Positive electrode material, secondary battery and electrical equipment

Abstract

The present application discloses a positive electrode material, a secondary battery and an electric device. The positive electrode material of the present application comprises a ternary positive electrode material and a conductive network distributed inside the ternary positive electrode material: LiNi x Mn y Co 1‑x‑y O 2 , wherein the value range of x is 0.6-0.8, the value range of y is 0.1-0.3; the conductive network includes carbonized alginate groups and metal cations. This application constructs a conductive network inside the ternary positive electrode material, effectively improves the conductivity of the ternary material without affecting the overall energy density of the battery, reduces the impact of polarization on the material, improves the rate performance, and alleviates the problem of excessive temperature rise during battery use.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a positive electrode material, a secondary battery and an electrical device. Background Art

[0002] Ternary cathode materials, such as layered ternary nickel-cobalt-manganese oxide materials, have high theoretical specific capacity, compaction density, and operating voltage, and are widely used in lithium-ion batteries. Ternary materials are prone to polarization during use, resulting in poor rate performance and increased temperature rise, which will seriously affect the battery's service life and safety performance in the long run. Summary of the invention

[0003] The purpose of the present application is to provide a positive electrode material, a secondary battery and an electrical device. The present application can solve the above technical problems by constructing a conductive network inside the ternary positive electrode material.

[0004] The embodiment of the present application provides a positive electrode material, including a ternary positive electrode material and a conductive network distributed inside the ternary positive electrode material;

[0005] The chemical formula of the ternary cathode material is: LiNi x Mn y Co 1-x-y O2, where the value range of x is 0.6 to 0.8, and the value range of y is 0.1 to 0.3;

[0006] The conductive network includes carbonized alginate groups and metal cations.

[0007] In some embodiments, the mass ratio of the conductive network to the ternary positive electrode material is 1:80 to 1:100.

[0008] In some embodiments, the metal cations include Ni, Mn, and Co.

[0009] In some embodiments, the porosity of the precursor for preparing the ternary cathode material is 0.1-0.15%.

[0010] In some embodiments, the molecular weight of the alginate group is 80-100 KDa.

[0011] The embodiment of the present application provides a method for preparing a positive electrode material, comprising the following steps:

[0012] preparing a ternary cathode material precursor, and etching the obtained ternary cathode material precursor;

[0013] The etched ternary cathode material precursor is mixed with a sodium alginate solution and dried, and the obtained product is mixed with a lithium source and then calcined to obtain the cathode material.

[0014] In some embodiments, the precursor of the ternary cathode material is prepared by the following method: co-precipitating a metal salt containing a nickel source, a cobalt source, and a manganese source under alkaline conditions to obtain a ternary cathode material precursor.

[0015] In some embodiments, the etching method is: etching using a first acid solution with a concentration of 0.05 to 0.5 mol / L.

[0016] In some embodiments, the etching temperature is 30-50°C.

[0017] In some embodiments, the etching time is 30 minutes to 1 hour.

[0018] In some embodiments, the first acid solution is selected from one or more of hydrochloric acid, oxalic acid, citric acid, and benzenesulfonic acid.

[0019] In some embodiments, ultrasonic treatment with a power of 500W to 5000W is applied during the etching process.

[0020] In some embodiments, the sodium alginate solution chelates with metal cations in the presence of a second acid solution.

[0021] In some embodiments, the concentration of the second acid solution is 1-3 mol / L.

[0022] In some embodiments, the second acid solution is selected from one or more of hydrochloric acid, oxalic acid, citric acid, and benzenesulfonic acid.

[0023] In some embodiments, the calcination temperature is 600-800° C.; the calcination time is 5-8 hours.

[0024] Correspondingly, an embodiment of the present application further provides a secondary battery, comprising the above-mentioned positive electrode material or the positive electrode material prepared by the above-mentioned preparation method.

[0025] Correspondingly, an embodiment of the present application further provides an electrical device, comprising the above-mentioned secondary battery.

