3217 results about "Cyclic stability" patented technology

The invention relates to a preparation method of a nickel ion doped modified ferric sodium pyrophosphate positive electrode material, and belongs to the technical field of sodium ion battery positive electrode materials. The nickel ion doped modified ferric sodium pyrophosphate positive electrode material is prepared by adopting an integrated process system of liquid phase uniform mixing, spray granulation and precise segmented calcination. According to the process system, atomic-scale uniform doping of nickel ions and a specific microstructure of a precursor are realized through spray drying, and a plurality of inherent key technical problems of low electronic conductivity, low ion diffusion rate, impurity phase generation and the like of an NFPP material are solved together through a synergistic effect with a subsequent calcining process; furthermore, the discharge capacity of the ferric sodium phosphate pyrophosphate composite material at high rate is improved, so that the battery has relatively high cycling stability.

The invention relates to a doped modified argyrodite type solid electrolyte and a preparation method thereof, and belongs to the technical field of all-solid-state battery materials. The chemical formula of the electrolyte is Li < 5.5 + 2x + 2y > P < 1-x-y > Y < x > Bi < y > S < 4.5-1.5 x-1.5 y > O < 1.5 x + 1.5 y > Cl < 1.5 >, x is greater than or equal to 0.01 and less than or equal to 0.04, and y is greater than or equal to 0.01 and less than or equal to 0.04; the yttrium element and the bismuth element are doped at the P site of the argyrodite type electrolyte, and the oxygen element is doped at the S site of the argyrodite type electrolyte. After the argyrodite type electrolyte is in contact with metal lithium, an interface protection layer rich in lithium oxide can be formed in situ at an interface in a circulating process, so that lithium can be uniformly deposited, the generation of interface side reaction is inhibited, the interface stability of the argyrodite type electrolyte to a lithium metal negative electrode is improved, and the polarization voltage of a symmetrical battery is reduced; and the cycling stability of the all-solid-state lithium metal battery is enhanced.

The invention provides an electrolyte for quickly charging a sodium-ion battery without a negative electrode. The electrolyte comprises a sodium salt, a solvent and an additive. According to the electrolyte, metal oxide nanoparticles are introduced as a first additive, and a second additive is supplemented, so that rapid desolvation of sodium ions on an electrode interface and improvement of the ionic conductivity of an electrolyte body are realized at the same time, and compact and dendrite-free sodium deposition under high current density is realized. The negative-electrode-free sodium-ion battery prepared from the electrolyte can be quickly charged, and good cycling stability and high capacity retention ratio can be maintained, so that the use requirements of people can be met.

The invention discloses a composite solid electrolyte and a preparation method and application thereof, and belongs to the technical field of solid lithium batteries. The composite solid electrolyte comprises a polymer matrix, a lithium salt and a lithium ion modified ionic metal organic framework (MOF) material. The metal center of the ion-conducting MOF material can be selected from Zr, Ti, Hf and the like, and the organic ligand can be selected from organic acids containing sulfydryl, sulfo groups and the like. The MOF material can effectively inhibit crystallization of a polymer matrix and increase the proportion of an amorphous region, Lewis acid sites on the surface of the MOF material can promote dissociation of lithium salt, and a lithium ion coordination channel formed in the MOF material can provide an extra rapid transmission path for lithium ions. When the electrolyte is applied to the solid-state lithium battery, the growth of lithium dendrites can be effectively inhibited, and the rate capability, the cycling stability and the safety of the battery can be remarkably improved.

The invention relates to the technical field of lead-acid batteries, and particularly discloses a graphene-based composite material as well as a preparation method and application thereof. The graphene-based composite material comprises a graphene-CNTs three-dimensional composite skeleton, and tin dioxide and titanium dioxide which are loaded on the graphene-CNTs three-dimensional composite skeleton. In the material provided by the invention, the graphene-CNTs three-dimensional composite skeleton has excellent conductivity and mechanical strength, so that the resistivity of a negative plate is remarkably reduced, structural support is provided, and the binding force of lead powder and a negative electrode metal plate grid is enhanced, thereby reducing the falling of active substances and improving the cycling stability of the battery; meanwhile, tin dioxide and titanium dioxide are introduced into the graphene-based composite material and form a multi-stage synergistic system with the graphene-CNTs three-dimensional composite framework, so that the problems that the negative electrode of the lead-acid battery is easy to separate hydrogen, the conductivity is insufficient and active substances fall off can be effectively solved, and the cycle performance of the battery is remarkably improved.

