174 results about "Lithium intercalation" patented technology

The invention provides a preparation method of a hyperbranched polyimide-derived silicon-carbon negative electrode material, which comprises the following steps: S1, preparation of a carbon precursor: mixing 1, 3, 5-tris (4-aminophenyl) benzene and 4, 4 '-(hexafluoroisopropenyl) diphthalic anhydride for reaction to prepare hyperbranched polyimide; s2, preparing porous carbon; and S3, vapor phase silicon carbon deposition. The invention also correspondingly provides a silicon-carbon negative electrode, a lithium ion battery and an electrochemical device. According to the hyperbranched polyimide-derived silicon-carbon negative electrode material, the volume expansion of silicon in the lithium intercalation process is effectively relieved, the active material is prevented from falling off, and the cycling stability of the battery is improved.

The invention discloses a high-cycle-performance aqueous battery, which comprises an aqueous electrolyte, a negative electrode, a first positive electrode and a second positive electrode, wherein the first positive electrode and the second positive electrode are positioned on two sides of the negative electrode, and a first diaphragm and a second diaphragm are respectively arranged between the first positive electrode and the negative electrode and between the second positive electrode and the negative electrode; the battery is provided with an electromagnetic valve, the electromagnetic valve is electrically connected with the first positive electrode and the second positive electrode to control switching of the positive electrodes in the charging and discharging loop, and every time discharging and charging circulation are completed, the electromagnetic valve switches the electrode connection relation, and the first positive electrode and the second positive electrode are alternately connected into the charging and discharging loop. Switching of the two positive electrodes in the aqueous battery is accurately controlled through the electromagnetic valve, a positive-negative battery structure is formed in real time, the double positive electrodes alternately perform lithium removal-lithium intercalation reaction, excessive Li intercalation or insufficient positive electrode reduction caused by long-term charging and discharging of a single positive electrode is avoided, the structural stability of the positive electrode material is improved, and the service life of the battery is prolonged. The cycle life and the electrochemical performance stability of the aqueous battery are obviously improved.

The application relates to the technical field of lithium / sodium ion battery negative electrode materials, in particular to a phosphorus-based negative electrode material with a solid electrolyte interface and a preparation method and application thereof, the method comprises the following steps: mixing phosphorus powder, a carbon material and a metal fluoride and performing ball milling to obtain a composite negative electrode material; and performing sieving treatment on the composite negative electrode material to obtain the phosphorus-based negative electrode material. According to the application, the metal fluoride is doped to in-situ construct a solid electrolyte interface with high strength and high lithium ion / electron transmission, so that the cycle stability and the rate performance of the battery are improved. When the lithium ion battery is discharged, the metal fluoride can in-situ construct a solid electrolyte interface rich in fluorinated lithium with high Young's modulus and lithium-metal alloy with high ion / electron conductivity on the surface of phosphorus-carbon particles prior to phosphorus-carbon lithium intercalation, the solid electrolyte interface can enhance the strength of the solid electrolyte interface by means of the fluorinated lithium with high Young's modulus, so as to inhibit the expansion of the phosphorus-carbon negative electrode, and the cycle stability is improved.

The embodiment of the invention discloses a negative electrode and a preparation method thereof and a battery, the negative electrode comprises a silica material, a first material and a binder, the first material comprises MXene of a lithium intercalation layer and an elastic polymer electrolyte coating layer coating the surface of the MXene of the lithium intercalation layer, and a three-dimensional elastic network with ionic conductivity is constructed by adhering a binder to the periphery of the silica material. Under the combined action of the network and MXene particles of a rigid lithium intercalation dispersed in the network, the huge volume expansion of the silica material in the circulation process can be effectively bound and buffered, and the integrity and stability of the electrode structure are maintained. Meanwhile, the elastic polymer electrolyte is used as an ionic conductor, so that an additional path is provided for storage and transmission of lithium ions in lithium intercalation MXene; and meanwhile, the MXene of the lithium intercalation layer can also be used as a lithium supplementing material, so that the first coulombic efficiency of the battery is effectively improved.

