69 results about "Lithium ferrite" patented technology

The invention discloses a preparation method and application of a positive electrode lithium supplement agent, the positive electrode lithium supplement agent is of a core-shell structure, and a core layer comprises lithium-rich metal materials such as lithium-rich lithium ferrite, lithium-rich lithium nickelate and lithium-rich lithium manganate; and a shell layer comprises organic lithium salt materials such as lithium bis (oxalato) borate, lithium bis (fluorosulfonyl) imide, lithium difluorophosphate and lithium difluorobis (oxalato) phosphate. The lithium-rich metal material lithium supplementing agent is coated with the organic lithium salt lithium supplementing agent which is also used as the lithium supplementing agent, so that the lithium-rich metal material is prevented from being in contact with air, and the environmental stability of the lithium-rich metal material is improved; through chelation of specific groups and transition metal ions, the structural stability of the lithium-rich metal material is improved, a lithium ion transmission path is fixed, the capacity of the lithium supplement agent for the lithium-rich metal material can be exerted to the maximum extent, and the organic lithium salt also has a lithium supplement effect, so that the migration rate of lithium ions can be further improved, and the lithium supplement effect is improved. The lithium supplementing effect of the two lithium supplementing agents greatly improves the energy density and the cycling stability of the battery.

The invention discloses a composite lithium supplement additive and a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The composite lithium supplement additive provided by the invention comprises a lithium-rich lithium ferrite core; the conductive carbon coating layer and the pentafluoropropionamide coating layer are sequentially coated outside the lithium-rich lithium ferrite inner core from inside to outside, so as to form a core-shell structure. The composite lithium supplement additive prepared by the invention forms a three-dimensional interpenetrating electron transport network, significantly improves the material conductivity, optimizes the charge transfer dynamics, can effectively isolate lithium-rich lithium ferrite from contacting H2O and CO2 in the air, significantly reduces the generation of surface residual alkali, can adapt to the volume expansion of lithium-rich lithium ferrite in the charge-discharge process, and improves the lithium supplement efficiency. And material structure damage caused by interface stress is reduced, so that the cycling stability of the lithium ion battery is greatly improved, the service life of the lithium ion battery is greatly prolonged, and the material has a wide application prospect in the lithium ion battery.

The application belongs to the technical field of lithium ion batteries, and particularly relates to a carbon-nitrogen double-layer coated positive electrode lithium supplementing agent and a preparation method and application thereof. The preparation method of the carbon-nitrogen double-layer coated positive electrode lithium supplementing agent provided by the application is as follows: a carbon source such as sucrose, a nitrogen source such as melamine, and an iron source such as nano-iron oxide are uniformly mixed, and then one-step sintering is performed to make the mixture dehydrate; then in the second-step sintering, a lithium source such as pitch and lithium oxide (Li2O) is introduced to generate lithium ferrite (Li5FeO4), which effectively avoids water generated by dehydration of the carbon source such as sucrose and impurities generated by the reaction of lithium ferrite, improves the purity and performance of the positive electrode lithium supplementing agent, and meanwhile, the carbon-nitrogen double-layer coating can effectively coat the lithium ferrite and introduce nitrogen, thereby improving the stability, ion diffusivity and conductivity of the positive electrode lithium supplementing agent, so as to solve the technical problem of poor performance of the lithium manganate positive electrode lithium supplementing agent prepared by the existing preparation method.

The invention discloses a difunctional composite lithium supplement additive and a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The bifunctional composite lithium supplement additive provided by the invention comprises lithium-rich lithium ferrite as a core layer and a lanthanum gallate coating layer coating the outer surface of the core layer. The lithium supplementing additive prepared by the invention realizes dual inhibition on released high-active oxygen species, the released O2 is captured and fixed in the coating layer through oxygen vacancy adsorption and lattice constraint, and a physical barrier is synchronously formed in the coating layer in a deep lithium removal process to block a migration channel of active oxygen to an electrolyte, so that the lithium supplementing effect is improved. Therefore, the cycling stability of the lithium ion battery is greatly improved, the service life of the lithium ion battery is greatly prolonged, and the application prospect in the lithium ion battery is wide.

