithium Inorganic materials 0.000 description 19
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- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 3
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- 239000011230 binding agent Substances 0.000 description 3
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- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 3
- 229910003002 lithium salt Inorganic materials 0.000 description 3
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- 229920002943 EPDM rubber Polymers 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical group [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
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- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
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- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
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- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 2
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- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 2
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 2
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- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
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- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 description 1
- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 239000002585 base Substances 0.000 description 1
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- 238000010281 constant-current constant-voltage charging Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
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- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
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- 150000002148 esters Chemical class 0.000 description 1
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- 229910021385 hard carbon Inorganic materials 0.000 description 1
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- 239000007788 liquid Substances 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
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- CXHHBNMLPJOKQD-UHFFFAOYSA-M methyl carbonate Chemical compound COC([O-])=O CXHHBNMLPJOKQD-UHFFFAOYSA-M 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
Landscapes
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
The utility model provides a secondary battery and an electronic device, wherein the secondary battery comprises: a positive electrode sheet; a diaphragm; the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer positioned on at least one side of the negative electrode current collector, the thickness of the negative electrode active material layer is consistent, and the diaphragm is arranged between the negative electrode plate and the positive electrode plate; and a negative electrode tab disposed on one side of the negative electrode active material layer, the negative electrode tab including a first skived region and a first blank region, the first skived region being disposed between the negative electrode active material layer and the first blank region. The secondary battery and the electronic equipment provided by the utility model can improve the performance of the secondary battery and reduce the safety problem.
Description
Technical Field
The utility model relates to the technical field of secondary batteries, in particular to a secondary battery and electronic equipment.
Background
The secondary battery is used as a reusable secondary battery, and is widely applied to the fields of 3C digital products, two-wheelers, passenger cars, commercial vehicles, electric tools, standby power supplies of communication base stations, energy storage systems and the like, thereby leading to new social transformation in the energy field. However, with the popularization and application of secondary batteries, safety problems sometimes occur due to thermal runaway inside the secondary batteries, which causes great loss of life and property for humans.
On the one hand, due to abuse of the secondary battery and on the other hand, due to the quality of the secondary battery, during repeated charge and discharge of the secondary battery, due to thickening of a solid electrolyte interface film (Solid Electrolyte Interface, SEI), increase of internal resistance, drying of electrolyte, blocking of diaphragm pores and the like, lithium precipitation problems are generated, and lithium precipitation is accumulated to a certain extent, so that the use safety of the secondary battery is seriously affected, such as reduction of battery capacity, thermal runaway caused by penetration of lithium dendrites through the diaphragm and the like.
In the application of publication No. CN115020824a, by controlling the injection amount of the secondary battery electrolyte, the increase ratio of the edge thickness can be reduced, the edge lithium precipitation can be improved, and the cycle performance of the secondary battery can be improved. In the application of publication No. CN106093777a, it is directly determined whether or not lithium precipitation occurs in the secondary battery by comparing coulombic efficiency data of charge and discharge cycles of the secondary battery before and after standing. In order to ensure that the secondary battery has good electrochemical performance, the liquid injection amount is generally designed excessively, but the phenomenon of lithium precipitation at the edge of the pole piece still occurs, and the problem of lithium precipitation at the edge of the pole piece cannot be fundamentally solved.
Disclosure of Invention
The utility model provides a secondary battery and electronic equipment, which can reduce the phenomenon of lithium precipitation at the edge of a pole piece, improve the performance of the secondary battery and reduce the safety problem.
In order to solve the technical problems, the utility model is realized by the following technical scheme.
The present utility model provides a secondary battery, comprising at least:
a positive electrode sheet;
a diaphragm;
the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer positioned on at least one side of the negative electrode current collector, the thickness of the negative electrode active material layer is consistent, and the diaphragm is arranged between the negative electrode plate and the positive electrode plate; and
the negative electrode tab is arranged on one side of the negative electrode active material layer and comprises a first skived area and a first blank area, and the first skived area is arranged between the negative electrode active material layer and the first blank area.