A secondary battery (100) comprises a negative electrode sheet (10), wherein the negative electrode sheet comprises a current collector and a first active material layer (2); the first active material layer (2) is arranged on at least one surface of the current collector; and the first active material layer (2) comprises a silicon-based material and a solid electrolyte, and the solid electrolyte is at least partially bonded to the surface of silicon in the silicon-based material. In the secondary battery and the electric device, the solid electrolyte is at least partially bonded to the surface of silicon in the silicon-based material; therefore, the problem of the expansion of the silicon-based material can be ameliorated, and the structural integrity and structural stability of the negative electrode sheet (10) can be enhanced. Moreover, compared with a binder-coated silicon-based material in the prior art, due to the utilization of the solid electrolyte, the lithium intercalation capability of the silicon-based material can be improved, and the ion conduction rate of the negative electrode sheet (10) can be improved, that is, the problem of deteriorated dynamic properties of the secondary battery caused by a binder-coated silicon-based material can be ameliorated.

The invention relates to a method for synergistically improving electrochemical performance of a lithium nickelate positive electrode material by virtue of a plurality of trace elements, which is characterized in that a particle body crystal structure of the material is strengthened by virtue of a synergistic effect of the trace elements, and the surface is subjected to in-situ conversion to form a coherent rock salt phase surface layer, so that Li / Ni cation mixing and surface residual alkali amount are reduced, and the electrochemical performance of the lithium nickelate positive electrode material is improved. Structural distortion and surface harmful side reactions in the lithium intercalation and deintercalation process are effectively inhibited, so that the electrochemical performance such as the specific capacity, the cycle life, the rate and the high-temperature cycle stability of the material is improved. The stoichiometric formula of the lithium nickelate positive electrode material is Li < 1.05-x > Ni < 1-y-z > A < x > B < y > C < z > O < 2 >, the specific capacity can reach 250 mAh / g or above, the 10 C specific capacity reaches 158 mAh / g or above, the capacity retention ratio is 80.34% after charging and discharging circulation for 500 weeks at the normal temperature under the current rate of 1 C, and the capacity retention ratio is 62.83% after charging and discharging circulation for 500 weeks at the temperature of 55 DEG C. The positive electrode material has the characteristics of no cobalt or manganese, high specific capacity, long cycle life, good rate and high-temperature performance and the like, and has a wide application prospect in high-specific-energy lithium ion batteries in the fields of unmanned aerial vehicles, artificial intelligence, electric automobiles and the like.

The invention relates to the technical field of lithium battery negative electrode materials, and particularly discloses a composite graphite negative electrode material and a preparation method and application thereof.The composite graphite negative electrode material comprises an inner core and a coating layer coating the outer side of the inner core, the inner core is graphite, and the coating layer is graphite. And the coating layer is a carbon layer doped with metal M atoms and oxide nano-clusters / particles of the metal M atoms. The coating layer doped with the metal M atoms and the oxide nano-clusters / particles of the metal M atoms can effectively reduce the diffusion barrier of Li < + >, and the lithium intercalation potential (greater than 0.3) of MOx is higher than that (0.02-0.2 V) of graphite, so that the probability of precipitation of Li < + > on the surface of the graphite due to polarization is reduced, and the risk of lithium precipitation is reduced.

The application belongs to the technical field of electrode materials, and particularly relates to a silicon-carbon negative electrode material based on vertical graphene and a preparation method and application thereof. The method comprises the following steps: preparing mixed slurry containing nanosilicon-based material and micrometer graphite material; performing spray drying treatment to obtain silicon-carbon composite particles; performing sintering treatment on the silicon-carbon composite particles under a protective atmosphere, and performing screening to obtain micrometer porous silicon-carbon particles; and performing chemical vapor deposition treatment on the porous silicon-carbon particles under the condition of containing carbon source gas and etching atmosphere, to obtain the silicon-carbon negative electrode material based on vertical graphene. Vertical graphene nanosheets are grown in the internal pores and outer surface of the porous silicon-carbon particles, to form a developed and robust conductive network with high mechanical strength and structural stability, and to relieve the volume expansion of the silicon-based material in the lithium intercalation process. Meanwhile, the problem of low bulk density of the silicon-based material is solved in the secondary granulation process, the volume expansion effect of the silicon-based material is inhibited, and the rate charge-discharge performance is improved.

