29301results about "Positive electrodes" patented technology

The invention relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode assembly and an electrolyte, and the electrode assembly comprises a positive pole piece and a negative pole piece; the positive pole piece comprises a positive pole current collecting part and a positive pole film layer; the positive pole film layer comprises lithium-containing phosphate with an olivine structure; the negative pole piece comprises a negative pole current collecting part and a negative pole film layer, and the negative pole film layer comprises a carbon-based material; the electrolyte comprises a carboxylic ester solvent, a first additive and fluorine-containing lithium sulfimide, and the mass content of the carboxylic ester solvent is 8%-60%; the total mass content of the first additive is 2.5%-10%, the first additive comprises 1, 3-propane sultone with the mass content larger than or equal to 0, an ethylene carbonate derivative with the mass content larger than or equal to 0 and vinylene carbonate with the mass content larger than 0, and the ethylene carbonate derivative comprises a compound shown in the formula A; the mass content of the fluorine-containing lithium sulfimide is 4%-8%. According to the invention, the rapid charging performance and the cycle performance of the battery monomer can be improved. # imgabs0 # formula A

The present invention relates to a solid composite cathode material comprising a ceramic oxide electrolyte material and a lithium electrode material. It was found that the addition of lithium halide to the selected electrolyte and cathode materials strongly enhances the electrochemical performance.

Disclosed are a positive electrode material, a preparation method of a positive electrode material, a positive electrode plate, and a battery. The positive electrode material includes a sodium-containing oxide, an angle range of a first characteristic peak of the sodium-containing oxide is less than an angle range of a second characteristic peak, the first characteristic peak is a characteristic peak of the sodium-containing oxide at an initial voltage, the second characteristic peak is a characteristic peak of the sodium-containing oxide at a cut-off voltage, and a chemical formula of the sodium-containing oxide is LixNa1-xCo1-z MzO2. M includes a metal element or a non-metal element, 0.7<x<1, and 0.001<z<0.03.

The invention discloses a lithium iron phosphate positive electrode material, a preparation method thereof and a lithium battery, and relates to the technical field of lithium ion batteries. According to the method, the pressing index of the lithium iron phosphate positive electrode material is tested by adopting a specific method, so that the pressing index meets a specific range, meanwhile, the average circularity of larger particles in a Dv50-Dv100 range meets a proper range, the lithium iron phosphate positive electrode material has better particle movement capability, and the particles can move at a higher speed to be rearranged during pressing, so that the particle size of the lithium iron phosphate positive electrode material is reduced, and the quality of the lithium iron phosphate positive electrode material is improved. Therefore, the positive pole piece with high compaction density can be obtained, the charge-discharge capacity of the battery can be improved, and meanwhile, the particles can be prevented from being broken when being pressed, so that the positive pole piece has good anti-pressure capability. By adopting the lithium iron phosphate positive electrode material provided by the invention, the lithium battery has relatively high energy density and capacity retention ratio.

The invention provides a battery monomer, a secondary battery and an electric device, and belongs to the field of batteries. The battery monomer comprises a positive electrode plate, the positive electrode plate comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, and the volume particle size distribution Dv50 of the positive electrode active material is 0.3 [mu] m-3 [mu] m; the volume particle size distribution Dv10 is 100-800 nm, the volume particle size distribution Dv99 is less than 20 [mu] m, the positive electrode active material comprises M-doped lithium iron phosphate, M comprises Al and / or at least one transition metal element except Fe, and the mass content of M in the M-doped lithium iron phosphate is 200-1500 ppm. According to the present invention, the particle size of the positive electrode active material, the type of the doping element and the doping amount are simultaneously regulated and controlled in the above range, and the parameters are matched and co-act so as to provide the good cycle performance on the basis of the high power performance of the battery monomer.

