Porous carbon-coated ternary cathode material, preparation method and application thereof

Abstract

The present application relates to a kind of porous carbon-coated ternary positive electrode material and its preparation method and application, the preparation method includes the following steps: using initial wet impregnation method, quinone amine polymer is coated on the surface of ternary positive electrode material, high-temperature sintering, obtain porous carbon-coated ternary positive electrode material.The preparation method obtained by the present application avoids the problem that ternary positive electrode material is reacted with electrolyte during the cycle process, resulting in the problem of too fast life attenuation, while improving the conductivity, reducing impedance, without affecting the overall energy density.

Description

Technical Field

[0001] This invention relates to the field of cathode material technology, and in particular to a porous carbon-coated ternary cathode material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries are widely used in energy storage, power batteries, and other fields due to their high energy density and long cycle life. The cathode material is one of the core components of a lithium-ion battery. As the main component involved in the insertion and extraction of lithium ions during charging and discharging, the stability of the cathode material during the reaction process is crucial to battery performance. Currently, the mainstream cathode materials are ternary materials and lithium iron phosphate materials. Ternary materials have higher specific capacity, greater compaction density, and better power performance, making them a good choice for achieving long-range battery cells. However, ternary materials are prone to side reactions with the electrolyte, producing gas that can cause battery bulging and significantly reduce cycle life. To solve this problem, the most common method is coating modification, which involves coating the ternary material with an inert material to isolate it from side reactions.

[0003] Existing coating modifications mainly include oxide coating, fluoride coating, and carbon coating.

[0004] CN107768642A discloses a ternary lithium-ion battery material with a double-layer coating, comprising a nickel-cobalt-manganese ternary material. A lithium-rich layered oxide coating layer is coated on the surface of the nickel-cobalt-manganese ternary material, and an aluminum fluoride coating layer is coated on the surface of the lithium-rich layered oxide coating layer. This double-layer coated lithium-ion battery ternary material exhibits good chemical stability and high capacity, as the coating layers are not easily detached. The CN107768642A also discloses a method for preparing this lithium-ion battery ternary material. First, an organic complexing agent-assisted sol-gel method is used to coat the surface of the ternary material with a lithium-rich layered oxide to form a lithium-rich coating layer. Then, an aluminum fluoride coating layer is applied to the surface of the lithium-rich layered oxide using a liquid-phase method to obtain the double-layer coated lithium-ion battery ternary material.

[0005] CN114583125A discloses a method for preparing carbon-coated nickel-cobalt-manganese ternary materials, the carbon-coated nickel-cobalt-manganese ternary materials, and a lithium-ion battery cathode material having the same. The method includes: mixing the nickel-cobalt-manganese ternary material with a carbon source, and subjecting the nickel-cobalt-manganese ternary material and the carbon source to plasma discharge-assisted high-energy ball milling, so that the nickel-cobalt-manganese ternary material and the carbon source undergo a chemical reaction to obtain the carbon-coated nickel-cobalt-manganese ternary material; wherein the carbon source is obtained by high-temperature carbonization treatment of sugar-containing crops.

[0006] In existing technologies, oxides offer good stability and effectively isolate most reactions with the electrolyte, thus improving cycle performance. However, their poor conductivity affects the overall capacity and power performance of the material. Furthermore, oxides have a high density, which, since they do not contribute capacity during battery operation, leads to a decrease in battery energy density and impacts overall cell performance. Fluorides, similar to oxides, can suppress side reactions between the electrolyte and the cathode material, stabilizing the material structure. However, fluorides are highly toxic and unsuitable for large-scale industrial production. Carbon materials have low density, minimizing their impact on the overall system energy density, and possess good conductivity. However, the uneven coating uniformity of carbon materials negatively affects the overall cell performance.

