446 results about "Composite cathode" patented technology

The invention discloses a lithium manganese iron phosphate positive electrode material with a core-shell structure, which is prepared by the following steps: mixing a manganese source, an iron source, a phosphorus source, lithium carbonate and a carbon source, grinding and drying to prepare a pre-sintered material; then carrying out gas crushing on the pre-sintered material to obtain a pre-gas crushed material, and carrying out heat preservation at the temperature of 200-600 DEG C; putting the pre-gas crushed material subjected to heat preservation into an iron salt solution for quenching reaction to obtain iron compound coated lithium manganese iron phosphate; and finally, mixing the lithium iron manganese phosphate coated with the iron compound, a lithium source, a phosphorus source and a carbon source, grinding, drying, and carrying out secondary calcination to obtain the lithium iron manganese phosphate material with the core-shell structure. During preparation of the lithium manganese iron phosphate positive electrode material, a lithium manganese iron phosphate pre-sintered body and an iron salt solution are subjected to a quenching reaction to form an iron compound coated lithium manganese iron phosphate pre-sintered body, and then the iron compound coated lithium manganese iron phosphate pre-sintered body and other raw materials of lithium iron phosphate are subjected to a secondary calcination reaction to generate the composite positive electrode material with a core-shell structure. A coating structure is formed, the reaction between manganese and electrolyte is reduced, the dissolution of manganese is inhibited, the Gingtaler effect of manganese is relieved, and the stability of the material is improved; and the material has the advantages of high energy density, high power density, excellent cycle performance and strong core-shell interface bonding force.

The invention discloses a low-porosity and low-impedance dry positive electrode of a solid-state battery and a preparation method of the low-porosity and low-impedance dry positive electrode. The dry positive electrode of the solid-state battery comprises a large-particle positive electrode active material, a small-particle positive electrode active material, a first conductive agent, a second conductive agent, a third conductive agent, a small-size sulfide solid electrolyte, a large-size sulfide solid electrolyte and a binder. All the components are mixed in a manner of size matching and step-by-step embedding. Size matching among multi-stage particles is introduced, so that the size of gaps among different components is reduced, and the porosity is reduced; the binding agent and part of the conductive agent are premixed to form a'binding-conductive double network ', and then the active material and the electrolyte are gradually embedded, so that the purpose of low impedance of the composite positive electrode is achieved. And finally, the rate capability and the cycling stability of the solid-state battery are improved.

The invention discloses a positive electrode material formed by compounding polyanionic sodium ferric sulfate and a layered transition metal oxide, and a preparation method and application thereof, and the preparation method comprises the following steps: preparing a sodium ferric sulfate positive electrode material, preparing a layered transition metal oxide positive electrode material, and mechanically mixing the sodium ferric sulfate and the layered transition metal oxide material, the composite material is obtained. The production process of the two materials is easy for large-scale production, has high similarity with the existing battery industrial equipment, is simple in method for compounding the two materials, and has large-scale industrial application value. The composite material has the stability of a polyanionic material and the high energy density of a layered oxide material, and has more excellent comprehensive electrochemical performance.

The invention belongs to the technical field of all-solid-state lithium batteries, and particularly relates to a densified sulfide all-solid-state battery composite positive electrode material and a preparation method and application thereof. The preparation method of the composite positive electrode material comprises the following steps: (1) raw material pretreatment: mixing a positive electrode active substance, a sulfide solid electrolyte and an additive according to a predetermined mass ratio under the protection of an inert atmosphere, and carrying out mechanical grinding to obtain composite positive electrode powder; the additive is Li3PO4 (lithium phosphate); (2) isostatic pressing pretreatment: performing hot isostatic pressing treatment on the composite positive electrode powder, and then controlling the cooling rate to cool to room temperature to obtain a densified composite positive electrode blank; (3) adding a conductive agent and a binder into the densified composite positive electrode blank, and mixing; the composite positive electrode material is obtained; the binder is formed by compounding nano-scale polytetrafluoroethylene and micron-scale polytetrafluoroethylene according to a mass ratio of 1: 2-1: 4.

