213results about How to "Improve the first Coulombic efficiency" patented technology

The invention belongs to the technical field of batteries, and particularly relates to a lithium ferrite lithium supplement agent and a preparation method and application thereof. Compared with the prior art, a solid electrolyte coating layer is formed on the surface of the carbon-doped lithium iron oxide material through a low-temperature molten salt method, so that air can be effectively isolated, the air stability of the material is improved, the lithium removal phenomenon is reduced, and the structural integrity and lithium supplement performance of the material are kept; and the lithium ferrite lithium supplement agent combines the high theoretical lithium supplement capacity of Li5FeO4 and the excellent ionic conductivity of the solid electrolyte, so that the electrochemical performance of the material can be improved while the high lithium supplement capacity is maintained, and a new technical scheme is provided for commercial application of the high-energy-density lithium ion battery.

The invention discloses a watermelon structure-imitated silicon-carbon negative electrode material as well as a preparation method and application thereof. The preparation method comprises the following steps: step 1, liquid phase coating: adding nano silicon particles into a carbon source solution containing organic matters, uniformly stirring, filtering and drying to obtain an organic carbon source-coated nano silicon material; step 2, stirring and calcining the material obtained in the step 1 in the atmosphere of introducing protective gas, then heating, and introducing the protective gas to obtain an intermediate material; and 3, introducing a carbon source gas into the intermediate material obtained in the step 2, and collecting a product after carbon deposition on the surface of the intermediate material is completed, wherein the product is the silicon-carbon negative electrode material with the watermelon-like structure. According to the silicon-carbon negative electrode material disclosed by the invention, a gap is reserved between the carbon layer and the silicon, so that a space can be provided for volume expansion of the silicon, the carbon layer and the deposited carbon can provide buffer for the volume expansion of the silicon and inhibit the volume expansion of the silicon, so that a stable SEI film is formed on the outer side of the material, and the consumption of lithium ions is reduced.

The invention relates to a silicon-carbon negative electrode material as well as a preparation method and application thereof. The silicon-carbon negative electrode material comprises porous silicon and a carbon layer which is filled in pores of the porous silicon and coats the outside of the porous silicon, wherein the initial true density of the silicon-carbon negative electrode material is 1.7-2.1 g / cm < 3 >, and the change value of the true density of the silicon-carbon negative electrode material subjected to 500MPa cold pressing compared with the initial true density is 4-10%. According to the invention, the problem of volume expansion (greater than 300%) of the silicon negative electrode material in the charging and discharging process of the lithium ion battery can be effectively solved, the first discharge capacity and the first coulombic efficiency of the silicon-carbon negative electrode material are greatly improved, and the lithium ion battery adopting the silicon-carbon negative electrode material disclosed by the invention has better cycle performance.

The invention provides a negative electrode material and a battery, the negative electrode material comprises a silicon-based active substance and a carbon material located on at least part of the surface of the silicon-based active substance, and the silicon-based active substance comprises silicon, a silicon oxide and a metal M compound; the negative electrode material is subjected to a Lab chromatic aberration test, the brightness L, the red-green color degree a and the yellow-blue color degree b of the negative electrode material are obtained, L is larger than or equal to 15 and smaller than or equal to 35, a is larger than or equal to-2 and smaller than or equal to 5, and b is larger than or equal to-2 and smaller than or equal to 5; in the XRD spectrum of the negative electrode material, the half-peak width of the strongest characteristic peak in the compound of the metal M in the negative electrode material is FWHM (M), the half-peak width of the characteristic peak of the silicon (111) surface is FWHM (Si), and the ratio of FWHM (M) to FWHM (Si) is more than 0.2 and less than 0.8. According to the negative electrode material provided by the invention, the first efficiency and cycling stability of the negative electrode material can be improved, and the expansion efficiency of the negative electrode material is reduced.