[0026] The beneficial effect of the present application is that compared with the prior art, the present application provides a positive electrode material, a secondary battery and an electrical device. The positive electrode material of the present application includes a ternary positive electrode material and a conductive network distributed inside the ternary positive electrode material; the chemical formula of the ternary positive electrode material is: LiNi x Mn y Co 1-x-yO2, wherein the value range of x is 0.6-0.8, and the value range of y is 0.1-0.3; the conductive network includes carbonized alginate groups and metal cations. This application constructs a conductive network inside the ternary positive electrode material, which effectively improves the conductivity of the ternary material without affecting the overall energy density of the battery, reduces the impact of polarization on the material, improves the rate performance, and alleviates the problem of excessive temperature rise during battery use. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application. In addition, in the description of the present application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels, and no numerical requirements or order are imposed. Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and simplicity, and should not be understood as a hard limit to the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered range, such as 1, 2, 3, 4, 5 and 6, which are applicable regardless of the range. Additionally, whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range.

[0028] In order to improve the conductivity of ternary materials, inhibit polarization, improve rate performance, and reduce temperature rise, common material improvements are coating or doping modification. Although coating can improve polarization to a certain extent, it is difficult to achieve uniformity of the coating, so there will be free coating substances, which will affect the performance of the product; at the same time, the coating material does not exert its capacity, reducing the overall energy density of the battery. Commonly used elements for doping modification include Al, Ti, B, Cr, etc. The doped elements can broaden the lithium ion migration channel to a certain extent and improve the rate performance, but it will also affect the overall energy density. In order to solve the above problems, the embodiment of the present application provides a positive electrode material, including a ternary positive electrode material and a conductive network distributed inside the ternary positive electrode material; the chemical formula of the ternary positive electrode material is: LiNi x Mn y Co 1-x-yO2, wherein the value range of x is 0.6-0.8, and the value range of y is 0.1-0.3; the conductive network includes carbonized alginate groups and metal cations. This application effectively improves the conductivity of the ternary material, reduces the influence of polarization on the material, improves the rate performance, and alleviates the problem of excessive temperature rise during battery use by constructing an efficient conductive network inside the ternary positive electrode material without significantly affecting the overall energy density of the battery.

[0029] In some embodiments, the value of x is any value among 0.6, 0.7, 0.8, or a range consisting of any two values.

[0030] In some embodiments, the value of y is any value among 0.1, 0.2, 0.3, or a range consisting of any two values.

[0031] In some embodiments, the mass ratio of the conductive network to the ternary positive electrode material is 1:80 to 1:100.

[0032] In some embodiments, the mass ratio of the conductive network to the ternary positive electrode material can be any value among 1:80, 1:90, 1:100, or a range of any two values.

[0033] In some embodiments, the metal cations include Ni, Mn, and Co.

[0034] In some embodiments, the porosity of the precursor for preparing the ternary cathode material is 0.1-0.15%. The present application constructs a precursor with a porosity of 0.1-0.15%, provides a space for the conductive network to attach, and allows the alginate base to form an interconnected polymer chain, surround the precursor of the ternary cathode material, and form a uniformly distributed conductive network after calcination.

[0035] In some embodiments, porosity is measured by nitrogen adsorption-desorption.

[0036] In some embodiments, the molecular weight of the alginate group is 80-100KDa. The present application selects sodium alginate within this range to construct a conductive network well. When the molecular weight of the sodium alginate is too large, it causes the precursor to be difficult to disperse in the skeleton constructed by the sodium alginate. If the molecular weight of the sodium alginate is too small, the interconnected network formed is not sufficient. In some embodiments, the molecular weight (KDa) of the alginate group is any value of 80, 85, 90, 95, 100 or a range consisting of any two values.

