Ncma quaternary positive electrode material, preparation method thereof and all-solid-state battery

Abstract

The application discloses an NCMA quaternary positive electrode material and a preparation method and a full-solid-state battery thereof, and the preparation method comprises three steps: step 1, an NCMA precursor is prepared by using a coprecipitation method; step 2, a radial NCMA quaternary positive electrode material is prepared by using a solid-phase sintering method (primary roasting); and step 3, acid phosphate adhesion and sintering (secondary roasting) are performed on the prepared radial NCMA quaternary positive electrode material, so that the radial NCMA quaternary positive electrode material after acid phosphate adhesion is obtained. The NCMA quaternary positive electrode material prepared by the application has good structural stability, and the interface with a sulfide electrolyte has good capacitive characteristics, so that the high discharge specific capacity and stable cycle life of the NCMA quaternary positive electrode material can be effectively exerted in a sulfide electrolyte full-solid-state battery system. An effective scheme is provided for realizing the universal application of a high-nickel positive electrode material in the sulfide electrolyte full-solid-state battery system.

Description

Technical Field

[0001] This invention belongs to the field of cathode material technology, and in particular relates to an NCMA quaternary cathode material, its preparation method, and an all-solid-state battery. Background Technology

[0002] All-solid-state lithium batteries, which use non-flammable solid electrolytes, are expected to solve the safety problems of traditional lithium batteries, while simplifying the battery structure and enabling higher battery specific energy designs, and have attracted widespread attention in recent years.

[0003] The electrical performance of all-solid-state lithium batteries is closely related to the solid electrolyte, the cathode material, and the interfacial properties between the two. They boast high ionic conductivity comparable to liquid electrolytes (up to 10⁻⁶ at room temperature). -2 S cm -1 Sulfides are considered to be highly promising solid electrolytes for all-solid-state lithium batteries. Furthermore, exploring cathode materials suitable for sulfide electrolyte solid-state battery systems is crucial for constructing high-energy-density, long-life all-solid-state lithium batteries. Among these, high-nickel materials, especially the quaternary cathode material LiNi, are particularly important. x Co y Mn z Al 1-x-y-z O2 (NCMA) is considered to have great application potential in sulfide electrolyte all-solid-state battery systems due to its advantages such as high voltage, high specific capacity, longer lifespan than traditional ternary materials, and better thermal stability. However, due to the severe deterioration and failure of the quaternary cathode material / sulfide electrolyte interface during charge and discharge, the electrical performance of quaternary cathode materials in all-solid-state lithium batteries is far inferior to that of liquid lithium-ion batteries.

[0004] During battery fabrication or charge-discharge cycling, due to the difference between chemical and electrochemical potentials, side reactions occur between the quaternary cathode material and the sulfide electrolyte, forming a high-resistivity solid / solid interface layer that hinders Li... + The transport of ions is hindered by the presence of numerous free alkaline impurities on the surface of quaternary cathode materials. These insulating substances significantly impede ion transport. Furthermore, the strong oxidizing properties of the quaternary cathode material and its extremely poor compatibility with sulfide electrolytes severely reduce interfacial stability. Traditional cathode materials are composed of disordered primary particles, and in Li... + The repeated insertion and extraction process generates severe stress concentration, causing the material to crack severely after long cycles, which in turn leads to contact failure between material particles.

[0005] For example, CN 111640928A NCMA quaternary materials and their preparation methods, lithium battery cathode materials and lithium batteries, use NCMA as a substrate and obtain the coated quaternary cathode material by coating with two metal oxides, Co3O4 and V2O5. The cost is relatively high, the process steps are many, and after electrochemical testing, the capacity is not high enough and the cycle performance is poor, which is not conducive to industrial production. Summary of the Invention

[0006] The main objective of this invention is to provide an NCMA quaternary cathode material, its preparation method, and an all-solid-state battery, in order to solve the problem of poor electrical performance of cathode materials in sulfide electrolyte solid-state battery systems in the prior art.

