41results about How to "Improve low temperature discharge performance" patented technology

The invention relates to the technical field of lithium batteries, and provides a lithium ion secondary battery. The battery comprises a positive plate, a negative plate and electrolyte, the positive plate comprises lithium iron phosphate particles, and the Dv50 of the lithium iron phosphate particles is 5-15 [mu] m; the electrolyte comprises an organic solvent, and the organic solvent comprises a linear organic solvent and an annular organic solvent; the linear organic solvent comprises linear carbonic ester and linear carboxylic ester, and the cyclic organic solvent comprises cyclic carbonic ester; based on the total mass of the electrolyte, the mass ratio of the cyclic carbonate is recorded as S1, the mass ratio of the linear carbonate is recorded as S2, and the mass ratio of the linear carboxylic ester is recorded as S3; s = (S2 + S3) / S1; s satisfies 1.5 < = S < = 20; the electrolyte comprises lithium bis (fluorosulfonyl) imide and lithium hexafluorophosphate; the mass ratio of the lithium bis (fluorosulfonyl) imide to the lithium hexafluorophosphate is recorded as L, Lgt; 1. The battery provided by the invention has relatively good low-temperature discharge performance and high-temperature cycle performance.

The invention provides positive electrode slurry, a positive electrode plate, a lithium ion battery and a power utilization device, a positive electrode lithium supplement agent comprises a lithium iron phosphate main material, a binder, a conductive agent and a porous additive, the conductive agent comprises conductive carbon black with a high specific surface area, and the specific surface area of the conductive carbon black is greater than or equal to 130 m < 2 > / g. The space between the lithium iron phosphate particles in the positive electrode slurry provided by the invention is filled with the porous additive with the medium aperture and the conductive carbon black with the small aperture and the high specific surface area, so that a positive electrode plate applying the positive electrode slurry not only is small in internal pore spacing, but also forms gradient pore structure matching capable of reducing tortuosity of lithium ion transmission, and the lithium ion transmission efficiency is improved. And the technical effects of improving the electrolyte wettability of the electrode, improving the quick charge capacity, the cycle life, the low-temperature discharge capacity and the like of the battery are achieved.

The invention provides an electrolyte, an electrochemical device and an electronic device, the electrolyte comprises lithium difluorophosphate, a dinitrile compound and diethyl carbonate, based on the total mass of the electrolyte, the mass percentage content of the dinitrile compound is A%, the mass percentage content of the diethyl carbonate is B%, 10 < = A + B < = 24, and 0.8 < = A < = 3. The electrolyte comprising the lithium difluorophosphate, the dinitrile compound and the diethyl carbonate is adopted, the value of A + B is regulated and controlled, and the value of A is within the range, so that the high-temperature storage performance, the high-temperature cycle performance, the low-temperature discharge performance and the safety performance of the electrochemical device can be improved.

The invention provides a secondary battery. The secondary battery comprises a negative pole piece and an electrolyte, the negative pole piece comprises a silicon-based negative pole material; the electrolyte comprises a first additive and a second additive; the first additive comprises fluoroethylene carbonate; and the second additive comprises a compound as shown in formula I: # imgabs0 #. The secondary battery disclosed by the invention adopts a silicon-based negative electrode material and has a compact and stable interfacial film, so that the side reaction of the battery is reduced, and the normal-temperature cycle performance, the high-temperature cycle performance, the high-temperature storage performance and the low-temperature discharge performance of the battery are improved.

The invention provides an electrolyte and a lithium ion battery comprising the electrolyte. The electrolyte comprises an additive A, an additive B, a linear ester solvent and a cyclic ester solvent, the additive A comprises a fluoromononitrile compound, and the additive B comprises fluoroethylene carbonate; on the basis of the total mass of the electrolyte, the mass content of the additive A is awt%, the mass content of the additive B is b wt%, and the electrolyte meets the relational expression that b is larger than or equal to a / 5; based on the total mass of the electrolyte, the mass content of the linear ester solvent is greater than or equal to 30wt%, and the mass content of ethylene carbonate contained in the cyclic ester solvent is less than or equal to 10wt%. The electrolyte provided by the invention has high conductivity, and can give consideration to both interface stability and high-temperature stability under high conductivity.

