CN114094048A - Battery with improved battery capacity - Google Patents

Battery with improved battery capacity Download PDF

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Publication number
CN114094048A
CN114094048A CN202111394938.2A CN202111394938A CN114094048A CN 114094048 A CN114094048 A CN 114094048A CN 202111394938 A CN202111394938 A CN 202111394938A CN 114094048 A CN114094048 A CN 114094048A
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Prior art keywords
battery
carbonate
positive plate
meth
lithium
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母英迪
王海
李素丽
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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Priority to CN202111394938.2A priority Critical patent/CN114094048A/en
Publication of CN114094048A publication Critical patent/CN114094048A/en
Priority to KR1020237045396A priority patent/KR20240019174A/en
Priority to PCT/CN2022/133613 priority patent/WO2023093743A1/en
Priority to EP22897826.8A priority patent/EP4345934A1/en
Priority to US18/400,360 priority patent/US20240136686A1/en
Priority to US18/400,216 priority patent/US20240136684A1/en
Priority to US18/400,428 priority patent/US20240136687A1/en
Priority to US18/400,403 priority patent/US20240136582A1/en
Priority to US18/400,316 priority patent/US20240136685A1/en
Priority to US18/400,361 priority patent/US20240136581A1/en
Priority to US18/400,449 priority patent/US20240136688A1/en
Priority to US18/400,260 priority patent/US20240136580A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0088—Composites
    • H01M2300/0091—Composites in the form of mixtures
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides a battery. The battery can effectively improve the high-temperature performance of the battery cell prepared by the synergistic effect of the positive plate termination adhesive tape and lithium difluorophosphate in the non-aqueous electrolyte, and simultaneously can solve the problem of lithium precipitation at the edge of the positive plate after the battery cell is circulated, thereby avoiding the problems that the battery cell high-temperature storage thickness fails and the lithium is precipitated by high-temperature circulation due to the upwarp deformation of the positive plate termination adhesive tape in the high-temperature environment, the adhesive layer of the positive plate termination adhesive tape is easy to dissolve in the electrolyte, the electrolyte is easy to be oxidized, reduced and decomposed at the positive and negative electrode interfaces, and the like.

Description

Battery with improved battery capacity
Technical Field
The invention belongs to the technical field of batteries, relates to a battery, and particularly relates to a high-voltage battery with excellent high-temperature performance.
Background
In recent years, batteries have been widely used in the fields of smart phones, tablet computers, smart wearing, electric tools, electric vehicles, and the like. With the widespread use of batteries, consumer demands for energy density and use environment of batteries are increasing, which requires that batteries have excellent high-temperature safety performance at high voltage.
At present, potential safety hazards exist in the use process of the battery, for example, serious safety accidents easily occur under some extreme use conditions such as continuous high temperature and the like of the battery, and a battery core is deformed and ignited and even explodes. The main reasons for these problems are that the adhesive layer of the battery pole piece termination adhesive tape is easily dissolved in the electrolyte at high temperature and high pressure and loses the cohesiveness, so that the adhesive tape cannot effectively fix the battery pole piece termination adhesive tape, and the battery pole piece is locally deformed and warped or short-circuited to cause safety accidents; on the other hand, the electrolyte is easy to decompose at high temperature and high voltage, and oxidation-reduction decomposition occurs on the surfaces of the positive electrode and the negative electrode to damage an SEI film, so that the impedance of the battery cell is continuously increased, and the performance of the battery cell is deteriorated.
Disclosure of Invention
The invention aims to solve the problems that the high-temperature storage thickness of a battery core is invalid and lithium is separated out in a high-temperature cycle manner due to the warping deformation of a positive plate termination adhesive tape when the conventional battery is used in a high-temperature environment, a glue layer in the positive plate termination adhesive tape is easily soluble in a non-aqueous electrolyte, the non-aqueous electrolyte is easily oxidized, reduced and decomposed on positive and negative electrode interfaces, and the like, and provides a battery which is a high-voltage battery and has excellent high-temperature performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
a battery includes a positive electrode sheet, a negative electrode sheet, a nonaqueous electrolytic solution, and a separator; a positive plate termination adhesive tape is arranged at the paste coating tail of the positive plate, the non-aqueous electrolyte comprises a non-aqueous organic solvent, an electrolyte additive and lithium salt, wherein the electrolyte additive comprises lithium difluorophosphate;
the area of the positive plate termination adhesive tape is A cm2The mass percentage of the lithium difluorophosphate is B wt%, the width of the positive plate is C cm, and the ratio of A to B is in the range of 5-200; the ratio of A to C is in the range of 1-3.
