Raw material composition of positive electrode material, positive electrode material, preparation method thereof, electrode sheet and battery

Abstract

The application discloses a raw material composition of a positive electrode material, a positive electrode material, a preparation method of the positive electrode material, a pole piece and a battery. The raw material composition of the positive electrode material comprises a carbon source; the carbon source comprises a bisphenol compound; in a molecular structural formula of the bisphenol compound, R is one or more of an alkyl group, a sulfone group, an aryl group, an alicyclic group, a halogenated group and a sulfide group; R3, R4, R5 and R6 are each independently selected from -H, an alkyl group, a halogenated group or a phenyl group; and R7 and R8 are each independently selected from -H, a linear or branched C1-10 alkyl group. The positive electrode material prepared by using the raw material composition of the positive electrode material has low powder resistivity and better compaction density; and the battery prepared from the positive electrode material has better electrochemical performance.

Description

Technical Field

[0001] This invention relates to a raw material composition for a positive electrode material, a positive electrode material and its preparation method, an electrode sheet, and a battery. Background Technology

[0002] With the ongoing transformation of the global energy structure and the rapid development of a green and low-carbon economy, lithium-ion batteries, as a core component of energy storage systems, have been widely used in electric vehicles, portable electronic devices, and grid energy storage due to their advantages such as high energy density, long cycle life, and environmental safety. In the lithium-ion battery field, cathode materials such as lithium iron phosphate (LiFePO4) and lithium manganese iron phosphate are considered highly competitive energy storage materials due to their high safety, low cost, abundant resources, and non-toxicity. However, lithium iron phosphate has extremely low intrinsic conductivity (approximately 10⁻⁶ ppm). -9 S·cm -1 The low conductivity and ion diffusion coefficient of lithium manganese iron phosphate (LFP) limit its electrochemical performance, leading to polarization during high-rate charge and discharge. To address these technical challenges, researchers commonly employ coating conductive carbon materials onto the surface of cathode particles to construct efficient electron conduction channels, thereby significantly improving electrochemical performance. Similarly, sodium-ion batteries have received widespread attention as a potential alternative energy storage technology. While sodium-ion batteries offer advantages such as abundant resources and low cost, their cathode material systems typically face challenges like large volume expansion and poor cycle stability. Similar to lithium-ion batteries, these cathode materials also generally exhibit poor electronic conductivity, necessitating coating with conductive carbon layers to improve their electrochemical performance.

[0003] Currently, the conductive carbon sources for preparing cathode materials mainly rely on the following traditional sources: 1. Graphite carbon black (such as acetylene black): This is currently the most commonly used conductive carbon black in industry. It has high conductivity and good sphericity, and can coat the surface of lithium iron phosphate particles during ball milling. However, it is expensive and easily oxidized during high-temperature calcination, leading to a decrease in conductivity.

[0004] 2. Conductive polymers (such as polyaniline and polypyrrole): Although they can form conductive channels at low temperatures and effectively suppress high-temperature oxidation, they are expensive and easily decompose during high-temperature calcination, making it difficult to maintain stable conductivity.

[0005] 3. Organic carbon precursors (such as sucrose and glucose): These biomass-derived carbon sources are inexpensive and widely available, but during high-temperature roasting, they often cause the internal structure of the particles to collapse or generate too many pores, affecting the bulk density and electrochemical performance of the cathode material.

[0006] In summary, existing technologies still have shortcomings in terms of cost control of conductive carbon black, high-temperature stability of conductive polymers, and structural integrity of biomass carbon sources. There is an urgent need for a novel carbon source for preparing cathode materials that can form a stable and uniform carbon coating layer during high-temperature calcination, thereby further improving the electrochemical performance of batteries derived from cathode materials. Summary of the Invention

[0007] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies where insufficient carbon sources lead to poor electrochemical performance in batteries made from the resulting cathode materials. This invention provides a raw material composition for a cathode material, the cathode material itself, a method for preparing the same, an electrode sheet, and a battery. The cathode material prepared using the raw material composition of this application exhibits lower powder resistivity and better compaction density; the battery made from this cathode material demonstrates superior electrochemical performance.

[0008] The present invention solves the above-mentioned technical problems through the following technical solution: This invention provides a raw material composition for a cathode material, comprising a carbon source; said carbon source comprises bisphenol compounds; The molecular structural formula of the bisphenol compound is shown in Formula I below: Formula I; Wherein, R is one or more of alkyl, sulfonyl, aryl, alicyclic, halogenated and thioether groups; Wherein, R3, R4, R5 and R6 are each independently selected from -H, alkyl, halogroup or phenyl; Wherein, R7 and R8 are each independently selected from -H, straight-chain or branched C1-10 alkyl groups; The structural formula of M1 is shown in equation (I-1): Formula I-1; R9, R 10 Each is independently selected from -H and / or alkyl; the values ​​of n1 and n2 are each independently 0-5000, and n1+n2≠0; The structural formula of M2 is shown in equation (I-2): Formula I-2; the R 11 R 12 Each is independently selected from -H and / or alkyl groups; the values ​​of n3 and n4 are each independently 0-5000, and n3+n4≠0.

[0009] In this invention, the bisphenol compounds refer to a class of organic compounds in which two phenolic groups (usually p-hydroxyphenyl) are linked by bridging groups (such as methylene, sulfur atom, sulfonyl group, etc.).

[0010] In this invention, R is, for example, an alkyl or aryl group.

[0011] The alkyl group is preferably -C(CH3)2-, -CH2-, or -CH(CH3)-.

[0012] The aryl group is preferably -C(CH3)2-C6H4-C(CH3)2.

[0013] In this invention, the alicyclic group in R is preferably cyclohexyl.

[0014] In this invention, the halogenated group in R is preferably -C(CF3)2-.

[0015] In a preferred embodiment, the bridging group R in the bisphenol compound is -C(CH3)2-, which is a bisphenol A compound.

[0016] In a preferred embodiment, the bridging group R in the bisphenol compound is -CH2-, which is a bisphenol F compound.

[0017] In a preferred embodiment, the bridging group R in the bisphenol compound is -C(CH3)2-C6H4-C(CH3)2-, which is a bisphenol P-type compound.

[0018] In this invention, preferably, R3, R4, R5, and R6 are each independently selected from -H. Among R3, R4, R5, and R6, the alkyl group is preferably -CH3. Among R3, R4, R5, and R6, the halogenated group is preferably -Cl or -Br.

[0019] In this invention, preferably, R7 and R8 are each independently selected from -H.

[0020] In this invention, in M1, R9 and R 10 In M1, the alkyl group is preferably -CH3 or -CH2CH3. In M1, the values ​​of n1 and n2 are each preferably independently between 0 and 20, for example, 0, 5, 4, 7.5, or 10. n1+n2 is preferably between 2 and 40, for example, 5, 9, 7.5, or 14.

