40results about How to "Improve first-time efficiency" patented technology

The embodiment of the invention discloses a rolling control method and equipment based on pole piece thickness prediction and a medium. The rolling control method based on pole piece thickness prediction comprises the steps that rolling operation parameters and a data pair set corresponding to the pole piece thickness are obtained; according to the data pair set, determining a pole piece thickness prediction model capable of representing correlation characteristics between the rolling operation parameters and the pole piece thickness; inputting the current rolling operation parameters into the pole piece thickness prediction model to predict the numerical value of the current pole piece thickness; according to the difference between the numerical value of the current pole piece thickness and the target pole piece thickness threshold value, the current operation parameters of rolling are adjusted. According to the technical scheme provided by the embodiment of the invention, the thickness of the pole piece is accurately predicted through the pole piece thickness prediction model, so that the thickness consistency of the pole piece actually produced by rolling is relatively good, and the problem that the first-order optimal rate of the thickness of the pole piece is influenced due to the fact that the thickness of the pole piece manufactured by the existing pole piece manufacturing method is inconsistent is solved.

The invention relates to a lithium ion battery electrolyte additive, namely 2-(dimethyl phosphate)-18-crown-6-ether, and a corresponding high-energy-density lithium ion battery electrolyte. The electrolyte comprises the following components: lithium salt, an anhydrous organic solvent and an electrolyte additive; wherein the electrolyte additive comprises 2-(dimethyl phosphate ester group)-18-crown-6-ether, and the electrolyte additive comprises 2-(dimethyl phosphate ester group)-18-crown-6-ether; the use amount of the 2-(dimethyl phosphate)-18-crown-6-ether in the electrolyte is 0.1%-10% of the total mass of the electrolyte. According to the 2-(dimethyl phosphate)-18-crown-6-ether prepared by the invention, a phosphate functional group is introduced on the basis of crown ether; the electrolyte not only improves conductivity to meet charge and discharge requirements, reduces viscosity, reduces ion migration resistance (especially at low temperature), enhances chemical stability and improves thermal stability, but also improves compatibility of a positive electrode and a negative electrode, reduces problems of interface reaction, SEI membrane rupture and the like, and ensures performance and safety of the battery, thereby promoting technical development of the lithium ion battery.

The invention discloses a fast-charging low-temperature graphite composite material, a preparation method and application thereof, the composite material is of a core-shell structure, the core is porous graphite and a carbon nanotube doped with the porous graphite, and the shell is composed of a lithium supplement agent and a lithium sulfonate complex of the lithium supplement agent. The preparation method comprises the following steps: soaking porous graphite in a conductive polymer solution, adding a catalyst, a cross-linking agent and an oxidizing agent, carrying out oxidative polymerization and carbonization to obtain catalyst-doped porous graphite, and introducing carbon source gas through a vapor deposition method to obtain carbon nanotube-doped porous graphite; and adding the obtained material into a lithium sulfonate solution, adding a lithium supplement agent, uniformly mixing, and carrying out spray drying to obtain the graphite composite material. According to the obtained material, the electronic conductivity of the material is improved by using the carbon nanotubes grown on the inner core, and the lithium sulfonate coated on the outer shell has relatively strong solvation capability, so that the transmission rate of lithium ions is improved, and the rate capability is improved; meanwhile, the lithium supplement agent releases lithium ions in the charging and discharging process, the first efficiency is improved, and the low-temperature and fast-charging performance is improved.

The invention discloses a lithium-doped silicon-carbon composite material, a preparation method and application, and belongs to the technical field of preparation of lithium ion battery negative electrode materials. According to the lithium-doped silicon-carbon composite material disclosed by the invention, metal lithium is doped in porous carbon, and nano silicon is deposited on the surface of the porous carbon, so that the resistivity of the composite material is reduced; the rate capability of the lithium ion battery is improved; the surface of the nanometer silicon is coated with carbon twice through passivation gas and carbon source gas, so that the defects of the surface of the nanometer silicon are reduced, and the nanometer silicon is prevented from being in direct contact with an electrolyte, thereby reducing the side reaction of a negative electrode interface of the lithium ion battery, reducing the decomposition of the electrolyte, reducing the gas production and improving the first efficiency.