[0007] This invention is achieved as follows: a method for preparing an NCMA quaternary cathode material, comprising the following steps:

[0008] Step 1: Prepare NCMA precursor using co-precipitation method;

[0009] Step 2: Radial NCMA quaternary cathode material is prepared by solid-phase one-time calcination;

[0010] Step 3: The prepared radial NCMA quaternary cathode material is subjected to acid phosphate attachment and secondary calcination to obtain the radial NCMA quaternary cathode material after acid phosphate attachment.

[0011] The chemical formula of the NCMA quaternary cathode material is LiNi. w Co x Mn y Al z O2, where 0.88≤w≤0.95, 0.03≤x≤0.06, 0.01≤y≤0.03, 0.01≤z≤0.03, and w+x+y+z=1.

[0012] The mass ratio of the NCMA quaternary cathode material to the acidic phosphate is 0.001 to 0.05:1, and the acidic phosphate is Zr(HPO4)2·H2O.

[0013] The thickness of the coating layer of the radial NCMA quaternary cathode material is 10–50 nm.

[0014] In step 3, the temperature of the second roasting is 400-600℃, the time of the second roasting is 5-10 hours, and the second roasting is carried out in an oxygen atmosphere.

[0015] Step 2 is as follows: the NCMA precursor is mixed with LiOH and a directional growth inducer to obtain a mixture; the mixture is calcined for the first time to obtain a material after one calcination; the calcined material is cooled and pulverized to obtain a radial NCMA quaternary cathode material with a particle size of 6-20 μm; the molar ratio of NCMA precursor, LiOH and directional growth inducer is 1:1-1.06:0.001-0.01.

[0016] The directional growth inducer is WO3.

[0017] The mixing is a dry mixing process. The temperature of the first calcination is 700-850℃, the time of the first calcination is 10-20 hours, and the first calcination is carried out in an oxygen atmosphere.

[0018] The NCMA quaternary cathode material prepared by the above method.

[0019] A solid-state battery using the aforementioned NCMA quaternary cathode material.

[0020] The advantages and technical effects of this invention are as follows: The radially structured quaternary cathode material prepared by this invention improves the failure of the quaternary cathode material / sulfide electrolyte interface. Specifically, by directionally inducing the growth of primary particles of the quaternary cathode material, making them more uniform, cracking during long-cycle processing is significantly reduced. Introducing an acidic phosphate coating layer on the surface of the high-nickel ternary layered oxide material avoids its contact with the sulfide electrolyte, effectively suppressing side reactions. Simultaneously, the acidic phosphate effectively consumes alkaline impurities on the surface of the quaternary cathode material, improving the conductivity of the quaternary cathode material surface layer. Attached Figure Description

[0021] Figure 1 SEM images of the NCMA quaternary cathode material prepared in Example 1 (a. surface morphology of cathode material; b. cross-sectional morphology of cathode material).

[0022] Figure 2 SEM images of the NCMA quaternary cathode material prepared in Comparative Example 1 (a. Surface morphology of cathode material; b. Cross-sectional morphology of cathode material). Detailed Implementation

[0023] The method for preparing the NCMA quaternary cathode material of the present invention includes the following steps:

[0024] Step 1: Prepare NCMA precursor using co-precipitation method;

[0025] Step 2: Radial NCMA quaternary cathode material is prepared by solid-phase one-time calcination;

[0026] Step 3: The prepared radial NCMA quaternary cathode material is subjected to acid phosphate attachment and secondary calcination to obtain the radial NCMA quaternary cathode material after acid phosphate attachment.

[0027] The chemical formula of the NCMA quaternary cathode material is LiNi. w Co x Mn y Al z O2, where 0.88≤w≤0.95, 0.03≤x≤0.06, 0.01≤y≤0.03, 0.01≤z≤0.03, and w+x+y+z=1.