In order to solve the problem that high-rate discharge performance and high-temperature cycle performance of a lithium ion battery in a low-temperature environment are difficult to consider in the prior art, the invention provides a lithium ion battery which comprises a positive plate, a negative plate and an electrolyte, the positive plate comprises a positive electrode material layer, and the positive electrode material layer comprises a positive electrode active material and a solid electrolyte; the electrolyte comprises a first additive; the first additive comprises at least one of the following compounds: # imgabs0 #; the lithium ion battery satisfies the following conditions: 1.25 < = L / (D * S) < = 5; s% is the mass percentage content of the first additive in the electrolyte; l% is the mass percentage content of the solid electrolyte in the positive electrode material layer; and D [mu] m is the median particle diameter D50 of the solid electrolyte in the positive electrode material layer. According to the lithium ion battery provided by the invention, by adding the solid electrolyte and the first additive and adjusting the relationship among the first additive, the solid electrolyte and the median particle size D50 of the solid electrolyte in the positive electrode material layer, the high-rate discharge and high-temperature cycle performance of the lithium ion battery in a low-temperature environment is improved.

The invention belongs to the technical field of batteries, and particularly discloses an electrolyte, a battery and an electric device, the electrolyte comprises a solvent, an electrolyte salt and a first additive, the first additive comprises silicon difluorophosphate as shown in a formula 1 and silicon borate as shown in a formula 2: # imgabs0. The electrolyte is used in the battery, so that the normal-temperature cycle, high-temperature cycle, high-temperature storage and low-temperature discharge performance of the battery can be improved.

The multifunctional composite low-temperature diaphragm comprises a base film and a mixed coating layer, the mixed coating layer is formed on at least one side of the base film, and the mixed coating layer comprises an anti-dendritic crystal material and a solid electrolyte; or comprises a base film, a first coating layer and a second coating layer, the first coating layer comprises an anti-dendritic crystal material, and the second coating layer comprises a solid electrolyte; wherein the first coating is formed on one side of the base film, and the second coating is formed on the other side of the base film; or the first coating is formed on one side of the base film, and the second coating is formed on one side, opposite to the base film, of the first coating; or the second coating is formed on one side of the base film, and the first coating is formed on one side, opposite to the base film, of the second coating. According to the invention, the low-temperature discharge and the low-temperature cycle of the lithium battery are further improved through the synergistic effect between the dendritic crystal resistant material and the solid electrolyte. In addition, the invention also provides a preparation method of the multifunctional composite low-temperature diaphragm.

The invention relates to the technical field of lithium ion batteries, in particular to an ultralow-temperature electrolyte and a lithium ion battery comprising the same, the electrolyte comprises a lithium salt, an organic solvent and an additive, and the organic solvent comprises cyclic carbonate and carboxylic ester; the lithium salt comprises lithium hexafluorophosphate and sulfonyl imide salt of at least one selected from lithium bis (fluorosulfonyl) imide or lithium bis (trifluoromethane) sulfonyl imide. The lithium ion battery comprises a positive pole piece, a negative pole piece, electrolyte and a diaphragm, the negative pole piece comprises a negative pole material layer containing a negative pole active material, and the negative pole active material comprises a silicon-based material and a carbon material; the lithium ion battery satisfies the following conditions: 0.2 < = (0.01 * E + D) / (S + 10 * L) < = 3.5, 500 < = E < = 1200, 2 < = D < = 50, 15 < = S < = 35, 0.1 < = L < = 0.5; in order to meet the requirement of high gram volume in a low-temperature environment, the negative pole piece with high gram volume and low resistivity is adopted, and the composition of the solvent and the lithium salt is regulated and controlled, so that the electrolyte still has relatively high ionic conductivity and low viscosity characteristics in the low-temperature environment, and the low-temperature charge-discharge performance of the lithium ion battery is further effectively improved.