The invention provides a sodium-ion battery negative electrode material, a preparation method thereof and a sodium-ion battery, and relates to the technical field of battery negative electrode materials. According to the method, oxidized asphalt is used as a soft carbon material, and hydroxyl-rich biomass (chitin, chitosan and lignin) is used as a hard carbon precursor; and mixing the two materials, and performing crosslinking and carbonization treatment to obtain the sodium-ion battery negative electrode material. According to the technical scheme, by adjusting the proportion of soft carbon and hard carbon and optimizing crosslinking conditions, the crosslinking degree between the soft carbon and the hard carbon is improved, formation of a more stable crosslinking structure is promoted, the specific capacity and the rate capability of the negative electrode material can be effectively improved due to the appearance of the crosslinking structure, the rapid charging and discharging capacity of the negative electrode material under high rate is enhanced, and the service life of the negative electrode material is prolonged. The battery can meet the requirement of quick charging, the applicability of the battery in high-power application is expanded, and the battery has wide application prospects in the fields of electric automobiles, energy storage systems and the like.

The invention relates to the technical field of batteries, in particular to a porous carbon material, a silicon-carbon composite material and application of the porous carbon material and the silicon-carbon composite material. According to the porous carbon material, the micropore rate phi, the pore volume Pv and the compressive strength Cs meet the relational expression that (Cs * phi) / Pv is larger than or equal to 550 and smaller than or equal to 1050, and the micropore rate phi gt; and the compressive strength Cs is 600 to 850 MPa. The porous carbon material provided by the invention has high microporosity, and the microporosity phi, the pore volume Pv and the compressive strength Cs of the porous carbon material meet the relation that (Cs.phi) / Pv is more than or equal to 550 and less than or equal to 1050, so that the particle size of silicon particles can be effectively reduced, the absolute expansion of silicon in a carbon matrix is reduced, and the first effect and the cycling stability of the silicon-carbon composite material are improved.

The invention provides a silicon carbon material with a multilayer coating structure and a preparation method and application thereof, and relates to the technical field of battery materials. The silicon-carbon material with the multi-layer coating structure comprises a porous carbon core body, and a first carbon layer and a second carbon layer which sequentially coat the porous carbon core body from inside to outside, and the porous carbon core body comprises porous carbon and nano silicon particles deposited on the surface and in pore channels of the porous carbon; and a conductive nano carbon filler is dispersed in the second carbon layer. The silicon carbon material with the multilayer coating structure provided by the invention is used as a lithium ion battery negative electrode material, and has excellent specific capacity, coulombic efficiency and cycle performance. The result of the embodiment shows that when the silicon carbon material with the multi-layer coating structure is applied to the lithium ion battery, the first reversible capacity is 1882-2071 mAh / g, the first coulombic efficiency is 92.6-94.1%, and the capacity retention ratio of 100 cycles is 95.3-97.7%.

The invention relates to the technical field of photovoltaic crystalline silicon waste treatment, and discloses a method for preparing a lithium-rich silicon monoxide negative electrode material from photovoltaic crystalline silicon waste, and the method comprises the following steps: step 1, crushing and granulating the photovoltaic crystalline silicon waste; 2, preparing silicon monoxide particles; step 3, preparing lithium-rich silicon monoxide particles; step 4, preparing carbon-coated lithium-rich silicon monoxide particles; and 5, constructing a conductive network of the carbon-coated lithium-rich silicon monoxide particles to obtain the carbon-coated lithium-rich silicon monoxide negative electrode material with the three-dimensional conductive network. According to the scheme, high-value utilization is carried out on the photovoltaic silicon crystal waste, and the problem of subsequent treatment of solid waste is solved; the source pressure of the silicon-based negative electrode material is effectively relieved, and the preparation cost pressure of the silicon-based negative electrode material is reduced; the problems of low initial coulombic efficiency, obvious volume expansion, poor conductivity and the like of the silicon-based negative electrode material are solved by carrying out pre-lithiation, carbon coating, net coating, doping and the like on the material.

The invention provides a negative pole piece and a preparation method thereof, the negative pole piece comprises a current collector, a first active material layer and a second active material layer, the current collector is coated with the first active material layer and the second active material layer in sequence, and the gram volume of the first active material layer is larger than that of the second active material layer. The expansion rate of the first active material layer is greater than that of the second active material layer; the first active material layer comprises an alloy A supported by a carbon material; the second active material layer includes hard carbon. According to the negative pole piece, the alloy A supported by the carbon material combined by different alloys is prepared, so that the alloy A supported by the carbon material has different expansion coefficients and gram volumes, and the larger the gram volume is, the larger the energy density is; by preparing the N-doped and P-doped hard carbon, the conductivity of the material and the first effect of the lithium ion battery can be greatly improved, electron and lithium ion transport channels in the hard carbon are increased, the capacity of the material is effectively improved, and the performance of the battery adopting the negative pole piece is greatly improved.