The invention provides a multi-element lithium supplement agent and a preparation method thereof, a positive pole piece and a lithium ion battery, the multi-element lithium supplement agent comprises an inner core, a first coating layer and a second coating layer, the inner core comprises lithium-rich lithium aluminum ferrite, the first coating layer comprises lithium-rich lithium manganate, and the second coating layer comprises lithium-rich lithium nickelate; the chemical general formula of the multi-element lithium supplement agent is LixFeaAlbMncNidOy, 0.1 < = d / (a + b) < = 0.9, 0.62 < = a < = 0.96, 0.04 < = b < = 0.38, 0.005 < = c / (a + b) < = 0.02, 5a + 5b + 2c + 2d < = x < = 5.5 a + 5.5 b + 2.1 c + 2.1 d, and y = (x + 3a + 3b + 4c + 2d) / 2. Iron and aluminum are adopted as main elements, and lithium-rich lithium manganate and lithium-rich lithium nickelate are coated at the same time, so that the stability of the lithium supplementing agent can be improved, gas production can be reduced, the ionic conductivity can be improved, and the capacity exertion of the lithium supplementing agent can be promoted.

The invention provides a gradient-doped single-layer coated lithium-rich lithium ferrite material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion battery positive electrode lithium supplementing materials. According to the invention, a lithium source and an iron source are sintered at a low temperature to form an inner core, and then gradient doping and coating are realized through a ball milling process and dynamic CVD (Chemical Vapor Deposition). The material takes Li5FeO4 as an inner core, element distribution is optimized through a gradient doping technology, and a single-layer coating design is adopted, so that the air stability and the ionic conductivity of the material can be remarkably improved, and meanwhile, the loss of active lithium during first charge and discharge of a battery is compensated. When being used as a positive electrode lithium supplementing agent and matched with a silicon-carbon negative electrode, the lithium ion battery positive electrode lithium supplementing agent can improve the initial coulombic efficiency of a lithium ion battery to be greater than or equal to 88% and enhance the cycling stability.

The invention provides a lithium-rich lithium ferrite lithium supplement agent and a preparation method thereof, and belongs to the technical field of lithium ion batteries, the lithium-rich lithium ferrite lithium supplement agent comprises an intermediate and a composite carbon coating layer coating at least part of the surface of the intermediate, the intermediate comprises an inner core and a solid electrolyte coating layer coating at least part of the surface of the inner core; the inner core comprises lithium-rich lithium ferrite, and the solid electrolyte coating layer comprises LLZAO. According to the application, the LLZAO and the composite carbon are sequentially coated on the surface of the lithium-rich lithium ferrite, so that the contact between the lithium-rich lithium ferrite and external air and electrolyte can be effectively isolated by utilizing two formed coating layers, the air stability of the lithium-rich lithium ferrite is improved, meanwhile, the problem of continuous gas production in the charging and discharging process is avoided, and the service life of the lithium-rich lithium ferrite is prolonged. Further, the comprehensive performance of the lithium-rich lithium ferrite lithium supplement agent is effectively improved.

Described is an intrinsically multiplexed magnetostatic surface wave (MSSW) device comprising of a pair of transducers that couple to one or more plurality of ferrite films. In embodiments, the ferrite films may be provided as one or more of a YIG, Nickle Zinc Ferrite, Lithium Ferrite configured to simultaneously provide the MSSW device having an associated plurality of MSSW operational bandwidths. The concepts, structure and technique described herein may be used to provide broadband magnetostatic surface wave devices that employ intrinsic multiplexing techniques which enable customizable frequency responses over broad bandwidths.

The invention relates to a lithium supplement agent and a preparation method thereof and a battery, the lithium supplement agent is of a core-shell structure, and comprises a lithium ferrite inner core, and a first coating layer, a second coating layer and a carbon coating layer which sequentially coat the lithium ferrite inner core from inside to outside; the first coating layer comprises a porous carbon material, and the porous carbon material comprises one or more of activated carbon, carbon nanotubes, carbon nitride and carbon nitride nanotubes; the second coating layer comprises a metal compound, and metal elements in the metal compound comprise one or more of Al, Zr, Ti, Mg, Nb and Mo. The surface of the lithium ferrite inner core is sequentially coated with the first coating layer, the second coating layer and the carbon coating layer, so that the capacity release of the lithium supplement agent can be effectively improved, the gel problem of the electrode slurry is improved, and the long-cycle stability and the safety performance of the battery can be improved.