The invention discloses a negative electrode active material and a preparation method thereof, a negative electrode pole piece and a secondary battery, the negative electrode active material provided by the invention comprises a silicon-carbon composite material and an aluminum oxide layer coated on the surface of the silicon-carbon composite material, and the silicon-carbon composite material is a composite material of nitrogen-fluorine co-doped porous carbon and nano silicon particles. By optimizing and regulating the porosity and pore size distribution of the porous carbon, the ion transmission kinetics and the structural stability are improved, and the problems of poor rate capability, short cycle life and the like caused by single pore size of the traditional porous carbon are solved. By adopting the nitrogen and fluorine co-doped porous carbon skeleton, the conductivity of the electrode material is enhanced, and the cycling stability of the battery is improved. The nano silicon component uniformly deposited through a chemical vapor phase method provides high specific capacity, the aluminum oxide coating layer can effectively inhibit the decomposition reaction of the solid electrolyte, and the long-term stability and cycle performance of the electrode structure are jointly guaranteed through the dual effects.

The invention discloses a fast-charging lithium ion battery electrolyte, a preparation method thereof and a lithium ion battery containing the fast-charging lithium ion battery electrolyte. The fast-charging lithium ion battery electrolyte comprises the following components: electrolyte salt, an organic solvent and an electrolyte additive, the electrolyte additive comprises a first additive and a second additive; the first additive is a multi-element sulfate ester additive, and the mass percentage of the multi-element sulfate ester additive is 0.05%-2% based on the total mass of the electrolyte being 100%. By adding the polybasic sulfate additive with a specific structure, adopting a composite solvent system and cooperating with the synergistic effect of other additives, lithium salt and other components, dual stability of positive and negative electrode interface films is realized, the electrochemical window of the electrolyte is widened, and the thermal stability and cycling stability of the electrolyte are improved; and finally, the battery has the advantages of fast charging capability, high voltage compatibility, long cycle life and high thermal safety at the same time.

The invention belongs to the technical field of all-solid-state sulfide lithium metal batteries, and relates to a lithium battery electrode containing an interface self-repairing coating as well as a preparation method and application of the lithium battery electrode. The electrode comprises a lithium metal negative electrode substrate and the interface self-repairing coating coated on the surface of the lithium metal negative electrode substrate, the interface self-repairing coating is internally provided with a dynamic reversible network, and the dynamic reversible network is constructed by disulfide bonds and hydrogen bonds. A layer of interface self-repairing coating is formed on the surface of a lithium metal negative electrode substrate to serve as a physical isolation barrier, metal lithium and sulfide electrolyte are isolated and prevented from being directly subjected to reduction reaction, and coating microcracks generated by volume change in lithium metal circulation can be repaired, so that the possibility of interface exposure caused by coating breakage is reduced, and the service life of the lithium metal negative electrode is prolonged. Meanwhile, good interface contact can be kept, the synergistic effect of stable interface impedance, lithium dendrite inhibition and long-term cycle performance improvement is achieved, and the long-term cycle stability of the all-solid-state lithium battery is improved.

The invention discloses a composite solid electrolyte layer, a preparation method and application, the composite solid electrolyte layer comprises a porous membrane laminated on a negative pole piece, and pores in the porous membrane and gaps between the porous membrane and the negative pole piece are filled with in-situ generated polymers. Inorganic solid electrolyte is also dispersed in the porous membrane, and lithium salt is dispersed in the polymer and the porous membrane. The composite solid electrolyte layer is obtained through in-situ polymerization of a polymer in pores in the porous membrane and gaps between the porous membrane and the negative electrode plate, and a novel interface structure with the electrode-electrolyte integration characteristic is constructed. By adopting a collaborative optimization strategy of a polymer matrix and inorganic filler double-crosslinking network system and an interface stable layer, the volume effect problem of a silicon-based negative electrode, the electrolyte interface impedance problem and the battery safety problem can be solved at the same time, so that the cycling stability and the rate capability of the lithium ion battery are remarkably improved.

The invention discloses a high-entropy oxide composite negative electrode material as well as a preparation method and application thereof, and relates to the technical field of all-solid-state lithium battery negative electrode materials, and the high-entropy oxide composite negative electrode material comprises a metal element and an oxygen element, the high-entropy oxide composite negative electrode material comprises a metal element and an oxygen element, wherein the metal elements are at least five of a chromium element, an iron element, a nickel element, a manganese element, a molybdenum element, a copper element and a cerium element; the molar ratio of the metal element to the oxygen element is 3: 4; the high-entropy oxide composite negative electrode material is of a spinel structure. According to the prepared high-entropy oxide composite negative electrode material, the problems that a traditional negative electrode material is unstable in structure, poor in interface contact and short in cycle life are solved, the electrochemical performance is improved, and an all-solid-state lithium battery prepared from the high-entropy oxide composite negative electrode material shows high reversible specific capacity and excellent cycle stability.