In one embodiment of the utility model, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer positioned on at least one side of the positive electrode current collector, wherein the thickness of the positive electrode active material layer is consistent.
In an embodiment of the present utility model, the secondary battery further includes a positive electrode tab disposed at one side of the positive electrode active material layer.
In an embodiment of the present utility model, the positive electrode tab includes a second skived region and a second blank region, and the second skived region is disposed between the positive electrode active material layer and the second blank region.
In an embodiment of the present utility model, the width of the positive electrode active material layer is smaller than the width of the negative electrode active material layer, and the difference between the widths of the negative electrode active material layer and the positive electrode active material layer is smaller than 5mm.
In an embodiment of the present utility model, the length of the positive electrode piece is less than or equal to the length of the negative electrode piece; or alternatively, the first and second heat exchangers may be,
the first skived zone has a width greater than 0 and less than 40mm.
In one embodiment of the present utility model, the thickness of the anode coating layer on the first skived zone is smaller than the thickness of the anode coating layer on the anode active material layer.
In an embodiment of the present utility model, the thickness of the positive electrode coating layer on the second skived zone is smaller than the thickness of the positive electrode coating layer on the positive electrode active material layer.
In an embodiment of the present utility model, the shape of the negative electrode tab and/or the positive electrode tab is rectangular or trapezoidal.
The utility model also provides electronic equipment comprising the secondary battery.
In summary, the utility model provides a secondary battery and an electronic device, which can ensure that the thicknesses of active material layers of a positive electrode plate and a negative electrode plate are at the same level, ensure that the gaps of the positive electrode plate and the negative electrode plate are at the same level, ensure the consistency of charge and discharge, and improve the performance of the secondary battery. And solves the problem of lithium precipitation at the edge of the pole piece, which is easy to occur in the use process of the secondary battery, and reduces the safety problem.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic view of a secondary battery according to an embodiment.
Fig. 2 is a schematic view of a positive electrode current collector and a positive electrode coating in an embodiment.
Fig. 3 is a schematic side view of fig. 2.
Fig. 4 is a schematic view of a positive electrode sheet according to an embodiment.
Fig. 5 is a schematic view of a negative electrode current collector and a negative electrode coating in an embodiment.
Fig. 6 is a schematic side view of fig. 5.
Fig. 7 is a schematic view of a negative electrode tab in an embodiment.
Fig. 8 is a schematic view of the positive electrode sheet in comparative example 1.
Fig. 9 is a schematic view of the negative electrode tab in comparative example 1.
Fig. 10 is a schematic view of cycle performance of the secondary batteries obtained in example 1 and comparative example 1.
Description of the reference numerals:
100. a positive electrode sheet; 200. a negative electrode plate; 300. a diaphragm; 400. an electrolyte; 10. a positive electrode current collector; 11. a positive electrode active material layer; 111. a positive electrode coating; 12. a positive electrode thinning region; 121. a second skiving region; 13. a positive electrode blank region; 131. a second blank area; 14. a positive electrode tab; 20. a negative electrode current collector; 21. a negative electrode active material layer; 211. a negative electrode coating; 22. a negative electrode skiving area; 221. a first skiving region; 23. a negative electrode blank region; 231. a first blank area; 24. and a negative electrode tab.
Detailed Description
Other advantages and effects of the present utility model will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present utility model with reference to specific examples. The utility model may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present utility model.
It should be understood that the structures, proportions, sizes, etc. shown in the drawings attached hereto are merely for the purpose of understanding and reading the disclosure by those skilled in the art and are not intended to limit the scope of the present disclosure, but rather should be construed as limited to the embodiments, and any structural modifications, proportional changes, or dimensional adjustments, without affecting the efficacy or achievement of the present disclosure, should fall within the scope of the disclosure. Also, the terms such as "upper," "lower," "left," "right," "middle," "lower," "first," "second," and "a" and the like are used in this specification for descriptive purposes only and not for purposes of limiting the scope of the present utility model, as the relative relationship changes or modifications within the scope of the present utility model are not to be construed as being practical without materially altering the technical context.