The embodiments of the present application provide a negative electrode lithium replenishment method, a negative electrode lithium replenishment device, a negative electrode and a battery, wherein the negative electrode lithium replenishment method comprises sequentially passing the negative electrode through a first lithium replenishment stage and a second lithium replenishment stage; the lithium replenishment current of the first lithium replenishment stage is greater than the lithium replenishment current of the second lithium replenishment stage. The negative electrode lithium replenishment method adopts a staged lithium replenishment method, wherein the first lithium replenishment stage can quickly replenish lithium for the negative electrode and improve the lithium replenishment efficiency of the negative electrode, and the second lithium replenishment stage can accurately control the lithium replenishment degree of the negative electrode, thereby ensuring the uniformity of lithium replenishment and avoiding local excessive or insufficient lithium replenishment. Moreover, the first lithium replenishment stage and the second lithium replenishment stage generate a structurally stable SEI film to ensure the structural stability of the negative electrode, and on the basis of improving the initial efficiency of the negative electrode, effectively suppress the volume expansion of the active component layer in the negative electrode.

The invention discloses a preparation method of a hard carbon sodium battery negative electrode material, and relates to a preparation method of a negative electrode material. The method comprises the following steps: 1, pre-oxidation treatment; 2, preparing an asphalt / binder mixture; 3, heat treatment; 4, rough grinding; 5, carbonizing; and 6, crushing. Asphalt which is low in cost and stable in supply is used as a raw material, surface oxygen-containing functional groups are enhanced through surface oxidation, then resin is added to serve as a binder to enable the asphalt to form a cross-linked structure, a large number of irregular closed-pore structures exist in a generated hard carbon structure through high-temperature carbonization, the sodium storage performance of the material is improved, meanwhile, the specific surface area is reduced, and the specific surface area is increased. Therefore, side reactions are reduced, the first efficiency is improved, and the high-performance sodium battery negative electrode material with the reversible capacity higher than 300mAh / g and the first efficiency higher than 90% is obtained. The hard carbon sodium battery negative electrode material can be obtained.

The invention belongs to the technical field of battery materials, and discloses a pre-lithiated silicon negative electrode, a preparation method thereof and an all-solid-state battery. The pre-lithiated silicon negative electrode sequentially comprises a foamed nickel substrate, a lithium intercalation body layer and a lithium source layer from bottom to top, and components in a lithium intercalation body permeate into pores of the foamed nickel substrate. Through the interaction of the foamed nickel substrate, the lithium source layer and the lithium intercalation body layer, the pre-lithiated silicon negative electrode can more effectively intercalate and deintercalate lithium ions in the first charge-discharge cycle, the first coulombic efficiency of the battery is remarkably improved, and the waste of the lithium source is reduced; and the stress caused by volume expansion of silicon is also relieved, so that the cycling stability of the pre-lithiated silicon negative electrode is enhanced.

The invention provides a negative electrode material, a negative plate and a battery, the negative electrode material comprises a carbon matrix and an active substance, the carbon matrix has holes, the active substance is at least partially distributed in the holes, the area proportion alpha of the holes with the aperture greater than 50nm in any cross section of the negative electrode material is less than or equal to 10%; wherein alpha is obtained by the following test method: the sum of the cross-sectional areas of pores with the pore diameter of more than 50nm in the region of the cross section of the single negative electrode material particle is recorded as S0, and the cross-sectional area of the single negative electrode material particle in the region is recorded as S, the area ratio of pores with the pore diameter larger than 50 nm in the cross section of a single negative electrode material particle is defined as alpha ', alpha' = S0 / S, alpha is the arithmetic average of alpha 'values of at least 10 negative electrode material particles, and the problems that in the prior art, the first efficiency is low, the volume expansion rate is large, and the cycle performance and the processing performance are poor are solved.