[0037] The present application provides a method for preparing the above-mentioned positive electrode material, comprising the following steps:

[0038] preparing a ternary cathode material precursor, and etching the obtained ternary cathode material precursor;

[0039] The etched ternary cathode material precursor is mixed with a sodium alginate solution and dried, and the obtained product is mixed with a lithium source and then calcined to obtain the cathode material.

[0040] In the present application, a ternary positive electrode material precursor is etched, sodium alginate is ion exchanged with the ternary positive electrode material precursor to obtain a polymer cross-linked structure, and a ternary positive electrode material precursor surrounded by a polymer chain is formed. The precursor is calcined with a lithium source at a high temperature to obtain a ternary positive electrode material having an efficient conductive network therein.

[0041] In some embodiments, the precursor of the ternary cathode material is prepared by the following method: co-precipitating a metal salt containing a nickel source, a cobalt source, and a manganese source under alkaline conditions to obtain the ternary cathode material precursor.

[0042] In some embodiments, a coprecipitation method is used to prepare a precursor of a ternary positive electrode material. Taking a nickel-cobalt-manganese hydroxide precursor as an example, nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate hexahydrate are added to water in appropriate amounts to dissolve all three to obtain a mixed metal salt solution. Subsequently, sodium hydroxide powder is added, and an ammonia solution is added dropwise to adjust the pH of the solution to 11. The reaction is stirred continuously for 10 to 15 hours at a stirring speed of 800 to 1000 r / min. The reaction temperature is maintained at a constant 55 to 60°C. After the reaction is completed, the product is filtered, washed with water and dried to obtain a ternary positive electrode material precursor.

[0043] In some embodiments, the etching method is: etching with a first acid solution having a concentration of 0.05 to 0.5 mol / L. When the concentration of the first acid solution is too high, it will cause excessive dissolution of the precursor, resulting in a large loss of the precursor during the preparation process; when the concentration of the first acid solution is too low, it will not be sufficiently etched, and an interconnected porous structure cannot be effectively formed. In some embodiments, the concentration of the first acid solution (in mol / L) is any value of 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, or a range consisting of any two values.

[0044] In some embodiments, the etching temperature is 30-50° C., such as the etching temperature (in ° C.) is any value of 30, 35, 40, 45, 50, or a range consisting of any two values.

[0045] In some embodiments, the etching time is 10 min to 1 h, such as the etching time is any value of 10 min, 30 min, 1 h, or a range consisting of any two values.

[0046] In some embodiments, the first acid solution is selected from one or more of hydrochloric acid, oxalic acid, citric acid, and benzenesulfonic acid.

[0047] In some embodiments, ultrasonic treatment with a power of 500 W to 5000 W is applied during the etching process, such as the applied power (in W) is any value of 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, or a range consisting of any two values.

[0048] In some embodiments, the ternary cathode material precursor is etched by the following method: adding the ternary cathode material precursor powder to a 0.05-0.5 mol / L hydrochloric acid solution, stirring to mix it evenly, ultrasonically treating the mixed solution for 10 min to 1 h to perform an etching process, then filtering and separating the product, washing it with clean water, and drying it to obtain a loose porous precursor.

[0049] In some embodiments, the sodium alginate solution is chelated with cations in the presence of a second acid solution.

[0050] In some embodiments, the concentration of the second acid solution is 1 to 3 mol / L. The present application dissociates the metal cations by adding the second acid solution and then reacts with the sodium alginate to form a chelate reaction. When the concentration of the second acid solution is too high, the precursor will be excessively dissolved, resulting in excessive pores, and when the concentration of the second acid solution is too low, the chelate reaction cannot be fully carried out. In some embodiments, the concentration of the second acid solution (in mol / L) is any value of 1, 1.5, 2, 2.5, 3, or a range consisting of any two values.

[0051] In some embodiments, the second acid solution is selected from one or more of hydrochloric acid, oxalic acid, citric acid, and benzenesulfonic acid.

[0052] In some embodiments, the chelation time is 10 min to 1 h, such as the chelation time is any value of 10 min, 30 min, 1 h, or a range consisting of any two values.