The technical solution of the present utility model will be described in further detail below with reference to several embodiments and the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
Referring to fig. 1, the present utility model provides a secondary battery, and the secondary battery includes a positive electrode tab 100, a negative electrode tab 200, a separator 300, and an electrolyte 400, wherein the positive electrode tab 100 and the negative electrode tab 200 are stacked alternately, the separator 300 is disposed between the positive electrode tab 100 and the negative electrode tab 200, and the electrolyte 400 is filled between the positive electrode tab 100, the negative electrode tab 200, and the separator 300.
In an embodiment of the present utility model, the positive electrode sheet 100 and the negative electrode sheet 200 are stacked, for example, by lamination or winding, and the secondary battery is a chemical system such as ternary positive electrode material, lithium manganate, lithium iron phosphate or lithium titanate, and the secondary battery has a square, cylindrical or soft package structure. In other embodiments, the secondary battery is replaced with other alkali metal ion batteries, other chemical systems, or other structures, for example, and the present utility model is not particularly limited.
Referring to fig. 1 to 4, in an embodiment of the present utility model, a positive electrode sheet 100 includes a positive electrode current collector 10, and the positive electrode current collector 10 includes a positive electrode active material layer 11, a positive electrode skiving region 12, and a positive electrode blank region 13. The positive electrode current collector 10 may be a foil formed by surface treatment of nickel, titanium, aluminum, nickel, silver, stainless steel, carbon, or the like, and the positive electrode current collector 10 may be any one or a combination of a plurality of forms such as a film form, a net form, a porous form, a foam form, a nonwoven fabric, or the like, in addition to the foil, and the thickness of the positive electrode current collector 10 may be, for example, 8 μm to 18 μm, specifically, 8 μm, 9 μm,10 μm, 12 μm, 15 μm, 18 μm, or the like.
Referring to fig. 2 to 3, in an embodiment of the present utility model, a positive electrode coating 111 is disposed on one side or both sides of a positive electrode current collector 10 to form a positive electrode active material layer 11 and a positive electrode thinned region 12, and the thickness of the positive electrode coating 111 at different positions in each direction on the positive electrode active material layer 11 is uniform, i.e., the thickness range of the positive electrode active material layer 11 is uniform with respect to the positive electrode thinned region 12. The positive electrode coating 111 includes a positive electrode material, such as one or more of ternary positive electrode material, lithium manganate, lithium iron phosphate, lithium titanate, and the like, a binder, such as one or more of polyvinylidene fluoride (Polyvinylidene Fluoride, PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate (polymethyl methacrylate) (Polymethyl Methacrylate, PMMA), ethylene-propylene-diene terpolymer (EPDM), polyhexafluoropropylene (polyhexafluoropolyene), styrene-butadiene rubber (Polymerized Styrene Butadiene Rubber, SBR), and the like, and a conductive agent, such as one or more of conductive carbon black, acetylene black, carbon nanotubes, graphene, and the like. The thickness of the positive electrode coating is not limited, and is specifically selected according to the battery requirements. By setting the thickness of the positive electrode active material layer uniform, the uniformity of charge and discharge of the positive electrode sheet can be improved.
Referring to fig. 2 to 3, in an embodiment of the present utility model, a cathode skiving region 12 and a cathode blank region 13 are disposed on one side of a cathode active material layer 11, and the cathode skiving region 12 is located between the cathode active material layer 11 and the cathode blank region 13. The positive electrode coating 111 is coated on the positive electrode thinning area 12, and the thickness of the positive electrode coating on the positive electrode thinning area 12 is smaller than that of the positive electrode coating on the positive electrode active material layer 11, so that the edge of the edge pole piece is prevented from swelling, the problems of edge bursting and the like in the rolling and rolling processes are solved, and meanwhile, the production efficiency is improved. In one embodiment of the present utility model, the width a of the positive electrode active material layer 11 is greater than 0mm, and the specific width is determined according to the cell size, for example, 50mm to 800mm. The width x of the positive electrode thinned region 12 is, for example, 0< x <40mm, and is, for example, 20mm,30mm or 40mm, and the width c of the positive electrode blank region 13 is greater than 0mm, for example, 10mm to 50mm,10mm to 30mm, 10mm to 20mm, or the like, and is specifically selected according to the tab size.