The invention provides a silicon-based negative electrode material which comprises a silicon-based inner core and a coating layer coating the silicon-based inner core, the coating layer is made of a carbon material and a fast ion conductor, and the mass content of the fast ion conductor in the coating layer is gradually increased in the direction from the silicon-based inner core to the coating layer. The silicon-based negative electrode material is excellent in ionic conductivity and electronic conductivity, stable in structure and beneficial to being used in a negative electrode. The invention also provides a preparation method of the silicon-based negative electrode material, a negative electrode, a battery and electric equipment.

The invention provides a silicon-carbon composite negative electrode material as well as a preparation method and application thereof, and relates to the technical field of electrode materials, the silicon-carbon composite negative electrode material sequentially comprises nano silicon, porous hard carbon, porous metal and a carbon coating layer from inside to outside; pores of the porous metal are filled with the porous hard carbon, and the nano silicon is distributed in the pores of the porous hard carbon; and the carbon coating layer is coated on the surfaces and pores of the porous metal and the porous hard carbon. The technical problems of low battery energy density and poor cycle performance caused by low conductivity, easy crushing and high charging volume expansion of the existing silicon-carbon negative electrode material are solved, the technical effects that the silicon-carbon negative electrode material has relatively high initial efficiency, relatively low charging volume expansion and relatively long cycle are achieved, and when the silicon-carbon negative electrode material is applied to the lithium ion secondary battery, the service life of the lithium ion secondary battery is prolonged. The first efficiency and the cycle life of the lithium ion battery can be effectively improved.

The application discloses a preparation method of a nitrogen-containing heterocyclic compound and an alkali metal salt of the nitrogen-containing heterocyclic compound, and steps of the preparation method of the nitrogen-containing heterocyclic compound comprise: (1) uniformly mixing trithiocyanic acid with a first solvent, introducing sulfuryl fluoride gas or adding an alkenyl sulfonyl fluoride to perform a reaction, and obtaining a crude product through a crude treatment after the reaction is finished; (2) purifying the crude product to obtain the nitrogen-containing heterocyclic compound shown in a structural formula 1; wherein R1, R2 and R3 are each independently selected from -H, -SO2F or -CH2-(CH2) n -SO2F, n is an integer selected from 1-10, and R1, R2 and R3 are not H at the same time. The preparation method of the nitrogen-containing heterocyclic compound and the alkali metal salt of the nitrogen-containing heterocyclic compound can be applied to a large amount of trithiocyanic acid in a lithium battery electrolyte, raw materials are easy to obtain, operation is simple, the yield is high, the condition is mild, the requirement for equipment is low, and the method is suitable for industrial production.

The invention discloses a silicon-carbon negative electrode material prepared based on biomass hard carbon as well as a preparation method and application of the silicon-carbon negative electrode material. The preparation method comprises the following steps: immersing hard carbon into an acid I solution, heating to 60-80 DEG C, preserving heat for 10-24 hours, filtering, and washing to be neutral to obtain activated hard carbon; dipping the activated hard carbon in a silicon source aqueous solution system for 6-8 hours, and filtering; leaching the filtered hard carbon adsorption material with an acid II solution, soaking the material in an acid III solution containing a dispersing agent for 2-4 hours, filtering, and washing with water until the material is neutral and the content of metal ions is less than 50 ppm, so as to prepare the in-situ acidified hard carbon material for adsorbing the silicon source; and carrying out gradient heating to 1200-1600 DEG C in an inert gas and hydrogen atmosphere, carrying out heat preservation, cooling, and grinding to obtain the biomass hard carbon silicon carbon negative electrode material. According to the invention, the biomass hard carbon which is cheap and easy to obtain and cannot be graphitized at a high temperature is used as a carrier and is impregnated in the silicon source dilute solution at a low temperature, and the silicon-carbon negative electrode material prepared from the biomass hard carbon is prepared through in-situ reduction and is applied to a lithium battery, so that the working efficiency and the safety performance of the battery are improved.