The invention relates to a niobium-based solid electrolyte and a preparation method and application thereof, the niobium-based solid electrolyte has the following chemical general formula: xLia Ab-yNbCl5-(1-y) McBd, 0.1 < = x < = 3, 0 < y < 1, 0 < a < = 3, 0 < b < = 1, 0 < c < = 3 and 0 < d < = 8, and M comprises at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, W, Ce and Eu. The niobium-based solid electrolyte can effectively reduce the influence of inactive components such as electrolyte in a composite positive electrode of a solid-state battery on the energy density of the solid-state electrolyte, effectively improves the energy density and power density of the solid-state lithium battery, has good room-temperature ionic conductivity, and has a good application prospect in the field of lithium batteries.

A composite cathode active material and a cathode and a lithium battery including the composite cathode active material. The composite cathode active material has a core including a plurality of primary particles including a nickel-containing first lithium transition metal oxide having a layered crystal structure; a grain boundary disposed between adjacent primary particles of the plurality of primary particles; and a shell on the core, the shell including a second lithium transition metal oxide having a spinel crystal structure, wherein the grain boundary includes a first composition having a spinel crystal structure.

According to the cobalt-doped molybdenum disulfide lithium-sulfur battery composite positive electrode material, the preparation method and the application, a cobalt-doped stable molybdenum disulfide defect structure composite nitrogen-doped graphene material is prepared by combining a solvothermal method and an annealing technology, and the process is mature; the method is simple, and the composite positive electrode material with high sulfur content is easy to obtain. According to the lithium-sulfur battery composite sulfur positive electrode material disclosed by the invention, the strong chemical adsorption effect and catalytic conversion effect of the cobalt-doped stable molybdenum disulfide defect structure composite nitrogen-doped graphene carrier on polar lithium polysulfide are utilized, so that the diffusion of the lithium polysulfide in an ether electrolyte is inhibited, and the electrochemical reaction kinetics is improved; therefore, the shuttling effect is slowed down, and the lithium-sulfur battery has the characteristics of high capacity and long service life.

The invention relates to a sodium ion battery composite positive electrode, a preparation method and a prepared secondary sodium ion battery. The composite positive electrode of the sodium ion battery sequentially comprises a collector electrode, a layered oxide layer and an MOF layer, when the sodium ion battery composite positive electrode is prepared, the layered oxide layer and the MOF layer are respectively formed by adopting a dry method. The surface of the manganese-based layered oxide layer is directly coated with the MOF layer, so that the stability of the layered oxide in air is improved, the layered oxide is prevented from being corroded by electrolyte, proper sodium ion conductors and electronic conductors are added into the MOF layer, transmission of sodium ions is promoted, meanwhile, gas products and solid by-products of side reaction of the battery are adsorbed, and the service life of the battery is prolonged. And a sodium ion conductor and an electronic conductor in the MOF layer can ensure rapid transmission of sodium ions and electrons, and the activity of the positive electrode is improved, so that higher capacity, more excellent rate capability and longer cycle life of the battery are realized.

The invention particularly relates to a sulfur-loaded carbon microsphere with a hierarchical pore structure as well as a preparation method and application of the sulfur-loaded carbon microsphere. The invention provides a NiX (X = Se, Te) selenium and tellurium porous carbon microsphere sulfur-loaded positive electrode material prepared based on a spray drying technology. According to the material, gamma-cyclodextrin is used as a carbon source, NaCl is used as a template, and three-dimensional porous carbon microspheres with the particle size of 10-20 microns are formed through a spray drying method. Then, the carbonized particles are activated by KOH, and rich micropores are introduced on the basis of an original macroporous structure; and finally, loading sulfur into the porous carbon structure through a melt permeation method to prepare the sulfur composite positive electrode material suitable for the room-temperature sodium-sulfur battery. The three-dimensional porous carbon skeleton of the material can effectively buffer the volume change of sulfur in the sodium ion intercalation / deintercalation process, the electronic conductivity of an electrode is also remarkably improved, and the construction of a room-temperature sodium-sulfur battery positive electrode material with high specific capacity and high stability is facilitated.

