1122 results about "Amorphous carbon" patented technology

The invention relates to the technical field of batteries, in particular to a silicon-carbon negative electrode material, a preparation method thereof and a lithium ion battery. The invention provides a silicon-carbon negative electrode material. The silicon-carbon negative electrode material comprises silicon nanoparticles, a porous carbon skeleton, an amorphous carbon layer and a carbon material array structure, pores of the porous carbon skeleton are filled with the silicon nanoparticles; the amorphous carbon layer is coated on the surface of the porous carbon skeleton; the carbon material array structure vertically grows on the surface of the amorphous carbon layer; the carbon material array structure comprises a carbon nanotube array and / or a graphene array. According to the silicon-carbon negative electrode material disclosed by the invention, the compressive strength and the conductivity of the silicon-carbon negative electrode material are improved by vertically growing the carbon nanotube array and / or the graphene array on the surface; therefore, the cycle performance and the rate capability are improved, and the cycle expansion rate is reduced.

The invention discloses a LiAlO2 fast ion conductor coated silicon-carbon composite material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion battery materials. The LiAlO2 fast ion conductor coated silicon carbon composite material has a core-shell structure; an inner core of the composite material is a silicon-carbon composite material, the silicon-carbon composite material is formed by coating a three-dimensional carbon material with an amorphous carbon layer and loading a nano silicon compound, a shell of the composite material is a LiAlO2 fast ion conductor layer, and the silicon-carbon composite material with a three-dimensional network structure is constructed, and the surface of the silicon-carbon composite material is coated with the LiAlO2 fast ion conductor layer, so that the composite material is obtained. According to the present invention, with the LiAlO2, the volume expansion of the nanometer silicon during the charge-discharge process can be effectively relieved, the stability of the silicon-carbon composite material structure can be improved so as to significantly improve the cycle performance of the battery, and the LiAlO2 can provide the rapid channel for the transmission of the lithium ion during the charge-discharge process so as to improve the rate performance of the battery;

The invention relates to the technical field of lithium ion batteries, and provides a negative plate and a lithium ion battery. The negative plate comprises a negative current collector and a negative active material layer arranged on at least one side surface of the negative current collector; the negative electrode active material layer comprises a first negative electrode active material layer and a second negative electrode active material layer, and the second negative electrode active material layer is arranged between the negative electrode current collector and the first negative electrode active material layer; the first negative electrode active material layer comprises an amorphous carbon coated graphite material, and the second negative electrode active material layer comprises a graphite material; the Dv50 of the amorphous carbon coated graphite material is recorded as P1 [mu] m, the Dv50 of the graphite material is recorded as P2 [mu] m, and P1 and P2 satisfy: P1gt; p2. The negative plate adopts a double-layer coating design to form the negative plate of which the surface layer has quick charge and the bottom layer has high energy density, so that the negative plate has both high energy density and quick charge performance.

The invention discloses a graphite composite material as well as a preparation method and application thereof, and belongs to the technical field of preparation of negative electrode materials. The graphite composite material has a core-shell structure, and the core of the core-shell structure comprises magnetic metal oxide doped porous graphite; and the shell of the core-shell structure comprises a carbon nanotube, a lithium supplement agent and amorphous carbon. The specific capacity is improved by doping the magnetic oxide in the porous graphite, and the carbon nanotube lithium supplement agent amorphous carbon is coated on the porous graphite, so that the energy density and the fast charging performance of the battery are improved.

The invention discloses a calcining carbon removal-supercritical expansion stripping method for regenerating graphene from graphite of a waste lithium battery, and belongs to the field of lithium battery recovery and nano material preparation. Comprising the following steps: treating the waste lithium battery to obtain waste lithium battery positive and negative electrode mixed powder, and then roasting to obtain battery powder; leaching the battery powder in a nitric acid solution to obtain purified graphite slag; the method comprises the following steps: mixing graphite slag with supercritical gas fluid, treating, quickly releasing pressure to normal pressure, and separating to obtain graphene. According to the method, on the basis of interlayer structure characteristics of the waste graphite negative electrode, organic matters and amorphous carbon are removed through multi-stage calcination, a supercritical N2 / CO2 mixed fluid permeation and pressure relief expansion synergistic stripping technology is combined, and low-damage dissociation is achieved through graphite microcracks. According to the method, physical stripping and liquid nitrogen shock cooling strengthening are coupled, and the obtained graphene sheet layer is high in integrity and few in structural defect and can be directly used for manufacturing conductive composite materials and energy storage devices.