The invention relates to the technical field of flexible electronics and sensing, in particular to a capacitive flexible pressure sensor based on a barium titanate composite dielectric layer, which sequentially comprises a lower electrode layer, an upper electrode layer, a lower electrode layer and an upper electrode layer from bottom to top, the composite dielectric layer is arranged on the lower electrode layer and is formed by compounding an elastic polymer matrix and a high-dielectric-constant barium titanate (BaTiO3) filler; the upper electrode layer is made of a flexible conductive material and is arranged on the composite dielectric layer; the lower electrode layer and the upper electrode layer are connected with an external capacitance measuring circuit through wires. According to the sensor disclosed by the invention, the comprehensive performance of high sensitivity, wide detection range, low hysteresis and excellent cycle stability is realized by optimizing the shape of the barium titanate filler, surface modification and composite structure design.

The invention belongs to the field of electrochemical energy storage material and device manufacturing, and particularly relates to a method for preparing super-capacitor carbon through ultrasonic atomization, the super-capacitor carbon and a super-capacitor electrode. The method comprises the following steps: preparing a carbonized material, a bridging conductive agent and a composite binder into slurry, performing ultrasonic atomization to form spherical liquid drops, and performing drying, pre-activation and CO2 etching to prepare the supercapacitor carbon with an integrated three-dimensional network. Through a synergistic process of spherical template construction-networked reconstruction-etching modification, controllable transformation of a material structure is realized, and the tap density, a pore channel system and a conductive network of the electrode are optimized, so that the electrode with high specific capacity, excellent rate capability and cycling stability is obtained, and the process is environment-friendly and coherent and is suitable for large-scale production.

The invention provides an oxygen vacancy defect carbon nitride anchored iron atom cluster catalyst and a preparation method and application thereof, and belongs to the technical field of catalysts. Iron atoms are anchored in a carbon nitride (Ov-C3N4) structure containing oxygen vacancy defects in a cluster form, and Fe-Ov-C defect bonds are formed between the oxygen vacancy defects in C3N4 and iron atom clusters to stabilize the iron atom clusters, so that the problem of thermodynamic instability of the catalyst is solved while higher atom utilization efficiency is obtained; the Fe-Ov-C defect bond atoms can reasonably regulate and control the electronic structure of the center of an iron cluster d band, so that the catalytic activity and the cycling stability are greatly enhanced; besides, iron atom clusters and persulfate act to cause O-O bond breakage, non-free radical singlet oxygen is formed, and the problem that the catalytic efficiency is sharply reduced due to free radical annihilation in a complex water environment can be effectively solved.

The invention discloses a method for efficiently depolymerizing polyethylene glycol terephthalate, which comprises the following steps: mixing a PET material, ethylene glycol and a core-shell type magnetic nano composite catalyst, and carrying out alcoholysis reaction at 160-200 DEG C for 30-180 minutes; after the reaction is finished, separating the catalyst from a reaction system through an external magnetic field to obtain a solution containing bis (2-hydroxyethyl) terephthalate; the core-shell type magnetic nano composite catalyst comprises a magnetic FeO core, a SiO shell layer and active metal sites, the FeO core is coated with the SiO shell layer, the SiO shell layer is an insulating inorganic layer and is of a porous structure, the active metal sites are fixed to the surface of the SiO shell layer through coordinate bonds, and active metal is selected from one or more of Co, Ni, Cu, Ce, La and Al. The problems that an existing PET alcoholysis catalyst is easy to dissolve out, difficult to separate, harsh in reaction condition and poor in cycling stability are solved.