[0007] In summary, to effectively avoid the rapid lifespan decay caused by side reactions between the ternary cathode material and the electrolyte during cycling, while simultaneously improving conductivity, reducing impedance, and maintaining overall energy density, it is crucial to provide a method for preparing ternary cathode materials with porous carbon coating protection. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a porous carbon-coated ternary cathode material, its preparation method, and its application. The porous carbon-coated ternary cathode material obtained by the preparation method avoids the problem of rapid lifespan decay caused by side reactions between the ternary cathode material and the electrolyte during cycling, while improving conductivity, reducing impedance, and not affecting the overall energy density.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a porous carbon-coated ternary cathode material, the method comprising the following steps:

[0011] A quinone-amine polymer was coated onto the surface of a ternary cathode material using a wet impregnation method, followed by high-temperature sintering to obtain a porous carbon-coated ternary cathode material.

[0012] In this invention, the preparation method utilizes the initial wet impregnation method to form porous channels during the process of coating the quinone amine polymer onto the surface of the ternary cathode material. The resulting porous carbon-coated ternary cathode material can effectively avoid the side reactions between the ternary cathode material and the electrolyte during cycling, which would lead to excessively rapid lifespan decay. At the same time, it improves conductivity, reduces impedance, and does not affect the overall energy density.

[0013] Preferably, the initial wet impregnation method includes: mixing a solution of quinone monomers and a solution of amine monomers to obtain a quinone-amine prepolymer, then placing the quinone-amine prepolymer on the surface of a ternary cathode material to an initial wet state, and allowing it to stand and dry.

[0014] In this invention, the initial wet impregnation method has the advantage of reducing the amount of coating material used, improving preparation efficiency, and greatly improving coating uniformity compared to conventional preparation methods.

[0015] In this invention, the initial wet state refers to the state in which the liquid just completely wets the powder material.

[0016] Preferably, the mixing method includes adding a solution of amine monomers dropwise to a solution of quinone monomers.

[0017] In this invention, the mixing method is preferred because it slows down the polymerization reaction, making it easier to perform initial wet impregnation. If the amine monomer, quinone monomer, and solvent are mixed, the polymerization reaction will proceed too quickly, making it impossible to perform the initial wet impregnation operation. Similarly, if the quinone monomer solution is added dropwise to the amine monomer solution, the polymerization reaction will also proceed too quickly, making it impossible to perform the initial wet impregnation operation.

[0018] Preferably, the quinone monomer includes any one or a combination of at least two of benzoquinone, naphthoquinone, phenanthrene, or anthraquinone, wherein typical but non-limiting combinations include: combinations of benzoquinone and naphthoquinone, combinations of phenanthrene and anthraquinone, combinations of benzoquinone, naphthoquinone, phenanthrene, and anthraquinone, etc.

[0019] Preferably, the solvent used in the solution of the quinone monomer includes any one or a combination of at least two of ethanol, methanol, or diethyl ether, wherein typical but non-limiting combinations include: a combination of ethanol and methanol, a combination of methanol and diethyl ether, a combination of ethanol, methanol, and diethyl ether, etc., with ethanol being more preferred.

[0020] In this invention, ethanol is preferred as the solvent because, in the initial wet state, anhydrous ethanol continuously evaporates during the settling process, leaving porous channels, making the method simple and easy to operate.

[0021] Preferably, the mass concentration of the quinone monomer in the solution is 5-15 g / L, such as 6 g / L, 8 g / L, 10 g / L, 12 g / L, 14 g / L, etc.

[0022] In this invention, the preferred mass concentration of the quinone monomer is 5-15 g / L. This is because controlling the concentration within this range allows the polymerization reaction to proceed smoothly. If the concentration is too high, the polymerization reaction will proceed too quickly, making initial wet impregnation impossible. If the concentration is too low, the polymerization reaction will not proceed.

[0023] Preferably, the amine monomer includes any one or a combination of at least two of phenylenediamine, naphthylamine, phenanthreneamine, or anthraceneamine, wherein typical but non-limiting combinations include: a combination of phenylenediamine and naphthylamine, a combination of naphthylamine, phenanthreneamine, and anthraceneamine, a combination of phenylenediamine, naphthylamine, phenanthreneamine, and anthraceneamine, etc.