In the battery, the number of the positive plate termination adhesive tapes is two, namely, one positive plate termination adhesive tape is arranged on each of the two side surfaces of the positive current collector in the positive plate, and the area A of each positive plate termination adhesive tape is the area of the positive plate termination adhesive tape arranged on the surface of one side of the positive current collector in the positive plate. Furthermore, the areas of the anode plate termination adhesive tapes arranged on the surfaces of the two sides of the anode current collector in the anode plate are the same.
According to the invention, the ratio of A to B is 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 120, 150, 180, 200 or any point in the range of the two endpoints. When the ratio of A to B is in the range of 5-200, lithium difluorophosphate in the non-aqueous electrolyte and the positive plate stop adhesive tape can have a better synergistic effect; in particular, lithium difluorophosphate can more fully adsorb and complex small molecular substances (such as Cl) in the electrolyte-、SO4 2-、HF、H2O, and the like) to inhibit hydrolysis of the adhesive layer in the positive plate termination adhesive tape after the non-aqueous electrolyte is soaked, thereby effectively increasing the stability of a macromolecular cross-linking structure in the adhesive layer, strengthening the molecular structure of the adhesive layer, keeping the adhesive layer with better viscosity, reducing liquefaction and flow, delaying aging failure of the positive plate termination adhesive tape at high temperature, avoiding the adhesive layer overflowing the positive plate termination adhesive tape and covering the surface of a positive active material to cause hole blockage, improving the deformation of a battery cell caused by warping of the positive plate termination adhesive tape after the battery cell is stored at high temperature, and simultaneously improving the problems of lithium precipitation at the edge caused by hole blockage in the battery cell circulation process.
According to the invention, the ratio of A to C is 1, 1.2, 1.5, 1.6, 1.7, 1.8, 1.9, 2,3 or any point in the range of the two endpoints. When the ratio of the A to the C is in the range of 1-3, the adhesive layer area of the positive plate stopping adhesive tape more reasonably covers the paste coating and the surface of the empty foil, so that the influence of the electrolyte on the adhesive layer is reduced.
According to the invention, the paste coating tail part of the positive plate is provided with the positive plate termination adhesive tape, and the positive plate termination adhesive tape can fix the tail part of the battery core and cover burrs of the edge cutting of the positive plate, so that the short circuit of the battery is prevented, and the insulation protection effect is achieved.
According to the invention, the positiveThe area A of the pole piece termination adhesive tape is 3-120 cm2Between the ranges; illustratively, the area A of the positive electrode tab termination tape is 3cm2、5cm2、10cm2、20cm2、30cm2、40cm2、50cm2、60cm2、70cm2、80cm2、90cm2、100cm2、110cm2Or 120cm2。
According to the invention, the width C of the positive plate is within the range of 1-120 cm; illustratively, the width C of the positive electrode sheet is 1cm, 3cm, 5cm, 6cm, 8cm, 10cm, 16cm, 20cm, 30cm, 40cm, 50cm, 60cm, 70cm, 80cm, 90cm, 100cm, 110cm, or 120 cm.
According to the invention, the positive plate termination adhesive tape comprises a PET (polyethylene terephthalate) base material and a (methyl) acrylic acid termination adhesive layer coated on the surface of the PET base material.
In the present invention, the (meth) acrylic acid means acrylic acid and/or methacrylic acid.
According to the invention, the thickness of the positive plate termination adhesive tape is 8-20 μm.
According to the invention, the (meth) acrylic stop glue layer comprises a cross-linking modified (meth) acrylic acid and/or a cross-linking modified (meth) acrylate.
According to the invention, the crosslinking agent which crosslinks the modified (meth) acrylic acid and/or crosslinks the modified (meth) acrylate comprises vinylene carbonate.
According to the invention, the (meth) acrylic esters are chosen from (meth) acrylic acid C1-10Alkyl esters illustratively selected from at least one of isooctyl acrylate, n-butyl acrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, and the like.