The invention discloses an unsaturated carboxylic ester compound-containing lithium ion battery electrolyte, which comprises a main lithium salt, a non-aqueous solvent and an additive, and the additive at least comprises an unsaturated carboxylic ester compound as a first additive, a cyclic sulfate compound as a second additive and a lithium salt additive as a third additive, the specific structure is shown in the specification. When the first additive, the second additive and the third additive are added into the electrolyte to be applied to the lithium ion secondary battery, the second additive is added to facilitate the inhibition of the consumption of the first additive in the formation stage, and the second additive and the first additive cooperate to improve the high-temperature storage performance, the high-temperature cycle performance and the normal-temperature cycle performance of the battery; by adding the third additive, the internal resistance of the battery can be further reduced, and the low-temperature discharge performance is improved, so that the high-temperature and low-temperature performance of the battery can be considered.

The present invention discloses a safety coating and its application, an electrode sheet and a lithium-ion battery, and relates to the technical field of secondary battery materials. By limiting the particle size of inorganic fillers in the safety coating, the grading of large and small particles is achieved, which can make the safety coating have a denser structure, thereby reducing the probability of contact between the positive and negative electrodes, thereby improving the safety performance of the battery core. At the same time, the amount of binder in the safety coating is optimized to promote the absorption of electrolyte by the safety coating, which can improve the rate performance, low-temperature discharge performance and cycle performance of the battery core. Finally, the present invention can improve the rate performance, low-temperature discharge performance and cycle performance of the battery core while improving the safety performance of the battery core by limiting the particle size of inorganic fillers and selecting binders.

The utility model relates to an AGM lead-acid storage battery and a special groove body thereof. The groove body comprises a battery groove body, the battery jar body is an open groove defined by a left side wall, a right side wall, a front side wall, a rear side wall and a bottom wall, the upper end of the open groove is open, and two end parts of an inner cavity of the open groove are divided into symmetrical occupied spaces by two partition walls; a plurality of reinforcing ribs are uniformly distributed in the occupied space side by side and are perpendicular to the partition wall and the left and right side walls of the battery jar body; and the space between the two partition walls is divided into a plurality of unit cells capable of accommodating battery cells by partition plates. The utility model solves the problem that the assembling pressure cannot meet the requirement in the assembling process of the AGM battery, has the characteristics of simple design and convenience in manufacturing, can use a thin polar plate to produce the battery meeting the standard requirement by utilizing the groove body, improves the low-temperature performance, greatly reduces the production cost, and can relieve the swelling problem of the battery at the same time.

The invention relates to the technical field of lithium ion batteries, in particular to a high-entropy electrolyte, a preparation method thereof and a lithium ion battery. The invention provides a high-entropy electrolyte. The high-entropy electrolyte comprises a lithium salt, an organic solvent and an additive, the types of the organic solvents are more than or equal to 6, and the mass of each organic solvent accounts for more than 6% of the total mass of the organic solvents; the types of the lithium salts are greater than or equal to 2, and the mass of each lithium salt accounts for more than 20% of the total mass of the lithium salts. According to the high-entropy electrolyte disclosed by the invention, the low-temperature performance of the electrolyte is improved, and meanwhile, other performances such as normal-temperature cycle performance and high-temperature cycle performance can be considered by improving the confusion degree of the organic solvent and the lithium salt, increasing the entropy value of the electrolyte and adjusting the solvation structure of lithium ions; the high-entropy electrolyte is used in the lithium ion battery, so that the lithium ion battery has excellent low-temperature DCR, low-temperature discharge performance, normal-temperature cycle performance and high-temperature cycle performance.