[0024] Preferably, the phenylenediamine includes any one or a combination of at least two of o-phenylenediamine, m-phenylenediamine, or p-phenylenediamine, wherein typical but non-limiting combinations include: a combination of o-phenylenediamine and m-phenylenediamine, a combination of m-phenylenediamine and p-phenylenediamine, a combination of o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine, etc.

[0025] Preferably, the solvent used in the solution of the amine monomer includes any one or a combination of at least two of ethanol, methanol, or diethyl ether, wherein typical but non-limiting combinations include: a combination of ethanol and methanol, a combination of methanol and diethyl ether, a combination of ethanol, methanol, and diethyl ether, etc.

[0026] Preferably, the mass concentration of the amine monomer in the solution is 10-30 g / L, such as 12 g / L, 14 g / L, 16 g / L, 18 g / L, 20 g / L, 22 g / L, 24 g / L, 26 g / L, 28 g / L, etc.

[0027] In this invention, the mass concentration of the amine monomer is preferably 10-30 g / L, because controlling it within this range allows the polymerization reaction to occur smoothly; if the concentration is too high, the polymerization reaction will proceed too quickly, making initial wet impregnation impossible; if the concentration is too low, the polymerization reaction will not proceed.

[0028] Preferably, the molar ratio of the quinone monomer to the amine monomer is 1:(0.8-1.2), wherein 0.8-1.2 can be 0.85, 0.8, 0.95, 1, 1.05, 1.1, 1.15, etc.

[0029] Preferably, the ternary cathode material includes any one or a combination of at least two of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or lithium nickel cobalt manganese aluminum oxide. Typical but non-limiting combinations include: a combination of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, a combination of lithium nickel cobalt aluminum oxide and lithium nickel cobalt manganese aluminum oxide, a combination of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium nickel cobalt manganese aluminum oxide, etc.

[0030] Preferably, the high-temperature sintering temperature is 300-750℃, such as 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, etc.

[0031] Preferably, the high-temperature sintering time is 1-5 hours, such as 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, etc.

[0032] As a preferred technical solution, the preparation method includes the following steps:

[0033] (1) Mix the solution of quinone monomers and the solution of amine monomers to obtain quinone amine prepolymer, and then place the quinone amine prepolymer on the surface of the ternary cathode material until it is initially wet, and let it stand to dry.

[0034] (2) The material obtained in step (1) is sintered at 300-750℃ for 1-5 hours to obtain the porous carbon-coated ternary cathode material.

[0035] In a second aspect, the present invention provides a porous carbon-coated ternary cathode material, wherein the porous carbon-coated ternary cathode material is obtained by the preparation method described in the first aspect.

[0036] Thirdly, the present invention provides a lithium-ion battery, the lithium-ion battery comprising the porous carbon-coated ternary cathode material described in the second aspect.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The porous carbon-coated ternary cathode material obtained by the preparation method described in this invention avoids the problem of excessively rapid life decay caused by side reactions between the ternary cathode material and the electrolyte during cycling, while improving conductivity, reducing impedance, and not affecting the overall energy density.

[0039] (2) The porous carbon-coated ternary cathode material NCM622 obtained by the preparation method of the present invention has an initial discharge specific capacity between 175-182 mAh / g, a capacity retention rate of over 88% after 50 cycles, and a 50% SOC discharge DCR increase of less than 33.5 mΩ. Within the preferred range, the porous carbon-coated ternary cathode material NCM622 obtained by the preparation method has an initial discharge specific capacity between 181-182 mAh / g, a capacity retention rate of over 97% after 50 cycles, and a 50% SOC discharge DCR increase of less than 13.2 mΩ; the porous carbon-coated NCM811 has an initial discharge specific capacity between 213-215 mAh / g, a capacity retention rate of over 97% after 50 cycles, and a 50% SOC discharge DCR increase of less than 14.2 mΩ. Detailed Implementation