The invention provides a sphere-like silicon-carbon negative electrode material and a preparation method and application thereof, and particularly relates to the technical field of negative electrode materials, the negative electrode material comprises a sphere-like porous carbon skeleton, silicon nanoparticles distributed in the sphere-like porous carbon skeleton, and an amorphous carbon layer coating the surface of the sphere-like porous carbon skeleton, the particle appearance of the sphere-like porous carbon skeleton is of a round irregular or asymmetric polyhedral structure and comprises one or more of a potato shape, an ellipse shape, an olive shape, a long strip shape and a pomegranate shape, the particle of the sphere-like porous carbon skeleton is provided with a plurality of asymmetric faces, fillets are formed between the faces, and the radius of the fillets does not exceed 20 microns. The problem of structural damage of the material under the action of external force such as rolling can be effectively relieved, good mechanical stability is kept, excellent bonding performance can be achieved in the electrode coating process, the ion transmission path of the material is improved, and the electronic conductivity and the lithium ion diffusion performance are improved.

The invention relates to the technical field of lithium ion batteries, and provides a lithium ion battery, which comprises a negative plate and an electrolyte, the negative plate comprises a negative active material, the negative active material comprises a graphite matrix and a coating layer, and the coating layer comprises an amorphous carbon material; the electrolyte comprises a carbonic ester additive and a chalcogenide additive; based on the total mass of the electrolyte, the mass ratio of the carbonic ester additive is 0.01%-8%, and the mass ratio of the sulfur additive is 0.01%-3%; the mass ratio of the carbonic ester additive to the sulfur additive is 0.3-300. In the lithium ion battery, the negative electrode active material used by the negative electrode is the graphite matrix surface coated amorphous carbon material, so that the low-temperature charging performance of the battery can be improved. Meanwhile, the carbonic ester additive and the sulfur additive are added into the electrolyte, so that the reaction activity of the negative electrode active material can be reduced, side reactions are reduced, the high-temperature performance of the battery is improved, and the battery has high and low temperature performance.

The invention discloses a silicon-carbon material as well as a preparation method and application thereof. The silicon-carbon material comprises nitrogen-doped porous carbon and an amorphous carbon layer coating the nitrogen-doped porous carbon, and pores of the nitrogen-doped porous carbon are filled with boron-doped nano silicon. The nitrogen-doped porous carbon improves the affinity of silane gas while improving the electron conductivity, a high-conductivity and high-density silicon-carbon composite structure is realized, the boron-doped nano silicon and the nitrogen-doped porous carbon form a nano heterojunction site, and the migration rate of lithium ions is improved, so that electrochemical reaction kinetics is improved, and the electrochemical performance of the lithium ion battery is improved. The material has the advantages of high rate and long cycle performance.

Systems or techniques are provided for facilitating improved digital twin calibration for scientific instruments. In various embodiments, a system can synchronize, via execution of a state-wide Bayesian filter, a parametric state of a digital twin with a physical state of a scientific instrument. In various instances, the state-wide Bayesian filter can comprise a set of calibration iterations, each of which can comprise a Bayesian update to an entirety of the parametric state based on an iteration-common observable that is exhibitable by the scientific instrument and simulatable by the digital twin. In various cases, the scientific instrument can be a charged-particle microscope, the parametric state of the digital twin can be an aberration coefficient vector of the charged-particle microscope, and the iteration-common observable can be a Fourier transform of a convergent beam electron diffraction pattern of an amorphous carbon specimen captured by the charged-particle microscope.

The invention discloses a high-initial-efficiency fast-charge graphite composite material and a preparation method thereof, the composite material is of a core-shell structure, the core is graphite, and the shell is lithium sulfonate / lithium molybdate and an amorphous carbon coating layer thereof; the mass ratio of the shell is 5-15 wt% according to the mass ratio of the composite material being 100%. The preparation method comprises the following steps: adding a molybdenum compound into a solvent to prepare a solution, adding graphite oxide, an inorganic lithium salt and a carbon nanotube conductive solution, reacting for 2-12 hours at the temperature of 50-120 DEG C, filtering, carbonizing filter residues to obtain a lithium molybdate conductive agent coated graphite material, and depositing a lithium sulfonate derivative on the surface of the lithium molybdate conductive agent coated graphite material by an atomization method to obtain the lithium molybdate conductive agent coated graphite material. The electron and ion conductivity of the material can be improved, and the rate and the first efficiency of the material can be improved.