The invention provides a battery module convenient for temperature adjustment, the module comprises a plurality of battery units arranged in parallel, a heat conduction module is arranged between two adjacent battery units, the heat conduction module is of a hollow structure, and the heat conduction module is filled with heat conduction oil; the heat conduction module is in an inverted T shape and comprises a heat conduction part and a heat conduction oil storage part which are sequentially arranged from top to bottom. The heat conduction part is a hollow plate and is tightly attached to the battery unit, and the surface area of the heat conduction part is smaller than or equal to that of the battery unit; the heat conduction oil storage part is positioned below the battery unit, and the heat conduction part and the heat conduction oil storage part are communicated with each other; the heat conduction module further comprises an oil guide pipe, and the oil guide pipe is arranged on the side face of the heat conduction part. One end of the oil conduit is communicated with the top end of the heat conduction part, and the other end is communicated with the heat conduction oil storage part; the oil guide pipe is used for backflow and heat dissipation of heat conduction oil. In the working process of the battery module, the battery units can generate a large amount of heat, and the temperature of the heat-conducting oil in the heat-conducting part rises, so that the heat-conducting oil in the heat-conducting part flows upwards and flows back to the heat-conducting oil storage part through the oil guide pipe to form a heat dissipation circulation loop.

The present application provides a secondary battery and a device containing the secondary battery, wherein the secondary battery comprises a negative electrode plate, a negative electrode current collector and a negative electrode film disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material; an electrolyte, comprising an electrolyte salt, an organic solvent and an additive; the negative electrode active material comprises a silicon-based material; the additive comprises an additive A and an additive B; the additive A is selected from one or more of the compounds shown in Formula 1; the additive B is selected from one or more of the compounds described in Formula 2; the melting point of the additive B is less than or equal to 5°C. The secondary battery of the present application and the device containing the secondary battery can simultaneously take into account good high-temperature cycle performance, high-temperature storage performance and low-temperature discharge performance. #imgabs0#NC——R2——CNFormula 2.

The invention relates to a modified graphite negative electrode material and a preparation method thereof, a negative electrode and a lithium ion battery. The modified graphite negative electrode material comprises graphite particles and an SEI precursor layer which is uniformly coated on the surface of each graphite particle and is constructed by lithium salt, wherein the lithium salt is of a crystalline state structure, and the thickness of the SEI precursor layer is 1-500 nm; during the first charging and discharging process of the battery, the lithium salt of the SEI precursor layer is subjected to electrochemical reaction prior to electrolyte, and an inorganic phase SEI with LiF and / or Li3PO4 as a main component is formed on the surface of graphite particles in situ. The negative electrode material disclosed by the invention realizes active formation and uniform distribution of SEI, even in a thick electrode, a continuous SEI layer can be formed on the surface of a deep graphite particle in the first charge-discharge and cycle process of a battery, the first-cycle coulombic efficiency is remarkably improved, the cycle life is remarkably prolonged, and the low-temperature and rate performance is improved; in addition, the electrolyte can more easily infiltrate the electrode, so that Li < + > is more smoothly transmitted in the thick electrode, and the electrochemical performance of the electrode is improved.

This invention discloses a lithium-ion battery negative electrode slurry and its preparation method. The dry matter of the slurry is composed of the following components by mass percentage: 0.5%–2% conductive agent, 1.7%–2.2% binder, 0.5%–2% thickener, with the balance being negative electrode active material. The conductive agent is conductive carbon black, the thickener is sodium carboxymethyl cellulose, and the binder is a mixture of polyacrylic acid binder and styrene-butadiene rubber binder. The lithium-ion battery negative electrode slurry provided by this invention employs a polyacrylic acid and styrene-butadiene rubber composite binder system, which leverages the high bonding strength and low impedance advantages of PAA while imparting good flexibility to the electrode sheet through SBR, significantly reducing the brittleness and material shedding risk of the electrode sheet. Simultaneously, the slurry does not exhibit a blue discoloration phenomenon, demonstrates excellent stability, and the coated negative electrode sheet has high peel strength and low electrode resistance, effectively suppressing electrode sheet expansion and roller sticking problems, thereby improving the rate performance, low-temperature discharge performance, and cycle life of the lithium-ion battery.

