120results about How to "Improve the first Coulombic efficiency" patented technology

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 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 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 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 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 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.

The invention provides a hard carbon material and a preparation method and application thereof, in a Raman spectrum of the hard carbon material, the ratio of the peak intensity at the wavelength of 1345 cm <-1 > to the peak intensity at the wavelength of 1600 cm <-1 > is 0.9-1.3, and the powder impedance of the hard carbon material under the pressure of 16-20 MPa is 0.02-0.07 omega.cm. According to the invention, the reversible specific capacity, the first coulombic efficiency and the rate capability of the battery can be improved.

The invention discloses a biomass hard carbon surface optimization method and application of the biomass hard carbon surface optimization method in a sodium-ion battery, and belongs to the technical field of sodium-ion batteries. The biomass hard carbon surface optimization method comprises the following steps: pre-oxidizing a biomass raw material, and carrying out high-temperature carbonization in an inert atmosphere to obtain primary carbonized powder; dispersing the preliminarily carbonized powder and dopamine hydrochloride in a buffer solution, and reacting to obtain hard carbon powder coated with polydopamine; and carrying out high-temperature carbonization on the hard carbon powder coated with the polydopamine in an inert atmosphere to obtain the biomass hard carbon. The biomass hard carbon prepared by the invention has high first coulombic efficiency, high reversible specific capacity, excellent rate capability and good cycle stability, and can overcome the problems of low first coulombic efficiency and poor rate capability of the existing hard carbon negative electrode.

The invention discloses a method for preparing a sodium-ion battery hard carbon negative electrode material by co-pyrolysis of biomass and plastic and application of the sodium-ion battery hard carbon negative electrode material. The preparation method comprises the following steps: mixing biomass powder and plastic powder, adding the mixture into a phosphate solution, and stirring for 0.2-2 hours; drying the obtained mixture, and carbonizing in an inert atmosphere; and carrying out acid pickling on the obtained carbonized product, cleaning with deionized water, and drying to obtain the sodium-ion battery hard carbon negative electrode material. According to the invention, biomass and plastic are used as raw materials, an inorganic phosphate solution is used as an aperture regulator, and in the heating carbonization process, biomass and plastic co-pyrolysis greatly improves the carbon yield of pure biomass raw materials. Compared with other methods for preparing hard carbon by using biomass materials, the method is completed in one step, further modification post-treatment is not needed, and the method has the advantages of being simple, practical, low in cost and high in performance.

The invention discloses a preparation method of pitch-based porous carbon with an adjustable pore volume ratio, a product of the pitch-based porous carbon and application of the pitch-based porous carbon as a substrate to preparation of a silicon-carbon negative electrode material, the preparation of the porous carbon comprises the following steps: S1, dissolving cellulose in an alkali / urea / aqueous solution, fully hydrolyzing to obtain a uniform solution, adding pitch, and uniformly stirring; after fully mixing, heating and drying to obtain a cellulose and asphalt composite material; s2, heating the cellulose and asphalt composite material to carry out pre-oxidation crosslinking, and then carrying out pre-carbonization treatment in a protective atmosphere to obtain a carbonized material; and S3, activating the carbonized material to obtain the pitch-based porous carbon with an adjustable pore volume ratio. The asphalt-based porous carbon prepared by the method disclosed by the invention has extremely high particle strength, the micropore rate and the micropore-mesopore ratio are adjustable, and the silicon-carbon negative electrode material prepared by taking the asphalt-based porous carbon as the substrate has excellent cycling stability, high reversible specific capacity and first coulombic efficiency.

The invention relates to a negative electrode material and a preparation method thereof, a negative electrode plate, a battery and an electronic device. The preparation method of the negative electrode material comprises the following steps: dissolving a hard carbon precursor in a first solvent, and carrying out a hydrothermal reaction to obtain an intermediate A; performing heat treatment and acid pickling on the obtained intermediate A in a first protective gas atmosphere to obtain a hard carbon material; and adding 2, 2-dimethyl vinyl boric acid into a second solvent, stirring for the first time, adding the obtained hard carbon material, stirring for the second time, and baking to obtain the negative electrode material. The negative electrode material prepared by the preparation method disclosed by the invention has a stable and compact artificial solid electrolyte interface (SEI) membrane, the irreversible capacity of the material can be remarkably reduced, and the first coulombic efficiency and the capacity retention ratio of the battery are improved.