[0040] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0041] Example 1

[0042] This embodiment provides a method for preparing a porous carbon-coated ternary cathode material, the method comprising the following steps:

[0043] (1) Measure 70 mL of anhydrous ethanol into a beaker, then weigh 0.5 g of p-benzoquinone powder and add it to the ethanol, stirring until homogeneous. Measure 30 mL of anhydrous ethanol into another beaker, weigh 0.5 g of o-phenylenediamine powder and add it to the ethanol, stirring until homogeneous. Then, use a dropper to add the o-phenylenediamine-ethanol mixture to the p-benzoquinone-ethanol mixture, stirring continuously. After the addition is complete, a black quinone amine prepolymer is formed in the system.

[0044] (2) Take another beaker and weigh 5g of lithium nickel cobalt manganese oxide (NCM622, Ni:Co:Mn=6:2:2) powder and spread it evenly in it. Then, use a dropper to slowly add the quinone amine prepolymer onto the lithium nickel cobalt manganese oxide until the solution just completely wets the powder, forming lithium nickel cobalt manganese oxide coated with quinone amine polymer.

[0045] (3) The sample was then allowed to stand until the ethanol evaporated completely and the sample was transferred to a crucible. The sample was then calcined at high temperature in a tube furnace. The calcination atmosphere was argon. The temperature was initially maintained at 300℃ for 2 hours, followed by 750℃ for 2 hours, with a heating rate of 5℃·min. -1 After the sample cooled naturally to room temperature, it was collected under dry conditions to obtain a porous carbon-coated ternary cathode material.

[0046] Example 2

[0047] The difference between this embodiment and Embodiment 1 is that the o-phenylenediamine is replaced with an equal mass of m-phenylenediamine; all other aspects are the same as in Embodiment 1.

[0048] Example 3

[0049] The difference between this embodiment and Embodiment 1 is that the o-phenylenediamine is replaced with an equal mass of p-phenylenediamine; all other aspects are the same as in Embodiment 1.

[0050] Example 4

[0051] This embodiment provides a method for preparing a porous carbon-coated ternary cathode material, the method comprising the following steps:

[0052] (1) Measure 70 mL of anhydrous ethanol into a beaker, then weigh 0.5 g of p-benzoquinone powder and add it to the ethanol, stirring until homogeneous. Measure 30 mL of anhydrous ethanol into another beaker, weigh 0.5 g of o-phenylenediamine powder and add it to the ethanol, stirring until homogeneous. Then, use a dropper to add the o-phenylenediamine-ethanol mixture to the p-benzoquinone-ethanol mixture, stirring continuously. After the addition is complete, a black quinone amine prepolymer is formed in the system.

[0053] (2) Take another beaker and weigh 5g of lithium nickel cobalt manganese oxide (NCM811, Ni:Co:Mn=8:1:1) powder and spread it evenly in it. Then, use a dropper to slowly add the quinone amine prepolymer onto the lithium nickel cobalt manganese oxide until the solution just completely wets the powder, forming lithium nickel cobalt manganese oxide coated with quinone amine polymer.

[0054] (3) The sample was then allowed to stand until the ethanol evaporated completely and the sample was transferred to a crucible. The sample was then calcined at high temperature in a tube furnace. The calcination atmosphere was argon. The temperature was initially maintained at 300℃ for 2 hours, followed by 700℃ for 2 hours, with a heating rate of 5℃·min. -1 After the sample cooled naturally to room temperature, it was collected under dry conditions to obtain a porous carbon-coated ternary cathode material.

[0055] Example 5

[0056] The difference between this embodiment and Embodiment 4 is that the o-phenylenediamine is replaced with an equal mass of m-phenylenediamine; all other aspects are the same as in Embodiment 4.

[0057] Example 6

[0058] The difference between this embodiment and Embodiment 4 is that the o-phenylenediamine is replaced with an equal mass of p-phenylenediamine; all other aspects are the same as in Embodiment 4.