The invention relates to the technical field of batteries, in particular to a negative active material, a negative plate comprising the negative active material and a battery. The negative electrode active material comprises silicon-carbon composite particles; the silicon-carbon composite particles have closed pores, and the volume ratio of the closed pores is 4-50%; the silicon-carbon composite particle has a core-shell structure, and the shell thickness of the core-shell structure is t, 0 lt; t < = 10 nm; the cross section of each silicon-carbon composite particle is provided with a first region and a second region, the content of a silicon element in the first region is c1, the content of a silicon element in the second region is c2, and 0.15 < = c2 / c1 < = 1.4; wherein the size of a vertical line of a tangent line of any point on the edge of the cross section on the cross section is L, on the vertical line, an area which is 0.001 L-0. 1L away from the edge of the cross section forms a first area, and an area which is 0.1 L-0. 5L away from the edge of the cross section forms a second area. The battery provided by the invention can give consideration to relatively high energy density, first coulombic efficiency, rate capability and cycling stability.

The invention provides a composite sodium supplementing agent, a sodium-ion battery positive plate and a preparation method of the sodium-ion battery positive plate, and relates to the technical field of sodium-ion batteries. The composite sodium supplement provided by the invention comprises the following components in percentage by mass: 10%-30% of an alkaline sodium supplement and 70%-90% of acidic sodium salt. The acidic sodium salt and the alkaline sodium supplementing agent are compounded according to a certain proportion, the alkaline sodium supplementing agent is used for providing sufficient sodium ions, the acidic sodium salt neutralizes the alkalinity of the positive electrode slurry, oxalic acid does not need to be additionally added to adjust the pH value when the positive electrode slurry is prepared, the technological process of positive electrode preparation is optimized, meanwhile, the situation that an electrode cannot be prepared due to a gel phenomenon is avoided, and the service life of the electrode is prolonged. And the first coulombic efficiency and the cycling stability of the sodium ion battery can be effectively improved.

The invention belongs to the field of energy storage of new energy materials, and relates to an asphalt-based hard carbon negative electrode material with high initial efficiency, high magnification and high capacity and a preparation method thereof. The hard carbon negative electrode material has a long and complete carbon layer edge, the specific surface area is 2-8 m < 2 > / g, and / or the aperture of the hard carbon negative electrode material is 1-12 nm. The method comprises the following steps: pre-oxidizing asphalt, mixing the pre-oxidized asphalt with a fusion repair-decomposition etching dual-function additive, and carrying out two-step high-temperature carbonization treatment in an inert atmosphere: melting metal salt in the first step of high-temperature carbonization so as to catalytically connect an edge carbon layer and repair defects; in the second step of high-temperature carbonization, the metal salt is decomposed to generate gas, pores are formed in the material, and the temperature of the first step of high-temperature carbonization is controlled to only melt the metal salt but not decompose the metal salt. Through single-additive two-step reaction, the first coulombic efficiency, the rate capability and the capacity are improved at the same time.

The invention discloses a porous carbon microsphere material, a silicon-carbon composite material and a preparation method and application thereof, and the preparation method of the porous carbon microsphere material comprises the following steps: S1, mixing a polymer, a solvent and conductive carbon black to obtain a precursor solution; s2, preparing the precursor solution into a carbon microsphere precursor material by adopting an electrostatic spraying method; s3, sequentially carrying out pre-oxidation and heat treatment on the carbon microsphere precursor material to obtain a spherical carbon material; s4, performing supercritical hydrothermal activation on the spherical carbon material, and performing post-treatment to obtain a porous carbon microsphere material; the activation temperature is 300 to 600 DEG C; the activation pressure is 15 to 30 MPa; the activation time is 0.5 to 1 hour. The porous carbon microspheres prepared by the invention have a series of adjustable physical and chemical characteristics, highly developed pore structures, high mesoporosity and better mechanical strength, and can enable lithium ion batteries to have the characteristics of low pole piece expansion rate, high first coulombic efficiency, excellent cycling stability and the like when being further applied to the lithium ion batteries.