The invention discloses a preparation method of a high-compaction-density lithium iron phosphate material, through grading of large and small particle lithium iron phosphate, optimization of a sintering process and reasonable selection of a carbon source and a titanium dopant, the compaction density and the electrochemical performance of the material are remarkably improved, and the preparation method specifically comprises the following steps: mixing iron phosphate, lithium carbonate, the carbon source and auxiliary materials; the preparation method comprises the following steps: carrying out coarse grinding and fine grinding, respectively preparing large-particle lithium iron phosphate and small-particle lithium iron phosphate (a material A and a material B) by adopting spray drying and high-temperature calcination processes, mixing the material A and the material B according to a ratio, adding auxiliary materials, grinding, further carrying out spray drying, calcining and crushing to obtain a final lithium iron phosphate product, and the maximum compaction density of the prepared material can reach 2.712 g / cm < 3 >. According to the present invention, the maximum 1C discharge specific capacity can achieve 140.5 mAh / g, the maximum 1C 3.2 V discharge platform retention rate is 91.4%, and the prepared lithium ion battery negative electrode material has characteristics of excellent conductivity, high discharge capacity and good cycle stability, and is suitable for power batteries and energy storage batteries.

The invention discloses a positive electrode material and a preparation method thereof, a battery and a power utilization device. The positive electrode material comprises an inner core; the first coating layer comprises a first coating material, and the first coating material comprises at least one of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte and a polymer composite solid electrolyte; the first coating layer coats the inner core, the second coating layer coats the inner core, the first coating layer coats the second coating layer, the second coating layer comprises a second coating material, and the second coating material comprises a halide solid electrolyte. The coating layer plays a certain role in isolating the material of the inner core from the external environment, and the situation that the material in the inner core has side reaction with external substances or the property of the material is changed due to other reasons is reduced. Therefore, the performance stability of the positive electrode material is kept.

The present invention relates to a sodium-ion battery material, and specifically relates to a sodium ferric phosphate pyrophosphate composite material, and a preparation process, evaluation method and process optimization method therefor and the use thereof. The sodium ferric phosphate pyrophosphate composite material has a spinel-type NaFePO4 phase; and in an XRD diffraction pattern obtained by subjecting the sodium ferric phosphate pyrophosphate composite material to XRD diffraction using CuKα radiation, there are a characteristic diffraction peak T of sodium ferric phosphate pyrophosphate and a characteristic diffraction peak O of spinel-type NaFePO4 at 2θ of 33.6±0.2° and 32.8±0.2°, respectively, the peak intensities thereof are respectively IT and IO, and the diffraction peak intensity ratio Ir is equal to IT / IO, wherein 6.19≤Ir≤13.

The invention provides a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive pole piece, an isolating membrane, a negative pole piece and electrolyte, and the positive pole piece, the isolating membrane and the negative pole piece are arranged in a laminated manner; the positive pole piece comprises a positive current collector and a positive active layer arranged on at least one side of the positive current collector, the negative pole piece comprises a negative current collector and a negative active layer arranged on at least one side of the negative current collector, and the positive active layer comprises lithium iron phosphate primary particles; the isolating membrane comprises a base membrane and a bonding layer, the bonding layer is of a porous continuous structure, and the bonding layer is at least arranged on one side, facing the positive electrode active layer, of the base membrane; the electrolyte comprises a first solvent, and the first solvent comprises one or more of dimethyl carbonate and linear carboxylic ester. The battery monomer has relatively good cycle performance.

Batteries, component structures and manufacturing methods, in particular including a glassy embedded battery electrode assembly having a composite material structure composed of interpenetrating material components including a porous electroactive network including a solid electroactive material, and a continuous glassy medium including a Li ion conducting sulfide glass, can achieve enhanced power output, reduced charging time and / or improved cycle life.

The invention provides a positive plate, a preparation method thereof and a battery. The positive plate comprises a positive current collector, and a first positive active coating and a second positive active coating which are sequentially arranged on at least one side of the positive current collector, the first positive electrode active coating is close to one side of the positive electrode current collector, and the first positive electrode active coating comprises a first manganese iron lithium phosphate active material and a nickel-cobalt-manganese ternary active material; in the first positive electrode active coating, the mass ratio of the first lithium manganese iron phosphate active material to the nickel-cobalt-manganese ternary active material is (80-90): (8-15); the second positive electrode active coating is far away from one side of the positive electrode current collector, and the second positive electrode active coating comprises a second lithium manganese iron phosphate active material; the surface density rho1 of the first positive electrode active coating and the surface density rho2 of the second positive electrode active coating meet the following conditions: rho1 is greater than or equal to 240 g / m < 2 >, and rho2 is greater than or equal to 240 g / m < 2 >; and rho1-rho2 is less than or equal to 5g / m < 2 >. The positive plate has relatively high electron conduction and ion conduction performance, meanwhile, the polarization of the positive plate is effectively reduced, and the cycle performance and the thermal stability of the battery are greatly improved.