[0021] In this invention, in M2, R 11 R 12 In this context, the alkyl group is preferably -CH3 or -CH2CH3. The values ​​of n3 and n4 are each preferably 0-20, for example, 0, 5, 4, 7.5 or 10. n1+n2 are preferably 2-40, for example, 5, 9, 7.5 or 14.

[0022] In this invention, M1 and M2 are polymerized from one or more of ethylene oxide, propylene oxide, and butane oxide. When M1 and M2 are polymerized from two or more of ethylene oxide, propylene oxide, or butane oxide, the polymerization method is blending or block copolymerization.

[0023] In a preferred embodiment, n1 is 5 and n2 is 0.

[0024] In a preferred embodiment, n1 is 4 and n2 is 5.

[0025] In a preferred embodiment, n1 is 7.5 and n2 is 0.

[0026] In a preferred embodiment, n1 is 4 and n2 is 10.

[0027] In a preferred embodiment, n3 is 5 and n4 is 0.

[0028] In a preferred embodiment, n3 is 4 and n4 is 5.

[0029] In a preferred embodiment, n3 is 7.5 and n4 is 0.

[0030] In a preferred embodiment, n3 is 4 and n4 is 10.

[0031] In a preferred embodiment 1, in the molecular structural formula of the bisphenol compound, R is -C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H. The structural formula of M1 is... R9 is selected from -H, n1 is 5, n2 is 0; the structural formula of M2 is R 11 Selected from -H, n3 is 5, n4 is 0.

[0032] In a preferred embodiment 2, in the molecular structural formula of the bisphenol compound, R is -CH2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H. The structural formula of M1 is... R9 is selected from -H, n1 is 5, n2 is 0; the structural formula of M2 is R 11 Selected from -H, n3 is 5, n4 is 0.

[0033] In a preferred embodiment 3, in the molecular structural formula of the bisphenol compound, R is -C(CH3)2-C6H4-C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H. The structural formula of M1 is... R9 is selected from -H, n1 is 5, n2 is 0; the structural formula of M2 is R 11Selected from -H, n3 is 5, n4 is 0.

[0034] In a preferred embodiment 4, in the molecular structural formula of the bisphenol compound, R is -C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H. The structural formula of M1 is... R9 is selected from -CH3, R 10 Selected from -H, n1 is 4, n2 is 5; the structural formula of M2 is R 11 Selected from -H,R 12 Selected from -CH3, n3 is 5, n4 is 4.

[0035] In a preferred embodiment 5, in the molecular structural formula of the bisphenol compound, R is -CH2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H. The structural formula of M1 is... R9 is selected from -H, n1 is 7.5, and n2 is 0; the structural formula of M2 is R 11 Selected from -H, n3 is 7.5, n4 is 0.

[0036] In a preferred embodiment 6, in the molecular structural formula of the bisphenol compound, R is -C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H. The structural formula of M1 is... R9 is selected from -CH3, R 10 Selected from -H, n1 is 4, n2 is 10; the structural formula of M2 is R 11 Selected from -H,R 12 Selected from -CH3, n3 is 10, n4 is 4.

[0037] In this invention, the carbon source may also include other carbon sources, preferably one or more selected from sucrose, glucose, polyethylene glycol, starch, citric acid, and asphalt, such as polyethylene glycol and / or glucose. The polyethylene glycol is preferably PEG1500, PEG6000, or PEG-200.

[0038] In a preferred embodiment, the carbon source includes glucose and the bisphenol compound, and the mass ratio of glucose to the bisphenol compound can be (0.5-8):1, preferably (1-5):1, for example 0.57:1, 0.67:1, 0.75:1, 0.8:1, 1:1, 1.2:1, 1.5:1 or 2:1.

[0039] In a more preferred embodiment, the carbon source includes bisphenol A polyoxyethylene (10) ether and glucose.

[0040] In a more preferred embodiment, the carbon source includes bisphenol F polyoxyethylene (10) ether and glucose.

[0041] In a more preferred embodiment, the carbon source includes bisphenol P polyoxyethylene (10) ether and glucose.

[0042] In a more preferred embodiment, the carbon source includes bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether and glucose.

[0043] In a more preferred embodiment, the carbon source comprises bisphenol F polyoxyethylene (15) ether and glucose.

[0044] In a more preferred embodiment, the carbon source includes bisphenol A polyoxyethylene (20) ether polyoxypropylene (8) ether and glucose.

[0045] In a preferred embodiment, the carbon source includes polyethylene glycol and the bisphenol compound, and the mass ratio of the polyethylene glycol to the bisphenol compound can be (0.5-5):1, preferably (0.5-2):1, for example 0.8:1, 1:1 or 1.2:1.

[0046] In a more preferred embodiment, the carbon source includes bisphenol A polyoxyethylene (10) ether and PEG-200.

[0047] In this invention, the mass percentage of the carbon source can be 3%-15%, preferably 3.5%-12%, for example 8.2%, 8.9%, 7.5%, 6.8%, 10.2%, 5.3%, 5.8%, 4.7%, 3.6%, 6.4% or 12%. The mass percentage represents the mass percentage of the carbon source in the composition of the cathode raw material.

[0048] In this invention, the bisphenol compound accounts for 25%-100% of the mass percentage of the carbon source, preferably 30%-100%, for example 45.5%, 50%, 40%, 33.3%, 57.1%, 100%, 55.6%, 60% or 63.6%.

[0049] In this invention, the raw material composition of the positive electrode material preferably also includes raw materials conventional in the art.

[0050] In this invention, the cathode material is preferably lithium iron phosphate, lithium manganese iron phosphate, or sodium iron manganese phosphate.

[0051] In a preferred embodiment, the cathode material is lithium iron phosphate, and the raw material composition of the cathode material includes an iron source, a lithium source, a phosphorus source, a carbon source, and a solvent.

[0052] The iron source can be of a type conventional in the art, such as iron phosphate. The lithium source can be of a type conventional in the art, such as lithium carbonate. The phosphorus source can be of a type conventional in the art, such as phosphoric acid. The phosphorus source is generally added in the form of an aqueous phosphoric acid solution. The mass concentration of phosphoric acid in the aqueous phosphoric acid solution is preferably 75-90 wt%, for example, 85 wt%. The solvent can be of a type conventional in the art, such as water. The preferred mass ratio of the iron source, lithium source, phosphorus source and carbon source is (800-1200):(200-300):(3-9):(60-160), more preferably (900-1100):(210-240):(5-8):(80-140), for example 995:226:6.73:110, 995:226:6.73:120, 995:226:6.73:100, 995:226:6.73:90 or 995:226:6.73:140.

[0053] In a preferred embodiment, the cathode material is lithium iron phosphate, and the raw material composition of the cathode material further includes a metal dopant. The metal dopant is preferably one or more of a Ti compound, a V compound, and a Nb compound, more preferably a Ti compound, such as titanium dioxide. The mass ratio of the metal dopant to the iron source is preferably (800-1200):(3-9), more preferably (900-1100):(5-7), for example 995:5.97.