The invention relates to a negative active material and a preparation method thereof, a negative pole piece and a lithium ion battery, and belongs to the technical field of electrochemistry. The negative electrode active material comprises a composite core material and a coating material, the composite core material comprises a substrate material and a first material, the substrate material is provided with a plurality of pores, and the first material is arranged on the pore walls of the pores of the substrate material; the coating material coats at least part of the outer surface of the composite core material; wherein the nucleation overpotential of lithium on the first material is smaller than the nucleation overpotential of lithium on the coating material, so that lithium ions are more prone to nucleation and deposition on the first material, and formation of lithium dendrites is reduced; the coating material further protects the inner core material and prevents the inner core material from being in direct contact with the electrolyte, so that the probability of side reaction between the metal lithium and the electrolyte / electrolyte is reduced, and the cycle performance is improved.

The invention discloses a sulfur-doped composite hard carbon material as well as a preparation method and application thereof. Sulfonated resin is used as a carbon source and a sulfur source, and non-metal sulfur atoms with the atomic radius larger than that of carbon are doped in situ, so that the carbon layer spacing of hard carbon is increased, and the rate capability of the hard carbon is improved; and the sulfonated resin is subjected to surface pre-coating modification by using a cheap biomass carbon source, so that the specific surface area and defect sites of hard carbon are reduced, the number of closed pores is increased, and the specific capacity and the first coulombic efficiency of the hard carbon are improved.

The invention discloses low-impurity biomass hard carbon as well as a preparation method and application thereof. The low-impurity biomass hard carbon is prepared from biomass raw material powder through impurity removal and carbonization; the invention discloses a preparation method of low-impurity biomass hard carbon. The preparation method comprises the following steps: mixing biomass raw material powder with a strain of macro fungi, and culturing until the macro fungi grow sporocarp; the application of the low-impurity biomass hard carbon is that the low-impurity biomass hard carbon is used for preparing a sodium ion battery negative electrode material. According to the method provided by the invention, impurities such as inorganic salts and metal elements in the biomass raw material for preparing the biomass hard carbon can be effectively removed, and meanwhile, the microporous structure of the biomass hard carbon material is maintained, so that the sodium storage performance and the cycling stability of the biomass hard carbon material serving as a sodium-ion battery negative electrode material are improved.

The present invention relates to the technical field of hard carbon negative electrode materials for sodium ion batteries, in particular to a phosphorus-sulfur co-doped hard carbon negative electrode material and its preparation method and application, wherein the preparation method is as follows: crushing and sieving a carbon source; mixing the obtained sieved material with an aqueous solution of a phosphorus source and placing it in a closed reactor for heat treatment; adding concentrated sulfuric acid, reacting under stirring, and stopping stirring after the product cools to room temperature after the reaction is completed; washing, drying, and ball milling the product in sequence; and carbonizing the product under the protection of an inert gas. Compared with the prior art, the present invention does not require pre-carbonization treatment, so it has low energy consumption, simple operation, high production efficiency, and low production cost, and is conducive to large-scale production; the specific amount of phosphorus and sulfur doped synergistically improves the specific capacity of the hard carbon negative electrode material, while taking into account the high first coulomb efficiency.

The invention discloses a silicon monoxide-based negative electrode material and preparation and application thereof, and belongs to the technical field of lithium ion battery preparation, and the preparation method comprises the following steps: bombarding pure silicon monoxide powder by nitrous oxide plasma to form N-attached modified porous silicon monoxide powder; more lithium ions can be accommodated for intercalation and deintercalation due to the porosity, the volume effect of the material in the electrochemical reaction process can be relieved, so that the cycle life of the battery is prolonged, and meanwhile, the N element is doped in the generated carbon layer, so that the conductivity and the lithium storage capacity are improved; the two prepared coating layers form a compact carbon coating layer after high-temperature carbonization, the structural integrity of the silicon monoxide negative electrode material in the charging and discharging process is enhanced, the compact carbon coating layer can effectively relieve stress caused by volume change and reduce repeated generation and fracture of an SEI film in the embedding and de-embedding process of lithium ions, and the lithium ion battery has the advantages of being simple in preparation process, low in cost and high in reliability. The first coulombic efficiency is improved, and the capacity and performance stability of the battery can be maintained.

The invention discloses a composite silicon-carbon material, a preparation method and application thereof and a lithium ion battery. The composite silicon carbon material comprises a sandwich structure, and the sandwich structure comprises a graphene nanobelt coated with a silicon layer and a graphene layer in sequence. The composite silicon-carbon material has good conductivity and good mechanical properties, and the lithium ion battery containing the composite silicon-carbon material can give consideration to excellent initial coulombic efficiency, cycle performance and rate capability, and has good capacity performance.