[0028] The mass ratio of the NCMA quaternary cathode material to the acidic phosphate is 0.001 to 0.05:1, and the acidic phosphate is Zr(HPO4)2·H2O.

[0029] The thickness of the coating layer of the radial NCMA quaternary cathode material is 10–50 nm.

[0030] In step 3, the temperature of the second roasting is 400-600℃, the time of the second roasting is 5-10 hours, and the second roasting is carried out in an oxygen atmosphere.

[0031] Step 2 is as follows: the NCMA precursor is mixed with LiOH and a directional growth inducer to obtain a mixture; the mixture is calcined for the first time to obtain a material after one calcination; the calcined material is cooled and pulverized to obtain a radial NCMA quaternary cathode material with a particle size of 6-20 μm; the molar ratio of NCMA precursor, LiOH and directional growth inducer is 1:1-1.06:0.001-0.01.

[0032] The directional growth inducer is WO3.

[0033] The mixing is a dry mixing process. The temperature of the first calcination is 700-850℃, the time of the first calcination is 10-20 hours, and the first calcination is carried out in an oxygen atmosphere.

[0034] The NCMA quaternary cathode material prepared by the above method.

[0035] A solid-state battery using the aforementioned NCMA quaternary cathode material.

[0036] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Those skilled in the art will readily identify various non-critical parameters that can be varied or modified to produce substantially the same results.

[0037] Example 1

[0038] A method for preparing an NCMA quaternary cathode material includes the following steps:

[0039] NCMA precursor (molar ratio: Ni:Co:Mn:Al = 88:6:3:3), LiOH, and directional growth inducer WO3 were directly stirred and mixed in a high-speed powder mixer at a molar ratio of 1:1.05:0.003 to obtain a mixture. This mixture was then calcined in a roller kiln at 765℃ under an oxygen atmosphere for 15 hours, cooled, pulverized, and sieved to obtain radially shaped NCMA quaternary cathode material with a particle size of 12.5 μm. The chemical formula of this NCMA quaternary cathode material is LiNi. 0.88 Co 0.06 Mn 0.03 Al 0.03 O2. Because W is present in very small amounts, it is not represented in the chemical formula.

[0040] A radially oriented NCMA quaternary cathode material and Zr(HPO4)2·H2O were fluidized bed coated at a mass ratio of 1:0.005, allowing Zr(HPO4)2·H2O to uniformly adhere to the surface of the NCMA quaternary cathode material, resulting in the coated material. The coated material was calcined at 500℃ in an oxygen atmosphere for 8 hours, then cooled, pulverized, sieved, and demagnetized to obtain the NCMA quaternary cathode material. The coating thickness of this NCMA quaternary cathode material was 31 nm.

[0041] Example 2

[0042] Compared with Example 1, NCMA quaternary cathode material and Zr(HPO4)2·H2O were dry-mixed at a mass ratio of 1:0.001, while other conditions remained unchanged.

[0043] A method for preparing an NCMA quaternary cathode material includes the following steps:

[0044] NCMA precursor (molar ratio: Ni:Co:Mn:Al = 88:6:3:3), LiOH, and directional growth inducer WO3 were directly stirred and mixed in a high-speed powder mixer at a molar ratio of 1:1.05:0.003 to obtain a mixture. This mixture was then calcined in a roller kiln at 765℃ under an oxygen atmosphere for 15 hours, cooled, pulverized, and sieved to obtain radially shaped NCMA quaternary cathode material with a particle size of 12.3 μm. The chemical formula of this NCMA quaternary cathode material is LiNi. 0.88 Co 0.06 Mn 0.03 Al 0.03 O2. Because W is present in very small amounts, it is not represented in the chemical formula.