According to the invention, the vinylene carbonate is present in an amount of 0.5 to 5 wt.%, for example 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.2 wt.%, 1.5 wt.%, 1.8 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 3.8 wt.%, 4 wt.%, 4.5 wt.% or 5 wt.%, based on the mass of the cross-linked modified (meth) acrylic acid and/or the cross-linked modified (meth) acrylate.
According to the invention, the (meth) acrylic acid stop glue layer further comprises an auxiliary agent, for example, at least one selected from an antioxidant, an inorganic filler and the like.
According to the invention, the antioxidant is a conventionally used antioxidant suitable for crosslinking-modified (meth) acrylic acid and/or crosslinking-modified (meth) acrylic esters.
According to the invention, the inorganic filler is a conventionally used inorganic filler suitable for crosslinking-modified (meth) acrylic acid and/or crosslinking-modified (meth) acrylic esters.
According to the invention, the mass percentage of the lithium difluorophosphate is the mass percentage of the lithium difluorophosphate in the total mass of the nonaqueous electrolyte.
According to the invention, the mass percentage of the lithium difluorophosphate is 0.1-3 wt.%; preferably, the mass percent content of the lithium difluorophosphate is 0.2-1 wt.%. Illustratively, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.2 wt.%, 1.5 wt.%, 1.8 wt.%, 2 wt.%, 2.2 wt.%, 2.5 wt.%, 2.8 wt.%, or 3 wt.%.
According to the invention, the electrolyte additive also comprises at least one of 1, 3-propane sultone, 1, 3-propene sultone, fluoroethylene carbonate, ethylene sulfite, ethylene sulfate, lithium bis (oxalato) borate, lithium difluoro (oxalato) phosphate and vinyl ethylene carbonate, and the content of the at least one of the 1, 3-propane sultone, the 1, 3-propene sultone, the lithium fluoro (oxalato) carbonate and the ethylene sulfite accounts for 0-10 wt% of the total mass of the nonaqueous electrolyte.
According to the invention, the non-aqueous organic solvent is selected from at least one of carbonate, carboxylic ester and fluoroether, wherein the carbonate is selected from one or more of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate and methyl propyl carbonate; the carboxylic ester is selected from one or more of ethyl propionate and propyl propionate; the fluoroether is selected from 1,1,2, 3-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether.
According to the present invention, the lithium salt is selected from at least one of lithium bistrifluoromethylsulfonyl imide, lithium bisfluorosulfonimide and lithium hexafluorophosphate.
According to the invention, the positive plate comprises a positive current collector and a positive active material layer coated on one side or two sides of the positive current collector, the positive active material layer comprises a positive active material, a conductive agent and a binder,
the positive active material is selected from lithium cobaltate or lithium cobaltate subjected to doping coating treatment of two or more elements of Al, Mg, Mn, Cr, Ti and Zr, and the chemical formula of the lithium cobaltate subjected to doping coating treatment of two or more elements of Al, Mg, Mn, Cr, Ti and Zr is LixCo1-y1-y2-y3-y4Ay1By2Cy3Dy4O2(ii) a X is more than or equal to 0.95 and less than or equal to 1.05, y1 is more than or equal to 0.01 and less than or equal to 0.1, y2 is more than or equal to 0.1, y3 is more than or equal to 0.1, y4 is more than or equal to 0 and less than or equal to 0.1, and A, B, C, D is selected from two or more elements of Al, Mg, Mn, Cr, Ti and Zr.
According to the present invention, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer coated on one or both surfaces of the negative electrode current collector, the negative electrode active material layer including a negative electrode active material, a conductive agent and a binder,
the negative active material is selected from graphite or a graphite composite material containing 1-12 wt% of SiOx/C or Si/C.
According to the present invention, the charge cut-off voltage of the battery is 4.45V or more.
According to the invention, the battery is a lithium ion battery.
In the present invention, the term "between … … ranges" includes the end points, exemplarily "between 5 and 200 ranges" and means greater than or equal to 5 and less than or equal to 200.
The invention has the beneficial effects that:
the present invention provides a battery which is a high voltage type battery and has excellent high temperature performance. The inventor of the invention finds through keen research that the synergistic effect of the positive plate termination adhesive tape and lithium difluorophosphate in the non-aqueous electrolyte can effectively improve the high-temperature performance of the battery cell of the prepared battery, and simultaneously can solve the problem of lithium precipitation at the edge of the pole piece after the battery cell is circulated, and avoid the problems of failure of the high-temperature storage thickness of the battery cell, lithium precipitation at high temperature, easy dissolution of the adhesive layer of the positive plate termination adhesive tape in the electrolyte, easy redox decomposition of the electrolyte at the positive and negative electrode interfaces and the like caused by the upwarp deformation of the positive plate termination adhesive tape when the battery is used in a high-temperature environment.