[0053] In some embodiments, the chelated product is further freeze-dried to effectively strengthen and preserve the polymer chain structure.

[0054] In some embodiments, the calcination temperature is 600-800°C; the calcination time is 5-8h. For example, the calcination temperature (°C) is any value among 600, 650, 700, 750, 800, or a range value consisting of any two values. For example, the calcination time (h) is any value among 5, 6, 7, 8, or a range value consisting of any two values.

[0055] In some embodiments, the conductive network is constructed by the following method: adding sodium alginate powder with a molecular weight of 80 to 100 kDa to water, heating and stirring in a water bath at 45 to 50°C to completely dissolve it, adding the aforementioned sodium alginate solution to the etched loose porous precursor, and pouring into a 1 to 3 mol / L hydrochloric acid solution, reacting at room temperature for 10 min to 1 h, assisted by slight slow stirring, and then centrifuging and washing the product with water, freeze-drying it in a freeze dryer, and evenly premixing the freeze-dried powder product with lithium hydroxide powder in a high-speed mixer, and calcining it at 600 to 800°C in an oxygen atmosphere for 5 to 8 hours to obtain a ternary positive electrode material containing an interconnected and efficient conductive network.

[0056] The embodiments of the present application also provide a secondary battery, comprising the above-mentioned positive electrode material or the positive electrode material prepared by the above-mentioned preparation method.

[0057] The secondary battery provided in the embodiment of the present application includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. In specific implementation, the positive electrode sheet, the negative electrode sheet, the separator and the electrolyte are assembled into a secondary battery.

[0058] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and the positive electrode active material layer includes the above-mentioned positive electrode material, a conductive agent, and a binder. In specific implementation, the above-mentioned positive electrode material, the conductive agent, the binder, and the solvent are uniformly stirred, and the positive electrode sheet is made through the processes of screening, coating, rolling, slitting, and cutting.

[0059] There is no limitation on the type of conductive agent, and any known conductive agent can be used. Examples of conductive agents may include, but are not limited to, one or more of the following: natural graphite, artificial graphite, Super P conductive carbon black, acetylene black, needle coke, carbon nanotubes, graphene and other carbon materials. The above positive electrode conductive agents can be used alone or in any combination.

[0060] The type of binder used in the manufacture of the positive electrode active material layer is not particularly limited. In the case of the coating method, it can be any material that is soluble or dispersible in the liquid medium used in the manufacture of the electrode. The binder includes, but is not limited to, one or more of the following: polyethylene, polypropylene, polyvinylidene fluoride (PVDF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, etc. The above binders can be used alone or in any combination.

[0061] There is no restriction on the type of solvent used to form the positive electrode slurry, as long as it is a solvent that can dissolve or disperse the positive electrode active material, the conductive agent, and the binder. The solvent used to form the positive electrode slurry includes any one of an aqueous solvent and an organic solvent. Aqueous solvents include, but are not limited to, water, a mixed medium of alcohol and water, etc. Organic solvents include, but are not limited to, hexane, benzene, toluene, xylene, pyridine, acetone, tetrahydrofuran (THF), N-methylpyrrolidone (NMP), etc.

[0062] The negative electrode material used in the negative electrode plate can be one or more of artificial graphite, natural graphite, mesophase carbon microbeads, and amorphous carbon.

[0063] An embodiment of the present application further provides an electrical device, comprising the above-mentioned secondary battery.

[0064] In some embodiments, the electrical equipment of the present application includes, but is not limited to: backup power supplies, motors, electric vehicles, electric motorcycles, power-assisted bicycles, bicycles, power tools, large household batteries, etc.