An electrochemical cell has a cathode active material selected from mixed lithium transition metal oxides containing Mn and at least one second transition metal; lithium intercalating mixed oxides containing Ni, Al and at least one second transition metal; and lithium metal phosphates, wherein the outer surface of the particulate cathode active material is at least partially coated with an oxide selected from transition metal oxides, lanthanide oxides, and oxides of metals and half metals of groups 2, 13, and 14 of the periodic system; and an electrolyte composition containing at least one silyl ester phosphonate of formula (I)and at least one silyl ester phosphonate of formula (II)

The invention discloses an in-situ characterization method of graphite electrode microstructure stress in an electrochemical process. The in-situ characterization method comprises the following steps: measuring microstructure three-dimensional strain evolution information in situ by adopting a spectrum comprehensive technology; calculating modulus evolution of the typical lithium intercalation structure by adopting DFT (Discrete Fourier Transform); and establishing an electrochemical induced stress characterization model based on microstructure strain and modulus. The invention provides a novel electrochemical induced microstructure stress characterization method based on experiments, simulation and modeling, key factors such as microstructure anisotropy, strain types, modulus nonlinearity and the like are considered, the accuracy of mechanical description is ensured, and comprehensive characterization of microstructural mechanics is realized. Based on the provided microstructure stress characterization method, the important function of graphite electrode microstructural mechanics in the lithium storage process can be analyzed, meanwhile, the method can be further popularized to other layered electrode materials and sodium and potassium storage systems, and an important means is provided for mechanical-electrochemical coupling analysis.

This invention relates to a method for iodine-induced lithium intercalation and exfoliation of two-dimensional materials, comprising the following steps: uniformly mixing a target bulk layered material with an inorganic salt to obtain mixture A; the inorganic salt contains lithium iodide; heating mixture A to 280–400°C under a vacuum environment or protective atmosphere, while simultaneously applying ultraviolet light irradiation, and obtaining mixture B through solid-state lithiation treatment; dispersing mixture B in deionized water, and obtaining the two-dimensional material through hydrolysis exfoliation, separation, washing, and drying. This invention uses an inorganic salt containing lithium iodide as the intercalation medium, and through the synergistic excitation of a light field and a thermal field, induces the oxidative decomposition of halide ions and the release of electrons, driving alkali metal ions to intercalate into the interlayer gaps of the bulk layered material to achieve in-situ solid-state intercalation. Then, through hydrolysis exfoliation, an ultrathin two-dimensional material with a large lateral dimension is obtained. The process is safe, has high intercalation efficiency, and good versatility.

The application relates to the technical field of preparation of lithium ion battery negative electrode materials, in particular to a graphene-coated silicon-carbon composite material and a preparation method and application thereof. The preparation method of the graphene-coated silicon-carbon composite material comprises the following steps: microwave-assisted sand milling mixing of a nano-silicon dispersion liquid, a pitch dispersion liquid, a three-block copolymer Pluronic F127 and zirconium oxide beads to obtain a mixed solution of pitch silicon particles; microwave-assisted sand milling dispersion of a sulfonated graphene dispersion liquid into the mixed solution of pitch silicon particles to obtain a slurry of sulfonated graphene-coated pitch silicon particles; and drying and heat treatment of the slurry of sulfonated graphene-coated pitch silicon particles to obtain the graphene-coated silicon-carbon composite material. The graphene prepared by the preparation method effectively buffers the volume effect generated in the lithium intercalation and deintercalation process of the silicon-based negative electrode material, so that the electrochemical performance of the material is improved.