The invention relates to the technical field of electrode materials, and discloses a preparation method of a lithium iron manganese phosphate material and a lithium ion battery. The lithium iron manganese phosphate material is prepared by the following steps: performing in-situ growth in a cavity of polyethylene glycol-sucrose hybrid aerogel with a three-dimensional porous network structure to form a manganese iron phosphate precursor; the hybrid aerogel can control excessive agglomeration and disordered growth of ferromanganese phosphate precursor particles and avoid particle agglomeration, so that the finally formed lithium ferromanganese phosphate material particles are finer and more uniformly distributed, and an amorphous carbon-aluminum layer is formed during later calcination, so that the performance of the material is improved. The surface of lithium manganese iron phosphate particles is tightly coated with the composite material, electron transmission can be accelerated, particle pulverization can be reduced, meanwhile, corrosion of corrosive components in electrolyte can be inhibited, interface side reactions such as transition metal ion dissolution can be reduced, and finally the conductivity and cycling stability of the lithium ion battery are remarkably improved.

The invention provides a metal doped silicon carbon negative electrode material and a preparation method thereof, and the preparation method comprises the following steps: a modified amorphous carbon material and a metal silane precursor are respectively prepared, the particle size of the modified amorphous carbon material is 7-8 [mu] m, and the internal pore size of the modified amorphous carbon material is 0.1-10 nm; the modified amorphous carbon material is placed in a chemical vapor deposition reactor, nitrogen is introduced, the temperature is increased to 500-700 DEG C, then composite gas is introduced, the deposition reaction is carried out for 100-800 minutes, a pre-product is obtained, the composite gas comprises a metal silane precursor, doping auxiliary gas and acetylene gas, and the doping auxiliary gas is used for regulating and controlling growth of sediments; and heating the pre-product to 750-850 DEG C for 10-30 minutes, cooling the pre-product to 500-600 DEG C, introducing acetylene gas again, and keeping the temperature for 30-300 minutes to obtain the metal-doped silicon-carbon negative electrode material. Therefore, the electrochemical performance and the cycle life are effectively improved.

The invention discloses a silicon-carbon composite material and a preparation method thereof. The composite material is composed of porous hard carbon, inorganic lithium salt doped with the porous hard carbon and a porous metal frame as a matrix, nano silicon deposited in pores of the matrix, and an amorphous carbon composite material coated on the surface. The preparation method comprises the following steps: uniformly mixing resin, inorganic lithium salt and a porous metal framework, and carrying out hydrothermal reaction, activation and secondary carbonization to obtain a porous carbon complex; and depositing nano silicon and coating the nano silicon with an organic lithium salt through a vapor deposition method to obtain the silicon-carbon composite material. According to the obtained material, expansion is reduced through large-aperture deposited nanometer silicon of the metal frame structure, the defects are reduced through the inorganic lithium salt of the inner core and the organic lithium salt of the outer shell, the ion diffusion rate is increased, and the first efficiency and the rate performance are improved.

The invention relates to the technical field of powder metallurgy materials, and discloses rare earth microalloyed ultrahigh-strength high-toughness hot work die steel and a preparation method thereof.The die steel is prepared from 4Cr5MoSiV1 pre-alloyed powder, rare earth hydride, boron carbide and porous amorphous carbon powder loaded with a nickel catalyst. The preparation method comprises the steps of material mixing, sheath packaging, graded dynamic reaction thermal devolatilization, hot isostatic pressing densification and heat treatment, in the graded dynamic reaction thermal devolatilization, active hydrogen generated by decomposition of rare earth hydride is used for reducing oxide on the surface of powder, and nickel catalyzed carbon powder is used for capturing water vapor at low temperature to generate CO to be discharged. An oxide film on the surface of the powder is thoroughly removed through in-situ chemical reaction, original particle boundaries are eliminated, meanwhile, a nano strengthening phase with high thermal stability is generated in situ, and the high-temperature strength, impact toughness and tissue compactness of the die steel are remarkably improved.

Disclosed is a negative electrode including a negative electrode active material layer, wherein the negative electrode active material layer includes a negative electrode active material and a conductive agent. The negative electrode active material includes carbon-based active material particles including natural graphite and an amorphous carbon-based material. The carbon-based active material particles have a specific surface area of 1.4 m2 / g to 2.3 m2 / g, and the conductive agent includes carbon nanotubes having an average length of 1 μm to 12 μm. A secondary battery including the negative electrode is also disclosed.