Referring to fig. 3 to 4, in an embodiment of the present utility model, the processing procedure of the electrode plate further includes cutting and die cutting, and the like, and a plurality of positive electrode tabs 14 are disposed on the positive electrode plate, and the positive electrode tabs 14 are located at the same position after the positive electrode plate is wound or laminated. The shape of the positive electrode tab 14 is, for example, rectangular or trapezoidal, and the present utility model is not particularly limited. In the present embodiment, the positive electrode tab 14 has a trapezoidal shape, for example. The positive electrode tab 14 includes a second skived region 121 and a second blank region 131, the second skived region 121 is obtained by cutting the positive electrode skived region 12, the second blank region 131 is obtained by cutting the positive electrode blank region 13, and the width is unchanged. By cutting the positive pole skiving area 12 in the process of forming the positive pole lug 14, the pole piece thickness at each position of the positive pole piece is ensured to be at a consistent level, the excessive gap of the pole pieces is prevented, the lithium ions cannot be embedded in time, and further, the lithium precipitation is caused, so that the lithium precipitation is reduced.
Referring to fig. 5 to 7, in an embodiment of the present utility model, a negative electrode tab 200 includes a negative electrode current collector 20, and the negative electrode current collector 20 includes a negative electrode active material layer 21, a negative electrode skiving region 22, and a negative electrode blank region 23. The negative electrode current collector 20 is, for example, any one or a combination of a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector, a stainless steel current collector, or the like, and the thickness of the negative electrode current collector 20 is, for example, 8 μm to 18 μm, and specifically, the thickness of the negative electrode current collector 10 may be 8 μm, 9 μm,10 μm, 12 μm, 15 μm, 18 μm, or the like.
Referring to fig. 5 to 6, in an embodiment of the present utility model, a negative electrode coating layer 211 is disposed on one side or both sides of a negative electrode current collector 20 to form a negative electrode active material layer 21 and a negative electrode skiving region 22, and the thickness of the negative electrode coating layer 211 at different positions in each direction on the negative electrode active material layer 21 is uniform, i.e., the thickness range of the negative electrode active material layer 21 is uniform with respect to the negative electrode skiving region 22. The negative electrode coating layer 211 includes a negative electrode material, such as any one or a combination of at least two selected from soft carbon, hard carbon, artificial graphite, natural graphite, silicon, a silicon oxygen compound, a silicon carbon compound, lithium titanate, or the like, a binder, a thickener, a conductive agent, and the like. The binder is selected from one or more of polyvinylidene fluoride, polyamide, polypropylene, polyacrylate, polyvinyl ether, polymethyl methacrylate, polyhexafluoropropylene, styrene-butadiene rubber, and the like. The conductive agent is selected from any one or more of conductive carbon black, acetylene black, carbon nanotubes, graphene and the like, and the thickener is selected from sodium carboxymethyl cellulose. The utility model does not limit the thickness of the negative electrode coating, and is specifically selected according to the battery requirements. By setting the thickness of the anode active material layer uniform, the uniformity of charge and discharge of the anode tab can be improved.