[0065] Example 1

[0066] Preparation of nickel-cobalt-manganese hydroxide precursor: weigh 69.79g nickel nitrate hexahydrate, 8.73g cobalt nitrate hexahydrate, and 8.61g manganese nitrate hexahydrate, add them together and add them to 1L deionized water, stir to dissolve all three to obtain a mixed metal salt solution. Then weigh 10g sodium hydroxide powder and add it to the above mixed metal solution, and add 4mol / L ammonia solution to adjust the solution pH to 11. Continue stirring the reaction for 10h, stirring speed 800r / min, maintain a constant reaction temperature of 60°C, after the reaction is completed, the product is filtered, washed and dried to obtain the NCM811 ternary positive electrode material precursor. Then weigh 46.17g of the precursor powder and add it to 1L 0.1M hydrochloric acid solution, stir to mix it evenly, ultrasonically treat the mixed solution for 30min for etching, then filter and separate the product, wash it with clean water, and dry it to obtain a loose porous precursor. Weigh 2g of sodium alginate powder (molecular weight 80-100kDa), add it to 1L of clean water, heat it in a water bath at 45℃, and stir it mechanically to completely dissolve it. Then weigh 40g of the etched loose porous precursor, add the aforementioned sodium alginate solution, and pour in 50mL of 2M hydrochloric acid solution. React at room temperature for 30min, assisted by slight slow stirring. The product is then centrifuged and washed with water, and freeze-dried in a freeze dryer. After the freeze-dried powder product is uniformly premixed with lithium hydroxide powder in a high-speed mixer, it is calcined at 700℃ in an oxygen atmosphere for 6h to obtain the NCM811 ternary positive electrode material (LiNi 0.8 Mn 0.1 Co 0.1 O2), which contains an interconnected and highly efficient conductive network.

[0067] Examples 2 to 5: The preparation method is the same as that of Example 1, except that the porosity of the precursor is adjusted by changing the concentration of hydrochloric acid used for etching. The specific parameters are shown in Table 1.

[0068] Examples 6-7: The preparation method is the same as that of Example 1, except that the power of ultrasound is adjusted to thereby adjust the porosity of the precursor.

[0069] Example 8: The preparation method is the same as that of Example 1, except that no ultrasonic treatment is applied during the etching process.

[0070] Example 9: The preparation method is the same as that of Example 1, except that the hydrochloric acid used for etching is changed to oxalic acid.

[0071] Example 10: The preparation method is the same as that of Example 1, except that the second acid solution is not added during the chelating process.

[0072] Examples 11 to 14: The preparation method is the same as that of Example 1, except that the calcination temperature is changed.

[0073] Example 15: Weigh 52.34g of nickel nitrate hexahydrate, 8.73g of cobalt nitrate hexahydrate, and 25.83g of manganese nitrate hexahydrate, add them together and add them to 1L of deionized water, stir to dissolve all three to obtain a mixed metal salt solution. Then weigh 10g of sodium hydroxide powder and add it to the above mixed metal solution, and add 4mol / L ammonia solution to adjust the solution pH to 11. Continue stirring and react for 10h, the stirring speed is 800r / min, and the reaction temperature is maintained constant at 60°C. After the reaction is completed, the product is filtered, washed and dried to obtain the NCM613 ternary positive electrode material precursor. Then weigh 45.79g of the precursor powder and add it to 1L of 0.1M hydrochloric acid solution, stir to mix it evenly, and then ultrasonically treat the mixed solution for 30min to perform the etching process, then filter and separate the product, wash it with clean water, and dry it to obtain a loose porous precursor. Weigh 2g of sodium alginate powder (molecular weight 80000-100000), add it to 1L of clean water, heat it in a water bath at 45℃, and stir it mechanically to completely dissolve it. Then weigh 40g of the etched loose porous precursor, add the aforementioned sodium alginate solution, and pour in 50mL of 2M hydrochloric acid solution. React at room temperature for 30min, assisted by slight slow stirring. Then the product is centrifuged and washed with water, and freeze-dried in a freeze dryer. The freeze-dried powder product is evenly premixed with lithium carbonate powder in a high-speed mixer, and then calcined at 750℃ in an oxygen atmosphere for 6h to obtain NCM613 (LiNi 0.6 Mn 0.1 Co 0.3 O2) ternary positive electrode material, which contains an interconnected and efficient conductive network.