The embodiment of the invention relates to a lithium cobalt oxide positive electrode material with a composite phase as well as a preparation method and application of the lithium cobalt oxide positive electrode material. The chemical general formula of the lithium cobalt oxide positive electrode material with the composite phase is AXCo (1-y) M (1y) O2, wherein x is more than or equal to 0.5 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 0.03, A is Li or Li and Na, and M1 is one or more of A1, Zr, Ni, Mn, Y, Nb, La, Fe, Cu, Cr, Ti, W, Mg, Mo or Yb; the composite phase of the lithium cobalt oxide positive electrode material comprises an O2 phase, a T2 phase and an O3 phase; wherein the sum of the molar ratios of the O2 phase and the T2 phase in the composite phase is greater than or equal to 90%, and the molar ratio of the O3 phase is less than or equal to 10%. By regulating and controlling the composite phase proportion of the lithium cobalt oxide positive electrode material, the rate capability, the structural stability under high voltage, the stability of a thermodynamic structure, the specific capacity, a discharge platform and other characteristics of the positive electrode material can be effectively improved, so that the lithium cobalt oxide positive electrode material with high energy density and high stability is realized.

The invention discloses a composite positive electrode material and a preparation method thereof, a positive plate and a lithium ion battery. The composite positive electrode material comprises lithium iron phosphate and a carbon coating layer coating the surface of the lithium iron phosphate, wherein the integral intensity ratio ID / IG of a D peak to a G peak of the carbon coating layer in a Raman spectrum is 0.2-0.9, and the resistivity of the composite positive electrode material is 0.1-10 omega.cm. According to the preparation method, the graphitization degree of the carbon coating layer is controlled within a proper range (ID / IG is 0.2-0.9), so that good conductivity is ensured, and structural instability caused by excessive graphitization is avoided. The moderate graphitization degree is beneficial to formation of an ordered carbon layer structure, provides more electron transport channels and reduces the potential barrier of electron migration, so that the conductivity of the composite material is greatly improved, and the resistivity is reduced to an excellent level of 0.1-10 omega.cm.

Disclosed are a lithium iron phosphate precursor, a lithium iron phosphate material, a preparation method therefor, and a use thereof. The lithium iron phosphate material comprises a flower cluster structure, the flower cluster structure comprises secondary particles, and the secondary particles are formed by agglomerating primary particles by means of a coating layer; the material of the primary particles is lithium iron phosphate. The lithium iron phosphate material of the present invention has good electrochemical properties and processing properties when used in batteries.

A composite positive electrode material, a preparation method therefor and the use thereof. The composite positive electrode material comprises an inner core and a carbon coating layer covering at least part of the surface of the inner core and / or embedded in the inner core; the inner core comprises NaFePO4 and a compound represented by formula 1; Na4+xFe3-y(PO4)2+zP2O7 formula 1, where -0.15≤x≤0.8, 0≤y≤0.5, and -0.2≤z≤0.2; the particle size of NaFePO4≤100 nm. When being used for batteries, the composite positive electrode material can improve the capacities and rate capabilities of the batteries.

The invention relates to the technical field of secondary batteries, and particularly provides a positive active material, a positive pole piece, a secondary battery and an electric device. The positive electrode active material includes a lithium-containing phosphate and a lithium-containing metal oxide. Wherein the lithium-containing metal oxide accounts for 1%-20% of the positive electrode active material in percentage by mass. An X-ray diffraction pattern of the lithium-containing metal oxide comprises a diffraction peak of a crystal face (003) and a diffraction peak of a crystal face (104), the diffraction peak of the crystal face (003) and the diffraction peak of the crystal face (104) meet the condition that the value of I (003) / I (104) is smaller than or equal to 1.2, I (003) represents the intensity of the diffraction peak of the crystal face (003), and I (104) represents the intensity of the diffraction peak of the crystal face (104). The positive electrode plate comprises a current collector and a positive electrode film layer arranged on the current collector. The positive electrode film layer comprises the positive electrode active material. And the positive electrode active material accounts for 90-97% of the mass of the positive electrode film layer. The positive electrode active material provided by the invention can provide cycle performance of the secondary battery.