Referring to fig. 2, 3, 5 and 6, in an embodiment of the present utility model, a negative electrode skiving region 22 and a negative electrode blank region 23 are disposed on one side of the negative electrode active material layer 21, and the negative electrode skiving region 22 is located between the negative electrode active material layer 21 and the negative electrode blank region 23. The negative electrode coating is coated on the negative electrode thinning area 22, and the thickness of the negative electrode coating on the negative electrode thinning area 22 is smaller than that of the negative electrode coating on the negative electrode active material layer 21, so that the edge of the edge electrode plate is not bulged, the edge of the edge is not burst in the rolling and rolling processes, and the production efficiency is improved. In one embodiment of the present utility model, the width b of the anode active material layer 21 is greater than 0mm, and the specific width is determined depending on the cell size, for example, 50mm to 800mm,50mm to 400mm, 50mm to 100mm, or the like. The width y of the negative electrode skiving region 22 is, for example, 0< y <40mm, for example, 15mm, and the width d of the negative electrode blank region 23 is greater than 0mm, for example, 10mm to 50mm, and is specifically selected according to the tab size. In this embodiment, the width b of the anode active material layer 21 is greater than the width a of the cathode active material layer 11, 0<b-a is less than 5mm, the length of the cathode active material layer 11 is less than or equal to the length of the anode active material layer 21, and the length of the anode sheet is less than or equal to the length of the anode sheet, i.e., the size of the cathode active material layer 11 of the anode sheet is less than the size of the anode active material layer 21 of the anode sheet, which can reduce the lithium precipitation phenomenon at the edge of the sheet, and improve the cycle life and safety performance of the battery.
Referring to fig. 5 to 7, in an embodiment of the present utility model, the processing procedure of the electrode plate further includes cutting, die cutting, and the like, a plurality of negative electrode tabs 24 are disposed on the negative electrode plate, and the negative electrode tabs 24 are located at the same position after the winding or lamination of the negative electrode plate. The shape of the negative electrode tab 24 is, for example, rectangular or trapezoidal, and the present utility model is not particularly limited. In the present embodiment, the negative electrode tab 24 has a trapezoidal shape, for example. The negative electrode tab 24 includes a first skived region 221 and a first blank region 231, the first skived region 221 is obtained by cutting the negative electrode skived region 22, the first blank region 231 is obtained by cutting the negative electrode blank region 23, and the width is unchanged. By cutting the negative pole skived region 22 during the process of forming the negative pole tab 24, the pole piece thickness at each location of the negative pole piece is ensured to be at a consistent level. The utility model cuts the thinned area to the position of the tab in the production process, the active material layer does not contain the thinned area, the thickness of the active material layer of the positive electrode plate and the negative electrode plate is ensured to be consistent and level, the gap between the positive electrode plate and the negative electrode plate is ensured to be consistent and level, the consistency of charge and discharge is ensured, the problem of lithium precipitation at the edge of the electrode plate easily occurring in the use process of the secondary battery is solved, the performance of the secondary battery is improved, and the safety problem is reduced.
Referring to FIG. 1, in one embodiment of the utility model, the electrolyte 400 comprises a solvent, a lithium salt, an additive, and the like, wherein the solvent comprises an ester solvent, for example, and the ester solvent comprises dimethyl carbonate (Dimethyl Carbonate, DMC), methyl carbonate, for exampleEthyl ester (Ethyl Methyl Carbonate, EMC), ethylene carbonate (Ethylene Carbonate, EC), propylene carbonate (Propylene Carbonate, PC), diethyl carbonate (Diethyl Carbonate, DEC), or the like, or a combination of at least two thereof. Lithium hexafluorophosphate (LiPF) 6 ) Lithium tetrafluoroborate (LiBF) 4 ) One or more of lithium bis (fluorosulfonyl) imide (LiFSI) or lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), etc., and the additive includes, for example, a negative electrode film-forming additive, and one or more of vinylene carbonate (Vinylene carbonate, VC), fluoroethylene carbonate (Fluoroethylene carbonate, FC), 1,3-Propane Sultone (PS), etc.
Referring to fig. 1, in an embodiment of the present utility model, the separator 300 is, for example, a Polyethylene (PE), a Polypropylene (PP), a glass fiber film, a Polyethylene film, a composite film, or the like. In the present embodiment, the separator 300 is a composite film of polyethylene and ceramic, for example, and the thickness of the separator 300 is 8 μm to 15 μm, for example. In an embodiment of the utility model, the positive pole piece, the diaphragm and the negative pole piece are sequentially laminated, so that the diaphragm is positioned between the positive pole piece and the negative pole piece to play a role in isolation. Electrolyte is filled between the positive electrode plate, the diaphragm and the negative electrode plate.