The invention relates to a uniform carbon-coated mesoporous silicon carbon negative electrode material and a preparation method and application thereof.The preparation method comprises the steps that a product obtained after pyrolysis and carbonization of a biomass carbon source is subjected to alkali activation treatment, acid pickling, drying, smashing, passivation, water washing and drying are conducted to obtain a mesoporous carbon matrix, nanometer silicon particles are deposited in pores of the mesoporous carbon matrix, and the uniform carbon-coated mesoporous silicon carbon negative electrode material is obtained. Then selecting a low-temperature carbonization material and polyethylene glycol to perform pre-carbonization and complete carbonization treatment on the mesoporous silicon carbon material to obtain a carbon coating layer, and finally obtaining the uniform carbon-coated mesoporous silicon carbon negative electrode material. When the uniform carbon-coated mesoporous silicon carbon negative electrode material is applied to a lithium battery, the mesoporous skeleton can effectively inhibit volume expansion of silicon in a battery circulation process, and the uniform carbon-coated layer can effectively reduce the risk of direct contact between the negative electrode material and an electrolyte, so that a stable SE I film is formed to reduce the occurrence of side reactions; and the first coulombic efficiency and the cycle performance of the battery are further improved.

The invention provides a silicon-carbon composite negative electrode material, a preparation method of the silicon-carbon composite negative electrode material, a lithium ion battery negative electrode plate containing the silicon-carbon composite negative electrode material and a lithium ion battery, and relates to the technical field of lithium ion batteries. The silicon-carbon composite negative electrode material comprises a porous carbon skeleton, silicon distributed in internal pores of the porous carbon skeleton, and a functional interface layer covering the outer surface of the skeleton, wherein no free silicon elementary substance exists on the outer surface of the porous carbon skeleton, and the functional interface layer comprises a metal fluoride passivation layer formed by reacting metal elements doped in the carbon skeleton with a fluorine-containing etching agent; and the hybrid electrolyte coating layer is formed by reacting an oxygen-containing or nitrogen-containing functional group grafted on the surface of the carbon skeleton with a fluorine-containing etching agent. According to the technical scheme, the stable interface layer with passivation protection and ion conduction functions can be constructed in situ while high-activity silicon on the surface is removed, so that the first coulombic efficiency, the cycling stability and the rate capability of the battery are remarkably improved, side reactions are reduced, and the safety of the battery is improved.

The invention discloses a Si / C negative electrode water-based binder for a lithium ion battery and a preparation method of the Si / C negative electrode water-based binder. The invention relates to a lithium ion battery Si / C negative electrode water-based binder, which is a polyacrylic acid-based cationic water-based polyurethane binder, and is formed by bonding a cationic water-based polyurethane emulsion with a thermal reversible self-repairing function and a polyacrylic acid aqueous solution through hydrogen bonds, ionic bonds and covalent ester bonds, the mass ratio of polyurethane to polyacrylic acid is (15: 1)-(4: 1). The aqueous binder provided by the invention can effectively inhibit the expansion of negative silicon-based particles in the charging and discharging process, keeps the stability of an electrode structure, and has excellent first coulombic efficiency and good battery cycle stability.

The invention provides a lithium metal negative electrode protection layer, a preparation method and application thereof, and a lithium metal battery, and relates to the technical field of lithium metal batteries, the protection layer is formed on the surface of a metal lithium foil, and comprises a polymer and an inorganic substance; the polymer comprises polyvinylidene fluoride-hexafluoropropylene; the inorganic substance includes lithium phosphate. The components of the protective layer cooperate with each other, so that lithium dendrites can be physically inhibited, the first discharge specific capacity, the first coulombic efficiency and the cycle performance can be effectively improved, gas can be actively consumed, and the cycle stability and the safety performance of the lithium metal battery can be cooperatively improved from multiple dimensions; the technical problems that an existing protective layer cannot actively eliminate gas, the lithium dendrite inhibiting effect is poor, and the interface stability is poor are solved.

The invention provides a carbonaceous material and a preparation method thereof, and a negative pole piece, a secondary battery and an electric device containing the carbonaceous material, after the carbonaceous material is subjected to an adsorption test for 100 hours by adopting water vapor under the conditions of 25 DEG C and 100% RH constant temperature and humidity, the adsorption mass of the water vapor is recorded as A, the initial mass of the carbonaceous material is recorded as B, and A / B is greater than or equal to 0.13 and less than or equal to 0.50. The capacity and the first coulombic efficiency of the carbonaceous material can be improved at the same time.