The invention discloses a lithium iron phosphate positive electrode material and a preparation method and application thereof, and belongs to the technical field of lithium iron phosphate positive electrode materials. The lithium iron phosphate positive electrode material comprises a lithium iron phosphate matrix and a carbon coating layer coating the surface of the lithium iron phosphate matrix, the average standard deviation of the thickness of a carbon coating layer in the lithium iron phosphate positive electrode material is # imgabs0 #, and sigma (d) is more than or equal to 0.05 nm and less than or equal to 0.35 nm; the average standard deviation of the carbon content in the lithium iron phosphate positive electrode material is sigma (Cwt%), and sigma (Cwt%) is larger than or equal to 0.02 wt% and smaller than or equal to 0.35 wt%. The lithium iron phosphate positive electrode material has a uniform carbon coating layer, and the thickness of the carbon coating layer and the carbon content at each position are relatively consistent, so that the improvement of the carrier mobility of the lithium iron phosphate positive electrode material is facilitated, and the further improvement of the electrochemical performance of a battery prepared from the lithium iron phosphate positive electrode material is facilitated.

The present disclosure relates to a carbon-based nanomaterial composition that may be formed from a gas mixture and a sulfur powder. The gas mixture may include a carbon based gas, an oxygen gas, and a hydrogen gas. The carbon-based nanomaterial composition may include sulfur doped nanospheres.

The invention relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode assembly and an electrolyte, and the electrode assembly comprises a positive pole piece and a negative pole piece; the positive pole piece comprises lithium-containing phosphate with an olivine structure; the negative pole piece comprises graphite particles; the electrolyte comprises a carboxylic ester solvent and a first additive, the thickness of the single-side negative electrode film layer is 50 microns to 75 microns, and the volume average particle size of the graphite particles is 8.5 microns to 13.5 microns; based on the mass of the electrolyte, the mass content of the carboxylic ester solvent is 8%-60%, the total mass content of the first additive is 3%-10%, the first additive comprises 1, 3-propane sultone with the mass content larger than or equal to 0, an ethylene carbonate derivative with the mass content larger than or equal to 0 and vinylene carbonate with the mass content larger than or equal to 3%, and the ethylene carbonate derivative comprises a compound shown in the formula A. According to the invention, the rapid charging performance and the cycle performance of the battery monomer under high energy density can be improved. # imgabs0 # formula A

The invention relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrolyte, a positive pole piece and a negative pole piece, the positive pole piece comprises a positive pole current collecting part and a positive pole film layer located on at least one surface of the positive pole current collecting part and containing a positive pole active material, and the positive pole active material comprises lithium-containing phosphate of an olivine structure; the coating weight of one side of the positive electrode film layer is 200mg / 1540.25 mm < 2 > to 370mg / 1540.25 mm < 2 >, the negative electrode plate comprises a negative electrode current collecting part and a negative electrode film layer which is positioned on at least one surface of the negative electrode current collecting part and contains a negative electrode active material, the negative electrode active material comprises a carbon-based material, the conductivity of the electrolyte is 13-20mS / cm, the battery monomer is subjected to constant-current discharge from a 100% state of charge (0.33 C) to 2.0 V at 25 DEG C, and a discharge platform voltage V1 is 3.19-3.235 V. According to the invention, the fast charging performance, the energy density and the cycle performance of the battery monomer can be improved.

The invention belongs to the technical field of sodium ion batteries, and particularly relates to a calcium ion doped modified sodium ion positive electrode material and a preparation method thereof, a positive electrode plate and a half battery. The calcium ion doped modified sodium ion positive electrode material comprises a sodium source, a doping source and a precursor, and is characterized in that the chemical general formula of the positive electrode material is Na < 1-x > M < x > Ni Fe Mn < c > O < 2 >, the value range of the doping sources M and x is x < = 0.05, a + b + c = 1, and all elements in the chemical formula meet charge balance. Sodium sites in a layered structure are replaced by calcium ion doping, so that interlayer spacing is enlarged, sodium ion transmission kinetics is enhanced, and adverse phase change is inhibited. The sodium ion positive electrode material shows high specific capacity and excellent cycle stability, the capacity retention ratio is 93.03% after 100 times of cycle charge and discharge at 1C, and the sodium ion positive electrode material has the characteristics of simple preparation, low cost, high specific capacity and excellent cycle performance.