The invention relates to the technical field of battery negative electrode materials, in particular to irregular spherical porous carbon and a preparation method and application thereof, and a silicon-carbon composite material and a preparation method and application thereof. The liquid phenolic resin is emulsified, compounded, cross-linked and cured under the condition of an oil-soluble and water-soluble compound emulsifier, meanwhile, the shape of the obtained resin is changed in an ultrasonic-assisted mode under the combined action of ultrasonic disturbance and different interfacial tensions, spherical resin is adjusted into irregular spherical resin, and the spherical resin is prepared into the irregular spherical resin. And performing pyrolysis and gas activation to obtain the irregular porous spherical carbon. Compared with spherical carbon, the irregular spherical carbon prepared by the invention has the advantages that on the premise of keeping the strength of the spherical carbon, the irregular spherical carbon can increase the contact area between carbon particles and a binder, and the carbon particles and the binder are not easy to separate, so that the cycling stability of a battery (especially a lithium ion battery) is improved.

The invention relates to a CO2 absorbent with high cycle capacity and high cycle stability and application of the CO2 absorbent, and belongs to the technical field of atmospheric CO2 pollution treatment in the environmental protection industry. The CO2 absorbent is a polyamide-amine dendritic polymer (represented by PAMAM-2 (2 + G) NH2, G is the algebra, and 2 (2 + G) is the number of terminal amino groups), wherein primary amino is used as a terminal group, alkylene diamine is used as a core, and the algebra G is 1-5. The polyamidoamine dendritic polymer provided by the invention has the advantages of high-density terminal amino groups, high CO2 absorption capacity, large circulation capacity and high circulation absorption stability.

The invention provides a treatment method for recovering high-purity graphite from black powder leaching residues. The treatment method comprises the following steps: removing impurity elements in graphite from the black powder leaching residues in a Joule heat flash evaporation manner; the black powder leaching residues obtained after impurity removal are put into a ball mill, liquid phenolic resin is added, full mixing is conducted, and ball milling is conducted; and putting the ball-milled mixture into flash evaporation Joule thermal equipment, and carbonizing and graphitizing the phenolic resin to obtain regenerated graphite. According to the method, the temperature of the black powder leaching residues can be increased within an extremely short time, metal impurities in the black powder leaching residues are gasified, and impurities in graphite are removed. Phenolic resin is used for carbonization and graphitization, generated disordered carbon can fill up particle cracks in waste graphite and internal lattice defects, a conductive network among graphite particles is established, a compact carbon layer is formed on the surface of graphite, and graphite structure transformation can also be induced in the step. The regenerated graphite obtained by the method is similar to commercial graphite in capacity and good in cycling stability.

The invention relates to the technical field of lithium battery negative electrode materials, and discloses a preparation method of a lithium battery silicon-carbon composite negative electrode material with high cycle stability, and the preparation method comprises the following steps: carrying out magnesiothermic reduction and acid etching on micron silicon powder and magnesium powder to prepare porous silicon particles; growing carbon nanotubes on the surfaces of the porous silicon particles and in pore channels in situ to construct a three-dimensional conductive network; styrene butadiene rubber and glucose are adopted as a composite carbon source to coat the product, and a composite carbon layer is formed through drying and gradient carbonization; and finally grinding and sieving the carbonized product. According to the preparation method disclosed by the invention, pores are constructed in micron silicon, and the micron silicon is externally coated with the composite carbon layer with flexibility and rigidity, so that the volume expansion of silicon is effectively buffered; the in-situ grown carbon nanotube network provides a stable electron conduction path; the micron-sized substrate reduces the specific surface area of the material and improves the first coulombic efficiency. Therefore, the prepared negative electrode material has high cycling stability and excellent rate capability.

The invention discloses a modified lithium-rich manganese-based positive electrode material, a preparation method thereof and application of the modified lithium-rich manganese-based positive electrode material in a solid-state lithium battery, and belongs to the field of lithium ion battery materials. The modified lithium-rich manganese-based positive electrode material comprises a lithium-rich manganese-based positive electrode material and a coating layer LiAl thereof, the molecular formula of the lithium-rich manganese-based positive electrode material is xLi2MnO3. (1-x) LiMO2, M is one or more of transition metals Ni, Co and Mn, and x is more than 0 and less than 1; and the coating layer LiAl is formed by decomposing LiAlH4. The preparation method comprises the following steps: uniformly mixing a lithium-rich manganese-based positive electrode material xLi2MnO3. (1-x) LiMO2 and LiAlH4 through a solid phase method or a liquid phase method, and then annealing in an inert atmosphere to prepare the modified lithium-rich manganese-based positive electrode material. The problems of unstable interface and poor transmission kinetics in the sulfide-based all-solid-state lithium ion battery are solved at the same time, and the first-circle charge-discharge specific capacity and cycle stability of the solid-state lithium ion battery can be improved.