Hereinafter, the present utility model will be more specifically explained by referring to examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the utility model, which fall within the technical scope of the utility model.
Example 1
Positive pole piece: mixing lithium iron phosphate, conductive carbon black and polyvinylidene fluoride according to a mass ratio of 97:2:1, and adding a solvent N-methylpyrrolidone to obtain positive electrode slurry. And uniformly coating the positive electrode slurry on an aluminum foil current collector with the thickness of 13 mu m, drying, and then rolling, slitting and die cutting to obtain the positive electrode plate. As shown in fig. 4, the positive electrode sheet 100 has a length of 300mm, the positive electrode active material layer 11 has a width of 80mm, the positive electrode thinned region has a width of 20mm, the positive electrode blank region has a width of 20mm, and the positive electrode tab includes a second thinned region 121 and a second blank region 131.
Negative pole piece: mixing artificial graphite, conductive agent acetylene black, conductive carbon black, styrene-butadiene rubber and sodium carboxymethylcellulose according to a mass ratio of 96:2:1:1, adding deionized water, and fully stirring to obtain negative electrode slurry. And uniformly coating the negative electrode slurry on a copper foil with the thickness of 13 mu m, and drying, rolling, slitting and die cutting to obtain the negative electrode plate. The shape of the negative electrode tab as shown in fig. 7, the length of the negative electrode tab 200 is 300mm, the width of the negative electrode active material layer 21 is 84mm, the width of the negative electrode skived region is 15mm, the width of the negative electrode blank region is 20mm, and the negative electrode tab includes a first skived region 221 and a first blank region 231.
A diaphragm: a composite film of polyethylene and ceramic having a thickness of 11 μm.
Electrolyte solution: the solvent consists of ethylene carbonate, methyl ethyl carbonate and diethyl carbonate according to the mass ratio of 3:5:2, 1,3-propane sultone with the mass content of 1.5% is also added into the electrolyte, lithium hexafluorophosphate is selected as lithium salt, and the concentration of the lithium salt is 1mol/L.
And (3) a secondary battery: the positive pole piece, the diaphragm negative pole piece and the diaphragm are sequentially stacked, a bare cell is obtained through a winding process, then a square aluminum shell is wrapped outside the bare cell, the bare cell is transferred into a vacuum oven, after drying, electrolyte is injected into the bare cell, sealing is carried out, and after standing, hot and cold pressing, formation, clamping and capacity division processes, the secondary battery is prepared, and the battery capacity of the secondary battery is 300Ah.
Comparative example 1
As shown in fig. 8 to 9, when forming the positive electrode tab, the positive electrode thinned region 12 is not cut, but only the positive electrode blank region is cut, that is, the positive electrode tab 14 of the positive electrode sheet includes only the blank region. When the negative electrode tab is formed, the negative electrode thinned region 22 is not cut, but only the negative electrode blank region is cut, i.e., the negative electrode tab 24 of the negative electrode tab only comprises the blank region. Other operations and parameters were consistent with example 1.
In the utility model, different secondary batteries are obtained in the embodiment 1 and the comparative example 1, and the cycle performance of the secondary batteries is tested, specifically, the cycle test is carried out by carrying out constant-current constant-voltage charging to 3.65V at a 1C multiplying power, carrying out constant-voltage charging to 0.05C, carrying out standing for 30min, then carrying out constant-current discharging to 2.5V at a 1C, carrying out standing for 30min, and repeating the steps in the environment of 25 ℃.
Referring to fig. 10, it can be seen from the results of the cycle test of the secondary batteries of example 1 and comparative example 1 that the overall battery decay rate of comparative example 1 was higher than that of example 1, and that the life of comparative example 1 was 1000 times less than that of example 1 when 75% capacity retention was reached, indicating that the battery decay rate was significantly improved in example 1. The main difference between the embodiment 1 and the comparative example 1 is that the active material layer of the electrode sheet does not contain a thinned area, so that the thickness consistency of the electrode sheet at different positions in all directions can be ensured, the excessive gap between the electrode sheets is prevented, lithium ions cannot be timely inserted, and further lithium precipitation is caused, thereby obviously improving the cycle performance of the secondary battery and improving the safety of the secondary battery.