The invention provides a silicon-carbon negative electrode material and a preparation method thereof, and particularly relates to the technical field of lithium battery negative electrode materials. The silicon-carbon negative electrode material comprises coating porous carbon, coating silicon deposited in channels of the coating porous carbon and an amorphous carbon layer coating the outer layer of the coating porous carbon, the coating porous carbon comprises porous carbon and a first silicon nitride coating; the first silicon nitride coating coats the interiors of pore channels of the porous carbon and the outer surface of the porous carbon; and the coating silicon comprises silicon and a second silicon nitride coating coated on the surface of the silicon. In the silicon-carbon negative electrode material provided by the invention, the porous carbon is protected through the first silicon nitride coating, side reaction is reduced, charge and discharge stress is buffered, and structural damage is prevented. The second silicon nitride coating relieves the stress of the silicon material and protects the structural integrity. The layered silicon nitride enhances the electrochemical performance, and the amorphous carbon layer reduces the side reaction, thereby improving the efficiency and service life of the battery, and ensuring the double improvement of the battery performance and structural stability.

The invention belongs to the technical field of coating material preparation, and particularly relates to a copper-titanium co-doped amorphous carbon coating and a high-throughput preparation method. The invention firstly provides a high-throughput preparation method, the method does not need to prepare a plurality of target materials with different metal contents, a plurality of deposition samples can be obtained only by preparing a plurality of matrixes once through ingenious arrangement of matrix sample positions and specific quality control index requirements, and then test screening is carried out in combination with the quality control index requirements. And the bimetallic-doped amorphous carbon coating with the optimal performance can be rapidly screened out with relatively low process cost for practical application.

The present invention belongs to the field of liquid flow energy storage battery materials, and particularly relates to a multi-dimensional conductive material, a preparation method thereof, and an application thereof in a vanadium redox flow battery. The present invention uses a biomass precursor to bond graphite and multi-walled carbon nanotubes, and through stepwise pyrolysis, converts the carbon-based biomass into graphitized carbon nanotubes. The amorphous carbon in the graphite and the original carbon nanotubes is also further graphitized, and finally a multi-dimensional conductive material with carbon nanotubes inserted into a graphite matrix is formed. The multi-dimensional characteristics on the surface of the multi-dimensional conductive material are beneficial to forming a longitudinal conductive path on the bipolar plate, reducing the vertical bulk resistance of the bipolar plate, and also facilitating the wetting of epoxy resin between conductive particles and the mechanical interlocking of its molecular chains, improving the mechanical strength of the bipolar plate, effectively enhancing the service performance of the bipolar plate, meeting the requirements of long-term operation of the flow battery, relatively reducing the material cost of the flow battery, strongly promoting the industrialization of the bipolar plate, and having good application value.

The invention provides a silicon-carbon negative electrode material, a preparation method thereof and a secondary battery. The silicon-carbon negative electrode material comprises a carbon skeleton, nano silicon particles and a carbon coating layer, wherein the carbon skeleton is a complex of carbon nanotubes and amorphous carbon. The amorphous carbon has a hierarchical pore structure, and the hierarchical pore structure comprises 65-85% of micropores and 15-35% of mesopores. At least part of the nanometer silicon particles are contained in the grading hole structure, and the carbon framework is coated with the carbon coating layer. The silicon-carbon negative electrode material has a carbon skeleton with a hierarchical pore structure, volume expansion of nano silicon can be effectively relieved, the cycle performance of the material is improved, and a three-dimensional conductive network constructed by the carbon nanotubes is also beneficial to improvement of the rate capability of the material.

The invention discloses a carbon microsphere-silicon negative electrode material and a preparation method thereof, mesocarbon microbeads are prepared by adding a nano template agent, porous mesocarbon microbead green pellets are obtained through acid etching, and nano-silicon-loaded mesocarbon microbeads are obtained through hydrothermal reaction reduction deposition of organic silicon in pore channels generated through etching, so that the carbon microsphere-silicon negative electrode material is obtained. And coating the outermost layer with a layer of amorphous carbon, and carbonizing to obtain the carbon microsphere-silicon negative electrode material. The mesocarbon microbeads prepared by taking the nano template agent as an additive have the advantages that the particle size distribution is concentrated, the particle size is moderate, a large amount of nano template agent exists inside and on the surface, and rich nano-scale pore channels are obtained after acid etching; in the hydrothermal process, organic silicon is deposited in situ on the outer surfaces of the mesocarbon microbeads and in pore channels to form uniform coating layers, the organic silicon and the mesocarbon microbeads are combined more tightly, the nanometer silicon loaded mesocarbon microbeads are obtained through magnesiothermic reduction, and the advantages of good conductivity, good rate capability and stable cycle performance are achieved.