In the invention, lithium difluorophosphate in the non-aqueous electrolyte and the positive plate stop adhesive tape can have better synergistic effect; in particular, lithium difluorophosphate can adsorb and complex more small molecular substances (such as Cl) in the electrolyte-、SO4 2-、HF、H2O, and the like) to inhibit hydrolysis of an acrylic acid termination adhesive layer in the positive plate termination adhesive tape after the non-aqueous electrolyte is soaked, thereby effectively increasing the stability of a macromolecular cross-linked structure in the acrylic acid termination adhesive layer, strengthening the molecular structure of the acrylic acid termination adhesive layer, keeping the acrylic acid termination adhesive layer with better viscosity, reducing liquefaction and flow, delaying aging failure of the positive plate termination adhesive tape at high temperature, avoiding blockage caused by overflow of the acrylic acid termination adhesive layer from the positive plate termination adhesive tape and covering the surface of a positive active material, improving cell deformation caused by upwarping of the positive plate termination adhesive tape after cell high-temperature storage, and simultaneously improving the problems of edge lithium precipitation and the like caused by the blockage of the hole in a cell circulation process.
Furthermore, the lithium difluorophosphate in the non-aqueous electrolyte is combined with the protonic acid in the non-aqueous electrolyte, so that not only is the corrosion damage of the protonic acid to the acrylic acid stop glue layer avoided, but also the influence of the protonic acid to the electrode material can be avoided, an excellent electrode/electrolyte interface film is formed on the positive electrode and the negative electrode, the insertion/extraction of ions (such as lithium ions) on the surface of the electrode is optimized, and the cycle performance of the lithium secondary battery is improved.
Furthermore, the acrylic acid termination adhesive layer in the positive termination adhesive tape contains vinylene carbonate which can participate in acrylic acid cross-linking polymerization, so that the acrylic acid termination adhesive layer contains a branched chain of an ethyl carbonate structure, the acrylic acid termination adhesive layer is more resistant to high temperature and high pressure, the adhesive layer structure is stabilized, and the high-temperature performance of the battery core is further improved.
Drawings
Fig. 1 is a schematic structural view of a positive electrode sheet according to a preferred embodiment of the present invention.
Fig. 2 is a schematic structural view of a positive electrode sheet according to another preferred embodiment of the present invention.
Fig. 3 is a side view of the positive electrode tab shown in fig. 2.
Reference numerals: 1-the head of the positive plate; 2-the tail part of the positive plate; 3-empty foil area; 4, stopping the adhesive tape on the positive plate; 5, the tail part of the positive plate on one surface; 6, terminating the adhesive tape on the positive plate on one side; 7-the tail part of the positive plate on the other side; 8-the other side positive plate is terminated with adhesive tape.
Detailed Description
In the present invention, the "positive electrode tab terminating tape" refers to a tape provided at the tail of a paste (e.g., a positive electrode active material layer) on the surface of a positive electrode current collector in a positive electrode tab, and the positive electrode tab terminating tape partially covers the paste on the surface of the positive electrode current collector and partially covers the surface of the positive electrode current collector (i.e., a blank foil on the surface of the positive electrode current collector), as specifically shown in fig. 1 to 3.
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
Comparative examples 1 to 5 and examples 1 to 7
The lithium ion batteries of comparative examples 1 to 5 and examples 1 to 7 were each prepared according to the following preparation method, differing only in the positive electrode tab terminating tape and the nonaqueous electrolytic solution at the tail of the positive electrode tab pasting, as specifically shown in table 1.
(1) Preparation of positive plate
LiCoO as positive electrode active material2Mixing polyvinylidene fluoride (PVDF) as a binder and acetylene black as a conductive agent according to the weight ratio of 97.2:1.3:1.5, adding N-methylpyrrolidone (NMP), and stirring under the action of a vacuum stirrer until a mixed system is uniformA flowable positive electrode slurry; uniformly coating the positive electrode slurry on an aluminum foil with the thickness of 9-12 mu m; baking the coated aluminum foil in 5 sections of baking ovens with different temperature gradients, drying the aluminum foil in a baking oven at 120 ℃ for 8 hours, rolling and slitting to obtain the required positive plates with different sizes, wherein the specific width of each plate is shown in table 1.