The utility model also provides electronic equipment, which comprises the secondary battery provided by the utility model, can ensure the consistency of charge and discharge, solves the problem of lithium precipitation at the edge of the pole piece, which is easy to occur in the use process of the secondary battery, improves the performance of the electronic equipment, and reduces the safety problem.
In summary, the present utility model provides a secondary battery and an electronic device, in which a tab is formed by cutting a thinned region and an empty region, the thickness of an active material layer on a pole piece is uniform, and the uniformity of charge and discharge of the battery is improved. The thickness of the active material layers of the positive electrode plate and the negative electrode plate can be guaranteed to be consistent and level, the gap between the positive electrode plate and the negative electrode plate is guaranteed to be consistent and level, the consistency of charge and discharge is guaranteed, and the performance of the secondary battery is improved. And solves the problem of lithium precipitation at the edge of the pole piece, which is easy to occur in the use process of the secondary battery, and reduces the safety problem.
The foregoing description is only illustrative of the preferred embodiments of the present application and the technical principles employed, and it should be understood by those skilled in the art that the scope of the utility model in question is not limited to the specific combination of features described above, but encompasses other technical solutions which may be formed by any combination of features described above or their equivalents without departing from the inventive concept, such as the features described above and the features disclosed in the present application (but not limited to) having similar functions being interchanged.
Other technical features besides those described in the specification are known to those skilled in the art, and are not described herein in detail to highlight the innovative features of the present utility model.
Claims (10)
1. A secondary battery, characterized by comprising at least:
a positive electrode sheet;
a diaphragm;
the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer positioned on at least one side of the negative electrode current collector, the thickness of the negative electrode active material layer is consistent, and the diaphragm is arranged between the negative electrode plate and the positive electrode plate; and
the negative electrode tab is arranged on one side of the negative electrode active material layer and comprises a first skived area and a first blank area, and the first skived area is arranged between the negative electrode active material layer and the first blank area.
2. The secondary battery according to claim 1, wherein the positive electrode tab includes a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector, the positive electrode active material layer having a uniform thickness.
3. The secondary battery according to claim 2, further comprising a positive electrode tab provided on one side of the positive electrode active material layer.
4. The secondary battery according to claim 3, wherein the positive electrode tab includes a second skived region and a second blank region, the second skived region being disposed between the positive electrode active material layer and the second blank region.
5. The secondary battery according to claim 2, wherein the width of the positive electrode active material layer is smaller than the width of the negative electrode active material layer, and the difference between the widths of the negative electrode active material layer and the positive electrode active material layer is smaller than 5mm.
6. The secondary battery according to claim 1, wherein the length of the positive electrode tab is less than or equal to the length of the negative electrode tab; or alternatively, the first and second heat exchangers may be,
the first skived zone has a width greater than 0 and less than 40mm.
7. The secondary battery according to claim 1, wherein a thickness of the anode coating layer on the first thinned region is smaller than a thickness of the anode coating layer on the anode active material layer.
8. The secondary battery according to claim 4, wherein a thickness of the positive electrode coating layer on the second skived zone is smaller than a thickness of the positive electrode coating layer on the positive electrode active material layer.
9. The secondary battery according to claim 3, wherein the shape of the negative electrode tab and/or the positive electrode tab is rectangular or trapezoidal.
10. An electronic device comprising the secondary battery according to any one of claims 1 to 9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117878384A (en) * | 2024-03-08 | 2024-04-12 | 宁德时代新能源科技股份有限公司 | Battery cell, battery and electricity utilization device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117878384A (en) * | 2024-03-08 | 2024-04-12 | 宁德时代新能源科技股份有限公司 | Battery cell, battery and electricity utilization device |
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