The invention discloses a high-potential-corrosion-resistant composite coating as well as a preparation method and application thereof. The high-potential-corrosion-resistant composite coating comprises a metal transition layer, a graphite-like amorphous carbon layer and a SnO2 hole sealing layer which are sequentially formed on the surface of the metal bipolar plate serving as a substrate, wherein the SnO2 hole sealing layer is prepared in an atomic layer deposition mode. According to the high-potential-corrosion-resistant composite coating provided by the invention, the SnO2 layer is deposited on the surface of the amorphous carbon coating, so that the effect of closing amorphous carbon defects is achieved, and the high-potential-corrosion-resistant composite coating has excellent corrosion-resistant protection performance under 1.6 V high-potential corrosion.

The invention discloses an amorphous carbon-coated sodium ion battery negative electrode biomass hard carbon negative electrode material and a preparation method thereof, and the preparation method comprises the following steps: S1, biomass precursor preparation: soaking a biomass raw material in an acid solution, and carrying out centrifugal drying to obtain a biomass precursor; s2, pre-carbonization: carrying out pre-carbonization treatment on the biomass precursor obtained in the step S1, and crushing and sieving to obtain a pre-carbonized material; s3, coating treatment: carrying out coating treatment on the pre-carbonized material obtained in the step S2 to obtain a coated activated material; and S4, high-temperature carbonization: performing high-temperature carbonization treatment on the coated activated material obtained in the step S3 to obtain the sodium-ion battery hard carbon negative electrode material coated with a carbon layer on the surface. The composite material has the characteristics of excellent structural stability, good cycling stability and high compactness.

The invention provides a silver-containing silicon carbon composite material and a preparation method and application thereof. The silver-containing silicon-carbon composite material comprises a carbon skeleton material, a silver-containing silicon-carbon composite material and a silver-containing silicon-carbon composite material, the conductive layer comprises a silver layer, and the conductive layer is at least formed in the porous structure of the carbon framework material; the nano silicon particles are at least distributed in the porous structure and are deposited on the conductive layer in the porous structure; the composite coating layer comprises an organic conductive polymer and an amorphous carbon material which are mixed and interwoven, and the composite coating layer is formed on the surface of the carbon framework material. The silver-containing silicon-carbon composite material provided by the invention can well inhibit volume expansion of silicon and has excellent conductivity, and the lithium ion battery prepared based on the silver-containing silicon-carbon composite material has good cycle performance and fast charge capability.

The invention discloses a method for preparing graphene coated inorganic nonmetal powder through chemical vapor deposition and a composite material prepared by the method. According to the method, graphene directly grows on the surface of inorganic non-metal powder through chemical vapor deposition to obtain the graphene-coated inorganic non-metal powder composite material, a metal catalyst and / or a non-metal catalyst are / is adopted in vapor deposition, the metal catalyst is fixed in a low-temperature area of a reactor for chemical vapor deposition, and the non-metal catalyst is fixed in a low-temperature area of the reactor for chemical vapor deposition. The temperature of the low-temperature region is lower than the melting point of the metal catalyst. According to the method, the catalyst (including the non-metal catalyst and / or the metal catalyst) is introduced into vapor deposition, high-quality graphene can be grown on the surface of the non-metal powder under the catalytic action of the catalyst, amorphous carbon and other impurity phases in the composite material are reduced, meanwhile, the use amount of hydrogen can be reduced, and the production safety can be improved.

A negative electrode material, comprising composite particles. Each of the composite particles comprises a core and an amorphous carbon coating layer located on the surface of the core, wherein the core comprises a graphite framework and amorphous carbon in the graphite framework; and the amorphous carbon coating layer has a thickness of 10-50 nm. Raman spectral area scanning is performed on the negative electrode material, and there are 400 Raman spectral area scanning points; and the average ID / IG value of the Raman spectrum of the negative electrode material is 0.10-0.20, wherein the proportion of the number of scanning points having a single-point ID / IG value of less than 0.2 is greater than 60%. The negative electrode material has a high compaction density, a high capacity, a low expansion rate, good rate performance, and good high-temperature cycling performance.