The invention provides a modified graphite negative electrode material, a preparation method thereof and a lithium ion battery, and relates to the technical field of lithium ion battery graphite negative electrodes. The invention discloses a preparation method of a modified graphite negative electrode material. The preparation method comprises the following steps: S1, heating and uniformly mixing a lithium-containing compound, a soft carbon precursor or a hard carbon precursor in the atmosphere of protective gas to obtain a lithium-containing coating agent; s2, adding the lithium-containing coating agent in the step S1 into the graphite main body material, uniformly mixing, and sintering in the atmosphere of shielding gas to obtain a first modified graphite negative electrode material; and S3, uniformly dispersing the first modified graphite negative electrode material in the step S2 into deionized water, adding a hydrophobic surface modifier, uniformly stirring, standing, and drying to obtain the modified graphite negative electrode material. The lithium ion battery containing the modified graphite negative electrode material provided by the invention has excellent first efficiency, cycling stability, liquid absorption performance of a negative electrode and rate capability of a battery cell.

The invention relates to the technical field of batteries, in particular to a composite negative electrode material as well as a preparation method and application thereof. The composite negative electrode material comprises an inner core matrix and a composite layer arranged on at least part of the surface of the inner core matrix, the inner core matrix comprises graphite; the composite layer comprises a complex of porous titanium oxide, a conductive carbon material and a lithium phenyl sulfonate compound. According to the composite negative electrode material, through coating of the composite layer, the cycle performance and the rate capability of the composite negative electrode material can be improved, and the composite negative electrode material is good in fast charging performance and high in safety performance.

The invention discloses a lithium ion battery negative electrode with long cycle life and high first efficiency and a preparation method thereof. The lithium ion battery negative electrode comprises a composite current collector, a silicon-carbon negative electrode active material coating coated on at least one surface of the composite current collector, and a lithium supplementing coating coated on the outer surface of the silicon-carbon negative electrode active material coating, the lithium supplementing coating comprises an inorganic lithium-containing compound, halloysite nanotube powder and lithium polyacrylate, and the mass part ratio of the inorganic lithium-containing compound to the halloysite nanotube powder to the lithium polyacrylate is (20-25): (65-75): (2-5); the inorganic lithium-containing compound is a mixture formed by lithium borate and lithium carbonate according to the mass ratio of (1-2): 1. Compared with the prior art, the lithium ion battery negative electrode provided by the invention has relatively high first efficiency, relatively long cycle life and relatively high safety performance.

This invention discloses a mesoporous carbon composite material and its preparation method. The preparation method is as follows: S1: Using tetraethyl orthosilicate as the silicon source, an ethanol / deionized water mixture, a surfactant as the solvent system, and a conductive agent as the dopant, a polycondensation reaction is carried out under acid-base catalysis. A silica / soft template composite is formed through a sol-gel process, followed by high-temperature sintering to obtain a silica composite template; S2: A mixed solution A is prepared by mixing a phenol source, a dispersant, and water; a mixed solution B is prepared by mixing an aldehyde source, a lithium supplement, and a catalyst; S3: Mixed solutions A, B, and the silica composite template are reacted, carbonized, and activated. The resulting material is then added to a hydrofluoric acid solution to dissolve the template, and the resulting material undergoes thermal reduction to obtain the mesoporous carbon composite material. The mesoporous carbon prepared using the template method exhibits advantages such as high uniformity, large pore volume, and low powder resistivity. It can be applied to silicon-carbon composite materials to increase the deposition amount of nano-silicon, improve specific capacity, and reduce the expansion of silicon-carbon materials.