[0059] Example 7

[0060] The difference between this embodiment and Example 1 is that the operation of adding the o-phenylenediamine-ethanol mixture to the o-phenylenediamine-ethanol mixture is replaced by adding the p-benzoquinone-ethanol mixture to the o-phenylenediamine-ethanol mixture. All other aspects are the same as in Example 1.

[0061] Example 8

[0062] The difference between this embodiment and embodiment 1 is that the raw materials in step (1) are directly mixed and continuously stirred to form a black quinone amine prepolymer. The rest is the same as in embodiment 1.

[0063] Example 9

[0064] The difference between this embodiment and Example 1 is that the amount of p-benzoquinone powder added is kept at 0.5g, and the amount of anhydrous ethanol added is adjusted until the mass concentration of the p-benzoquinone-ethanol mixed solution is 4g / L. All other aspects are the same as in Example 1.

[0065] Example 10

[0066] The difference between this embodiment and Example 1 is that the amount of p-benzoquinone powder added is kept at 0.5g, and the amount of anhydrous ethanol added is adjusted until the mass concentration of the p-benzoquinone-ethanol mixed solution is 16g / L. All other aspects are the same as in Example 1.

[0067] Example 11

[0068] The difference between this embodiment and Example 1 is that the amount of o-phenylenediamine powder added is kept at 0.5g, and the amount of anhydrous ethanol added is adjusted to the mass concentration of the o-phenylenediamine-ethanol mixed solution is 9g / L. All other aspects are the same as in Example 1.

[0069] Example 12

[0070] The difference between this embodiment and Example 1 is that the amount of o-phenylenediamine powder added is kept at 0.5g, and the amount of anhydrous ethanol added is adjusted to the mass concentration of the o-phenylenediamine-ethanol mixed solution is 31g / L. All other aspects are the same as in Example 1.

[0071] Comparative Example 1

[0072] This comparative example directly uses the lithium nickel cobalt manganese oxide (NCM622) used in Example 1, without any additional processing.

[0073] Comparative Example 2

[0074] This comparative example directly uses the lithium nickel cobalt manganese oxide (NCM811) used in Example 4, without any additional processing.

[0075] Comparative Example 3

[0076] The difference between this comparative example and Example 1 is that in step (2), the quinone amine polymer is directly mixed with lithium nickel cobalt manganese oxide, and the lithium nickel cobalt manganese oxide is fully dissolved in the quinone amine polymer. The rest is the same as in Example 1.

[0077] Performance testing

[0078] The porous carbon-coated ternary cathode materials described in Examples 1-12 and Comparative Examples 1-3 were subjected to the following tests:

[0079] (1) Initial discharge specific capacity: Tested according to GB / T 37201-2018.

[0080] (2) Capacity retention rate after 50 charge-discharge cycles: Tested according to GB / T 37201-2018.

[0081] (3) 50% SOC discharge DCR growth: Tested according to GB / T 37201-2018.

[0082] The test results are summarized in Table 1.

[0083] Table 1

[0084]

[0085]

[0086] Analysis of Table 1 shows that the porous carbon-coated ternary cathode material NCM622 obtained by the preparation method of the present invention has an initial discharge specific capacity between 175-182 mAh / g, a capacity retention rate of over 88% after 50 cycles, and a DCR increase of less than 33.5 mΩ at 50% SOC. Within the preferred range (taking Examples 1-3 as examples), the porous carbon-coated ternary cathode material NCM622 obtained by the preparation method has an initial discharge specific capacity between 181-182 mAh / g, and a capacity retention rate of over 88% after 50 cycles. The porous carbon-coated NCM811 exhibits a first discharge specific capacity of over 213-215 mAh / g, and after 50 cycles, the capacity retention rate is over 97%, with a 50% SOC discharge DCR increase of less than 13.2 mΩ. The method described in this invention avoids the problem of rapid lifespan decay caused by side reactions between the ternary cathode material and the electrolyte during cycling, while simultaneously improving conductivity, reducing impedance, and not affecting the overall energy density.