The invention provides a composite positive electrode material and a preparation method and application thereof, the composite positive electrode material comprises a matrix and a carbon coating layer on the surface of the matrix, and the matrix comprises a porous LMFP material; the porous LMFP material comprises doped metal elements, and holes of the porous LMFP material comprise a lithium supplement agent. Doping elements in the composite positive electrode material can improve the stability of a crystal structure and reduce high-temperature storage and cyclic gas production, and the lithium supplement agent in the porous LMFP material can prolong the cycle life of the material and can be decomposed to form pores again after first-time charging, so that an electrolyte can enter the interior of material particles, and the service life of the material is prolonged. And the carbon coating layer can improve the conductivity of the material and reduce the polarization impedance of the material, and meanwhile, the processing problems that residual alkali on the surface of the lithium supplementing agent reacts with a glue solution, so that slurry is gelled and the like can be avoided.

The utility model provides a device suitable for preparing lithium sulfide by a continuous double decomposition method. The device mainly comprises a material stirring reaction kettle, a solvent storage tank, continuous solid-liquid separation equipment, continuous solvent evaporation equipment, a first condensing tower and continuous dynamic vacuum calcination equipment, the device disclosed by the utility model can smoothly realize continuous production and preparation of lithium sulfide, and is simple in operation process and free from harmful gas pollution; in the preparation process, a single solvent is used and the solvent is recycled, so that the preparation method has the advantages of energy conservation and low cost, and cross contamination of multiple solvents is avoided; in addition, during continuous production of lithium sulfide, only one-time high-temperature calcination operation is carried out, and a lithium sulfide product with high purity and small particle size is successfully prepared; the composite cathode material can be directly used for preparing a sulfide solid electrolyte and a lithium-sulfur battery. The method has high industrial application value.

The invention discloses a layered structure solid oxide fuel cell composite cathode catalyst as well as a preparation method and application thereof, and belongs to the field of solid oxide fuel cells. The invention aims to solve the problem that the electro-catalytic performance and low-oxygen reduction reaction activation energy of the existing medium-temperature solid oxide fuel cell are poor. The Sr2. 9Ca0. 1Fe2O7-CuO composite cathode catalyst is prepared by adopting a sol-gel method and a solid phase method, the components in a sol-gel system are in a nanometer range, the reaction is easier to carry out, the reaction temperature is low, the prepared materials are uniformly mixed, and the sol-gel method is carried out in a solution, so that even if the content of doped elements is very low, the doping can be easily realized; the material is prepared by adopting a solid phase method, and the method has the advantages of convenience in operation, simple synthesis process, uniform particle size, no agglomeration of powder particles, good filling property, low cost, high yield and the like, so that the electrochemical performance of the cathode catalyst is improved, and the method is convenient to operate and suitable for industrial production.

The invention discloses a composite positive electrode material for realizing sodium ion internal compensation based on electrochemical potential difference as well as a preparation method and application thereof, relates to a sodium ion battery composite positive electrode material as well as a preparation method and application thereof, and aims at solving the problems of polarization increase, capacity reduction and poor rate capability of the existing sodium ion battery positive electrode material at the discharge end and in a low-temperature environment. The composite positive electrode material is formed by compounding a main phase material A and an auxiliary phase material B with the electrochemical potential higher than that of the main phase material A in a physical mode; at the final stage of discharge or at low temperature and high rate, the auxiliary phase spontaneously releases sodium ions to the main phase based on the electrochemical potential difference of the two phases without the action of an external electric field, and the available capacity of the main phase is improved through internal compensation. The specific discharge capacity of the sodium vanadium fluorophosphate and sodium vanadium phosphate composite material is 119.2 mAh g <-1 >, the specific discharge capacities of the sodium vanadium fluorophosphate and sodium vanadium phosphate composite material are 76.4 mAh g <-1 > and 107.4 mAh g <-1 > at the multiplying power of 30 C and the multiplying power of-20 DEG C and the multiplying power of 0.1 C, and the sodium vanadium fluorophosphate and sodium vanadium phosphate composite material can be applied to the field of sodium ion batteries.