This application provides an electrochemical device comprising a negative electrode and an electrolyte. The negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector. The negative active material layer comprises a negative active material. The negative active material contains a silicon-based active material, and the mass percentage of the silicon-based active material in the negative active material is X%. The electrolyte contains metal ions, and based on the mass of the electrolyte, the mass percentage of the metal ions is A ppm, where X and A satisfy the relationship: 0 < X / A ≤ 8. During the charging process of the electrochemical device, the metal ions can undergo a reduction reaction at the negative electrode and form a stable Si-metal binary alloy phase or Si-O-metal ternary alloy phase with the silicon element in the silicon-based active material. This effectively suppresses the lithium intercalation expansion of the silicon-based active material, reduces electrolyte consumption, and effectively improves the cycle performance of the electrochemical device.

The invention belongs to the technical field of batteries, and discloses a carbon-coated submicron silicon dioxide negative electrode material as well as a preparation method and application thereof. The preparation method comprises the following steps: by taking biomass derived silicon dioxide and reducing carbohydrates as main preparation raw materials, carrying out acid pickling and ball milling on silicon dioxide to obtain submicron silicon dioxide particles; the reducing carbohydrates grow a carbon layer with a porous structure on the surface of the submicron silicon dioxide in situ through a hydrothermal reaction, and the carbon-coated submicron silicon dioxide negative electrode material is synthesized. The material combines the characteristics of high capacity of a siloxy active material and high conductivity and high stability of a carbon-based material, so that the energy density of the battery can be remarkably improved; and the porous carbon layer is grown on the surface, and a conductive network is constructed, so that the proportion of the active silicon dioxide is increased, the volume expansion of the silicon dioxide in the lithium intercalation process is effectively inhibited, and the structural stability and the cycling stability of the material are further improved.

The invention relates to the technical field of battery materials, in particular to a silicon-carbon negative electrode material and a preparation method and application thereof. Through a three-step preparation process, firstly, inner carbon coating is formed on the surface of nano silicon through first chemical vapor deposition, so that volume expansion of silicon in a lithium intercalation process can be relieved preliminarily, and a good interface is provided for subsequent compounding. Then a water-soluble template agent and an elastic polymer precursor are introduced, after spray drying and carbonization, a carbon intermediate layer with elastic and porous characteristics is formed, and the structure can effectively adapt to and buffer repeated volume change of silicon in circulation. And finally, a compact and continuous outer carbon shell is formed through second chemical vapor deposition, so that the structural integrity, the conductivity and the interface stability of the material are further enhanced. The multistage composite system synergistically inhibits the volume effect of silicon from different scales, and effectively delays material pulverization, interface stripping and continuous fracture of a solid electrolyte interface film, thereby improving the structural durability and cycle stability of the material.

The present application relates to a negative electrode active material, a method for preparing the same, a negative electrode composition, a negative electrode for a lithium secondary battery comprising the negative electrode composition, and a lithium secondary battery comprising the negative electrode. According to the present invention, a crystalline surface is etched by surface-etching a pulverized silicon-based active material itself via an alkaline solution treatment, so that lithium ion mobility can be controlled, and specific surface areas of a 111 plane and a 220 plane in the silicon-based active material can be adjusted in response to a change in etching conditions, thus, the lithium intercalation / deintercalation reaction is uniform, and the stress on the silicon-based active material is reduced.

The invention provides a boron-nitrogen doped resin coated graphite material and a preparation method thereof, a battery negative electrode and a lithium ion battery, and the method comprises the following steps: mixing graphite and a boron doping agent, and presintering to obtain boron-doped graphite; mixing the boron-doped graphite with resin and a nitrogen doping agent to obtain composite particles, and then roasting the composite particles to obtain the boron-nitrogen-doped resin coated graphite material, the mass ratio of the graphite to the boron doping agent is 10: (0.1-2), and the mass ratio of the boron-doped graphite to the nitrogen doping agent to the resin is 10: (0.1-2): (0.1-2). The graphite-resin material with a core-shell structure is prepared by performing boron doping on the graphite material and then coating the resin doped with the nitrogen element, the loss of the graphite material caused by lithium intercalation and deintercalation is effectively inhibited by the structure, the cycle life of the material is prolonged, meanwhile, the strength of the material is also improved by boron doping, and the service life of the material is prolonged. And the cycle life and the capacity of the material are greatly improved.