[0087] Analysis of Comparative Example 1 and Example 1 shows that the performance of Comparative Example 1 is inferior to that of Example 1, proving that the porous carbon-coated ternary cathode material obtained by the preparation method described in this invention has better performance. The comparison results between Comparative Example 2 and Example 4 are similar.

[0088] Analysis of Comparative Example 3 and Example 1 shows that the performance of Comparative Example 3 is not as good as that of Example 1, proving that the porous carbon-coated ternary cathode material obtained by the initial wet impregnation method has better performance.

[0089] Analysis of Examples 7-8 and Example 1 shows that the performance of Examples 7-8 is not as good as that of Example 1, proving that the porous carbon-coated ternary cathode material obtained by the preferred initial wet impregnation method has better performance.

[0090] Analysis of Examples 9-12 and Example 1 shows that the performance of Examples 9-12 is not as good as that of Example 1, proving that the porous carbon-coated ternary cathode material obtained by solutions of quinone monomers and amine monomers within their respective preferred ranges has better performance.

[0091] The present invention has been illustrated with the above embodiments to explain the detailed method of the present invention. However, the present invention is not limited to the detailed method described above, that is, it does not mean that the present invention must rely on the detailed method described above to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a porous carbon-coated ternary cathode material, characterized in that, The preparation method includes the following steps: Using the initial wet impregnation method, quinone amine polymers were coated onto the surface of ternary cathode materials, followed by high-temperature sintering to obtain porous carbon-coated ternary cathode materials. The initial wet impregnation method includes: mixing a solution of quinone monomers and a solution of amine monomers to obtain a quinone-amine prepolymer, then placing the quinone-amine prepolymer on the surface of a ternary cathode material to an initial wet state, and allowing it to stand and dry. The mass concentration of the quinone monomer in the solution is 5-15 g / L; In the solution of the amine monomer, the mass concentration of the amine monomer is 10-30 g / L; The mixing method includes adding a solution of amine monomers dropwise to a solution of quinone monomers; The molar ratio of the quinone monomer to the amine monomer is 1:(0.8-1.2).

2. The preparation method according to claim 1, characterized in that, The quinone monomers include any one or a combination of at least two of benzoquinone, naphthoquinone, phenanthrenequinone, or anthraquinone.

3. The preparation method according to claim 1, characterized in that, The solvent used in the solution of the quinone monomer includes any one or a combination of at least two of ethanol, methanol, or diethyl ether.

4. The preparation method according to claim 1, characterized in that, The amine monomers include any one or a combination of at least two of phenylenediamine, naphthylamine, phenanthreneamine, or anthraceneamine.

5. The preparation method according to claim 4, characterized in that, The phenylenediamine includes any one or a combination of at least two of o-phenylenediamine, m-phenylenediamine, or p-phenylenediamine.

6. The preparation method according to claim 1, characterized in that, The solvent used in the solution of the amine monomer includes any one or a combination of at least two of ethanol, methanol, or diethyl ether.

7. The preparation method according to claim 1, characterized in that, The ternary cathode material includes any one or a combination of at least two of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, or lithium nickel cobalt manganese aluminum oxide.

8. The preparation method according to claim 1, characterized in that, The high-temperature sintering temperature is 300-750℃.

9. The preparation method according to claim 1, characterized in that, The high-temperature sintering time is 1-5 hours.

10. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix the solution of quinone monomers and the solution of amine monomers to obtain quinone amine prepolymer, and then place the quinone amine prepolymer on the surface of the ternary cathode material until it is initially wet, and let it stand to dry; (2) The material obtained in step (1) is sintered at 300-750℃ for 1-5 h to obtain the porous carbon-coated ternary cathode material.

11. A porous carbon-coated ternary cathode material, characterized in that, The porous carbon-coated ternary cathode material is prepared by the preparation method described in any one of claims 1-10.

12. A lithium-ion battery, characterized in that, The lithium-ion battery includes the porous carbon-coated ternary cathode material as described in claim 11.

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