The invention relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode assembly and an electrolyte, the electrode assembly comprises a positive pole piece and a negative pole piece, the positive pole piece comprises a positive current collector and a positive film layer, the positive film layer comprises a positive active material, the positive active material comprises lithium-containing phosphate of an olivine structure, and the electrolyte is a lithium-containing lithium-containing phosphate of a lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing lithium-containing electrolyte. The resistance of the positive pole piece is 0.1 ohm to 30 ohm, the negative pole piece comprises a negative current collector and a negative film layer, the resistance of the negative pole piece is 0.001 ohm to 0.01 ohm, the electrolyte comprises an organic solvent, the organic solvent comprises a chain ester solvent, and the mass content of the chain ester solvent in the organic solvent is 5% to 75%; the conductivity of the electrolyte at room temperature is 13 mS / cm to 20 mS / cm. The heat production amount of the battery monomer can be reduced, and the use reliability and the cycle performance of the battery monomer can be improved.

The invention provides a battery monomer, a battery device and a power utilization device. Each battery monomer comprises a shell and an electrode assembly in the shell, the electrode assembly comprises a positive pole piece, a negative pole piece and an isolating membrane between the two pole pieces, the positive pole piece comprises a positive current collector and a positive active layer arranged on at least one side of the positive current collector, and the positive active layer comprises a positive active material; the positive electrode active material comprises a nickel-containing lithium transition metal oxide and a lithium-containing phosphate, the molar weight of the Ni element in the nickel-containing lithium transition metal oxide accounts for 70-95% of the total molar weight of the transition metal, the positive electrode active material comprises Ni, Co, Mn, Fe and Li elements, and the ratio of the mass of the Ni element in the positive electrode active material to the sum of the mass of the Fe element and the mass of the Mn element is 0.15-2.

The invention discloses a carbon-coated lithium iron phosphate active material and a preparation method thereof, a positive pole piece and a lithium battery, and relates to the technical field of lithium batteries. According to the method, the structure of the carbon coating layer of the carbon-coated lithium iron phosphate active material is comprehensively evaluated through the carbon coating factor beta, # imgabs0 can evaluate the amount of graphitized carbon on the unit surface area of the carbon-coated lithium iron phosphate active material, and compared with amorphous carbon, the graphitized carbon has more excellent conductivity and can better improve the conductivity of a lithium iron phosphate matrix. By regulating and controlling a carbon coating layer structure of the carbon-coated lithium iron phosphate active material, a carbon coating factor beta meets a specific value range, so that the uniform conductivity of the carbon-coated lithium iron phosphate active material is improved; the lithium ion battery prepared from the lithium ion battery positive electrode material is small in internal resistance growth rate, charge transfer impedance Rct sample standard deviation and Warburg coefficient sample standard deviation, and the overall electrical performance of the lithium ion battery is improved.

The invention provides a lithium ion secondary battery, a battery device, a power utilization device, a preparation method of a positive electrode active material and a preparation method of a positive electrode plate. The lithium ion secondary battery comprises a positive pole piece, a negative pole piece and an electrolyte, the positive pole piece comprises a positive current collector and a positive film layer arranged on at least one side of the positive current collector, and the positive film layer comprises a positive active material; the positive electrode active material comprises lithium-containing transition metal phosphate particles, at least part of the surfaces of the lithium-containing transition metal phosphate particles are provided with carbon coating materials, and in the tangent plane of the positive electrode film layer in the thickness direction of the pole piece, DA90 of the particles is 1400 nm to 2100 nm; the particle size concentration ratio (DA90-DA10) / DA50 is 1.855-2.375, and DA90, DA50 and DA10 refer to the particle sizes of the corresponding particles when the cumulative area distribution of the particles reaches 90%, 50% and 10% in an area cumulative distribution curve of the particles.