The invention relates to the technical field of solid-state batteries, and discloses a positive electrode material which comprises a positive electrode active material, a first coating layer, a second coating layer and an additive. A positive electrode active material including a ternary oxide; the first coating layer comprises lithium phosphate and is coated on the positive electrode active material; the second coating layer comprises lithium phosphorus sulfur chlorine and is coated on the first coating layer to form a composite positive electrode material; the additive comprises lithium difluorophosphate and lithium bis (fluorosulfonyl) imide which are dissolved in an acetonitrile solution; wherein the additive is uniformly dispersed on the surface of the composite positive electrode material through a spray drying method. Therefore, the side reaction of the positive electrode and the solid electrolyte interface can be effectively inhibited, and the interface impedance is reduced. And meanwhile, the stability of circulation and the structure can be improved. The invention also discloses a preparation method of the positive electrode material, a positive plate and a solid-state battery.

The invention relates to the technical field of electrochemical wastewater treatment, and discloses a method for treating industrial wastewater through electrochemical enhanced hydrolytic acidification. Pollutant degradation is achieved by constructing a reaction system containing a heterojunction anode, a composite cathode and a charcoal particle electrode, the heterojunction anode forms a gradient conductive structure through a titanium matrix composite metal oxide and a conductive polymer, and the bioelectrochemical activity is enhanced by fixing a symbiotic flora of sulfur reducing bacteria and electroactive bacteria; modifying the composite cathode based on the activated carbon felt; the biochar particle electrode is subjected to iron doping modification to form a porous interface. The method utilizes electrochemical redox to destroy sulfur bonds and cyclic structures of biotin, couples microbial metabolism to realize deep mineralization, has efficient electron migration and biological membrane stability, significantly improves the conversion efficiency of organic matters, reduces sludge byproducts, and is suitable for efficient treatment of biotin-containing wastewater in the fields of medicine and chemical industry.

The invention discloses a hydrogenated butadiene-acrylonitrile rubber (HNBA)-polyacrylic acid (PAA) composite positive electrode binder for a secondary battery as well as a preparation method and application of the hydrogenated butadiene-acrylonitrile rubber-polyacrylic acid composite positive electrode binder. The composite positive electrode binder comprises the following raw materials: HNBA and PAA in a mass ratio of (1-10): (1-10); the content of residual hydrogen bonds in the HNBR is 1-10%, and the content of ACN is 10-40%; the molecular weight of the PAA is 3 * 10 < 5 >-1 * 10 < 6 >. The adhesive is compounded through a solution blending method, and based on the synergistic effect between HNBR and PAA, the viscosity of the material is greatly improved on the premise that it is guaranteed that the adhesive has excellent corrosion resistance. When the binder is used for preparing the positive pole piece of the secondary battery, not only can the bonding strength and the mechanical property among the components of the positive pole be effectively improved, but also the interfacial compatibility of the material can be effectively improved, the ion transmission efficiency can be improved, and the comprehensive performance of the battery can be effectively improved.

A lithium iron phosphate / carbon / lithium-rich lithium iron oxide composite cathode material and a preparation method and an application thereof are provided. The preparation method includes the following steps: mixing iron salt, lithium compound, orthophosphate and an organic salt with water, to obtain a mixed slurry; performing a spray granulation on the mixed slurry, to obtain a precursor powder; and performing a heat preservation on the precursor powder in a protective atmosphere, to obtain a lithium iron phosphate / carbon / lithium-rich lithium iron oxide composite cathode material. The preparation method is based on the characteristics that electric double layer physical energy storage of porous carbon can enhance the rate, and lithium-rich lithium iron oxide additive can increase the system lithium source and prolong the service life, combined with the synthesis process of lithium iron phosphate and lithium-rich lithium iron oxide, a lithium iron phosphate / carbon / lithium-rich lithium iron oxide composite cathode material is synthesized by one-step method.