The present invention provides a negative electrode material, a preparation method and an application thereof; the negative electrode material comprises a graphite material coated and modified by an aluminum oxide / graphene composite material, wherein the aluminum oxide and the graphene are uniformly coated on the surface of the graphite material by forming a composite material. The present invention can improve the conductivity of the negative electrode material and the rate performance by coating and modifying the graphene; and can improve the compatibility of the negative electrode material with the electrolyte by coating and modifying the aluminum oxide, utilizing its good stability, inhibiting the decomposition of the electrolyte, and improving the cycle performance of the battery.

The embodiment of the present invention discloses a silver-doped hard carbon composite material, which is obtained by carboxylating hard carbon, mixing it with a silver ammonia solution and a formaldehyde solution to load silver, and then mixing it with an organic solution of a lithium salt for pre-lithiation, and then carbonizing it. The present invention uses a silver mirror reaction to load nanosilver on the hard carbon material. During the silver mirror reaction, silver ions will gradually deposit on the hard carbon material to form a large number of nanosilver particles, making the silver distribution more uniform and the binding of nanosilver to the hard carbon material stronger. The hard carbon precursor is carboxylated, and the acidic groups on the surface of the carboxylated hard carbon will destroy the conversion balance of the silver ammonia complex ions in the alkaline silver ammonia solution, making it easier for nanosilver to deposit and grow on the surface of the carboxylated hard carbon grafted with acidic groups, and finally forming nanosilver particles with higher binding strength to the surface of the carboxylated hard carbon. The present invention improves the electronic conductivity of the material, improves the rate performance and increases its first efficiency.

The invention discloses a preparation method of a pre-lithiation silicon-based composite material, a pre-lithiation silicon-based composite material and an application thereof. A Li2CO3-coated lithium rod is used as a working electrode and a mixed solvent is used as a solvent. A silicon-based composite material is deposited on the surface of the working electrode by an electrochemical deposition method. The silicon-based composite material is subjected to high-temperature carbonization sintering to obtain the pre-lithiation silicon-based composite material. The mixed solvent comprises a silicon-based precursor material and a polymer monomer which are respectively and evenly dispersed in an ionic liquid. The invention has the advantages of high silicon deposition density, controllable and stable process, fast time, high lithium replenishment consistency, etc. The pre-lithiation of the silicon-based material is achieved by a core metal lithium rod. The obtained silicon-based composite material has the characteristics of high initial efficiency, low expansion, etc. Compared with the traditional chemical polymerization method, impurities caused by oxidants are avoided and the reaction efficiency is high.

The invention belongs to the technical field of batteries, and particularly relates to a battery cell and a formation method thereof, an energy storage device and a power utilization device. The battery cell formation method comprises the following steps: executing multi-stage charging formation operation at a preset temperature: charging a to-be-charged battery cell with a first charging current until the to-be-charged battery cell increases a first charge state; charging with the second charging current to the Nth charging current in sequence until the state of charge reaches the target state of charge; the first charging current to the Nth charging current are gradually increased in sequence, and at least one of the second charging current to the Nth charging current is not less than 0.5 C. The formation time of the battery is obviously shortened, the production efficiency is improved, and the manufacturing cost is reduced; meanwhile, through the stepped current design and the temperature and pressure synergistic effect, the technical problems that electrolyte infiltration in a large-size battery cell is uneven and gas is difficult to discharge can be effectively solved, a more uniform and compact SEI film is formed, the consistency of the battery cell is improved, the cycle life of the battery cell is prolonged, and the safety performance of the battery cell is improved.

This invention discloses a method for preparing SnCo-doped hard carbon composite material and its application in sodium-ion batteries. The preparation method involves adding an organotin compound to an organic solvent, followed by the addition of a graphene oxide solution. The sodium salt compound is then uniformly dispersed, and a porous tin / graphene compound is prepared through hydrothermal reaction and freeze-drying. This compound is then ground and mixed uniformly with cobalt powder and sintered at 600-1000℃ to obtain a tin-cobalt / graphene composite. This composite is then added to a starch solution, uniformly dispersed, and spray-dried. The mixture is then sintered at 500-800℃ for 1-6 hours under an inert atmosphere, followed by a further increase in temperature to 1000-1800℃ for 1-10 hours to obtain the SnCo-doped hard carbon composite material. The resulting material exhibits excellent power performance and high specific capacity in sodium-ion batteries.