This invention provides a high heat-resistant composite multilayer coating and its preparation method, specifically relating to the field of surface coating technology. The invention discloses a high heat-resistant composite multilayer coating comprising a Cr bonding layer, a Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer 3, and an nc-CrAlN-a-CNX functional layer sequentially coated on a cemented carbide substrate. The Cr1-XAlXN / nc-CrAlN-a-CNX multilayer transition layer and the nc-CrAlN-a-CNX functional layer proposed in this invention not only effectively bond Cr... 1‑X Al X N and CN X The enhanced properties and the composite multilayer structure endow it with excellent wear resistance, thereby achieving good lubrication and wear resistance in high-temperature environments. It significantly expands the high heat resistance of the amorphous carbon-nitrogen layer. At the same time, the transition of CrAl and C content in the composition and the construction method of multilayer support layer effectively improve the film-substrate bonding force between the substrate and the coating, enhance the toughness and load-bearing capacity of the top coating, alleviate the internal stress of the functional layer amorphous carbon layer, and significantly reduce the friction coefficient and wear rate of the amorphous carbon-based solid lubricating coating, thereby greatly improving the overall wear performance.

The invention relates to the technical field of batteries, in particular to an electrode composite material and a preparation method and application thereof. The electrode composite material comprises a base material and a coating layer located on at least part of the surface of the base material, the base material comprises etched graphite and carbon nanotubes located on the surface of the etched graphite, and the coating layer comprises a composite layer of cobalt fluoride and amorphous carbon. In the electrode composite material disclosed by the invention, the electronic conductivity of the base material can be improved through the synergistic effect of the etched graphite and the carbon nanotubes; according to the composite layer of cobalt fluoride and amorphous carbon, the intercalation and deintercalation rate of lithium ions can be increased by using the strong solvation ability of cobalt fluoride, and the amorphous carbon material can construct a surface electronic network and can improve the rate capability by cooperating with cobalt fluoride; the electrode composite material disclosed by the invention has high electron and ion conductivity, and the rate capability and the cycle performance can be remarkably improved.

The invention belongs to the technical field of lithium ion negative electrode materials, and particularly relates to a graphite negative electrode material and a preparation method thereof. The graphite negative electrode material comprises: (1) a three-dimensional porous graphite sheet layer matrix; (2) a nitrogen-doped amorphous carbon layer coated on the surfaces of the graphite particles, wherein the nitrogen element exists in the form of pyridine nitrogen and graphite nitrogen; and (3) after the material is subjected to CO2 atmosphere heat treatment, an aperture micropore structure is formed on the surface. The preparation method comprises the following steps: (1) carbonizing raw materials; (2) crushing treatment; (3) wrapping and granulating; (4) high-temperature treatment; and (5) performing subsequent treatment. According to the invention, the interface stability is obviously improved, the ion diffusion kinetics is optimized, the cycle life of the battery is obviously prolonged, the uniformity and process stability of the coating layer are improved, the energy consumption of high-temperature treatment is reduced, and the comprehensive performance and suitability of the battery are obviously optimized by reasonably controlling the capacity ratio of the positive electrode and the negative electrode and the content of a specific additive in the electrolyte.

The invention provides a negative electrode material, preparation thereof, a negative electrode plate, a secondary battery and a device, the negative electrode material comprises a silicon-based material, a first coating layer located on at least one part of the surface of the silicon-based material, and a second coating layer located on at least one part of the surface of the first coating layer, the first coating layer comprises amorphous carbon; the second coating layer comprises lithium titanate; and the number of particles of the silicon-based material in the first coating layer is 1-15. The negative electrode material disclosed by the invention has the core-shell structure, so that the cyclic expansion of the silicon-based material can be improved, different electrical property requirements can be met by different core-shell gap blending, and meanwhile, the mechanical strength in the needling process can be improved by coating the surface of the silicon-based material with lithium titanate, so that the electrical property of the silicon-based material can be improved. After lithium titanate is rapidly discharged to form Li4Ti5O12 under the condition of short circuit, the internal resistance is increased, and the generation of Joule heat is reduced, so that the mechanical safety performance can be obviously improved.

The present disclosure relates to a PET composite material and a preparation method therefor. The composite material comprises the following components in parts by mass: 50-100 parts of PET, 5-30 parts of an inorganic filler, and 5-30 parts of a PET copolyester. The PET copolyester is obtained by melting a waste pressure-sensitive adhesive product, adding an alcoholysis agent and a catalyst, and then performing polycondensation, wherein the waste pressure-sensitive adhesive product comprises a PET matrix and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer comprises a copolyester elastomer, the copolyester elastomer is a copolymer of a carboxyl-terminated polyester and an amorphous carbon dioxide-based polyester diol, and the number-average molecular weight of the PET copolyester is 50,000 or below.