A method for manufacturing composite cathode particles based on a dual-coated ternary oxide for an electrochemical battery by a high speed rotation includes the steps of: placing a plurality of large NCM (lithium nickel manganese cobalt oxide) particles and a glass phase material into a first mixer for stirring by a first high speed rotation to form a plurality of glass-phase-layer-contained NCM particles; then mixing a plurality of small LLZO particles and the glass-phase-layer-contained NCM particles by a second high speed rotation of a second mixer to form a plurality of composite NCM particles; and then mixing the composite NCM particles, a plurality of first carbon nanotubes and a plurality of nanoscale amorphous carbons to form a plurality of carbon-material-contained positive electrode particles.

The invention belongs to the technical field of sodium ion battery positive electrode materials, and relates to a gas-liquid mixture source plasma constructed high-capacity interface dual-modified sodium ferric pyrophosphate composite positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: taking sodium ferric phosphate pyrophosphate as a matrix, taking sulfur hexafluoride as a gas source, introducing a liquid source, and carrying out fluorine and sulfur element synergistic doping modification and surface carbon layer coating on sodium ferric phosphate pyrophosphate by utilizing a plasma technology to obtain the sodium ferric phosphate pyrophosphate composite positive electrode material. The composite positive electrode material shows excellent sodium storage cycle stability and rate capability, and has a wide market application prospect. Meanwhile, the preparation method provided by the invention is simple, rapid, efficient and convenient, is easy to control, and contributes to promoting the development and application of the high-performance sodium-ion battery positive electrode material.

The present application belongs to the technical field of secondary batteries, and specifically relates to a lithium iron phosphate composite cathode active material, and further discloses a preparation method thereof, as well as an application thereof for use in the preparation of battery plates and secondary batteries. The lithium iron phosphate composite cathode active material of the present application comprises a core containing a lithium iron phosphate material and iron phosphide particles, as well as a carbon coating layer and / or a LiBO2-containing coating layer at least partially coated on the surface of the core.

The invention provides a lithium-sulfur battery composite positive electrode material based on a high-entropy rare-earth metal oxide carrier and a preparation method of the lithium-sulfur battery composite positive electrode material, and relates to the technical field of lithium-sulfur batteries. The lithium-sulfur battery composite positive electrode material based on the high-entropy rare-earth metal oxide carrier is prepared by mixing, grinding and roasting the high-entropy rare-earth metal oxide carrier and elemental sulfur, the mass ratio of the HE-REO2 to the elemental sulfur is 1: (1-4); rE is La, Ce, Pr, Nd or Sm. The four rare earth elements La, Pr, Nd and Sm are introduced into CeO2 crystal lattices to form a nanofiber carrier of a single cubic fluorite structure, the chemical adsorption and catalytic capacity to lithium polysulfide is remarkably enhanced by means of the high oxygen vacancy concentration characteristic of the nanofiber carrier, the shuttle effect is effectively inhibited, and the finally constructed sulfur-based composite material shows excellent comprehensive electrochemical performance.

The invention relates to the technical field of batteries, in particular to a lithium ion battery positive electrode composite material and a preparation method thereof, a positive electrode plate and a battery. The lithium ion battery positive electrode composite material comprises a lithium ion battery positive electrode material and a coating layer coating at least part of the surface of the lithium ion battery positive electrode material, a coating agent for forming the coating layer comprises an organic matter containing an electron-rich group, wherein the electron-rich group comprises at least one of-OH,-COO-,-F,-Cl,-Br,-I,-SO4 or-SO3; the electron-rich group is suitable for being combined with a Li element or a non-Li metal element in the positive electrode material of the lithium ion battery through an ionic bond. The positive plate comprises the positive electrode composite material. The battery comprises the positive plate. According to the positive electrode composite material provided by the invention, the problem of relatively low bonding strength of the current positive electrode material and the coating layer can be relieved, the bonding stability of the positive electrode material and the coating layer can be improved, and the electrochemical performance of the positive electrode composite material is further improved.