(2) Preparation of negative plate
Preparing a slurry from an artificial graphite negative electrode material with the mass ratio of 96.5%, a single-walled carbon nanotube (SWCNT) conductive agent with the mass ratio of 0.1%, a conductive carbon black (SP) conductive agent with the mass ratio of 1%, a sodium carboxymethylcellulose (CMC) binder with the mass ratio of 1% and a Styrene Butadiene Rubber (SBR) binder with the mass ratio of 1.4% by a wet process, coating the slurry on the surface of a negative current collector copper foil, drying (the temperature is 85 ℃, the time is 5h), rolling and die cutting to obtain negative electrode sheets with different sizes.
(3) Preparation of non-aqueous electrolyte
In a glove box filled with argon (moisture)<10ppm, oxygen content<1ppm), Ethylene Carbonate (EC), Propylene Carbonate (PC), Propyl Propionate (PP), Ethyl Propionate (EP) were mixed uniformly in a mass ratio of 1:1:3:2, and 13 wt.% of LiPF based on the total mass of the nonaqueous electrolyte solution was slowly added to the mixed solution6And lithium difluorophosphate (the specific amount of lithium difluorophosphate is shown in table 1), and uniformly stirring to obtain the nonaqueous electrolytic solution.
(4) Preparation of the separator
Selecting a polyethylene diaphragm with the thickness of 7-9 mu m.
(5) Preparation of positive plate termination adhesive tape
The method comprises the following steps of uniformly stirring 38 parts by weight of isooctyl acrylate, 3 parts by weight of butyl acrylate, 3 parts by weight of vinyl acetate, 3 parts by weight of acrylic acid, 5 parts by weight of isoprene rubber, 1 part by weight of pentaerythritol trimethacrylate, 1 part by weight of azobisisobutyronitrile and 36 parts by weight of ethyl ester at the temperature of 80 ℃ to obtain a mixed solution, then adding a certain part by weight of a crosslinking agent vinylene carbonate into the mixed solution, uniformly stirring at normal temperature, uniformly mixing, and coating the mixed solution on the surface of a PET (polyethylene terephthalate) substrate to obtain the anode plate termination adhesive tape. The positive plate termination adhesive tape comprises a PET (polyethylene terephthalate) base material and an acrylic acid termination adhesive layer coated on the surface of the PET base material, wherein the specific dosage of vinylene carbonate in the acrylic acid termination adhesive layer is shown in table 1, and the area of the positive plate termination adhesive tape is shown in table 1.
(6) Preparation of lithium ion battery
Winding the prepared positive plate, the diaphragm and the negative plate, and pasting a positive plate termination adhesive tape at the ending part of the positive plate (the areas of the positive plate termination adhesive tapes on the two sides of the positive current collector are the same), so as to obtain a naked battery cell without liquid injection; placing the bare cell in an outer packaging foil, injecting the prepared electrolyte into the dried bare cell, and performing vacuum packaging, standing, formation, shaping, sorting and other processes to obtain the required lithium ion battery.
TABLE 1 lithium ion batteries prepared in comparative examples 1 to 5 and examples 1 to 7
Figure BDA0003369933900000081
The cells obtained in the above comparative examples and examples were subjected to electrochemical performance tests, as described below:
45 ℃ cycling experiment: placing the batteries obtained in the above examples and comparative examples in an environment of (45 +/-2) DEG C, standing for 2-3 hours, when the battery body reaches (45 +/-2) DEG C, keeping the cut-off current of the battery at 0.05C according to 1C constant current charging, standing for 5min after the battery is fully charged, then discharging to the cut-off voltage of 3.0V at 0.7C constant current, recording the highest discharge capacity of the previous 3 cycles as an initial capacity Q, and when the cycles reach 400 times, recording the last discharge capacity Q of the battery1And disassembling the cycle 400T battery to record whether the battery edge is subjected to lithium separation, and recording results as shown in Table 2.