This invention relates to a silicon-based anode material with a self-healing layer, its preparation method, and its application, belonging to the field of lithium-ion battery technology. By mixing and drying silicon nanoparticles, a carbon source, and a gallium source in the liquid phase, followed by a one-step high-temperature annealing, a hierarchical structure of "core-buffered intermediate layer-shell" is obtained. This structure consists of a silicon nanoparticle core, a gallium oxide intermediate layer covering the core surface, and a carbon shell layer covering the intermediate layer. The in-situ transformation and alloying reaction of the gallium oxide intermediate layer during lithium intercalation buffers the expansion stress of the internal silicon core, fundamentally preventing the outermost carbon shell from cracking. Simultaneously, the liquid metal network generated in the intermediate layer bridges the broken silicon particles, achieving self-healing of the electrode, thereby achieving high specific capacity, long cycle life, and low macroscopic expansion rate.

The application discloses an electrochemical lithium extraction system and method, comprising: a lithium extraction device combined by three circulation chambers and a cation exchange membrane and an anion exchange membrane, an illumination device and a power supply. The first circulation chamber contains a first slurry for adsorbing and desorbing lithium ions; the second circulation chamber contains a liquid containing lithium ions and chloride ions; the third circulation chamber contains a second slurry for adsorbing and desorbing chloride ions; the lithium ions in the liquid can pass through the cation exchange membrane into the first circulation chamber; and the chloride ions can pass through the anion exchange membrane into the third circulation chamber. The electrochemical lithium extraction system provided by the application can improve the average current of the lithium intercalation and deintercalation process, improve the selectivity and extraction rate of lithium ions by adopting photothermal assistance, and can increase the lithium-sodium molar ratio of simulated concentrated seawater from the initial 0.00059 to 0.04977 through three circulations, about 84 times.

The invention relates to the technical field of battery material performance testing, and discloses a silicon negative electrode particle voltage endurance capability characterization testing method which comprises the following steps: preparing silicon negative electrode slurry; coating a pole piece; rolling the pole piece; assembling and testing for the first time to obtain first capacity and first efficiency data; placing the pole piece in a specific humidity environment; assembling and testing for the second time to obtain retested capacity and first efficiency data; the voltage endurance capability is judged, if the difference value of the two lithium intercalation capacities is larger than 1% of the initial lithium intercalation capacity, it is judged that the silicon negative electrode particles do not tolerate the rolling pressure, and otherwise, the silicon negative electrode particles tolerate the rolling pressure; by simulating the actual stress condition in the battery manufacturing process, the characterization test result of the voltage endurance capability of the silicon negative electrode particles is closer to the actual application scene, and the accuracy and reliability of the test are improved; physical testing is carried out, and the stability of the silicon negative electrode particles in electrochemical reaction is evaluated through electrochemical testing, so that the voltage endurance capability of the silicon negative electrode particles is evaluated more comprehensively.

This invention discloses a method for preparing titanium-doped carbon fiber anode material. The method involves intercalating graphite and then combining it with carbon fiber, followed by sequential carbon coating, carbonization, and pulverization to obtain the anode material. Physical adsorption is used to combine the intercalated graphite with carbon fiber, improving conductivity and reducing the amount of carbon fiber used, thus lowering costs. Furthermore, the very small particle size of graphite allows it to fill defects in the carbon fiber through adsorption, providing volume support during charge and discharge, dispersing stress generated during carbon fiber deformation, and further limiting the expansion and contraction of the core structure by forming a core-shell structure, thereby improving cycle performance. Additionally, titanium dioxide is uniformly dispersed in the coating solution, resulting in a uniform distribution of titanium dioxide particles on the shell structure. Titanium dioxide has a large interlayer spacing structure, which can serve as a lithium-ion transport interface, improving the initial coulombic efficiency of the material and increasing the lithium intercalation capacity of the shell material, thereby improving the specific capacity and energy density of the anode.