This invention relates to the field of battery technology, specifically to a lithium-ion secondary battery. The lithium-ion secondary battery includes an electrode assembly, which includes a positive electrode sheet. The positive electrode sheet includes a positive current collector, a positive active layer, a protective layer, and a surface coating layer. The positive active layer is located on at least one side surface of the positive current collector, the protective layer is located between the positive current collector and the positive active layer, and the surface coating layer is located on the outer surface of the positive active layer away from the positive current collector. The thickness of the surface coating layer containing a solid electrolyte is 'a', where 'a' is 0.5 μm to 5 μm; the thickness of the protective layer is 'b', where 'b' is 0.2 μm to 5 μm; 0.1 ≤ a / b ≤ 10. The negative electrode sheet includes a negative current collector and a negative active layer comprising silicon-carbon material. One side outer surface of the positive electrode sheet has several protrusions. The lithium-ion secondary battery of this invention combines high energy density, low-temperature discharge performance, and needle penetration safety performance.

The present application provides an electrochemical device and an electronic device containing the same, wherein the electrochemical device comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte comprises an additive; the electrochemical device has a liquid retention coefficient of ag / Ah, satisfying 0.5≤a≤3.5; based on the total mass of the electrolyte, the mass percentage of the additive is b%, satisfying 0.005≤b≤3; wherein the additive comprises at least one of lithium bis(oxalatoborate), ethylene carbonate, methylene disulfonate, triallyl phosphate, trifluoromethylethylene carbonate or propenyl-1,3-sultone. The electrochemical device of the present application can effectively improve the low-temperature discharge performance and safety performance of the electrochemical device by adopting an appropriate electrolyte retention amount and adding an appropriate amount of the above-mentioned additives to the electrolyte. The electronic device containing the electrochemical device also has good low-temperature discharge performance and safety performance.

The invention provides a secondary battery and electric equipment. The secondary battery comprises a positive pole piece and an electrolyte, the positive pole piece comprises a positive current collector and a positive active material layer arranged on at least one surface of the positive current collector, the positive active material layer comprises a positive active material, the positive active material comprises lithium iron phosphate, and the lithium iron phosphate comprises secondary particles formed by gathering primary particles. The average particle size of the primary particles is D nm, the specific surface area of the lithium iron phosphate is BET m < 2 > / g, and D / BET is greater than or equal to 2 and less than or equal to 30; the electrolyte comprises an additive and an organic solvent, the additive comprises lithium fluorosulfonate, the mass percentage of the lithium fluorosulfonate in the electrolyte is a%, 0.05 < = a < = 0.5, the organic solvent comprises ethyl propionate, and the mass percentage of the ethyl propionate in the organic solvent is greater than or equal to 30%. The low-temperature discharge performance, the high-temperature storage performance and the high-temperature cycle performance of the secondary battery are improved by matching the proper positive electrode active material and the electrolyte.

The invention relates to the technical field of preparation methods of lithium iron phosphate materials, and provides a preparation method of a lithium iron phosphate material with low carbon content and high rate capability, the corresponding preparation method is simple in process and low in cost, and the lithium iron phosphate material prepared through one-time coating is more uniform in coating layer under the condition of ensuring low carbon content, and has a good application prospect. According to the present invention, the material conductivity is improved, the requirements of high energy density and high rate performance can be met, and the aging resistance is significantly improved, and the method comprises the following steps: firstly, adding an iron source and a lithium source of raw materials for preparing lithium iron phosphate into deionized water according to a certain ratio, and continuously stirring at room temperature to obtain a primary mixing system; and adding a second iron source, a phosphorus source and a carbon source into the primary mixed system to prepare a secondary mixed system, granulating the secondary mixed system by using a spray dryer to obtain precursor powder, sintering the powder obtained by drying the precursor powder in an inert atmosphere, and cooling after sintering is completed.

The invention relates to a high-nickel ternary positive electrode material, a preparation method of the high-nickel ternary positive electrode material, a positive plate and a battery. The high-nickel ternary positive electrode material comprises secondary particles formed by aggregating primary particles, the high-nickel ternary positive electrode material satisfies the following conditions: in the primary particles of the secondary particles, the ratio A [101] / A [104] of the total surface area A [101] of the [101] crystal face to the total surface area A [104] of the [104] crystal face satisfies 0.05 < = A [101] / A [104] < = 0.3; the concentration of the cobalt element in the secondary particle is in gradient distribution which is sequentially decreased from the surface to the center, and the cobalt element concentration C [surface] in the surface area of the secondary particle and the cobalt element concentration C [core] in the core area of the secondary particle meet the condition that (C [surface]-C [core]) / C [core] is larger than or equal to 0.05 and smaller than or equal to 0.2. According to the scheme provided by the invention, the low-temperature discharge capacity, the high-temperature storage stability and the long cycle life of the ternary material can be synergistically improved.