The calculation formula used therein is as follows: capacity retention (%) ═ Q1/Q×100％。
High temperature storage at 85 ℃ for 4 hours experiment: the cells obtained in the above examples and comparative examples were subjected to a charge-discharge cycle test at a charge-discharge rate of 0.5C for 3 times at room temperature, and then charged to a full charge state at a rate of 0.5C, and the maximum discharge capacity Q of the previous 0.5C cycles was recorded2And battery thickness T1. The battery in a full-charge state is stored for 4 hours at 85 ℃, the thickness T2 of the battery and the discharge capacity Q3 of 0.5C after 4 hours are recorded, experimental data such as the thickness change rate and the capacity retention rate of the battery stored at high temperature are obtained through calculation, and the recording results are shown in table 2.
The calculation formula used therein is as follows:
capacity retention (%) ═ Q3/Q2X 100%; thickness change rate (%) - (T)2-T1)/T1×100％
Thermal shock test at 130 ℃: the batteries obtained in the above examples and comparative examples were heated at an initial temperature of 25. + -. 3 ℃ by convection or a circulating hot air oven at a temperature change rate of 5. + -. 2 ℃/min, heated to 130. + -. 2 ℃ and held for 60min, and the test was terminated, and the results of the battery state were recorded as shown in Table 2.
TABLE 2 experimental test results of the batteries obtained in comparative examples 1 to 5 and examples 1 to 7
Figure BDA0003369933900000091
As can be seen from the results of table 2: according to the comparative example and the embodiment, the battery prepared by adding the lithium difluorophosphate and the positive plate termination adhesive tape into the electrolyte can effectively improve the high-temperature performance of the battery cell and solve the problem of lithium precipitation at the edge of the pole piece after the battery cell is circulated.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A battery includes a positive electrode sheet, a negative electrode sheet, a nonaqueous electrolytic solution, and a separator; a positive plate termination adhesive tape is arranged at the tail part of the paste coating of the positive plate, the non-aqueous electrolyte comprises a non-aqueous organic solvent, an electrolyte additive and lithium salt, wherein the electrolyte additive comprises lithium difluorophosphate;
the area of the positive plate termination adhesive tape is Acm2The mass percentage of the lithium difluorophosphate is Bwt%, the width of the positive plate is C cm, and the ratio of A to B is in the range of 5-200; the ratio of A to C is in the range of 1-3.
2. The battery according to claim 1, wherein the area A of the positive electrode tab terminal tape is 3-120 cm2The width C of the positive plate is within the range of 1-120 cm.
3. The battery according to claim 1, wherein the lithium difluorophosphate has a mass percentage B of 0.1 to 3 wt.%.
4. The battery according to claim 3, wherein the lithium difluorophosphate has a mass percentage B of 0.2 to 1 wt.%.
5. The battery according to any one of claims 1 to 4, wherein the positive electrode tab termination tape comprises a PET substrate and a (meth) acrylic termination adhesive layer coated on the surface of the PET substrate.
6. The battery of claim 5, wherein the (meth) acrylic stop gum layer comprises a cross-linked modified (meth) acrylic acid and/or a cross-linked modified (meth) acrylate, and the cross-linking agent of the cross-linked modified (meth) acrylic acid and/or the cross-linked modified (meth) acrylate comprises vinylene carbonate.
7. The battery according to claim 6, wherein the vinylene carbonate is contained in an amount of 0.5-5 wt.% based on the mass of the cross-linked modified (meth) acrylic acid and/or the cross-linked modified (meth) acrylate.
8. The battery according to any one of claims 1 to 7, wherein the electrolyte additive further comprises at least one of 1, 3-propane sultone, 1, 3-propene sultone, fluoroethylene carbonate, ethylene sulfite, ethylene sulfate, lithium dioxalate borate, lithium difluorooxalate phosphate and vinyl ethylene carbonate, and the content thereof is 0 to 10 wt% of the total mass of the nonaqueous electrolyte.
9. The battery according to any one of claims 1 to 8, wherein the non-aqueous organic solvent is selected from at least one of carbonate, carboxylic ester and fluoroether, wherein the carbonate is selected from one or more combinations of ethylene carbonate, propylene carbonate, fluoroethylene carbonate, dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, methylpropyl carbonate; the carboxylic ester is selected from one or more of ethyl propionate and propyl propionate; the fluoroether is selected from 1,1,2, 3-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether.
10. The battery according to any one of claims 1 to 9, wherein the charge cut-off voltage of the battery is 4.45V or more.
CN202111394938.2A 2021-11-23 2021-11-23 Battery with improved battery capacity Pending CN114094048A (en)

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