[0054] In a preferred embodiment, the cathode material is lithium manganese iron phosphate, and the raw material composition of the cathode material includes a lithium source, a manganese source, an iron source, a phosphorus source, a carbon source, and a solvent.

[0055] The lithium source can be of a type conventional in the art, such as lithium carbonate. The manganese source can be of a type conventional in the art, such as manganese acetate. The iron source can be of a type conventional in the art, such as ferrous oxalate. The phosphorus source can be of a type conventional in the art, such as phosphoric acid. The solvent can be of a type conventional in the art, such as anhydrous ethanol. The preferred mass ratio of the lithium source, manganese source, iron source, phosphorus source, carbon source and solvent is (200-500):(1000-1500):(5-15):(8-20):(50-150):(500-1500), more preferably (300-400):(150-300):(7-11):(10-15):(60-110):(800-1200), for example 350:1250:9:12:90:1000, 350:1250:9:12:100:1000, 350:1250:9:12:80:1000, 350:1250:9:12:60:1000 or 350:1250:9:12:110:1000.

[0056] In a preferred embodiment, the cathode material is sodium iron manganese phosphate, and the raw material composition of the cathode material includes a sodium source, a phosphorus source, an iron source, a manganese source, a carbon source, and a solvent.

[0057] The sodium source can be of a type conventional in the art, such as sodium carbonate. The phosphorus source can be of a type conventional in the art, such as ammonium dihydrogen phosphate. The iron source can be of a type conventional in the art, such as ferric oxide. The manganese source can be of a type conventional in the art, such as manganese dioxide. The solvent can be of a type conventional in the art, such as water. The molar ratio of the sodium, phosphorus, iron, and manganese sources, based on sodium, iron, manganese, and phosphorus elements, is preferably (1-9):(1-5):(0.01-0.1):(1-9), more preferably (3-5):(2-4):(0.01-0.03):(3-5), for example 4:2.98:0.01:4. The molar ratio of the carbon source to the iron and manganese sources, calculated by carbon, iron and manganese elements, is preferably (0.2-1):(0.5-2), more preferably (0.3-0.7):(0.8-1.2), for example 0.5:1.

[0058] The present invention provides a method for preparing a cathode material, comprising the following steps: sintering a precursor slurry to obtain the cathode material; wherein the precursor slurry comprises the raw material composition of the cathode material as described above.

[0059] In this invention, the sintering temperature can be 300-850℃, preferably 400-750℃, for example 480, 550, 700 or 720℃. The sintering time can be 1-20h, preferably 2-13h, for example 2, 7, 8, 10 or 12h.

[0060] In this invention, the sintering is preferably carried out under an inert atmosphere, such as a nitrogen atmosphere.

[0061] In this invention, the heating rate from room temperature to the sintering temperature is preferably 1-10°C / min, more preferably 2-6°C / min, for example 3 or 5°C / min.

[0062] In this invention, the sintering is preferably divided into a single-stage sintering and a two-stage sintering, wherein the temperature of the two-stage sintering is higher than that of the single-stage sintering.

[0063] The sintering temperature of the first stage is preferably 300-600℃, more preferably 400-500℃, for example 480℃. The sintering time of the first stage is preferably 1-4h, more preferably 2-3h, for example 2h. The heating rate from room temperature to the sintering temperature of the first stage is preferably 3-8℃ / min, more preferably 4-6℃ / min, for example 5℃ / min.

[0064] The preferred temperature for the second-stage sintering is 500-850℃, more preferably 650-750℃, for example 700℃. The preferred sintering time for the second stage is 5-10 hours, more preferably 7-9 hours, for example 8 hours. The heating rate from the temperature of the first-stage sintering to the temperature of the second-stage sintering is preferably 1-5℃ / min, more preferably 2-4℃ / min, for example 3℃ / min.

[0065] In a preferred embodiment, the cathode material is lithium iron phosphate, and the preparation method of the cathode material includes the following steps: spray granulation and sintering of the precursor slurry; the precursor slurry includes an iron source, a lithium source, a phosphorus source, a carbon source, and a solvent.

[0066] The iron source can be of a type conventional in the art, such as iron phosphate. The lithium source can be of a type conventional in the art, such as lithium carbonate. The phosphorus source can be of a type conventional in the art, such as phosphoric acid. The phosphorus source is generally added in the form of an aqueous phosphoric acid solution. The mass concentration of phosphoric acid in the aqueous phosphoric acid solution is preferably 75-90 wt%, for example, 85 wt%. The solvent can be of a type conventional in the art, such as water. The preferred mass ratio of the iron source, lithium source, phosphorus source, and carbon source is (800-1200):(200-300):(3-9):(60-160), more preferably (900-1100):(210-240):(5-8):(80-140), for example 995:226:6.73:110, 995:226:6.73:120, 995:226:6.73:100, 995:226:6.73:90, or 995:226:6.73:140. The preferred solid content of the precursor slurry is 30-60%, more preferably 35-50%, for example 40%. The preferred D50 of the precursor slurry is 250-500 nm, more preferably 350-400 nm, for example 370-380 nm.

[0067] The precursor slurry is preferably obtained by mixing an iron source, a lithium source, a phosphorus source, a carbon source, and a solvent, followed by sand milling. The sand milling time is preferably 60-180 min, more preferably 90-150 min, for example 120 min.

[0068] The precursor slurry preferably also includes a metal dopant. The metal dopant is preferably one or more of a Ti compound, a V compound, and a Nb compound, more preferably a Ti compound, such as titanium dioxide. The mass ratio of the metal dopant to the iron source is preferably (800-1200):(3-9), more preferably (900-1100):(5-7), for example 995:5.97.

[0069] The spray granulation temperature is preferably 180-300℃, more preferably 200-240℃, for example 220℃. During spray granulation, the flow rate of the precursor slurry is preferably 600-1000 ml / h, more preferably 700-900 ml / h, for example 800 ml / h.

[0070] The sintering temperature can be 300-850℃, preferably 400-750℃, for example 480, 550, 700 or 720℃. The sintering time can be 1-20h, preferably 2-13h, for example 2, 7, 8, 10 or 12h. The heating rate from room temperature to the sintering temperature is preferably 1-10℃ / min, more preferably 2-6℃ / min, for example 3 or 5℃ / min.

[0071] In a preferred embodiment, the cathode material is lithium manganese iron phosphate, and the preparation method of the cathode material includes the following steps: sintering a precursor slurry; the precursor slurry includes a lithium source, a manganese source, an iron source, a phosphorus source, a carbon source, and a solvent.