The application relates to the technical field of lithium ion batteries, and particularly discloses a lithium-embedded silicon-carbon material, a preparation method thereof and application of the lithium-embedded silicon-carbon material in lithium ion batteries. The lithium-embedded silicon-carbon material comprises a porous carbon substrate and ion-conductive agents, electron-conductive agents and lithium-silicon alloy particles distributed in the porous carbon substrate; the lithium-silicon alloy particles have reserved spaces around the lithium-silicon alloy particles for accommodating volume changes. Through a process of pre-embedding lithium-carbonization-in-situ de-lithiation in a porous carbon precursor, the reserved spaces which are in-situ matched with the expansion needs of the nano-silicon particles can be constructed around the nano-silicon particles, and the embedded amount and the final residual amount of lithium can be precisely controlled by means of a preset voltage threshold. Through the preparation method of the lithium-embedded silicon-carbon material, the lithium-embedded silicon-carbon material with low volume expansion rate, high initial coulombic efficiency and excellent cycle stability can be stably prepared, and an efficient and feasible technical path is provided for the industrialization of high-performance silicon-carbon negative electrodes.

The application belongs to the field of electrochemistry, and particularly relates to a silicon-carbon composite material and a preparation method and application thereof. The silicon-carbon composite material comprises a carbon layer skeleton and nano-silicon, the carbon layer skeleton comprises a flexible inner carbon layer and a rigid outer carbon layer, the flexible inner carbon layer surrounds a gap, the nano-silicon is filled between the flexible inner carbon layer and the rigid outer carbon layer, and the nitrogen element content of the carbon layer skeleton is 2at% to 10at%. The silicon-carbon composite material obtained by the application has a low electrode sheet expansion rate, the double-carbon-layer skeleton of the silicon-carbon can induce the nano-silicon particles to expand to the internal gap, and provide buffering and confinement for lithium intercalation expansion. Meanwhile, the nitrogen element contained in the carbon layer can increase the electronic conductivity and the transmission speed of lithium ions in the carbon layer.

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

This invention relates to the field of graphite anode material technology, specifically disclosing a surface-coated natural graphite, its preparation method, and its applications. The surface-coated natural graphite comprises a negatively charged natural spherical graphite core, which is coated with a positively charged micelle solution. A negatively charged MOF is grown on the positively charged micelles through electrostatic adsorption and crystal orientation induction. After curing and drying, a hard carbon source is coated on top, and high-temperature calcination is performed to prepare a natural spherical graphite core, an onion-like carbon framework and a nanocrystalline intercalation structure, an electrostatically coupled intermediate layer, and a hard carbon shell. The graphite anode material of this invention achieves optimized ion diffusion channels, optimized conductive networks, and expanded lithium intercalation sites. This structure significantly improves cycle life and specific capacitance, making it suitable for long-life lithium batteries.

The application discloses a kind of fast charging type lithium battery and preparation method thereof, belong to lithium battery technical field.The fast charging type lithium battery, including positive pole piece, diaphragm, negative pole piece and electrolyte, the negative pole active material of negative pole piece includes 6~8 parts of N-P doped hollow silicon-carbon particles, 3~5 parts of double network binder and 2~4 parts of conductive graphite;Double network binder is polyacrylic acid-polyvinyl alcohol double network binder containing ether oxygen chain.The hollow cavity in N-P doped hollow silicon-carbon particles in negative pole active material provides buffer space for the huge volume expansion of silicon in lithium intercalation process, and shortens lithium ion diffusion path, is conducive to realizing fast ion transport.N and P doping improves the electronic conductivity of the material, reduces the charge transfer impedance, improves the lithium ion migration ability, thereby reducing the generation and accumulation of heat.Double network binder provides an additional heat conduction path, which can achieve continuous charging rate at high rate.

