Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/10—Primary casings; Jackets or wrappings
  • H01M50/183—Sealing members
  • H01M50/184—Sealing members characterised by their shape or structure
• • 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
  • 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
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/362—Composites
  • H01M4/364—Composites as mixtures
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
  • H01M4/386—Silicon or alloys based on silicon
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
  • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
  • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
  • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• • 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
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
  • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
  • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/10—Primary casings; Jackets or wrappings
  • H01M50/102—Primary casings; Jackets or wrappings characterised by their shape or physical structure
  • H01M50/105—Pouches or flexible bags
• • 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
  • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • 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
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/028—Positive electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2220/00—Batteries for particular applications
  • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
• • 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

Definitions

• This application belongs to the field of electrochemical technology. More specifically, this application relates to a secondary battery and a device containing the secondary battery.
• secondary batteries As a new type of high-voltage, high-energy density rechargeable battery, secondary batteries have outstanding characteristics such as light weight, high energy density, no pollution, no memory effect, and long service life. They are a major trend in the development of new energy batteries.
• the use of silicon-based materials with high gram capacity as negative electrode active materials has great advantages in improving the energy density of secondary batteries.
• the negative electrode active material has the problem of volume expansion and contraction during the charge and discharge process.
• the negative electrode active material containing silicon-based materials is prone to severe volume expansion and contraction during the charge and discharge process, which limits the long-term use of the battery.
• the above problems are particularly prominent when the secondary battery is packaged in a pouch type.
• the first aspect of the present application provides a secondary battery, which can have both good high-temperature storage performance and safety performance under the premise of higher energy density.
• the secondary battery provided in the first aspect of the present application includes an outer packaging bag and a battery cell arranged in the outer packaging bag.
• the battery cell includes a positive pole piece, a negative pole piece and a separator.
• the pole piece includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material;
• the negative electrode piece includes a negative electrode current collector and is provided on at least one surface of the negative electrode current collector The negative electrode film layer on top and including the negative electrode active material;
• the positive electrode active material includes one or more of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, and at least a part of the positive electrode active material includes single crystal particles; wherein the negative electrode active material includes silicon-based Materials and graphite materials; and the width of the seal on the outer packaging bag is 3mm-8mm.
• the secondary battery in the present application contains specific types of positive electrode active materials and negative electrode active materials, and by controlling the seal width of the outer packaging bag within a certain range, the battery can have sufficient energy density under the premise of higher energy density.
• the over-current capability can also ensure that the tab welding position has better tensile resistance, thereby effectively improving the high-temperature storage performance and safety performance of the battery.
• any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and any upper limit can be combined with any other upper limit to form an unspecified range.
• every point or single value between the end points of the range is included in the range. Therefore, each point or single numerical value can be used as its own lower limit or upper limit in combination with any other point or single numerical value or in combination with other lower or upper limits to form an unspecified range.
• the secondary battery of the present application includes an outer packaging bag and a battery cell arranged in the outer packaging bag.
• the battery cell includes a positive pole piece, a negative pole piece and a separator.
• the positive pole piece includes a positive current collector and A positive electrode film layer on at least one surface of the positive electrode current collector and including a positive electrode active material;
• the negative electrode piece includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector and including a negative electrode active material
• the positive electrode active material includes one or more of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, and at least a part of the positive electrode active material includes single crystal particles; wherein the negative electrode active material Containing silicon-based materials and graphite materials; and wherein the width of the seal on the outer packaging bag is 3mm-8mm.
• the sealing area on the outer packaging bag is an important factor affecting the safety performance of the battery.
• the "seal area” refers to packing the positive pole piece, the negative pole piece, the separator film and the electrolyte in a packaging bag formed of, for example, a film, and then sealing the periphery of it. And the formation of the area combined with each other.
• the seal width refers to the width of the area where the outer packaging is in contact with each other and joined together.
• the width of the sealing area within a certain range can not only ensure sufficient over-current capability under the required capacity of the cell, but also ensure that the tab welding position has good tensile resistance, thereby taking into account the high energy density of the cell Under the electrical performance and safety performance.
• the width of the seal on the outer packaging bag is 3 mm to 8 mm, preferably 3 mm to 5 mm.