[0074] Example 16: The preparation method is the same as that of Example 15, except that the hydrochloric acid used for etching is changed to oxalic acid.

[0075] Comparative Example 1: The preparation method is the same as that of Example 1, except that after the reaction is completed, the product is filtered, washed with water, and dried to obtain the NCM811 ternary positive electrode material precursor, which is directly calcined without etching to construct a conductive network.

[0076] Comparative Example 2: The preparation method is the same as Example 15, except that after the reaction is completed, the product is filtered, washed with water, and dried to obtain the NCM613 ternary positive electrode material precursor, which is directly calcined without etching to construct a conductive network.

[0077] Preparation of battery: A 2023-type button half-cell was prepared according to the positive electrode materials prepared in Examples 1 to 16 and Comparative Examples 1 to 2. The specific preparation method is as follows:

[0078] Positive electrode sheet: The positive electrode material, conductive agent acetylene black, and binder PVDF were mixed and ground in a mass ratio of 8:1:1, and then mixed with solvent NMP to prepare positive electrode slurry. The positive electrode slurry was heated to 0.8 mg / cm 2 The surface density of the coating was coated on the positive electrode current collector aluminum foil, and the positive electrode sheet was obtained after vacuum drying.

[0079] Negative electrode: lithium sheet

[0080] Diaphragm: PP diaphragm

[0081] Electrolyte: electrolyte containing 1.0 mol / L bis(fluoromethanesulfonyl)imide (LiTFSI), 1.0 wt% LiNO3, 1,3-dioxane (DOL) and 1,2-dimethoxyethane (DME) (volume ratio 1:1)

[0082] The positive electrode sheet, the negative electrode sheet, the separator and the electrolyte were assembled to prepare a button-type half-cell. The performance of the obtained secondary battery was tested. The results are shown in Tables 2 and 3.

[0083] Performance measurement: The first discharge specific capacity at 0.1C rate and the capacity retention rate after 50 cycles of the positive electrode materials in Examples 1-16 and Comparative Examples 1-2 were measured respectively.

[0084] Refer to GB / T 37201-2018 to test the first discharge capacity at 0.1C rate.

[0085] Refer to GB / T 37207-2018 to determine the capacity retention rate and discharge DCR growth rate after 50 and 100 cycles of charge and discharge at 1C rate.

[0086] The constant current charging ratio at 0.33C, 0.5C, 1C, 2C and 3C charging rates was determined with reference to GB / T 37207-2018.

[0087] Table 1 Preparation parameters of Examples 1 to 16 and Comparative Examples 1 to 2

[0088]

[0089]

[0090]

[0091] Table 2 The first discharge specific capacity of different embodiments and comparative examples at 0.1C rate and the capacity retention rate and discharge DCR growth rate after 50 and 100 cycles of charge and discharge at 1C rate

[0092]

[0093]

[0094] Table 3 Constant current charging ratio of different embodiments and comparative examples at 0.33C, 0.5C, 1C, 2C, 3C charging rates

[0095]

[0096]

[0097] From the results of Tables 2 to 3, it can be seen that the positive electrode material constructed in Example 1 has a suitable porosity, so its conductive network formation effect is excellent. Compared with Comparative Example 1, the gram capacity is basically unaffected, and the cycle capacity retention rate, DCR growth rate, and constant current charging ratio at different rates are all improved. Compared with Comparative Example 1, the positive electrode materials prepared in Examples 2-8 are still better than Comparative Example 1 in DCR cycle growth rate and constant current charging ratio due to the construction of the conductive network. Compared with Example 1, when oxalic acid is used in etching, Example 9 affects the construction effect of the conductive network; Example 10 does not add the second acid solution, the degree of chelation reaction is not sufficient, and its performance is inferior to Example 1; It can be seen from Examples 11 to 14 that the calcination temperature can cause incomplete development of material particles or excessive sintering, affecting the performance of the prepared positive electrode material. From the results of Examples 9-14 and Comparative Example 1, it can be seen that the conductive network constructed in the positive electrode material improves the DCR growth rate and constant current charging ratio of the positive electrode material. It can be seen from the data of Example 15, Example 16 and Comparative Example 2 that the present application can improve the performance of the positive electrode material by constructing a conductive network inside the positive electrode material.