The invention provides a composite positive electrode material and a preparation method thereof, a positive plate and a lithium ion battery. The composite positive electrode material comprises a lithium-rich manganese-based positive electrode material and a perovskite type oxide coated on the surface of the lithium-rich manganese-based positive electrode material, the chemical formula of the perovskite type oxide is Li2x-ySr1-xZr1-yNbyO3, x is equal to 3y / 4, and y is equal to 0.5-0.7. The perovskite type oxide has relatively high ionic conductivity, a relatively wide electrochemical platform and a stable structure, and is coated on the surface of the lithium-rich manganese-based positive electrode material, so that on one hand, the contact between the lithium-rich manganese-based positive electrode material and an electrolyte is reduced, the generation of side reactions is reduced, and the service life of the lithium-rich manganese-based positive electrode material is prolonged; and on the other hand, the first coulombic efficiency can be improved. And the conductivity of the lithium-rich manganese-based positive electrode material can be improved, the lithium ion transfer impedance of a liquid phase and a solid phase can be reduced, and the rate capability can be enhanced.

The invention belongs to the technical field of all-solid-state lithium-sulfur battery materials, and relates to a lithium sulfide nano-composite positive electrode material with high reaction kinetics as well as a preparation method and application of the lithium sulfide nano-composite positive electrode material. The invention aims to overcome the defects of the lithium sulfide positive electrode material in the aspects of ion and electron conductivity, reduce the activation potential barrier of the lithium sulfide positive electrode material, improve the redox kinetics of the battery and further improve the rate capability and the cycle capacity of the battery. The lithium sulfide nano-composite positive electrode material is prepared by adopting an in-situ synthesis method, the obtained composite material has abundant metal atomic crystals embedded in a lithium sulfide matrix, and the surface of the composite material is uniformly coated with a layer of amorphous carbon. And the finally obtained lithium sulfide nano composite positive electrode material shows relatively high reversible capacity and excellent rate capability. The method has the characteristics of uniform coating, simple process and the like, is suitable for large-scale production, and has a wide application prospect in the field of all-solid-state lithium-sulfur batteries.

The invention relates to the technical field of lithium ion batteries, in particular to a lithium iron phosphate composite positive electrode material and a preparation method thereof and a lithium ion battery, the lithium iron phosphate composite positive electrode material comprises a core and a carbon coating layer coating the core, the core comprises a lithium iron phosphate-carbon composite material skeleton with a three-dimensional porous structure, and the carbon coating layer is coated on the lithium iron phosphate-carbon composite material skeleton. The conductive agent is loaded on the framework of the lithium iron phosphate-carbon composite material with the three-dimensional porous structure. When the lithium iron phosphate composite positive electrode material provided by the invention is used for the lithium ion battery, the discharge gram capacity under high rate is relatively high, so that the lithium iron phosphate composite positive electrode material has good rate capability.

The invention discloses a method for improving the interface stability of a sulfide all-solid-state battery. The method comprises the following steps: (1) mixing a positive electrode material and perfluorohexyl iodoalkane, and uniformly grinding; and (2) heating the mixture obtained in the step (1) under a vacuum condition to obtain the modified positive electrode material, (3) mixing the modified positive electrode material obtained in the step (2) with a part of sulfide solid electrolyte to obtain a composite positive electrode; and (4) assembling the composite positive electrode obtained in the step (3), the other part of sulfide solid electrolyte and a metal lithium negative electrode into an all-solid-state battery. The stability of the sulfide solid electrolyte is improved, and the cycling stability of the all-solid-state battery is greatly improved.