Disclosed in the present invention are a bimetallic-atom-loaded porous carbon framework material, and a preparation method therefor and the use thereof. The preparation method comprises: by taking a metal organic framework as a precursor raw material, and by using the self-polymerization of a high-molecular polymer on the surface of the metal organic framework, forming a polymer-coated metal-based organic framework material (PM@MOF) having a core-shell structure; and then capturing the metal of a metal chloride salt solution by using surface functional groups of the PM@MOF dispersed in n-hexane, so as to obtain a bimetallic element-doped polymer-coated metal-based organic framework material, and subjecting same to a high-temperature treatment in an argon gas atmosphere so as to obtain a bimetallic-atom-loaded porous carbon-based material (MD@PC). In the present invention, by loading bimetallic atoms on a nitrogen-doped porous carbon matrix to form MD-NX coordination sites, which have the dual functions of sulfur fixation and catalysis, the agglomeration degree of intermediate phase lithium sulfide can be reduced, thereby guaranteeing that the lithiation reaction of sulfur is more sufficient, rapid and efficient.

The invention provides a positive electrode, a low-temperature electrolyte, a low-temperature sodium-ion battery and a preparation method and application of the low-temperature sodium-ion battery, and belongs to the technical field of battery materials. The low-temperature sodium ion battery comprises a positive electrode, a negative electrode and a low-temperature electrolyte, wherein the positive electrode comprises a positive electrode active material, a binder, sodium salt containing fluorine and sulfur and conductive carbon; the positive electrode is improved by adding sodium salt containing fluorine and sulfur, sulfur / fluorine rich in anion derivatives can be formed on a contact interface of the positive electrode and an electrolyte to form a firm SEI film, the internal resistance of the battery is further reduced, and the coulombic efficiency of the battery during charging and discharging at normal and low temperatures is improved. The low-temperature electrolyte comprises an ester solvent and an ether additive, by adding the ether solvent, the physicochemical property of the electrolyte and the composition of an SEI film on a contact interface of an electrode and the electrolyte are optimized, the viscosity of the electrolyte at low temperature is reduced, the ionic conductivity is improved, and formation of the SEI film rich in sodium fluoride on the surface of a negative electrode can be promoted; and thus, the problem of low coulombic efficiency of battery charge-discharge cycle at low temperature is solved.

A positive electrode plate includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, where the positive electrode active material layer includes a first positive electrode active material represented by chemical formula (1) and a second positive electrode active material represented by chemical formula (2): Li1+xAaFeyMnzTivPO4−wSw (1), and Li2+rNasM1+qO2+t (2); and the positive electrode plate satisfies: 5.2≤R / Q≤13.5. Such a positive electrode plate can achieve a high specific discharge capacity of the electrochemical apparatus, thereby increasing energy density of the electrochemical apparatus. In addition, a relationship between compacted density R and single surface density Q of the positive electrode plate is limited, effectively improving cycling stability and rate performance of the electrochemical apparatus.

A positive electrode plate includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, where the positive electrode active material layer includes two respective positive electrode active materials represented by chemical formula (1) and chemical formula (2): Li1+xNaaCo1+yAlzMgpTiuMvO2+w (1), where in chemical formula (1), M includes at least one of Zr, La, or Y, −0.1<x<0.1, 0<a<0.005, −0.05<y<0.05, 0.01<z<0.05, 0.001<p<0.01, 0<u<0.005, 0<v<0.005, and −0.05<w<0.05; and Li2+rNasN1+qO2+t (2), where in chemical formula (2), −0.2<r<0.2, 0≤s≤0.05, −0.1<q<0.1, −0.05<t<0.05, and N includes at least one of Ni, Cu, Mn, Fe, or Co. Such a positive electrode plate can achieve a high specific discharge capacity of the electrochemical apparatus, thereby increasing high-temperature cycling performance and energy density of the electrochemical apparatus.

The invention provides a positive electrode material and a preparation method thereof, a positive electrode plate and a battery, the positive electrode material comprises lithium manganese iron phosphate particles, a first shell layer and a second shell layer, the first shell layer and the second shell layer sequentially coat the surfaces of the lithium manganese iron phosphate particles, the material of the first shell layer comprises nanoscale SiO2 particles, and the material of the second shell layer comprises nanoscale TiO2 particles. The surfaces of the lithium manganese iron phosphate particles are sequentially coated with the SiO2 layer and the TiO2 layer, so that the contact between the lithium manganese iron phosphate particles and an electrolyte can be reduced, the side reaction between the lithium manganese iron phosphate particles and the electrolyte in the electrochemical reaction process is reduced, the cycle life attenuation of the battery is relieved, the dissolution of Mn element is reduced, and the service life of the battery is prolonged. Therefore, the battery impedance increase caused by deposition of Mn < 2 + > on the negative electrode in the circulation process is relieved.