[0072] The lithium source can be of a type conventional in the art, such as lithium carbonate. The manganese source can be of a type conventional in the art, such as manganese acetate. The iron source can be of a type conventional in the art, such as ferrous oxalate. The phosphorus source can be of a type conventional in the art, such as phosphoric acid. The solvent can be of a type conventional in the art, such as anhydrous ethanol. The preferred mass ratio of the lithium source, manganese source, iron source, phosphorus source, carbon source and solvent is (200-500):(1000-1500):(5-15):(8-20):(50-150):(500-1500), more preferably (300-400):(150-300):(7-11):(10-15):(60-110):(800-1200), for example 350:1250:9:12:90:1000, 350:1250:9:12:100:1000, 350:1250:9:12:80:1000, 350:1250:9:12:60:1000 or 350:1250:9:12:110:1000.

[0073] The precursor slurry is preferably obtained by ball milling a lithium source, a manganese source, an iron source, a phosphorus source, a carbon source, and a solvent. The ball milling speed is preferably 200-400 r / min, more preferably 250-300 r / min, for example, 280 r / min. The ball milling time is preferably 1-7 h, more preferably 3-5 h, for example, 4 h. The ball-to-material ratio during ball milling is preferably (4-12):1, more preferably (6-10):1, for example, 8:1.

[0074] Prior to calcination, the precursor slurry preferably undergoes a process of solvent removal and particle size control. The solvent removal method can be conventional in the art, such as vacuum drying. The vacuum drying temperature is preferably 40-70°C, more preferably 50-60°C, for example, 55°C. The vacuum drying time is preferably 5-12 hours, more preferably 6-10 hours, for example, 8 hours. The particle size control method can be conventional in the art, such as grinding. The endpoint of particle size control is preferably that the material can pass through a 100-mesh sieve.

[0075] The sintering is preferably divided into a single-stage sintering and a two-stage sintering, wherein the temperature of the two-stage sintering is higher than that of the single-stage sintering.

[0076] The sintering temperature of the first stage is preferably 300-600℃, more preferably 400-500℃, for example 480℃. The sintering time of the first stage is preferably 1-4h, more preferably 2-3h, for example 2h. The heating rate from room temperature to the sintering temperature of the first stage is preferably 3-8℃ / min, more preferably 4-6℃ / min, for example 5℃ / min.

[0077] The preferred temperature for the second-stage sintering is 500-850℃, more preferably 650-750℃, for example 700℃. The preferred sintering time for the second stage is 5-10 hours, more preferably 7-9 hours, for example 8 hours. The heating rate from the temperature of the first-stage sintering to the temperature of the second-stage sintering is preferably 1-5℃ / min, more preferably 2-4℃ / min, for example 3℃ / min.

[0078] In a preferred embodiment, the cathode material is sodium iron manganese phosphate, and the preparation method of the cathode material includes the following steps: spray granulation and sintering of the precursor slurry; the precursor slurry includes a sodium source, a phosphorus source, an iron source, a manganese source, a carbon source, and a solvent.

[0079] The sodium source can be of a type conventional in the art, such as sodium carbonate. The phosphorus source can be of a type conventional in the art, such as ammonium dihydrogen phosphate. The iron source can be of a type conventional in the art, such as ferric oxide. The manganese source can be of a type conventional in the art, such as manganese dioxide. The solvent can be of a type conventional in the art, such as water. The molar ratio of the sodium, phosphorus, iron, and manganese sources, based on sodium, iron, manganese, and phosphorus elements, is preferably (1-9):(1-5):(0.01-0.1):(1-9), more preferably (3-5):(2-4):(0.01-0.03):(3-5), for example 4:2.98:0.01:4. The molar ratio of the carbon source to the iron and manganese sources, calculated by carbon, iron, and manganese elements, is preferably (0.2-1):(0.5-2), more preferably (0.3-0.7):(0.8-1.2), for example, 0.5:1. The solid content of the precursor slurry is preferably 30-60 wt%, more preferably 45-55 wt%, for example, 50 wt%.

[0080] The precursor slurry is preferably obtained by mixing a sodium source, a phosphorus source, an iron source, a manganese source, a carbon source, and a solvent, followed by sand milling. The sand milling speed is preferably 1400-2600 r / min, more preferably 1800-2200 r / min, for example, 2000 r / min. The sand milling time is preferably 3-10 h, more preferably 5-7 h, for example, 6 h.

[0081] The spray granulation temperature is preferably 180-300℃, more preferably 200-240℃, for example 250℃.

[0082] The sintering temperature can be 300-850℃, preferably 400-750℃, for example 480, 550, 700 or 720℃. The sintering time can be 1-20h, preferably 2-13h, for example 2, 7, 8, 10 or 12h. The heating rate from room temperature to the sintering temperature is preferably 1-10℃ / min, more preferably 2-6℃ / min, for example 3 or 5℃ / min.

[0083] In this invention, bisphenol compounds are selected as the carbon source for preparing the cathode material. Because bisphenol compounds contain at least two rigid benzene rings in their molecular structure, the presence of benzene rings significantly increases the residual carbon rate of the carbon source. Therefore, in the process of preparing the cathode material, the amount of carbon source added and the raw material cost of the cathode material can be significantly reduced. Moreover, as a rigid structure, benzene rings can easily generate ordered graphitized coated carbon on the surface of cathode material particles, thereby improving the conductivity and charge / discharge capacity of the battery obtained from the cathode material.

[0084] This invention provides a cathode material, which is prepared using the cathode material preparation method described above.

[0085] The present invention provides an electrode sheet comprising the positive electrode material as described above.

[0086] The present invention provides a battery comprising the electrodes as described above.

[0087] The positive and progressive effects of this invention are as follows: The cathode material prepared using the raw material composition of the cathode material of this application has a lower powder resistivity and a better compaction density; the battery made from the cathode material has better electrochemical performance, especially the first coulombic efficiency. Detailed Implementation

[0088] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0089] The structural formulas of the bisphenol compounds used in the following examples or comparative examples are as follows: 1. Bisphenol A polyoxyethylene (10) ether

[0090] 2. Bisphenol F polyoxyethylene (10) ether

[0091] 3. Bisphenol P polyoxyethylene (10) ether

[0092] 4. Bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether

[0093] 5. Bisphenol F polyoxyethylene (15) ether

[0094] 6. Bisphenol A polyoxyethylene (20) ether polyoxypropylene (8) ether

[0095] I. Preparation of Lithium Iron Phosphate Materials

[0096] Example 1

[0097] The raw material composition of the cathode material includes: bisphenol A polyoxyethylene (10) ether and glucose as carbon sources; iron phosphate, lithium carbonate and phosphoric acid aqueous solution as iron source, lithium source and phosphorus source respectively; titanium dioxide as metal dopant; wherein, the mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; and the mass percentage of bisphenol compounds in carbon source is 45.5%.