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a positive electrode lithium supplementing material, a preparation method and a lithium ion battery, the positive electrode lithium supplementing material is of a core-shell structure, and comprises an inner core, a middle layer and a shell; the inner core is lithium-rich lithium ferrite doped with cations, and the cations are Ti, Mg, Al, Zr or Ta; the shell is a coating layer formed by halogen and Li, and the halogen is one or more of F and Cl; the preparation method of the positive electrode lithium supplementing material comprises the following steps: in an inert atmosphere, heating a precursor, and enabling gas generated by heating to pass through a core material, so as to obtain the positive electrode lithium supplementing material; the precursor is a material capable of generating HF and / or HCl at a high temperature, and the core material is cation-doped lithium-rich lithium ferrite; the gas production rate and the interface impedance can be reduced.

The invention relates to the technical field of batteries, in particular to a battery and a power utilization device, and the battery comprises a positive pole piece, a negative pole piece and electrolyte; the positive pole piece comprises a positive current collector and a positive active layer arranged on at least one surface of the positive current collector, the positive active layer comprises a positive lithium supplement agent, and the positive lithium supplement agent comprises at least one of lithium ferrite and lithium nickelate; the electrolyte comprises a first additive, the first additive comprises a compound with a structure shown in a formula (I), R1, R2 and R3 are respectively and independently selected from one of allyl, divinyl methyl silane, vinyl dimethyl silane or trivinyl silane, and at least one of R1, R2 and R3 is selected from one of divinyl methyl silane group, vinyl dimethyl silane group or trivinyl silane group. By adding the first additive into the electrolyte, dissolution of iron ions or nickel ions in the lithium supplement agent is inhibited, the structural stability of the positive electrode lithium supplement agent is enhanced, and the cycle life of the battery is prolonged.

The invention discloses a carbon-loaded lithium iron metaphosphate positive electrode material as well as a preparation method and application thereof, and belongs to the technical field of electrochemical energy storage and lithium ion battery positive electrode materials. The preparation method of the carbon-loaded lithium iron metaphosphate positive electrode material comprises the following steps: S01, adding lithium ferrite into a first solvent, and carrying out ultrasonic dispersion and uniform mixing to obtain a lithium ferrite dispersion solution; s02, adding organic phosphonic acid and a second solvent into the lithium ferrite dispersion solution, and reacting in a nitrogen environment; after the reaction is finished, cooling to room temperature, and centrifuging the mixed solution to obtain a sample containing impurities; washing, centrifuging and drying to obtain a precursor material; and S03, carbonizing and crystallizing the precursor material in a nitrogen environment to obtain the carbon-loaded lithium iron metaphosphate positive electrode material. The metaphosphoric acid chain structure of the prepared carbon-loaded lithium iron metaphosphate positive electrode material has excellent chemical stability, so that the carbon-loaded lithium iron metaphosphate positive electrode material can be used as a lithium ion battery positive electrode material with safety advantage, cost advantage and structural novelty.

This invention discloses a lithium replenishing agent coated with a metal-organic framework (MOF), its preparation method, and its application, belonging to the field of lithium-ion batteries. The lithium replenishing agent comprises a matrix and a coating layer. The matrix is ​​lithium ferrite, and the coating layer is a MOF with a thickness of 0.5-10 nm. The MOF is prepared using fluorine-containing and carboxyl-containing compounds as ligands and zirconium tetrachloride as the metal source via a solvothermal method. The preparation method includes the following steps: preparing and activating a lithium ferrite intermediate; adding the activated lithium ferrite intermediate to a buffer solution containing dissolved dopamine hydrochloride to prepare lithium ferrite intermediate @PDA; performing in-situ growth of the MOF to construct a hydrophobic MOF-coated precursor; adding a lithium source to the precursor and performing programmed sintering to obtain the lithium replenishing agent. The lithium replenishing agent provided by this invention achieves excellent air stability, low gas production, and excellent conductivity.

The application relates to a double-coated positive electrode material and a preparation method thereof, and the preparation steps are as follows: a soluble ferrous salt solution is heated and stirred, a phosphorus source is added, heating and stirring are continuously carried out, a lithium source, an additive and water are added, a first mixed material is obtained after ball milling, sand milling and spraying; the first mixed material is calcined under an inert gas atmosphere and then crushed to obtain a first material; the first material is dispersed in a citric acid solution and continuously stirred, a soluble iron salt solution and a lithium carbonate solution are added, continuous stirring is carried out, and finally a carbon source is added, a second mixed material is obtained after sand milling and spraying; the second mixed material is calcined to obtain a double-coated lithium iron phosphate composite material. Through coating lithium ferrite on the surface of lithium iron phosphate and then carrying out carbon coating treatment, the double-coated lithium iron phosphate positive electrode material is formed, and the cycle performance, processing performance and safety performance of the material can be effectively improved.