The invention discloses a composite cathode material integrating electrocatalysis and ozone oxidation functions, a preparation method and application. The composite cathode material is composed of oxidized carbon nanotubes, cuprous oxide and copper oxide. The copper loading capacity of the composite cathode material is 1-10wt.%; the diameter of the oxidized carbon nanotube is 5 to 10 nm; the mass ratio of the oxidized carbon nanotubes to the cuprous oxide to the copper oxide is (298-27): (3.0-2.5): (0-1). A composite cathode material integrating electrocatalysis and ozone oxidation functions is elaborately designed and prepared and is applied to an electrocatalytic ozone coupling system, and continuous and efficient attack on antibiotic molecules and degradation intermediates thereof is realized by utilizing multiple synergistic effects among all components of the material and in the electrocatalytic ozone process, so that the electrochemical performance of the composite cathode material is improved. Therefore, the technical bottleneck of low TOC removal rate in the traditional advanced oxidation process is broken through, and a new technical approach is provided for thoroughly eliminating the antibiotic risk in the water environment.

This invention provides a TiS2 composite cathode and an all-solid-state battery device, employing a sulfide solid electrolyte with lithium replenishment and moisture absorption properties, and using TiS2 as the cathode active material. The sulfide solid electrolyte has the following chemical composition: Li 7+y‑ z M y As 1‑y S 6‑z X z Where M is Si, X is a halogen element, 0.3≤y≤0.9, 0≤z≤2. This invention yields a positive electrode with ultra-high load capacity, ultra-long cycle life, and the ability to charge and discharge at ultra-high rates and ultra-high current densities, as well as an all-solid-state battery.

This invention belongs to the field of lithium-ion battery technology, specifically relating to a composite cathode material for lithium-ion batteries and its preparation method. The composite cathode material consists of three parts: a cathode matrix material, a lithium replenishment material, and a catalyst material. The preparation method is as follows: (1) preparing a composite material of the cathode matrix material and the lithium replenishment material in situ; (2) dispersing the catalyst material on the surface of the composite material and forming a stable interface layer between the catalyst material and the lithium replenishment material. Through the method of this invention: the lithium replenishment material has both surface modification of the cathode matrix material and lithium replenishment of the negative electrode, simultaneously improving the battery's initial efficiency and cycle stability; introducing the catalyst material onto the surface of the lithium replenishment material in situ fixes the free O generated by the Li release from the lithium replenishment material, alleviating the battery swelling phenomenon and further improving the battery's cycle stability and safety; moreover, the preparation process is simple, the raw materials are cheap and readily available, the production cost is low, and it is easy to promote industrial production.

The invention provides a polyanion composite positive electrode material and a preparation method thereof, the chemical formula of the polyanion composite positive electrode material is Na < 4 + x > Fe3 (PO4) 2 (P2O7) / Na4VMn (PO4) 3 (at) C, Na < 4 + x > Fe3 (PO4) 2 (P2O7) and Na4VMn (PO4) 3 are used as core materials of the anion composite positive electrode material, a carbon coating layer coats the core materials to form the polyanion composite positive electrode material, and the content of the carbon coating layer in the polyanion composite positive electrode material is 0.5 wt%-2.5 wt%. The polyanion composite positive electrode material Na < 4 + x > Fe3 (PO4) 2 (P2O7) and Na4VMn (PO4) 3 are used as core materials of the anion composite positive electrode material, the Na < 4 + x > Fe3 (PO4) 2 (P2O7) and the Na4VMn (PO4) 3 are compounded, the interface impedance is reduced, the core materials are coated with the carbon coating layer to form the polyanion composite positive electrode material, the charge and discharge of impure-phase ferric sodium pyrophosphate and ferric sodium phosphate of ferric sodium pyrophosphate are greatly reduced, and the charge and discharge of the formed material are greatly reduced. The capacity and the battery performance of the material are improved, and the rate capability is remarkably improved.