[0098] 995 parts of ferric phosphate, 226 parts of lithium carbonate, 6.73 parts of 85%wt phosphoric acid aqueous solution, 5.97 parts of titanium dioxide, 60 parts of glucose, and 50 parts of bisphenol A polyoxyethylene (10) ether were added to a sand mill (WSP-0.5 of Changzhou Longxin Intelligent Equipment Co., Ltd.) and water was added. The mixture was sand milled for 120 minutes to obtain a precursor slurry with a solid content of 40% and a particle size D50 of 370-380nm. The precursor slurry was spray-granulated in a spray granulation equipment (SP1500 from Shanghai Shunyi Experimental Equipment Co., Ltd.), with an inlet temperature of 220℃ and a material flow rate of 800ml / h. The spray-granulated powder was sintered (using a QLYF-4-1200 sintering equipment from Shanghai Jingzhao Machinery Equipment Co., Ltd.), with a heating rate of 3℃ / min to 720℃ and a holding time of 7h to obtain lithium iron phosphate material.

[0099] The obtained lithium iron phosphate material was crushed to a particle size of D50=1.2-1.3μm using a traditional Chinese medicine crusher (Teruisi traditional Chinese medicine pulverizer); the particle size was tested using a Malvern Panaco Mastersizer-3000 laser particle size analyzer.

[0100] Example 2

[0101] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol F polyoxyethylene (10) ether, and the amount added is 50 parts. The other steps are the same as in Example 1. Among them, the mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; the mass percentage of bisphenol compounds in the carbon source is 45.5%.

[0102] Example 3

[0103] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol P polyoxyethylene (10) ether, and the amount added is 50 parts. The other steps are the same as in Example 1. Among them, the mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; the mass percentage of bisphenol compounds in the carbon source is 45.5%.

[0104] Example 4

[0105] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether, and the amount added is 50 parts. Other steps are the same as in Example 1. Among them, the mass percentage of carbon source in the raw material composition of the positive electrode material is 8.2%; the mass percentage of bisphenol compounds in the carbon source is 45.5%.

[0106] Example 5

[0107] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol F polyoxyethylene (15) ether, and the amount added is 60 parts. Other steps are the same as in Example 1. The mass percentage of carbon source in the raw material composition of the cathode material is 8.9%; the mass percentage of bisphenol compounds in the carbon source is 50%.

[0108] Example 6

[0109] The only difference from Example 1 is that the bisphenol A polyoxyethylene (10) ether is replaced with bisphenol A polyoxyethylene (20) ether polyoxypropylene (8) ether, and the amount added is 40 parts. The other steps are the same as in Example 1. The mass percentage of carbon source in the raw material composition of the cathode material is 7.5%; the mass percentage of bisphenol compounds in the carbon source is 40%.

[0110] Example 7

[0111] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol A polyoxyethylene (10) ether, and the amount added is 30 parts. The other steps are the same as in Example 1. The mass percentage of carbon source in the raw material composition of the cathode material is 6.8%; the mass percentage of bisphenol compounds in the carbon source is 33.3%.

[0112] Example 8

[0113] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol A polyoxyethylene (10) ether, and the amount added is 80 parts. Other steps are the same as in Example 1. The mass percentage of carbon source in the raw material composition of the cathode material is 10.2%; the mass percentage of bisphenol compounds in the carbon source is 57.1%.

[0114] Example 8-1

[0115] The only difference from Example 4 is that glucose is not added, but only 110 parts of bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether are added, and the other steps are the same as in Example 4; the mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; the mass percentage of bisphenol compounds in the carbon source is 100%.

[0116] Example 8-2

[0117] The only difference from Example 1 is that 60 parts of glucose are replaced with 60 parts of PEG-200, and the other steps are the same as in Example 1; the mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; and the mass percentage of bisphenol compounds in the carbon source is 45.5%.

[0118] Comparative Example 1

[0119] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with polyethylene glycol PEG1500, and the amount added is 50 parts. Other steps are the same as in Example 1. The mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; the mass percentage of bisphenol compounds in the carbon source is 0%.

[0120] Comparative Example 2

[0121] The only difference from Example 1 is that bisphenol A polyoxyethylene (10) ether is replaced with polyethylene glycol PEG6000, and the amount added is 50 parts. The other steps are the same as in Example 1. The mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; the mass percentage of bisphenol compounds in the carbon source is 0%.

[0122] Comparative Example 3

[0123] The only difference from Example 4 is that only 110 parts of glucose are added, and no bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether is added. The other steps are the same as in Example 4. The mass percentage of carbon source in the raw material composition of the cathode material is 8.2%; the mass percentage of bisphenol compounds in the carbon source is 0%.

[0124] II. Preparation of Lithium Manganese Iron Phosphate Materials

[0125] Example 9

[0126] The raw material composition of the cathode material includes: bisphenol A polyoxyethylene (10) ether and glucose as carbon sources; lithium carbonate, manganese acetate, ferrous oxalate and phosphoric acid as lithium source, manganese source, iron source and phosphorus source, respectively; the mass percentage of carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 55.6%.

[0127] 350 parts lithium carbonate, 1250 parts manganese acetate, 9 parts ferrous oxalate, 40 parts glucose, 50 parts bisphenol A polyoxyethylene (10) ether, 12 parts phosphoric acid, and 1000 parts anhydrous ethanol were added to an agate ball mill jar and ball-milled for 4 hours at a ball-to-material ratio of 8:1 at a speed of 280 r / min to obtain the precursor slurry. The obtained precursor slurry was transferred to an evaporating dish and vacuum dried at 55°C for 8 hours. After grinding through a 100-mesh sieve, it was placed in a tube furnace and argon gas was introduced at a flow rate of 50 mL / min for 30 minutes. The temperature was first increased to 480°C at a rate of 5°C / min and held for 2 hours. Then, the temperature was increased to 700°C at a rate of 3°C / min and held for 8 hours. After sintering, the argon atmosphere was maintained and the mixture was allowed to cool naturally to room temperature. The mixture was then ground in an agate mortar and passed through a 200-mesh sieve to obtain lithium manganese iron phosphate material.

[0128] Example 10

[0129] The only difference from Example 9 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol F polyoxyethylene (10) ether, and the amount added is 50 parts; the mass percentage of carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 55.6%.

[0130] Example 11

[0131] The only difference from Example 9 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol P polyoxyethylene (10) ether, and the amount added is 50 parts; the mass percentage of carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 55.6%.

[0132] Example 12

[0133] The only difference from Example 9 is that: bisphenol A polyoxyethylene (10) ether is replaced with bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether, and the amount added is 50 parts; the mass percentage of carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 55.6%.

[0134] Example 13

[0135] The only difference from Example 9 is that: bisphenol A polyoxyethylene (10) ether is replaced with bisphenol F polyoxyethylene (15) ether, and the amount added is 60 parts; the mass percentage of carbon source in the raw material composition of the cathode material is 5.8%; the mass percentage of carbon source in the raw material composition of the cathode material is 5.8%; and the mass percentage of bisphenol compounds in the carbon source is 60%.