The present application provides a solid-state hydrogen storage material and a preparation method and application thereof. Specifically, the preparation method comprises the following steps: (1) ball-milling a magnesium-based alloy powder, a light metal hydride, a nano-carbon material, a composite catalyst powder and an interface modifier to obtain a mixed powder; and (2) sintering the mixed powder under vacuum at 200-350 DEG C for 2-5 hours to obtain a sintered body, wherein: the magnesium-based alloy powder is a Mg-Mn-Al alloy powder; the light metal hydride is a mixture of LiAlH4 and NaBH4; the nano-carbon material is selected from one or more of graphene and carbon nanotubes; the composite catalyst powder is a mixture of TiO2, Fe3O4, CeO2 and La2O3; and the interface modifier is selected from one or more of a silane coupling agent and a titanate coupling agent. The solid-state hydrogen storage material has high hydrogen storage capacity, fast hydrogen absorption and desorption rate and good cycle stability.

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 field of lithium manganate positive electrode materials, in particular to a lithium manganate positive electrode material and a preparation method thereof, a positive electrode plate and a battery, which are used for solving the problems of Jahn-Teller distortion of Mn < 3 + >, Mn dissolution and low conductivity in circulation. Lithium carbonate, manganous-manganic oxide, potassium carbonate, aluminum nitrate and absolute ethyl alcohol are subjected to ball milling and then sintered to obtain K / Al co-doped lithium manganate powder, then the K / Al co-doped lithium manganate powder is coated with an acetylferrocene / diphenylamine polymer, finally, the K / Al co-doped lithium manganate powder is coated with an AlF3 (at) CeF3 suspension, and finally the lithium manganate positive electrode material is obtained. According to the lithium manganate positive electrode material, the electronic conductivity is greatly improved, the rate capability is improved, and the cycling stability is improved; and the material has excellent cycling stability and rate capability.

The invention relates to the technical field of sodium ion batteries, and discloses a low-overpotential uniform sodium deposition composite electrolyte and a preparation method of a sodium metal battery, the composite electrolyte comprises a sodium salt, a solvent, a film-forming additive and a sodium deposition regulating agent; the film forming additive is selected from at least one of NaPO2F2, NaDFOB and Na2SO3; the sodium deposition regulating agent is selected from at least one of CsTFSI, SnCl2 and Bi (OTf) 3. Through the synergistic effect of the film-forming additive and the sodium deposition regulating agent, a stable and firm SEI film can be formed on the interface of the negative electrode current collector, the overpotential of sodium deposition is obviously reduced to 20 mV or below, the growth of sodium dendrites is effectively inhibited, and dense and uniform deposition of sodium is realized. The negative-electrode-free sodium metal battery based on the composite electrolyte shows high first efficiency (greater than or equal to 90%), high coulombic efficiency (greater than 99.5%) and excellent cycling stability, and an effective scheme is provided for solving the core challenge of a sodium metal negative electrode.

The invention relates to the field of lithium ion batteries, in particular to a biomass carbon / silicon / conducting polymer ternary composite negative electrode material with a hierarchical pore structure and a preparation method and application thereof. According to the material, active nano silicon is effectively limited by utilizing natural graded pore channels of biomass, and a conductive polymer layer with elastic strain buffering capability is prepared by combining a low-temperature in-situ polymerization process. According to the structure, biomass carbon pores are filled with the conductive polymer layer, the specific surface area of the material can be reduced, interface side reaction can be inhibited, and therefore the first coulombic efficiency and cycling stability of the material are improved.

The invention relates to preparation of a crystalline allyl covalent organic framework material and application research of the crystalline allyl covalent organic framework material in benzamide cyclization green photocatalytic conversion. The SF-COF material is prepared by adopting a step-by-step synthesis method. The preparation method comprises the following steps: synthesizing a COF precursor by taking 1, 3-benzenetricarboxaldehyde and p-aminophenylacetonitrile as raw materials, and preparing the allylation covalent organic framework material with the electronic push-pull effect from the COF precursor and 5, 5 ', 5'-(benzene-1, 3, 5-triyl) tri (thiophene-2-formaldehyde) through a solvothermal method. The material is applied to the field of photocatalytic organic conversion, and benzamide cyclization and conversion of derivatives of benzamide are achieved under irradiation of a blue light LED. The prepared SF-COF has the advantages of efficient charge separation and electron conduction performance, good structural stability and chemical stability and the like. And a catalyzed organic reaction substrate has the advantages of wide universality range, good cycle stability and the like, and shows excellent photocatalytic conversion capability.