The invention discloses a preparation method of an efficient lithium ion battery electrolyte based on a novel polymer, and relates to the technical field of battery electrolytes.According to the polymer electrolyte, through reasonable molecular design and polymerization reaction, high ion conduction performance can be achieved, rapid transmission of lithium ions in a battery is ensured, and the service life of the battery is prolonged. According to the lithium ion battery, the migration resistance of ions in the transmission process is reduced, the ionic conductivity of the electrolyte is effectively improved, and the lithium ions can still rapidly and smoothly migrate between the positive electrode and the negative electrode in a low-temperature environment, so that the problem of discharge capacity attenuation caused by conductivity reduction is avoided, and the service life of the lithium ion battery is prolonged. According to the present invention, the lithium ion battery can maintain the high working efficiency under the extremely cold condition, and the diffusion resistance of the lithium ion in the electrolyte and the non-selective reaction of the lithium ion on the electrode surface are reduced by adding the various different functional additives so as to improve the cycle efficiency and the overall performance of the battery.

The application discloses an electrolyte, a positive electrode, a lithium ion battery and a vehicle. The electrolyte comprises a lithium salt, an organic solvent and an additive, and the additive comprises a first additive, the first additive is a dicyano cyclic ether compound, and a structural formula of the dicyano cyclic ether compound is as follows: wherein n, x, y and z are each independent positive integers, and 1<=n<=3, 0<=x<=5, 0<=y<=5 and 0<=z<=5; R1 is selected from one of a hydrogen atom, a halogen atom, a C1-C5 alkyl group, a C2-C5 unsaturated alkyl group, a C6-C 10 aryl group or a C7-C 10 alkylaryl group; and the hydrogen atom in the C1-C5 alkyl group, the C2-C5 unsaturated alkyl group, the C6-C 10 aryl group or the C7-C 10 alkylaryl group can be partially or totally substituted by a substituent. The electrolyte disclosed by the application has a small impedance growth at low temperature, is beneficial to improve the low-temperature discharge performance of the lithium ion battery, can preferentially form a stable interface protection film on the surface of the positive electrode, and improves the battery capacity, cycle life and the like of the battery at high voltage.

This invention belongs to the field of secondary batteries, and provides a novel structural additive, a preparation method, a non-aqueous electrolyte containing the novel structural additive, and a secondary battery. The novel structural additive is a complex of an inner salt compound containing a hydrocarbon sulfonate anion and a quaternary ammonium cation with difluorophosphate, having the structure shown in Formula I: where R1 is a hydrocarbon-like group with 1-6 carbon atoms; R2 is a chain-like or cyclic quaternary ammonium cation; R3 and R4 are independently selected from one of , , , , or ; R5, R6, and R7 are independently selected from hydrocarbon groups or hydrocarbon oxygen groups; R8, R9, and R... 10 The elements are independently selected from hydroxyl groups; n=1~6, m=1~6, p=1~6, and n, m, and p are independent of each other; M is a metallic element selected from Li or Na. A non-aqueous electrolyte and a secondary battery containing this novel structural additive are provided, which can improve the battery's low-temperature discharge performance and high-temperature storage performance, and extend cycle life.