[0136] Example 14

[0137] The only difference from Example 9 is that: bisphenol A polyoxyethylene (10) ether is replaced with bisphenol A polyoxyethylene (20) ether polyoxypropylene (8) ether, and the amount added is 40 parts; the mass percentage of carbon source in the raw material composition of the cathode material is 4.7%; and the mass percentage of bisphenol compounds in the carbon source is 50%.

[0138] Example 15

[0139] The only difference from Example 9 is that: the amount of bisphenol A polyoxyethylene (10) ether added is 20 parts; the mass percentage of carbon source in the raw material composition of the cathode material is 3.6%; and the mass percentage of bisphenol compounds in the carbon source is 33.3%.

[0140] Example 16

[0141] The only difference from Example 9 is that: 70 parts of bisphenol A polyoxyethylene (10) ether were added; the mass percentage of carbon source in the raw material composition of the cathode material was 6.4%; and the mass percentage of bisphenol compounds in the carbon source was 63.6%.

[0142] Example 16-1

[0143] The only difference from Example 9 is that glucose is not added, but only 90 parts of bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether are added; the mass percentage of carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 100%.

[0144] Example 16-2

[0145] The only difference from Example 9 is that 40 parts of glucose are replaced with 40 parts of PEG-200; the mass percentage of carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 55.6%.

[0146] Comparative Example 6

[0147] The only difference from Example 9 is that: polyethylene glycol PEG1500 is used as the carbon source, and the amount added is 50 parts; the mass percentage of the carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 0%.

[0148] Comparative Example 7

[0149] The only difference from Example 9 is that: polyethylene glycol PEG6000 is used as the carbon source, and the amount added is 50 parts; the mass percentage of the carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 0%.

[0150] Comparative Example 8

[0151] The only difference from Example 12 is that only 90 parts of glucose are added, and no bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether is added; the mass percentage of carbon source in the raw material composition of the cathode material is 5.3%; and the mass percentage of bisphenol compounds in the carbon source is 0%.

[0152] III. Preparation of Sodium Iron Manganese Phosphate Cathode Material for Sodium-Ion Batteries

[0153] Example 17

[0154] The raw material composition of the positive electrode material includes: bisphenol A polyoxyethylene (10) ether and glucose as carbon sources; sodium carbonate, ammonium dihydrogen phosphate, ferric oxide and manganese dioxide as sodium source, phosphorus source, iron source and manganese source, respectively; the mass percentage of carbon source in the raw material composition of the positive electrode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 50%.

[0155] Glucose and bisphenol A polyoxyethylene (10) ether were mixed in a mass ratio of 1:1 as a carbon source. The molar ratio of sodium, iron, manganese and phosphorus in the raw materials was controlled to be 4:2.98:0.01:4, and the ratio of the molar amount of carbon source (calculated as carbon) to the sum of the molar amounts of iron and manganese was 0.5:1. The raw materials and water were put into a sand mill and ground at a speed of 2000 r / min for 6 h to obtain a precursor slurry with a solid content of 50 wt% during grinding. The precursor slurry was prepared into a dry precursor powder at 250 °C using a spray drying method. The precursor powder was placed in a box furnace and sintered at 550 °C for 12 h under a N2 atmosphere and then naturally cooled to obtain sodium iron manganese sodium phosphate cathode material for sodium-ion batteries.

[0156] Example 18

[0157] The only difference from Example 17 is that bisphenol A polyoxyethylene (10) ether is replaced with bisphenol F polyoxyethylene (10) ether; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 50%.

[0158] Example 19

[0159] The only difference from Example 17 is that: bisphenol A polyoxyethylene (10) ether is replaced with bisphenol P polyoxyethylene (10) ether; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 50%.

[0160] Example 20

[0161] The only difference from Example 17 is that: bisphenol A polyoxyethylene (10) ether is replaced with bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 50%.

[0162] Example 21

[0163] The only difference from Example 20 is that glucose is not added, but only bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether is added; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 100%.

[0164] Example 22

[0165] The only difference from Example 17 is that glucose is replaced with PEG-200; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 50%.

[0166] Comparative Example 11

[0167] The only difference from Example 17 is that: bisphenol A polyoxyethylene (10) ether is replaced with polyethylene glycol PEG1500; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 0%.

[0168] Comparative Example 12

[0169] The only difference from Example 17 is that: bisphenol A polyoxyethylene (10) ether is replaced with polyethylene glycol PEG6000; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 0%.

[0170] Comparative Example 13

[0171] The only difference from Example 20 is that only glucose is added, and bisphenol A polyoxyethylene (10) ether polyoxypropylene (8) ether is not added; the mass percentage of carbon source in the raw material composition of the cathode material is 12%; and the mass percentage of bisphenol compounds in the carbon source is 0%.

[0172] Example 1

[0173] 1. The residual carbon content of the lithium iron phosphate materials prepared in the examples and comparative examples was tested using a Shanghai Dekai HCS-140 high-frequency infrared carbon-sulfur analyzer.

[0174] 2. The powder resistivity and compaction density of lithium iron phosphate materials prepared in the examples and comparative examples were tested using Xiamen Yuaneng four-probe powder resistivity PRCD2110.

[0175] The test results are shown in Table 1.

[0176] 3. The powder conductivity of lithium manganese iron phosphate materials prepared in the examples and comparative examples was tested using Xiamen Yuanneng four-probe powder resistivity PRCD2110.

[0177] The test results are shown in Table 2.

[0178] Example 2

[0179] 1. Batteries prepared using lithium iron phosphate as the positive electrode active material

[0180] The crushed lithium iron phosphate material (LiFePO4) obtained in the above examples and comparative examples was mixed with the above raw materials in a mass ratio of LiFePO4:conductive carbon black:polyvinylidene fluoride (PVDF) = 8:1:1. N-methylpyrrolidone was added to prepare a positive electrode slurry with a solid content of 55%. This slurry was uniformly coated onto carbon-coated aluminum foil, vacuum dried, rolled, and punched into a 2.01 cm² area. 2 Electrode assembly. The negative electrode uses a lithium metal sheet, the separator uses Celgard 2400PE film, and the electrolyte uses a commercially available product (SS-SHRG004, Dongguan Shanshan Battery Materials Co., Ltd.). The positive electrode, separator, and negative electrode are assembled in one go in a glove box (high-purity Ar atmosphere), and then the electrolyte (1 mol / L NaClO4 + EC:DMC:EMC(1:1:1) + 5% FEC) is injected to obtain a coin cell.

[0181] The coin cell was subjected to constant current charge-discharge cycle test at 25℃ and 0.1C, with a charge-discharge voltage of 2.0-3.7V. The initial coulombic efficiency was calculated. There was no special test method. The initial coulombic efficiency = initial discharge specific capacity / initial charge specific capacity. The coin cell battery was tested for rate capability at 25℃ and 2C. The test results are shown in Table 1.