• the ratio of the width of the seal to the length of the cell is 0.01 to 0.02.
• the packaging strength F of the seal area meeting the following conditions: 30N ⁇ F ⁇ 200N, preferably 40N ⁇ F ⁇ 100N, can ensure the integrity of the battery cell under high-temperature gas production conditions and inhibit production The role of qi.
• the positive electrode active material includes one or more of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, and at least a part of the positive electrode active material includes single crystal particles.
• the positive electrode active material in the form of single crystal particles can improve the overall compaction density and ductility of the positive electrode piece, while reducing the contact area between the positive electrode active material and the electrolyte, reducing the occurrence of interface side reactions, reducing gas production, and further improving lithium Cycle performance of ion batteries.
• the mass ratio of the single crystal particles in the positive electrode active material is ⁇ 30%; more preferably, 10%-20%.
• the excessive mass proportion of single crystal particles in the positive electrode active material will affect the cycle performance of the battery.
• the average particle size of the positive electrode active material is 8 ⁇ m to 12 ⁇ m, preferably 8.5 ⁇ m to 10 ⁇ m.
• the positive electrode active material includes Li a Ni b Co c M d M'e O f A g or Li a Ni b Co with at least a part of the surface provided with a coating layer.
• One or more of A is selected from one or more of N, F, S, and Cl.
• the positive electrode active material may also include lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium cobalt oxide and modified compounds thereof, but the application is not limited For these materials, other conventionally known materials that can be used as positive active materials for lithium-ion batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more kinds. Preferably, the positive electrode active material may be selected from LiNi 0.8 Co 0.1 Mn 0.1 O 2 , LiNi 0.805 Co 0.1 Mn 0.095 O 2 and combinations thereof.
• the mass ratio of the silicon-based material in the negative electrode active material is ⁇ 40%; more preferably, the mass ratio of the silicon-based material in the negative electrode active material The proportion is 15% to 30%.
• the negative electrode active material particles During the charging and discharging process of the secondary battery, ions undergo solid-phase conduction inside the negative electrode active material particles.
• the smaller the negative electrode active material particles the shorter the diffusion path of the active ions inside, which can reduce the occurrence of side reactions. Thereby improving the high-temperature storage gas production performance of the battery.
• the larger the particles of the negative electrode active material the more beneficial it is to increase the gram capacity of the negative electrode active material, thereby effectively increasing the energy density of the battery. Therefore, it is very important to design the average particle size of the negative electrode active material reasonably, which can realize the battery to a certain extent while taking into account the high energy density and high temperature storage performance.
• the average particle size of the negative electrode active material is 7 ⁇ m to 15 ⁇ m, preferably 9 ⁇ m to 12 ⁇ m.
• the porosity of the positive and negative electrode film layers can be designed to ensure better electron and ion transmission of the battery cell.
• ions undergo liquid phase conduction (including liquid phase diffusion and electromigration) in the porous electrode film layer. Therefore, the porosity of the pole piece film will affect the transmission of electrons and ions.
• the greater the porosity of the pole piece membrane layer the better the wettability of the electrolyte, the higher the liquid phase diffusion rate, and the easier it is for ions to be reduced during high-rate charging, thereby avoiding the formation of metal dendrites.
• the porosity of the positive electrode layer satisfies P n: 6% ⁇ P n ⁇ 15%.
• the porosity P negative of the negative electrode film layer satisfies: 15% ⁇ P negative ⁇ 25 %.
• the compaction density of the positive and negative electrode film layers can also be designed to ensure that the secondary battery has an improved cycle life.
• the compaction density of the positive and negative film layers are both high, the side reactions of the battery core can be reduced, thereby increasing the volume energy density of the battery.
• the compaction density of the positive and negative film layers cannot be too high. If the compaction density of the negative electrode film layer is too high, the electrolyte cannot be completely infiltrated, and then during the discharge process, the lithium ions cannot be embedded in the negative electrode active material through the electrolyte medium, and there is not enough electrolyte to repair the SEI film, resulting in secondary batteries. Cycle life is reduced.