The present application belongs to the field of positive electrode materials, and provides a lithium-rich lithium iron oxide material, and a preparation method therefor and the use thereof. The lithium-rich lithium iron oxide material comprises a particle of a core-shell structure, wherein the particle of a core-shell structure comprises a core, a first coating layer that coats the core, and a second coating layer that coats the first coating layer; the core is Li5FeO4, the first coating layer is a carbon layer, and the second coating layer is a mixed layer comprising polyoxyethylene and a lithium salt; and the mass ratio of the first coating layer to the core is (2:100) to (10:100), and the mass ratio of the second coating layer to the core is (3:100) to (13:100). The present application is conducive to improving the air stability of the lithium iron oxide material, and can also enhance the overall ionic conductivity of an electrode.

This invention provides a method for preparing phosphorus-doped lithium ferrite using waste lithium iron phosphate (LFP) electrode sheets and the resulting product, belonging to the field of materials synthesis technology. This method creatively recycles waste LFP electrode sheets in the form of phosphorus-doped lithium ferrite, greatly improving their utilization value. The method for synthesizing phosphorus-doped lithium ferrite using waste LFP electrode sheets has the following advantages: 1) This method requires no additional oxidant, is environmentally friendly, and solves the problem of difficult treatment of phosphorus-containing waste from the process; 2) Using waste LFP electrode sheets as raw materials not only reduces costs and yields high-value-added products, but also has high atom utilization, introduces no other impurities, and is pollution-free; 3) Phosphorus doping can improve the conductivity of lithium ferrite, reduce polarization, and improve structural and air stability.

The invention belongs to the technical field of battery materials, and particularly relates to a double-layer coated lithium-rich lithium ferrite material as well as a preparation method and application thereof. The double-layer coated lithium-rich lithium ferrite material comprises a Li5FeO4 inner core, a sulfide solid electrolyte layer coated on the surface of the inner core and a polydimethylsiloxane hydrophobic layer coated outside the sulfide solid electrolyte layer. According to the material, the migration path of lithium ions is optimized through electrolyte coating in double-layer coating, the discharge capacity of Li5FeO4 is improved, erosion of moisture and carbon dioxide in air can be effectively isolated through the hydrophobic layer, side reaction of active lithium in lithium-rich lithium ferrite and the external environment is inhibited, and the air stability of the material is improved.

The invention discloses a composite material containing lithium-rich lithium ferrite and a layered positive electrode material as well as a preparation method and application of the composite material. The composite material contains lithium-rich lithium ferrite and a main active substance layered positive electrode material, can contain or does not contain a carbon coating layer, and can contain or does not contain a coating layer of other elements except carbon. Wherein the lithium-rich lithium ferrite is mainly used for improving the first efficiency and the cycle performance of the battery cell; the carbon layer which can be contained or not contained is mainly used for improving the electronic conductivity and air stability of the material; the coating layer can contain or does not contain other elements and is mainly used for improving the electrical property and improving the air stability to a certain degree; in addition, the air stability of the LFO is further improved due to the layered material, particularly, when the composite material is applied to a high-nickel ternary material system, the compatibility of the composite material and the high-nickel ternary material can be further improved, and the problems of side reaction and gas production are solved.

The invention discloses a method for detecting the content of ferrous iron impurities in a lithium supplementing material and application of the method, and belongs to the technical field of lithium ion battery pre-lithiation. According to the technical scheme, the method comprises a lithium ferrite pretreatment step and a potassium permanganate titration step, the lithium ferrite pretreatment step comprises the following steps: adding lithium ferrite into concentrated hydrochloric acid for dissolving, carrying out suction filtration after dissolving to obtain a clear yellow green liquid, and then diluting to obtain a to-be-titrated liquid. The invention provides the method for detecting the content of the ferrous iron impurity in the lithium supplementing material, the detection method is simple and rapid to operate, has an important promotion effect on the detection of the purity of lithium ferrite, can also be used for analyzing and guiding the modification of the lithium ferrite material, and has important significance on improving the performance of the material.