[0182] As can be seen from the test results in Table 1, compared with the lithium iron phosphate material prepared using bisphenol compounds as a carbon source in Examples 1-8 and Examples 8-1 to 8-2, the lithium iron phosphate materials prepared using bisphenol compounds as a carbon source in Examples 1-8 and Examples 8-1 to 8-2, under the same residual carbon content, have significantly lower powder resistivity, higher compaction density, and significantly improved initial discharge capacity, initial coulombic efficiency, and 2C rate performance of the prepared coin cells. This indicates that the lithium iron phosphate materials prepared using bisphenol compounds as a carbon source in Examples 1-8 and Examples 8-1 to 8-2 have excellent coin cell performance.

[0183] Comparing Example 1 with Examples 7-8, it is shown that there is an optimal range for the amount of bisphenol compound added. When the amount of bisphenol compound added is too low, the resulting lithium iron phosphate material cannot build a complete and stable conductive and bonding network, resulting in a significant decrease in the electrochemical performance of the resulting coin cell. When the amount of bisphenol compound added is too high, the carbon layer of the resulting lithium iron phosphate material is too thick, which increases the electron transport path between the active material particles and the carbon layer and increases the interfacial resistance, resulting in a significant decrease in the electrochemical performance of the resulting battery.

[0184] Comparing Comparative Examples 1-2 and Examples 1-4, it is evident that, with the same total carbon source content, lithium iron phosphate materials prepared using bisphenol compounds as carbon sources have a significant advantage over those prepared using PEG compounds. This demonstrates that the molecular structure of the carbon source has a substantial impact on the electrical performance of the batteries assembled from the prepared lithium iron phosphate materials; a higher benzene ring structure slightly increases the residual carbon content and results in slightly higher initial charge-discharge efficiency. The bisphenol compounds in Examples 1-4 have structures suitable for a reasonable design that balances amorphous and rigid components, leading to lithium iron phosphate materials prepared using them that show a significant advantage over the comparative examples. Comparing Examples 8-2 and Example 1, replacing glucose with PEG-200 resulted in a significant increase in the powder resistivity of the obtained lithium iron phosphate material, and a significant decrease in the initial discharge capacity, initial coulombic efficiency, and rate performance of the prepared batteries. This indicates that bisphenol compounds and glucose have a better synergistic effect compared to bisphenol compounds and PEG-200.

[0185] Compared with Example 1, Comparative Example 3 did not contain bisphenol compounds and lacked a rigid structural framework such as a benzene ring; thus affecting the initial discharge capacity and initial coulombic efficiency of the resulting coin cell.

[0186] Table 1

[0187] 2. Batteries prepared using lithium manganese iron phosphate as the positive electrode active material.

[0188] 85g of lithium manganese iron phosphate material, 5g of polyvinylidene fluoride, 10g of conductive carbon black, and 150mL of N-methylpyrrolidone prepared in the above examples and comparative examples were placed in a beaker and mechanically stirred at 500r / min for 4h to form a slurry. The slurry was coated onto aluminum foil with a single-sided thickness of 80μm using a doctor blade coater. The foil was first pre-dried in a 60℃ forced-air drying oven for 30min, and then transferred to a 120℃ vacuum drying oven for 12h. The dried electrode was compacted using a roller press with a pressure controlled at 110MPa and cut into electrode sheets with a diameter of 14mm to obtain the positive electrode. Using lithium foil as the negative electrode and a Celgard 2400 polypropylene microporous membrane as the separator, and 1 mol / L LiPF6 (EC:DEC = 1:1, v / v) as the electrolyte, the positive electrode, negative electrode, separator, and electrolyte were assembled in an argon glove box with water and oxygen content all below 1 ppm. After assembly, the cells were allowed to stand for 24 hours to obtain coin cells. The discharge specific capacity at 0.1C and 5C rates was tested under charge / discharge cutoff voltages of 3.0-4.3V; the capacity retention rate after 100 cycles at 5C charge / discharge rate was also tested. The results are shown in Table 2.

[0189] As can be seen from the test results in Table 2, compared with the battery assembled using lithium manganese iron phosphate material prepared with conventional carbon source PEG, the coin cells assembled using lithium manganese iron phosphate material prepared with bisphenol compounds as carbon source in Examples 1-6 have a higher capacity retention rate.

[0190] Table 2

[0191] Comparing Examples 9, 15, and 16, it is shown that there is an optimal range for the amount of bisphenol compound added. When the amount of bisphenol compound added is too low, the resulting lithium manganese iron phosphate material cannot better construct a complete and stable conductive and bonding network, resulting in a significant decrease in the electrochemical performance of the resulting battery. When the amount of bisphenol compound added is too high, the thickness of the carbon layer of the resulting lithium manganese iron phosphate material increases, which lengthens the electron transport path between the active material particles and the carbon layer and increases the interfacial resistance, resulting in a significant decrease in the electrochemical performance of the resulting battery.

[0192] Comparing Comparative Examples 6-7 and Examples 9-12, it is evident that, with the same amount of bisphenol compounds, lithium manganese iron phosphate (LFP) materials prepared using bisphenol compounds as a carbon source have a significant advantage over LFP materials prepared using PEG-based carbon sources. It is clear that the molecular structure of the carbon source has a significant impact on the electrical performance of batteries assembled from the prepared LFP materials; a higher benzene ring structure slightly increases the residual carbon content and results in slightly higher initial charge-discharge efficiency. The bisphenol compounds in Examples 9-12 have structures suitable for a reasonable design that balances amorphous and rigid components, resulting in batteries assembled from the obtained LFP materials that show a significant advantage over the comparative examples. Comparing Examples 16-2 and Example 9, replacing glucose with PEG-200 significantly reduces the discharge specific capacity and capacity retention of batteries made from the obtained LFP materials. This indicates that bisphenol compounds and glucose have a better synergistic effect compared to bisphenol compounds and PEG-200.

[0193] Compared with Example 9, Comparative Example 8 did not contain bisphenol compounds and lacked a rigid structural framework such as benzene rings. As a result, the discharge specific capacity and capacity retention of the battery made from the lithium manganese iron phosphate material were significantly reduced.

[0194] 3. Batteries prepared using sodium iron manganese phosphate (sodium iron manganese phosphate) as the positive electrode active material for sodium-ion batteries.

[0195] The sodium-ion batteries prepared in the above examples and comparative examples were uniformly mixed with sodium iron manganese phosphate positive electrode material, acetylene black, and PVDF binder, and then coated onto aluminum foil. After vacuum baking at 100°C for 4 hours, electrode sheets were obtained. Based on the total weight of the positive electrode material, acetylene black, and PVDF binder, the amount of positive electrode material was 80 wt%, the amount of acetylene black was 10 wt%, and the amount of PVDF binder was 10 wt%. Using the sodium sheet as the negative electrode, a glass fiber optic GF / A Whatman potassium sodium lithium battery filter membrane was used as the separator, and a 0.8 M NaPF6 / EC-DMC electrolyte was used. Button batteries were assembled and their charge-discharge characteristics were tested. The charge-discharge current was 0.1C, where 1C = 129 mA / g. The discharge specific capacity and average discharge voltage of the comparative and examples are shown in Table 3.