This invention relates to the field of battery technology, specifically to a composite anode material, its preparation method, and its applications. A composite anode material includes a carbon material matrix and a coating layer disposed on the surface of the carbon material matrix. The coating layer contains amorphous carbon and a dual-conductor composite. The dual-conductor composite has a core-shell structure, with the core layer containing a carbon-based conductive agent and the shell layer containing a fast-ion conductor. The composite anode material of this invention, through the synergy of the various layers, can further improve the fast-charging performance of the anode material and enhance the battery's capacity and cycle performance.

The invention discloses a preparation method and application of a manganese self-doped double-coated silicon oxide negative electrode material. The preparation method comprises the following steps: using graphene oxide as a skeleton, preparing a heavy carbon hydrogel by hydrothermal reaction, and coating SiOx compounded with a titanium source in advance in the heavy carbon hydrogel during the gelation process; then repeatedly introducing carbon oxide tubes on the basis of the heavy carbon hydrogel for gelation, and simultaneously performing manganese doping during the gelation process; through repeated cycles of the gelation process, a new gel is in-situ grown on the old gel, and Mn 2+ The carbon aerogel is then coated on the SiOx surface by a multi-carbon hydrogel with a high conductivity and high density, and then freeze-dried, activated, and calcined to form a manganese self-doped double-coated silicon oxide negative electrode material with a porous network structure. The present invention has the advantages of high conductivity, high cycle stability, etc.

The application discloses a silicon-carbon negative electrode material, a preparation method, application and a battery. The preparation method of the silicon-carbon negative electrode material comprises the following steps: performing methane gas phase carbon coating on a silicon source to obtain the silicon-carbon negative electrode material; wherein, when the methane gas phase carbon coating is performed, the vacuum degree of the system is 300-5000 Pa; and the mass-volume ratio of the silicon source and methane is 1 kg:(10-150) L. The uniformity and coverage of the coating layer on the surface of the silicon source of the silicon-carbon negative electrode material are better, the carbon deposition layer has a special surface structure, the volume change of the negative electrode material in the charging and discharging process can be buffered, and the negative electrode material can realize better electrochemical performance.

The application relates to the technical field of secondary battery material preparation, and discloses a preparation method of a resin-based coated pitch-based hard carbon composite material, which comprises the following steps: S1, uniformly mixing pitch, sodium nitrite, 1,4-p-phenylenediamine and a catalyst, performing a diazotization reaction, and obtaining aminated pitch; S2, uniformly mixing the aminated pitch and an aldehyde solution, adding a graphene oxide solution and a nitrogen source, uniformly mixing again, adding a phenol solution, performing an oxidation-reduction reaction, forming a heteroatom-doped resin-based hard carbon composite shell outside the aminated pitch-based hard carbon, and obtaining a hard carbon precursor material; and S3, carbonizing the hard carbon precursor material to obtain a hard carbon composite material. Through the technical scheme, the problem that the first discharge specific capacity, the compaction density and the fast-charging performance of the hard carbon material cannot be balanced in the prior art is solved, so that the comprehensive performance of the hard carbon material is improved.