The application discloses a preparation method of a sodium ion battery hard carbon negative electrode material based on step-by-step synergistic regulation, and comprises the following steps: S1, biomass pretreatment; S2, low-temperature pre-carbonization to obtain biomass pre-carbonized carbon; S3, physical activation: the pre-carbonized carbon is placed in an activation atmosphere to perform medium-temperature activation, and biomass activated carbon is obtained; S4, high-temperature carbonization: the biomass activated carbon is placed in an inert atmosphere to perform high-temperature carbonization, and a hard carbon intermediate is obtained; S5, chemical vapor deposition coating: the hard carbon intermediate is placed in a mixed atmosphere of a coating carbon source and an inert gas to perform chemical vapor deposition coating, and a surface-coated biomass hard carbon negative electrode material is obtained. The application can realize a higher closed pore volume at a milder temperature, and the synergistic regulation pore forming mode of activating and forming pores first and then high-temperature closing pores also avoids the insufficient closed pores caused by single high-temperature treatment.

This invention belongs to the technical field of lithium battery anode materials, specifically relating to a highly conductive graphite electrode material and its preparation method. The preparation method includes: pre-dissolving sodium carboxymethyl cellulose into a gel solution, then ball-milling and mixing graphite and conductive carbon black, dispersing them together with a cobalt hexacyanorubium(II)-dodecyltungstencobalt(III) salt hybrid material and hafnium diboride nanomaterials in the gel solution, adjusting the acidity, adding styrene-butadiene rubber emulsion to obtain a uniform slurry, and then coating, drying, and compacting to obtain the anode sheet. This invention significantly improves the conductivity and structural stability of the graphite anode through the synergistic effect of the interface modification of the cobalt hexacyanorubium(II)-dodecyltungstencobalt(III) salt hybrid material and the conductive framework of the hafnium diboride nanomaterials. The process is safe and controllable, and suitable for industrial production of lithium-ion batteries.

The invention discloses a carbon-coated silicon-based composite material and a preparation method thereof.The preparation method comprises the steps that firstly, a silicon monoxide material and a lithium source liquid phase are mixed in the mode of solvent evaporation after liquid phase mixing, and a layer of lithium silicate precursor is evenly distributed on the surfaces of silicon monoxide particles through high-temperature sintering; and mixing the carbon-coated silicon-based composite material with an organic resin liquid phase, and carrying out high-temperature carbonization to obtain the carbon-coated silicon-based composite material. The invention also discloses an application of the carbon-coated silicon-based composite material as a lithium ion battery negative electrode material. The carbon-coated silicon-based composite material prepared by the method disclosed by the invention has relatively high first coulombic efficiency and excellent cycle performance and rate capability, and the method disclosed by the invention is simple in preparation process and further has the characteristic of industrialization.

This invention belongs to the field of hard carbon technology, specifically relating to a bamboo-based and lignin-based hard carbon composite material, its preparation method, and its applications. The process involves pretreating raw materials to obtain pretreated material; pretreating the pretreated material with an acidic oxidant to obtain acidic oxidant pretreated material; pre-oxidizing the acidic oxidant pretreated material to obtain pre-oxidized material; pre-carbonizing the pre-oxidized material under a protective atmosphere to obtain pre-carbonized material; pulverizing the pre-carbonized material to obtain pulverized material; acid washing followed by water washing to obtain purified material; soaking the purified material in acid, filtering, and drying to obtain soaked material; mixing the soaked material with a modifier, and high-temperature coating and carbonizing under a protective atmosphere to obtain bamboo-based coated hard carbon or lignin-based coated hard carbon. Mixing the two types of hard carbon and carbon coating yields a bamboo-based and lignin-based hard carbon composite material, which is used in negative electrode sheets and batteries. When applied to batteries, the hard carbon composite material of this invention can improve battery energy density.

The present invention discloses silicon dioxide material, its preparation method and its application in lithium-ion batteries. The process comprises: mixing silicon dioxide powder, silicon powder, metal powder and molten salt; pressing a blank, bombarding the blank with a high-energy electron beam under vacuum conditions; crushing the obtained silicon dioxide material precursor, carbon coating or / and conductive polymer coating, and obtaining a carbon-coated or / and conductive polymer-coated metal-reduced silicon dioxide material. The present invention uses a high-energy electron beam to cause silicon dioxide and silicon to undergo an alloying reaction and then performs metal reduction, followed by carbon coating or / and conductive polymer coating to obtain a carbon-coated or / and conductive polymer-coated metal-reduced high-initial-efficiency silicon dioxide material. Since the metal reduction generates the corresponding oxides and silicates, the subsequent consumption of lithium ions is reduced, thereby improving the initial coulombic efficiency and cycle stability of the silicon dioxide material, and is an excellent choice for negative electrode materials for lithium-ion batteries.