• the compaction density of the positive electrode film layer is too high, the electrolyte cannot be completely infiltrated into the positive electrode film layer, and lithium ions cannot be extracted during the charging process, thereby reducing the cycle life of the lithium ion battery. More importantly, the positive electrode particles may be broken during the compaction process, leading to the formation of new contact interfaces and new side reaction products.
• the packing density of the positive electrode layer satisfies PD n 3.3g / cm 3 ⁇ PD positive ⁇ 3.6g / cm 3, preferably from 3.4g / cm 3 ⁇ PD positive ⁇ 3.5g / cm 3; a negative 1.6 ⁇ PD packing density layer satisfies negative ⁇ 1.75g / cm 3, preferably 1.65 ⁇ PD negative ⁇ 1.7.
• a secondary battery includes an outer packaging bag, and a battery cell and an electrolyte provided in the outer packaging bag, and the battery cell includes a positive pole piece, a negative pole piece, and a separator.
• the positive and negative pole pieces are immersed in the electrolyte, and the ions use the electrolyte as the medium to move between the positive and negative electrodes to realize the charge and discharge of the battery.
• the positive and negative electrode layers need to be separated by a separator.
• the specific types and composition of the separator and the electrolyte are not specifically limited, and can be selected according to actual needs.
• the isolation film may be selected from polyethylene film, polypropylene film, polyvinylidene fluoride film and their multilayer composite film.
• a lithium salt solution dissolved in an organic solvent is usually used.
• the lithium salt is, for example, LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 and other inorganic lithium salts, or LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN(CF 3 SO 2 ) 2 , LiC(CF 3 SO 2 ) 3 , LiC n F 2n+1 SO 3 (n ⁇ 2) and other organic lithium salts.
• the organic solvent used in the non-aqueous electrolyte is, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
• cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.
• chain esters such as methyl propionate, cyclic esters such as ⁇ -butyrolactone, dimethoxyethane, diethyl ether, diglyme, triglyme and other chains
• chain esters such as methyl propionate, cyclic esters such as ⁇ -butyrolactone, dimethoxyethane, diethyl ether, diglyme, triglyme and other chains
• cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, nitriles such as acetonitrile and propionitrile, or mixtures of these solvents.
• a lithium ion secondary battery is taken as an example to briefly describe the secondary battery of the present application.
• the battery positive pole piece is prepared according to the conventional method in the field.
• a conductive agent for example, Super P, etc.
• a binder for example, PVDF
• other additives such as PTC thermistor materials can also be added.
• these materials are mixed together and dispersed in a solvent (such as NMP), stirred evenly and evenly coated on the positive electrode current collector, and dried to obtain the positive electrode sheet.
• a solvent such as NMP
• Materials such as metal foil such as aluminum foil or porous metal plate can be used as the positive electrode current collector.
• aluminum foil is used.
• the negative pole piece of the present application can be prepared by a well-known method in the art.
• the negative active material, optional conductive agent (such as Super P, etc.), binder (such as SBR, etc.), other optional additives (such as PTC thermistor material) and other materials are mixed together and dispersed in a solvent (such as In deionized water), the mixture is uniformly stirred and coated on the negative electrode current collector, and the negative electrode piece containing the negative electrode film layer is obtained after drying.
• a metal foil such as copper foil or a porous metal plate can be used.
• copper foil is used.
• the proportion of active material in the positive and negative film layer should not be too low, otherwise it will lead to too low capacity; the proportion of active material should not be too high, otherwise it will lead to conductive agent and binder Decrease, the conductivity of the pole piece and the degree of adhesion with the current collector are reduced, which in turn leads to a decrease in the electrical performance of the cell.
• the current collector when preparing the positive and negative pole pieces, can be coated on both sides or on one side. When the electrode current collector is coated on both sides, each parameter is measured for a certain single-sided electrode film layer.
• the present application can allow the secondary battery to improve the high-temperature storage performance and cycle life of the battery under the premise of a higher energy density. Therefore, it is of great significance for the manufacture of batteries.
• the second aspect of the present application provides a device, which includes any one or more of the secondary batteries described in the first aspect of the present application.
• the secondary battery may be used as a power source of the device.