The invention discloses a silicon-carbon negative electrode material, a preparation method and application thereof, and a battery. The method comprises the following steps: (1) performing low-temperature presintering, tabletting and high-temperature sintering on a mixture of lithium powder, metal M and silicon powder to obtain a lithium supplementing material; the metal M is Ag and / or Cu; and (2) calcining a mixture containing the lithium supplementing material, the inorganic silicon source material and the carbon precursor in an inert atmosphere, and granulating to obtain the silicon-carbon negative electrode material. According to the silicon-carbon negative electrode material prepared by the invention, lithium can be quickly supplemented when lithium is irreversibly damaged in a negative electrode charging and discharging process, and the initial coulombic efficiency and the rate capability of the silicon-carbon negative electrode material are improved.

The invention provides a preparation method of a sodium-ion battery negative electrode material with both high capacity and high first effect. According to the invention, biomass is used as a precursor of the hard carbon negative electrode material, the precursor is subjected to acid pickling purification, then is subjected to pre-oxidation treatment, and then is subjected to high-temperature secondary carbonization to prepare the hard carbon material with excellent electrochemical performance. The preparation method is simple to operate and low in cost, the obtained biomass derived hard carbon negative electrode material is applied to the sodium-ion battery, high capacity and high first efficiency can be both considered, meanwhile, excellent rate capability is shown, and reference significance is provided for preparation of the high-performance sodium-ion battery.

The invention provides a sodium ferric sulfate composite positive electrode material and a preparation method and application thereof. The porosity of the sodium ferric sulfate composite positive electrode material is 0.1%-10%, the compaction density is 2.1-3g / cm < 3 >, the specific surface area of the sodium ferric sulfate composite positive electrode material is 5-12m < 2 > / g, and the mass percentage of a sodium-rich impure phase in the sodium ferric sulfate composite positive electrode material is 0.1%-1%. According to the invention, the charge-discharge capacity, the first coulombic efficiency and other performances of the battery can be improved.

The invention provides a construction method and application of a hard carbon surface ordered carbon layer coating structure, and belongs to the technical field of sodium ion batteries, and the construction method comprises the following steps: pre-carbonizing an organic matter precursor in an inert atmosphere to obtain low-crystallinity hard carbon; then carrying out mechanical ball milling treatment on the obtained hard carbon under solid-phase and inert atmosphere conditions, and then carrying out purification treatment to obtain a carbon material of which the surface crystallinity is higher than that of the interior; and finally, carrying out high-temperature heat treatment on the obtained carbon material to obtain the hard carbon with an ordered carbon layer coating structure on the surface. By accurately controlling the surface microcrystalline structure of the hard carbon material, the electrochemical performance, including the first coulombic efficiency, the sodium storage capacity and the cycle performance, of the hard carbon as the sodium-ion battery negative electrode material is remarkably improved, and meanwhile, the constructed hard carbon material has higher surface carbon layer crystallinity and an optimized microcrystalline structure; the storage capacity of sodium ions is enhanced, and a foundation is laid for the development of sodium ion batteries.

The invention belongs to the technical field of batteries, and particularly relates to a negative plate and a preparation method and application thereof. The negative electrode plate comprises a negative electrode current collector and a negative electrode material layer arranged on at least one side surface of the negative electrode current collector, the negative electrode material layer comprises a negative electrode active substance, a negative electrode conductive agent and a composite binder, and the composite binder comprises carboxymethyl cellulose lithium and siloxane. The negative electrode plate has relatively high stripping force or crack resistance, and the first coulombic efficiency or cycle stability of the battery can be effectively improved when the negative electrode plate is applied to the battery.