The invention particularly relates to a high-capacity amorphous carbon-based negative electrode material and a preparation method and application thereof.The preparation method comprises the steps that a large number of oxygen-containing functional groups are introduced into a crushed carbon source precursor through deep oxidation, the carbon layer spacing is enlarged, and then the disordered blocky amorphous carbon negative electrode material is obtained through high-temperature carbonization; heteroatoms introduced by the strong oxidant are converted into CH4, CO2 and other gases to leave the surface of the carbon source, so that the surface defects of the carbon source are reduced, the first coulombic efficiency is high, and the method is simple in process and can be applied to large-scale industrial production; a strong oxidant is selected to deeply oxidize a precursor, inert groups on the edge of a polygonal carbon ring can be oxidized into oxygen-containing active groups while a large number of oxygen-containing functional groups are introduced, the defects that common amorphous carbon is low in initial coulombic efficiency, low in specific capacity and poor in rate capability are further overcome, and the requirements of a lithium / sodium ion battery for a negative electrode material are met.

The application discloses a preparation method of nitrogen-doped carbon-silicon nanofibers and application of the nitrogen-doped carbon-silicon nanofibers in a lithium ion battery negative electrode material, and belongs to the technical field of lithium ion battery negative electrode materials. The method comprises the following steps: mixing silicon nanoparticles and a carbon source, performing electrostatic spinning, stabilization treatment and carbonization treatment, and obtaining carbon-silicon nanofibers; and then mixing the carbon-silicon nanofibers with a nitrogen source, performing heat treatment under an inert atmosphere, making nitrogen elements doped into a carbon skeleton, and obtaining nitrogen-doped carbon-silicon nanofibers. The material obtained by the application is a one-dimensional nanofiber structure, silicon particles are uniformly wrapped in carbon fibers, and nitrogen elements are uniformly distributed in the carbon skeleton. The method can realize uniform nitrogen doping while maintaining the microstructure of the material, and significantly improves the electronic conductivity and interface stability of the material. The material obtained by the application is used as a lithium ion battery negative electrode, and exhibits high reversible capacity and excellent cycle stability.

The present application provides a negative electrode active material (100), a secondary battery comprising the same and an electrical device, wherein the negative electrode active material (100) comprises a matrix material and a silicon-based material, the matrix material comprises a plurality of pore structures, at least a part of the silicon-based material is located in pore structures of the matrix material, the silicon-based material comprises a crystalline silicon-based material, a region formed by extending from outer surface of particle of the negative electrode active material (100) to inside of the particle by a distance of 0.5 times a length between any point on the outer surface of the particle of the negative electrode active material (100) and a core of particle (O) is recorded as an outer region (101), and a region inside the outer region (101) is recorded as an inner region (102), and in cross-sectional image of the negative electrode active material (100), total cross-sectional area of the crystalline silicon-based material in the outer region (101) is smaller than total cross-sectional area of the crystalline silicon-based material in the inner region (102). The secondary battery provided by the present application can have high energy density, high First Coulombic Efficiency, long cycle life and long storage life at the same time.

The invention discloses a soft carbon coated sulfur-nitrogen co-doped coal-based hard carbon material and a preparation method thereof.The preparation method comprises the steps that firstly, bituminous coal powder and thiourea particles are dissolved in absolute ethyl alcohol, fully stirred and mixed to be uniform, and after drying, bituminous coal-thiourea mixed powder is prepared; carrying out primary carbonization treatment on the bituminous coal-thiourea mixed powder in an inert atmosphere to prepare a sulfur-nitrogen co-doped coal-based hard carbon material; and depositing asphalt on the surface of the sulfur and nitrogen co-doped coal-based hard carbon material, and carrying out secondary carbonization treatment on the product to prepare the soft carbon coated sulfur and nitrogen co-doped coal-based hard carbon material, a sodium ion battery based on the soft carbon coated sulfur-nitrogen co-doped coal-based hard carbon material has high sodium storage specific capacity and first coulombic efficiency and high potential platform area sodium storage capacity proportion.

The invention provides a biomass-based hard carbon negative electrode material, a preparation method thereof and a sodium ion battery, and relates to the technical field of sodium ion battery negative electrode materials. The preparation method of the biomass-based hard carbon negative electrode material comprises the following steps: S1, carrying out coarse crushing and pre-carbonization on a biomass hard carbon precursor to obtain a pre-carbonized material; s2, crushing, pickling, washing and drying the pre-carbonized material to obtain a purified material; s3, adding a silane coupling agent into water, carrying out primary mixing and stirring to obtain a first solution, adding the purified material into the first solution, carrying out secondary mixing and stirring to obtain a second solution, adding a phosphorus-containing dopant into the second solution, carrying out tertiary mixing and stirring, and drying to obtain a first precursor; and S4, carbonizing and screening the first precursor. The biomass-based hard carbon negative electrode material prepared by the invention has proper compaction density and specific surface area, and can effectively improve the specific capacity, the first coulombic efficiency and the rate capability of a sodium ion battery when being used in the sodium ion battery.