[0098] This application constructs a conductive network inside the ternary positive electrode material. First, the ternary positive electrode material precursor is etched to form a loose porous structure. Then, the sodium alginate polymer and divalent cations are used to react with each other to form interconnected polymer chains around and inside the precursor. The polymer chain structure is effectively reinforced and preserved by freeze-drying. After high-temperature calcination, the interconnected polymer chains are carbonized to form a conductive network, which greatly improves the conductive properties of the material, improves the capacity retention rate of the material during use, suppresses the growth of DCR, increases the constant current charging ratio, and effectively alleviates the polarization phenomenon.

[0099] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0100] The above is a detailed introduction to a positive electrode material, a secondary battery and an electrical device provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A positive electrode material, characterized in that: It includes a ternary positive electrode material and a conductive network distributed inside the ternary positive electrode material; The chemical formula of the ternary cathode material is: LiNi x Mn y Co 1-x-y O2, where the value range of x is 0.6~0.8 and the value range of y is 0.1~0.3; The conductive network includes carbonized alginate groups and metal cations; The ternary positive electrode material is prepared from a ternary positive electrode material precursor, the ternary positive electrode material precursor is etched and mixed with a sodium alginate solution, dried, and the obtained product is mixed with a lithium source and calcined to obtain the positive electrode material; The metal cations include Ni, Mn and Co; The precursor of the ternary positive electrode material is prepared by the following method: co-precipitating a metal salt containing a nickel source, a cobalt source and a manganese source under alkaline conditions to obtain a ternary positive electrode material precursor; The etching method comprises: etching with a first acid solution having a concentration of 0.05-0.5 mol / L; The etching temperature is 30-50°C; The etching time is 10min~1h; The first acid solution is selected from one or more of hydrochloric acid, oxalic acid, citric acid, and benzenesulfonic acid; The sodium alginate solution chelates with the metal cations in the presence of the second acid solution; The concentration of the second acid solution is 1-3 mol / L; The second acid solution is selected from one or more of hydrochloric acid, oxalic acid, citric acid, and benzenesulfonic acid.

2. The positive electrode material according to claim 1, characterized in that The mass ratio of the conductive network to the ternary positive electrode material is 1:80-1:

100.

3. The positive electrode material according to claim 1, characterized in that The porosity of the precursor for preparing the ternary cathode material is 0.1-0.15%; and / or, The molecular weight of the alginate group is 80-100 KDa.

4. A method for preparing a positive electrode material as claimed in claim 1, characterized in that: The following steps are involved: preparing a ternary cathode material precursor, and etching the obtained ternary cathode material precursor; The etched ternary cathode material precursor is mixed with a sodium alginate solution and dried, and the obtained product is mixed with a lithium source and then calcined to obtain the cathode material.

5. The method for preparing the positive electrode material according to claim 4, characterized in that: During the etching process, ultrasonic treatment with a power of 500W to 5000W is applied.

6. The method for preparing the positive electrode material according to claim 4, characterized in that: The calcination temperature is 600-800° C. and the calcination time is 5-8 hours.

7. A secondary battery, characterized in that: The invention comprises the positive electrode material as described in any one of claims 1 to 3 or the positive electrode material prepared by the preparation method as described in any one of claims 4 to 6.

8. An electrical device, characterized in that: Comprising the secondary battery as claimed in claim 7.

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