[0196] As can be seen from the test results in Table 3, compared with the sodium iron manganese phosphate cathode material for sodium-ion batteries prepared using conventional carbon source PEG, the batteries prepared using sodium iron manganese phosphate cathode material for sodium-ion batteries prepared using bisphenol compounds as carbon source in Examples 17-20 have higher specific capacity and capacity retention.

[0197] Comparing Comparative Examples 11-12 and Examples 17-20, it is evident that, with the same amount of bisphenol compounds, sodium iron manganese phosphate (SMP) cathode materials for sodium-ion batteries prepared using bisphenol compounds as a carbon source have significant advantages over those prepared using PEG-based carbon sources. This demonstrates that the molecular structure of the carbon source has a significant impact on the electrical performance of batteries assembled from the prepared SMP cathode materials; a higher number of benzene ring structures improves specific capacity and capacity retention. The bisphenol compounds in Examples 17-20 have structures suitable for a reasonable ratio design balancing amorphous and rigid forms, resulting in batteries with significantly better performance than the comparative examples. Comparing Examples 22 and 17, replacing glucose with PEG-200 significantly reduces the specific capacity and capacity retention of batteries made from the prepared SMP cathode materials. This indicates that bisphenol compounds and glucose have a better synergistic effect compared to bisphenol compounds and PEG-200.

[0198] Table 3

[0199] Compared with Example 17, Comparative Example 13 did not add a bisphenol carbon source and lacked a rigid structural framework such as a benzene ring, which resulted in a significant decrease in the specific capacity and capacity retention of the battery obtained by the sodium iron manganese phosphate cathode material for sodium-ion batteries.

[0200] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A raw material composition for a positive electrode material, characterized in that, It includes a carbon source; the carbon source includes bisphenol compounds; The molecular structural formula of the bisphenol compound is shown in Formula I below: Equation I; Wherein, R is one or more of alkyl, sulfonyl, aryl, alicyclic, halogenated and thioether groups; Wherein, R3, R4, R5 and R6 are each independently selected from -H, alkyl, halogroup or phenyl; Wherein, R7 and R8 are each independently selected from -H, straight-chain or branched C1-10 alkyl groups; The structural formula of M1 is shown in equation (I-1): Formula I-1; R9, R 10 Each is independently selected from -H and / or alkyl; the values ​​of n1 and n2 are each independently 0-5000, and n1+n2≠0; The structural formula of M2 is shown in equation (I-2): Formula I-2; the R 11 R 12 Each is independently selected from -H and / or alkyl groups; the values ​​of n3 and n4 are each independently 0-5000, and n3+n4≠0.

2. The raw material composition for the positive electrode material as described in claim 1, characterized in that, The raw material composition of the cathode material satisfies one or more of the following conditions: (1) The carbon source also includes one or more of sucrose, glucose, polyethylene glycol, starch, citric acid and asphalt; (2) The mass percentage of the carbon source is 3%-15%; the mass percentage represents the mass percentage of the carbon source in the composition of the cathode raw material; (3) The bisphenol compounds account for 25%-100% of the mass percentage of the carbon source; (4) The positive electrode material is lithium iron phosphate, lithium manganese iron phosphate or sodium iron manganese phosphate.

3. The raw material composition for the positive electrode material as described in claim 1, characterized in that, The raw material composition of the cathode material satisfies any one of the following conditions: In the molecular structural formula of the bisphenol compound, R is -C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H. The structural formula of M1 is... R9 is selected from -H, n1 is 5, n2 is 0; the structural formula of M2 is R 11 Selected from -H, n3 is 5, n4 is 0; Alternatively, in the molecular structural formula of the bisphenol compound, R is -CH2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H, and the structural formula of M1 is... R9 is selected from -H, n1 is 5, n2 is 0; the structural formula of M2 is R 11 Selected from -H, n3 is 5, n4 is 0; Alternatively, in the molecular structural formula of the bisphenol compound, R is -C(CH3)2-C6H4-C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H, and the structural formula of M1 is... R9 is selected from -H, n1 is 5, n2 is 0; the structural formula of M2 is R 11 Selected from -H, n3 is 5, n4 is 0; Alternatively, in the molecular structural formula of the bisphenol compound, R is -C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H, and the structural formula of M1 is... R9 is selected from -CH3, R 10 Selected from -H, n1 is 4, n2 is 5; the structural formula of M2 is R 11 Selected from -H,R 12 Selected from -CH3, n3 is 5, n4 is 4; Alternatively, in the molecular structural formula of the bisphenol compound, R is -CH2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H, and the structural formula of M1 is... R9 is selected from -H, n1 is 7.5, and n2 is 0; the structural formula of M2 is R 11 Selected from -H, n3 is 7.5, n4 is 0; Alternatively, in the molecular structural formula of the bisphenol compound, R is -C(CH3)2-, and R3, R4, R5, R6, R7, and R8 are all selected from -H, and the structural formula of M1 is... R9 is selected from -CH3, R 10 Selected from -H, n1 is 4, n2 is 10; the structural formula of M2 is R 11 Selected from -H,R 12 Selected from -CH3, n3 is 10, n4 is 4.

4. The raw material composition for the positive electrode material as described in claim 1, characterized in that, The raw material composition of the cathode material satisfies one or more of the following conditions: (1) The carbon source includes glucose and the bisphenol compound, wherein the mass ratio of glucose to the bisphenol compound is (0.5-8):1; Alternatively, the carbon source may include polyethylene glycol and the bisphenol compound, wherein the mass ratio of polyethylene glycol to the bisphenol compound is (0.5-5):1; (2) The mass percentage of the carbon source is 3.5%-12%; (3) The bisphenol compounds account for 30%-100% of the mass percentage of the carbon source.

5. A method for preparing a positive electrode material, characterized in that, It includes the following steps: sintering the precursor slurry to obtain the cathode material; the precursor slurry includes the raw material composition of the cathode material as described in any one of claims 1-4.

6. The method for preparing the cathode material as described in claim 5, characterized in that, The method for preparing the cathode material satisfies one or more of the following conditions: (1) The sintering temperature is 300-850℃; (2) The sintering time is 1-20 hours; (3) The heating rate from room temperature to the sintering temperature is 1-10℃ / min; (4) The sintering is divided into a first-stage sintering and a second-stage sintering, and the temperature of the second-stage sintering is higher than that of the first-stage sintering.

7. A positive electrode material, characterized in that, It is prepared using the method for preparing the positive electrode material as described in claim 5 or 6.

8. An electrode sheet, characterized in that, It includes the cathode material as described in claim 7.

9. A battery, characterized in that, It includes the electrode as described in claim 8.

Images