The invention relates to the technical field of batteries, in particular to a sodium ion battery which comprises a positive plate and a negative plate, the positive plate comprises a positive current collector and a positive active layer positioned on at least one side surface of the positive current collector; in the thickness direction of the positive plate, the positive active layer comprises a first region and a second region, the first region is located on the outermost layer of the positive active layer, the second region is close to the positive current collector, the positive active layer of the first region contains a first positive active material, and the first positive active material is composed of a first sodium-containing active material and a lithium-rich lithium ferrite material. According to the sodium ion battery, the SEI film with lithium-containing organic matter or inorganic matter as the main component (larger than or equal to 50%) can be formed in the first formation process, continuous consumption of the SEI film on active sodium ions is reduced, the SEI film under the positive and negative electrode system has higher stability, and therefore the cycle life of the sodium ion battery is guaranteed, and the long-life requirement of an energy storage scene is met.

The invention discloses an electrolyte capable of inhibiting gas production of lithium-rich lithium ferrite and a lithium ion battery, and belongs to the field of lithium ion batteries. An electrolyte capable of inhibiting gas production of lithium-rich lithium ferrite comprises a lithium salt, an organic solvent and an additive, the additive comprises a deoxidant, and the deoxidant has a sulfite group and a phosphite group. According to the electrolyte capable of inhibiting gas production of the lithium-rich lithium ferrite disclosed by the invention, due to the introduction of a sulfite group in the added deoxidant, not only can oxygen free radicals be absorbed, but also an interfacial film with relatively low impedance can be formed, the problem of high film-forming impedance of a phosphite group is relieved, and the rate capability of a lithium ion battery is ensured.

The present disclosure relates to the technical field of lithium-ion batteries, and provides a fast-charging lithium-ion battery, and a preparation method therefor and an application thereof. Specifically, a positive electrode of the lithium-ion battery comprises lithium iron phosphate and a positive electrode additive; the positive electrode additive comprises at least one of lithium ferrite, lithium oxalate, and lithium squarate; an electrolyte of the lithium-ion battery comprises a solvent, a lithium salt, and electrolyte additives; the solvent includes a low-viscosity solvent with a viscosity of ≤0.5 cps; and the electrolyte additives include a carbonate-based additive, a sulfur-containing additive, and a lithium salt additive. The lithium-ion battery of the present disclosure can effectively improve the fast-charging performance and low-temperature performance of lithium iron phosphate batteries, without causing degradation in the cycle performance and high-temperature performance of batteries. That is, the lithium-ion battery takes into account various electrical properties and has a good application prospect.

The application discloses a preparation method of lithium ferrite for anode material lithium supplement and application thereof. The lithium ferrite is prepared by the following steps: mixing lithium carbonate and a carbon source, sintering, obtaining conductive carbon coated lithium oxide, mixing the lithium oxide with nano Fe2O3, pressing, sintering, and cooling to obtain Li5FeO4. After a small amount of the lithium ferrite prepared by the application is added into a commercial lithium iron phosphate anode, the first circle of charge and discharge shows excellent lithium supplement performance, and the capacity attenuation problem of the lithium iron phosphate battery anode material is improved. In addition, the preparation process of the anode lithium supplement material is simple, the cost is low, the prepared Li5FeO4 has a proper particle size, and the lithium ferrite has great commercialization potential.

The application provides an electrochemical device and an electronic device. The electrochemical device comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode current collector, a first coating layer and a positive electrode material layer, the first coating layer is arranged on the surface of the positive electrode current collector, and the positive electrode material layer is arranged on the surface of the first coating layer away from the positive electrode current collector. The first coating layer comprises a first main material and a first binder, the first main material comprises a lithium supplement material, and the lithium supplement material comprises at least one of lithium iron phosphate, lithium manganese iron phosphate, lithium orthosilicate or lithium ferrite; the infrared spectrum of the first coating layer has a characteristic peak between 3200 cm ‑1 and 3400 cm ‑1 . The electrochemical device provided by the application can balance the nail penetration safety performance, capacity and volume energy density.

This invention discloses a lithium-rich lithium ferrite composite material and its preparation method. First, inexpensive straw is used as a carbon source and reacts with an iron source to generate an Fe / C precursor with Fe-O-C bonds. Then, this precursor is mixed with a lithium source and sintered to obtain an LFO / C composite. Finally, the surface is coated with a nitrogen-containing organic polymer to obtain the lithium-rich lithium ferrite composite material. The lithium-rich lithium ferrite composite material obtained by this invention has the characteristics of low production cost, excellent conductivity, and good stability in air, which is beneficial for improving the electrochemical performance of lithium-ion batteries.