The invention discloses a sodium-supplementing type sodium ion battery and a preparation method thereof, and the preparation method of the sodium-supplementing type sodium ion battery comprises the following steps: S1, preparing sodium oxalate composite slurry, the fineness of the slurry is less than or equal to 5 [mu] m, the sodium oxalate composite slurry comprises sodium oxalate, and the particle size of the sodium oxalate is 50-200 nm; s2, coating the sodium oxalate composite slurry on a positive electrode membrane, wherein the mass ratio of sodium oxalate to a positive electrode active material is less than or equal to 3.6%; and S3, preparing a battery cell, and performing formation treatment on the battery cell. The sodium oxalate material is pretreated to prepare the nanoscale sodium oxalate particles, and the decomposition voltage of the sodium oxalate is reduced to 3.9-4.0 V which is lower than the highest working voltage of the existing sodium ion battery. The sodium oxalate can be used as a good sodium supplementing material to be applied to the sodium ion battery, and the first efficiency of the sodium ion battery can be improved from 85% to 90% or above.

The invention discloses a preparation method and application of amorphous silicon and a lithium ion battery. The preparation method of the amorphous silicon comprises the following steps: S1, adding silane gas and a straight-chain saturated hydrocarbon solvent into a reactor according to a certain volume ratio; s2, heating and pressurizing the reactor to enable the reactor to reach a supercritical state; and S3, after keeping the supercritical state for a certain time, collecting to obtain the amorphous silicon. According to the method, the amorphous silicon is prepared by thermally decomposing the silane in a supercritical state, so that a high-efficiency and low-energy-consumption preparation technology is realized.

The present invention provides a graphite negative electrode composite material, a preparation method thereof and a lithium ion battery. The graphite negative electrode composite material comprises porous graphite doped with a conductive carbon material and a coating layer located on the surface thereof; the coating layer comprises a porous oxide layer; based on the total mass of the graphite negative electrode composite material being 100%, the mass percentage of the coating layer is 1-10%. The present invention improves the fast charging performance of the battery by oxidizing the surface of the graphite material to form pores and growing a conductive carbon material, and deposits a porous oxide shell layer on its outer surface to improve the initial efficiency of the lithium ion battery.

The invention provides a preformed film negative plate, a preparation method thereof and a lithium battery applying the preformed film negative plate, and the preparation method of the preformed film negative plate comprises the following steps: S1, adding a pre-lithiation reagent into the negative plate for pre-lithiation treatment to prepare a pre-lithiated negative plate; the pre-lithiation reagent comprises organic lithium and fluorine-containing lithium salt, and the fluorine-containing lithium salt comprises at least one of lithium hexafluorophosphate, lithium bis (fluorosulfonyl) imide and lithium tetrafluoroborate; s2, adding a pre-film-forming reagent for pre-film-forming treatment to prepare a pre-film-forming negative plate; the pre-film-forming reagent comprises a pre-film-forming additive, and the pre-film-forming additive comprises at least one of lithium bis (oxalato) borate and lithium difluoro (oxalato) borate. According to the invention, the pre-lithiation treatment and the pre-film-forming treatment are sequentially carried out on the negative plate, so that the formation of a good SEI film on the surface of the negative plate is promoted, the chemical composition of the SEI film is regulated and controlled, a negative electrode interface is protected, the consumption of active lithium in the charging and discharging process is reduced, and the first coulombic efficiency and the cycling stability of the battery are improved.

The invention relates to a dry-method electrode composite binder, a preparation method thereof, a negative plate and a lithium ion battery in the technical field of lithium battery production. The composite binder is formed by mixing high-swelling styrene-acrylic emulsion and high-molecular-weight PTFE emulsion. The swelling of the high-swelling styrene-acrylic emulsion is greater than or equal to 100%, and the molecular weight of the high-molecular PTFE emulsion is not less than 500W. According to the invention, the high-swelling styrene-acrylic emulsion and the PTFE emulsion are precipitated into the composite binder in a mixed co-precipitation form, the high-swelling styrene-acrylic in the composite material can improve certain wettability for the system, and the swelled styrene-acrylic may cover part of PTFE, so that the PTFE reaction sites are reduced, and the service life of the system is prolonged. And PTFE is prevented from reacting with Li and e-electrons to lose part of active lithium in the first-circle negative electrode lithium embedding process, and the first-time efficiency is improved, so that the battery has more stable performance and longer service life in subsequent circulation.