The application provides a battery and a power utilization device, a positive electrode sheet comprises a positive electrode active material, the positive electrode active material is doped and / or coated with a lanthanum element; a separator surface is coated with a ceramic coating; an electrolyte comprises a first solvent, a second solvent, a first additive and a second additive; the first solvent comprises a cyclic carbonate compound, the second solvent comprises a chain fluorosulfonamide compound, the first additive comprises mannitol carbonic acid sulfate, and the second additive comprises succinonitrile; by doping / coating the positive electrode active material with the lanthanum element, the application can effectively inhibit the release of lattice oxygen under high voltage or high temperature, and reduce the exothermic reaction activity at the thermal runaway starting temperature; the first additive and the second additive in the electrolyte form a dense, high-thermal-stability CEI film and SEI film on the positive and negative electrode surfaces respectively; the separator ceramic coating provides a physical barrier, improves the thermal shrinkage temperature of the separator, and prevents internal short circuit.

The present invention provides a negative thick electrode and a preparation method and application thereof, wherein the negative thick electrode comprises a current collector and a negative active material layer disposed on the surface of the current collector, wherein the negative active material layer comprises a negative active material, a conductive agent, a dispersant and a combined binder, wherein the combined binder comprises a binder A and a binder B, wherein the binder A comprises a block copolymer, wherein the middle of the block copolymer is a polyacrylate segment, and both ends comprise a polyacrylic acid segment and a polyvinyl alcohol segment, wherein the binder B comprises an emulsion-type binder, and the negative electrode sheet of the present invention comprises both the binder A and the binder B, and the electrode sheet comprising the binder A alone is hard and brittle, and has excellent dynamic performance. The simultaneous use of the binder A and the binder B makes the negative electrode sheet have good flexibility, is conducive to processing, reduces the situation where the active material falls off from the sheet, and reduces the risk of short circuit of the electrochemical energy storage device.

The invention relates to the technical field of batteries, in particular to a composite diaphragm, a preparation method thereof and a battery. The composite diaphragm comprises a base material and a functional coating arranged on at least one surface of the base material, the functional coating comprises porous ceramic particles, water-based polyamide and an auxiliary agent; and the particle size D50 of the porous ceramic particles is 0.4-0.6 mu m. The diaphragm provided by the invention has high heat resistance, effectively enhances the wettability of an electrolyte, improves the lithium ion transmission efficiency, effectively inhibits the increase of the air permeability value of the diaphragm, and improves the low-temperature discharge performance of the battery. Moreover, a water-based coating process can be adopted, so that the risk that an oil coating process is high in difficulty and high in environmental pollution is avoided.

The invention provides an electrochemical device and an electronic device. The electrochemical device comprises a positive pole piece, a negative pole piece and an electrolyte, wherein the electrolyte comprises a compound shown in a formula I and a compound shown in a formula II; wherein the compound in the formula I is # imgabs 0, and the compound in the formula II is # imgabs 1, based on the total mass of the electrolyte, the mass percentage content of the compound in the formula I is 1%-50%, and the ratio of the mass percentage content of the compound in the formula I to the mass percentage content of the compound in the formula II is within the range of 0.5-500. According to the electrochemical device, the cycle performance, the safety performance and the low-temperature discharge performance of the electrochemical device can be improved by controlling the components of the electrolyte in the electrochemical device and the content of the components.

The invention discloses a non-aqueous electrolyte and a lithium ion battery, the non-aqueous electrolyte comprises a lithium salt, a non-aqueous organic solvent and an additive, the additive comprises a compound A shown in a formula 1, # imgabs0 #, M is selected from O = S = O or C = O, and R is selected from CH2, CHF or CF2. The molecular radius of the compound A is large, the dissociation degree of lithium ions in the electrolyte can be improved, so that the conductivity of the electrolyte is improved, ohmic resistance in the battery is reduced due to improvement of the conductivity, heat generated in the charging and discharging process is reduced due to low ohmic resistance, and the service life of the battery is prolonged. Meanwhile, the high-conductivity electrolyte is also beneficial to improving the migration speed of lithium ions at a low temperature; importantly, the compound A can also participate in formation of a thinner, uniform and compact SEI film on the surface of the electrode, so that side reaction of electrolyte is inhibited, interfacial film impedance and potential difference polarization in the charge-discharge process are reduced, the transmission rate of lithium ions is improved, and the discharge performance of the battery under the low-temperature condition can be remarkably improved.