The invention relates to the technical field of batteries, and provides a composite coated high-performance lithium-rich lithium ferrite material as well as a preparation method and application thereof, and the composite coated high-performance lithium-rich lithium ferrite material is a modified lithium-rich lithium ferrite material. Comprising an inner core and a coating layer which at least partially coats the surface of the inner core and is used for enabling the modified lithium-rich lithium ferrite material to have conductivity, the inner core comprises a second lithium-rich lithium ferrite material which is obtained by doping cations and anions in a first lithium-rich lithium ferrite material and has a structural general formula of Li5Fe (1-x) MxO (4-y) Ny; through synergistic doping of cations and anions, the structural stability of the modified lithium-rich lithium ferrite material in the circulating process can be improved, generation of oxygen is inhibited, meanwhile, lithium ions can be easily removed, the capacity of the modified lithium-rich lithium ferrite material is improved, and the service life of the modified lithium-rich lithium ferrite material is prolonged. When the modified lithium-rich lithium ferrite material is applied to a lithium ion battery, the electrochemical performance and the cycle stability of the lithium ion battery can be improved.

The invention discloses a carbon-coated iron defect high-specific-capacity lithium ferrite lithium supplement agent and a preparation method and application thereof, the structural general formula of the lithium ferrite lithium supplement agent is C (at) Li5Fe (1-x) O4, and x is greater than or equal to 0 and less than or equal to 0.1; the coating amount of the carbon is less than or equal to 5% of the weight of the lithium ferrite lithium supplementing agent, and the coating thickness h of the carbon is set to be 0 lt; h < = 50nm. According to the invention, the high-purity phase structure synthesis of the LFO is improved by adjusting iron defects, the lithium supplement agent with less impurity content can be obtained, and the specific capacity of the material is improved. Compared with the prior art, the preparation method has the advantages that better electronic conductivity and air stability are realized synchronously through carbon coating, the electronic conductivity is improved, the specific capacity is further improved and can be up to 747.9 mAh / g, and the problem that the specific capacity is reduced due to poor air stability and easiness in generation of an impurity phase in the existing LFO synthesis technology is well solved.

Described is an intrinsically multiplexed magnetostatic surface wave (MSSW) device comprising of a pair of transducers that couple to one or more plurality of ferrite films. In embodiments, the ferrite films may be provided as one or more of a YIG, Nickle Zinc Ferrite, Lithium Ferrite configured to simultaneously provide the MSSW device having an associated plurality of MSSW operational bandwidths. The concepts, structure and technique described herein may be used to provide broadband magnetostatic surface wave devices that employ intrinsic multiplexing techniques which enable customizable frequency responses over broad bandwidths.

The invention relates to a lithium supplement additive and a preparation method thereof, a positive plate and a lithium ion battery. The lithium supplement additive comprises an inner core and a shell, the material of the inner core comprises a lithium-rich manganese-based composite material, and the lithium-rich manganese-based composite material comprises a lithium-rich manganese-based material matrix and a first solid electrolyte coating layer coating the surface of the lithium-rich manganese-based material matrix; the shell is made of a lithium-rich lithium ferrite composite material, and the lithium-rich lithium ferrite composite material comprises a lithium-rich lithium ferrite matrix and a second solid electrolyte coating layer coating the surface of the lithium-rich lithium ferrite matrix. The lithium supplement additive is constructed by taking the lithium-rich manganese-based composite material as the inner core and the lithium-rich lithium ferrite composite material as the shell, active lithium consumed by an SEI film formed through first charging is supplemented, lithium can be continuously supplemented in the subsequent charging and discharging process, and the cycle performance of the battery is improved.

The invention relates to the technical field of batteries, in particular to a composite lithium supplement material, a preparation method thereof, a positive plate and a battery. The composite lithium supplement material comprises a base material and a coating layer at least partially coating the surface of the base material, the coating layer comprises a first coating layer and a second coating layer; the surface of the base material is coated with the first coating layer, and the surface of the first coating layer is coated with the second coating layer; the base material comprises lithium-rich lithium ferrite; the first coating layer is a Mg1-XZnXAl2O4 oxide, and x is equal to 0 to 1.0; and the second coating layer is a carbon material. The composite lithium supplement material can stabilize the material structure, prevent the lithium supplement particles from generating cracks in the charging and discharging process to generate a new interface, reduce the side reaction with an electrolyte, reduce the gas production rate in the cell circulation and storage process, and improve the high-temperature storage performance and the high-temperature cycle performance of the material; meanwhile, residual alkali on the surface of the lithium supplement agent can be prevented from reacting with a glue solution to form slurry gel, and the processability of the material is improved.