The invention belongs to the technical field of battery positive electrode materials, and particularly relates to a high-rate manganese-based positive electrode material and a preparation method and application thereof.The high-rate manganese-based positive electrode material sequentially comprises a manganese-based active core, a mesoporous fast ion conductor shell layer and a pretreatment layer formed by coating the surface of the manganese-based active core with a boron-containing compound in situ from inside to outside, and the functionalized carbon nanotube three-dimensional conductive network penetrates through the active core and the shell layer. The preparation method comprises the following steps: carrying out boron-containing compound liquid phase pretreatment on a manganese-based active core to form a surface pretreatment layer, carrying out oxidation functionalization and lithiation modification on carbon nanotubes in sequence to construct an embedded three-dimensional conductive network, carrying out ball milling-ultrasonic dispersion to prepare precursor sol, and carrying out coating to form a fast ion conductor shell layer. According to the high-rate manganese-based positive electrode material and the preparation method thereof, through the synergistic effect of multiple structures, dissolution of manganese ions and collapse of the material structure are effectively inhibited, the high-rate performance and cycling stability of the material are improved, and the high-rate manganese-based positive electrode material has a good industrialization prospect.

The invention relates to the technical field of hydrogen storage alloys, in particular to a Ti-based hydrogen storage alloy and a preparation method and application thereof. The chemical formula of the Ti-based hydrogen storage alloy is TibZr (1.02b) CrcMn (1.6 c) Fe 0.4, b is larger than or equal to 0.92 and smaller than or equal to 0.95, and c is larger than or equal to 1.0 and smaller than or equal to 1.2. According to the invention, Ti or Cr is doped into a Ti0. 92Zr0. 1Cr1. 0Mn0. 6Fe0. 4 alloy matrix, and regulation and control of unit cell parameters and electronegativity are realized by means of alloying, so that the hydrogen compression material has a higher compression ratio, and the alloy crystal structure is stable, and has more excellent activation performance, longer cycle life and higher cycle stability.

The invention relates to the technical field of batteries, in particular to a high-dispersity and low-crystallinity composite solid electrolyte and an all-solid-state lithium metal battery. The composite solid electrolyte comprises a polymer matrix, a lithium salt, an inorganic filler and a quaternary ammonium salt surfactant, the mass ratio of the polymer matrix to the lithium salt to the inorganic filler to the quaternary ammonium salt surfactant is 100: (60-80): (10-20): (1-15). Through the quaternary ammonium salt additive, the inorganic filler is uniformly dispersed in a polymer matrix, and the crystallinity of polyethylene oxide (PEO) is effectively reduced, so that the ion transmission performance of the electrolyte and the cycling stability of a battery are remarkably improved, and the problem that organic-inorganic interfaces between PEO and LLZTO in the composite solid electrolyte are incompatible is systematically solved; and a key technical path is provided for developing a new generation of energy storage devices with high safety, long cycle life and excellent electrochemical performance.

The invention discloses a secondary battery, which belongs to the technical field of batteries, and is characterized in that the lithium-nickel mixing rate and the unit cell volume of a ternary material in a positive pole piece after charge-discharge cycle are cooperatively regulated, and the particle size ratio coefficient of the positive pole material is synchronously regulated; according to the present invention, the overall pole piece stability and the lithium ion de-intercalation reversibility of the positive pole piece can be effectively considered, the cycle stability of the secondary battery is improved, the efficiency of the lithium ion transmission process of the ternary material in the pole piece is improved, the good dynamic performance is ensured, and the DCR after the cycle is low.

The invention relates to a biomass hard carbon negative electrode material based on controllable pre-oxidation crosslinking as well as a preparation method and application of the biomass hard carbon negative electrode material. The method comprises: pretreating biomass with a metal salt structure directing agent; carrying out pre-oxidation crosslinking on the pretreated biomass precursor in an oxygen-enriched atmosphere; and carrying out stepped carbonization on the pre-oxidized cross-linked intermediate under the protection of an inert atmosphere to obtain the biomass hard carbon negative electrode material. The hard carbon material prepared by the invention has moderate specific surface area (5-50 m < 2 > / g), high closed porosity (gt, 40%) and expanded graphite interlamellar spacing (0.38-0.40 nm). Due to the unique structure, the high reversible capacity (gt, 330 mAh / g) and excellent cycling stability are realized when the biomass hard carbon material is used for the negative electrode of the sodium ion battery, and the problems of low reversible capacity and poor rate capability of the traditional biomass hard carbon are solved.