• the device may be, but not limited to, mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, Electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
• the positive electrode active material see Table 1 for the ingredients
• the conductive agent Super P
• the binder PVDF
• NMP solvent
• the positive electrode slurry is uniformly and transparently obtained; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil; the positive electrode current collector coated with the positive electrode slurry is dried at room temperature and then transferred to an oven for drying, and then subjected to cold pressing, Slitting and other processes to obtain the positive pole piece.
• the compacted density of the positive electrode film is 3.45g/cm3, and the areal density is 0.313g/1540.25mm2.
• the negative electrode active material (see Table 1 for ingredients), conductive agent (Super P), CMC-Na (sodium carboxymethyl cellulose), and binder (styrene butadiene rubber) are carried out at a mass ratio of 94.5: 1.5: 1.5: 2.5 Mix it with the solvent (deionized water) under the action of a vacuum mixer to prepare a negative electrode slurry.
• the negative electrode slurry is evenly coated on the copper foil of the negative electrode current collector, and the negative electrode current collector coated with the negative electrode slurry is kept at room temperature. After air-drying, it is transferred to an oven for drying, and then undergoes processes such as cold pressing and slitting to obtain the negative pole piece.
• the compacted density of the negative electrode film is 1.70g/cm3, and the areal density is 0.125g/1540.25mm2.
• EC ethylene carbonate
• EMC ethyl methyl carbonate
• DEC diethyl carbonate
• Test the strength of the seal area with a tensile machine Take samples with a length of 8mm on the seal area of the outer packaging bag of each embodiment and comparative example, and take 5 groups of each. Place the samples in the middle of the clamp, and clamp the upper and lower ends with clamps respectively. Stretch at a speed of 50mm/min and stretch until the seal area breaks. Record the tensile value. The average value of the 5 sets of samples is the seal strength.
• Step 1) Weigh the mass of the negative electrode film with a standard balance, and measure the coating area of the negative film with a ruler, and then calculate the mass per unit area (g/cm 2 ) of the positive/negative film.
• Step 2): According to the positive/negative film laminate density D positive/negative the mass per unit area of the positive/negative electrode film layer (g/cm 2 )/the thickness of the positive/negative electrode film layer (cm), calculate the positive/negative electrode
• the film compaction density D is positive/ negative , and the thickness of the negative positive/negative film layer can be measured by a micrometer.
• the average particle size of the positive/negative electrode active material (unit: micron)
• Porosity P (V1-V2)/V1*100%, where V1 is the apparent volume of the sample, and V2 is the true volume of the sample.
• Each sample was charged to 4.2V at a constant current of 1/3C at room temperature, and then charged to a current of 0.05C at a constant voltage of 4.2V, and the volume of the battery V 0 was tested; then each sample was placed in a thermostat at 60°C and stored for 50 After days, the battery was taken out to test its volume and recorded as V 50 .
• the volume expansion rate (%) of the lithium ion battery after high temperature storage for 50 days (V 50 -V 0 )/V 0 ⁇ 100%.
• each sample was checked every 5 days to determine whether the battery leaked by checking the appearance of the battery. A total of 10 times were checked, and the proportion of the number of leaking batteries was counted.
• the lithium-ion batteries prepared in the examples and comparative examples were fully charged at a rate of 1/3C and fully discharged at a rate of 1/3C, and the actual discharge energy was recorded at this time; at 25°C, an electronic balance was used to The lithium ion battery is weighed; the ratio of the actual discharge energy of 1/3C of the lithium ion battery to the weight of the lithium ion battery is the actual energy density of the lithium ion battery.
• Table 1 Parameters and battery performance of lithium ion secondary batteries according to Examples 1-9 and Comparative Examples 1-3 of the present application
• Examples 1-9 and Comparative Examples 1-3 show that when the positive and negative electrodes contain specific active materials, the seal width of the outer packaging bag is controlled within the range of 3mm-8mm, and the obtained battery not only has a higher energy density, but also Moreover, the high-temperature storage performance and safety performance of the battery are effectively improved.

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• Electrochemistry (AREA)
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• Inorganic Chemistry (AREA)
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• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
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• Secondary Cells (AREA)
• Battery Electrode And Active Subsutance (AREA)
• Sealing Battery Cases Or Jackets (AREA)

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• 2019
  • 2019-12-03 JP JP2022520024A patent/JP7332800B2/ja active Active
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