This invention belongs to the field of fungal keratitis treatment technology, and discloses a MoSe2-PEI quantum dot, an antifungal eye drop, its preparation method, and its application. The MoSe2-PEI quantum dot is a PEI-modified MoSe2 quantum dot. Preparation steps: (1) Prepare lithium-modified MoSe2 using lithium intercalation-assisted liquid phase exfoliation technology; (2) Disperse the lithium-modified MoSe2 in water by ultrasonication, centrifuge, collect the supernatant, and ultrafilter to obtain an aqueous solution of MoSe2 quantum dots; (3) Add PEI to the aqueous solution of MoSe2 quantum dots under stirring conditions, then sonicate, stir, and finally centrifuge and ultrafilter sequentially to obtain an aqueous solution of MoSe2-PEI quantum dots. An application of the MoSe2-PEI quantum dot in the preparation of a drug for treating fungal keratitis. The MoSe2-PEI quantum dot of this invention can effectively kill the main pathogens causing fungal keratitis.

The invention relates to the technical field of batteries, in particular to a niobium-based negative electrode material, a preparation method thereof, a negative electrode and a battery. The preparation method of the niobium-based negative electrode material comprises the following steps: S1, dispersing TiO2, Nb2O5, B2O3 and Tb4O7 in an ethanol solution; transferring into a high-energy ball mill for further ball-milling and mixing; drying to obtain a precursor; and calcining the prepared precursor at high temperature to obtain the niobium-based negative electrode material. According to the niobium-based negative electrode material, boron and terbium are adopted for modification, heteroatoms are introduced for bulk phase doping, the crystal structure of the material can be changed, the electronic conductivity of the material is improved through the electronic structure and energy band hybridization of the heteroatoms, and the material is high in lithium intercalation potential, excellent in fast charging performance and free of the risk of lithium precipitation.

This invention discloses a low-expansion, high-efficiency silicon-carbon anode material and its preparation method, belonging to the field of lithium-ion battery technology. The material uses a specific porous carbon framework without >4nm pores and with a mesopore volume ratio of 10-30%. A high-concentration silane vapor deposition process is used to directionally distribute nano-silicon on the shallow surface of the framework, achieving a silicon filling rate of 50-80%. Finally, a vapor-phase carbon source is used for surface sealing and coating. This invention utilizes the synergistic effect of high-concentration deposition kinetics and a specific micro-mesoporous structure to retain deep micropores as rigid buffer cavities, significantly suppressing macroscopic volume expansion during silicon lithium intercalation while ensuring high silicon loading. Experimental results show that the material has an extremely low specific surface area and excellent structural stability, with an initial coulombic efficiency ≥92% and a fully charged electrode expansion rate as low as 51-82%, solving the common problems of large expansion and low initial efficiency in porous silicon-carbon anodes.

The invention discloses a secondary battery and an electric device, and belongs to the technical field of batteries. According to the secondary battery provided by the invention, the propionate organic solvent containing propyl propionate and / or ethyl propionate is added into the electrolyte, and meanwhile, the mass percentage a of the silicon-carbon material in the negative electrode active material, the mass percentage b of the hydrogen element in the silicon-carbon material and the mass percentage c of the propionate organic solvent in the electrolyte are controlled; on one hand, the lithium intercalation kinetics of the silicon-carbon material can be accelerated and the transmission capability of lithium ions can be improved on the basis of effectively reducing the side reaction between the silicon-carbon material and an electrolyte under the conditions of normal temperature and high temperature, so that the internal resistance of the secondary battery is reduced, and the cycle performance of the secondary battery under the conditions of normal temperature and high temperature is improved; on the other hand, the excessive increase of the viscosity of the electrolyte under the high voltage condition can be relieved, and the floating charge performance of the secondary battery under the high voltage condition is improved.