The invention discloses a SiOX / microcrystalline graphite negative electrode material and a preparation method and application thereof. Relates to the technical field of lithium battery cathode materials. The preparation method comprises the following steps: by taking microcrystalline graphite as a base material, growing nano silicon oxide particles in situ on the surface of the microcrystalline graphite and in gaps of sheet layers by adopting a hydrothermal reaction method to form a SiOX / microcrystalline graphite composite material, and coating the surface of the SiOX / microcrystalline graphite composite material with a carbon coating layer with a complete carbon layer structure, and finally, the SiOX / microcrystalline graphite negative electrode material with the core-shell structure is formed. By adopting the technical scheme, the stress effect caused by silicon volume expansion in the charging and discharging process is counteracted and inhibited by utilizing the disordered layer structure characteristic that the structure orientation of fine scales of the microcrystalline graphite is different; meanwhile, the nano SiOX particles are filled in the gaps of the microcrystalline graphite flake layer, and the fine flake graphite constructs a three-dimensional conductive network structure, so that the problem of poor conductivity of the SiOX particles is solved.

The invention discloses a hard carbon material, a preparation method thereof, a pole piece, application and an electrochemical device. The preparation method of the hard carbon material comprises the following steps: sequentially carrying out heat treatment, carbonization treatment and carbon coating on a mixture of a carbon precursor and an activating agent to obtain the hard carbon material, the carbonization treatment temperature is higher than the heat treatment temperature; the heat treatment temperature is 700-900 DEG C; the hard carbon material prepared by the invention has a relatively large closed pore volume, and a battery assembled by the hard carbon material has relatively good electrochemical performance, and particularly has relatively good initial coulombic efficiency.

The invention relates to the technical field of batteries, in particular to a silicon-carbon composite material and application thereof. The silicon-carbon composite material comprises a porous carbon material and nano silicon particles positioned in pores of the porous carbon material, in a dQ / dV curve of lithium intercalation for the first time of the silicon-carbon composite material, the ratio of the intensity value of a lithium intercalation peak at 0.30-0.45 V to the strongest peak value within 0-0.25 V is less than 0.05. The silicon-carbon composite material has the advantages of high compressive strength, high charge-discharge capacity and good cycle stability.

The invention belongs to the technical field of sodium pre-treatment of sodium-ion battery positive electrode materials, and discloses a sodium-ion battery positive electrode chemical sodium pre-treatment reagent and method and a sodium-ion battery. The method comprises the following steps: preparing a chemical pre-sodium-modified solution from ethylene glycol diethyl ether, 2, 2 '-dipyridyl and metal sodium, placing the pre-sodium-modified solution in a drying room environment, soaking a plurality of positive plates in the pre-sodium-modified solution, taking out the positive plates after a certain time, washing and drying the positive plates, and thus obtaining the pre-sodium-modified sodium ion battery positive electrode. The chemical pre-sodium modification reagent used in the invention has the characteristics of suitable oxidation-reduction potential, good chemical stability and the like, and can be applied to commercial sodium ion batteries.

The invention relates to the technical field of lithium ion battery negative electrode materials, in particular to a graphite negative electrode material and a preparation method thereof, a negative electrode plate and a lithium ion battery. The graphite negative electrode material comprises composite particles, the composite particles comprise graphite particles and polymer films coating the surfaces of the graphite particles, and the materials of the polymer films comprise polyolefin and / or polyurethane; the weight loss ratio of a TG curve obtained by carrying out a thermal weight loss test on the graphite negative electrode material in an air atmosphere at 200-600 DEG C is 1%-5%. The surfaces of the graphite particles are coated with a small amount of polyolefin and / or polyurethane, so that the specific surface area can be remarkably reduced, and the compaction density can be improved.

The invention relates to the technical field of lithium ion battery negative electrode materials, in particular to a silicon-carbon negative electrode material, a preparation method thereof, a negative electrode plate and a lithium ion battery. The silicon-carbon negative electrode material comprises a composite fiber, wherein the composite fiber comprises a core layer and a carbon coating layer; the core layer has a pore structure and comprises a carbon skeleton and a silicon material; in the cross section of the composite fiber, the area of the pore structure is S pore, the area of the silicon element is S silicon, the area of the carbon element is S carbon, and 0.5 < = S pore / (S silicon + S carbon) < = 2. The silicon material in the core layer can provide higher gram volume, and the carbon skeleton can provide mechanical strength and enhance the conductivity of the material; the core layer has a pore structure and can provide a buffer space when the silicon material is charged, so that the cycle performance is improved; the carbon coating layer can effectively reduce the specific surface area of the material, avoids direct contact between the silicon material and an electrolyte, and improves the initial coulombic efficiency; the silicon material can be ensured to have enough buffer space by meeting the relational expression, and the cycle performance can be further improved.