[0045] A radially oriented NCMA quaternary cathode material and Zr(HPO4)2·H2O were fluidized bed coated at a mass ratio of 1:0.002, allowing Zr(HPO4)2·H2O to uniformly adhere to the surface of the NCMA quaternary cathode material, resulting in the coated material. The coated material was calcined at 500℃ in an oxygen atmosphere for 8 hours, then cooled, pulverized, sieved, and demagnetized to obtain the NCMA quaternary cathode material. The coating thickness of this NCMA quaternary cathode material was 15 nm.

[0046] Example 3

[0047] Compared to Example 1, the composition of the NCMA quaternary cathode material was designed to be LiNi. 0.90 Co 0.05 Mn 0.03 Al 0.02 O2

[0048] A method for preparing an NCMA quaternary cathode material includes the following steps:

[0049] NCMA precursor (molar ratio: Ni:Co:Mn:Al = 90:5:3:2) was directly stirred and mixed with LiOH and WO3, a directional growth inducer, in a high-speed powder mixer at a molar ratio of 1:1.05:0.003 to obtain a mixture. This mixture was then calcined in a roller kiln at 765℃ under an oxygen atmosphere for 15 hours, cooled, pulverized, and sieved to obtain NCMA quaternary cathode material with a particle size of 12.7 μm. The chemical formula of this NCMA quaternary cathode material is LiNi. 0.90 Co 0.05 Mn 0.03 Al 0.02 O2.

[0050] A radially oriented NCMA quaternary cathode material and Zr(HPO4)2·H2O were fluidized bed coated at a mass ratio of 1:0.005, allowing Zr(HPO4)2·H2O to uniformly adhere to the surface of the NCMA quaternary cathode material, resulting in the coated material. The coated material was calcined at 500℃ in an oxygen atmosphere for 8 hours, then cooled, pulverized, sieved, and demagnetized to obtain the NCMA quaternary cathode material. The coating thickness of this NCMA quaternary cathode material was 30 nm.

[0051] Example 4

[0052] Compared with Example 1, the doping ratio of the directional growth inducing agent was designed to be 1:0.005, while the other conditions remained unchanged.

[0053] A method for preparing a novel quaternary cathode material for all-solid-state batteries includes the following steps:

[0054] NCMA precursor (molar ratio: Ni:Co:Mn:Al = 88:6:3:3), LiOH, and directional growth inducer WO3 were directly stirred and mixed in a high-speed powder mixer at a molar ratio of 1:1.05:0.005 to obtain a mixture. This mixture was then calcined in a roller kiln at 765℃ under an oxygen atmosphere for 15 hours, cooled, pulverized, and sieved to obtain radially shaped NCMA quaternary cathode material with a particle size of 12.3 μm. The chemical formula of this NCMA quaternary cathode material is LiNi. 0.88 Co 0.06 Mn 0.03 Al 0.03 O2. Because W is present in very small amounts, it is not represented in the chemical formula.

[0055] A radially oriented NCMA quaternary cathode material and Zr(HPO4)2·H2O were fluidized bed coated at a mass ratio of 1:0.005, allowing Zr(HPO4)2·H2O to uniformly adhere to the surface of the NCMA quaternary cathode material, resulting in the coated material. The coated material was calcined at 500℃ in an oxygen atmosphere for 8 hours, then cooled, pulverized, sieved, and demagnetized to obtain the NCMA quaternary cathode material. The coating thickness of this NCMA quaternary cathode material was 30 nm.

[0056] Comparative Example 1

[0057] NCMA precursor (molar ratio: Ni:Co:Mn:Al = 88:6:3:3) and LiOH were directly stirred and mixed in a high-speed powder mixer at a molar ratio of 1:1.05 to obtain a mixture. This mixture was then calcined in a roller kiln at 765℃ under an oxygen atmosphere for 15 hours, cooled, pulverized, and sieved to obtain a disordered NCMA quaternary cathode material with a particle size of 12.5 μm. The chemical formula of this NCMA quaternary cathode material is LiNi. 0.88 Co 0.06 Mn 0.03 Al 0.03 O2.

[0058] All-solid-state battery fabrication: The NCMA quaternary cathode materials fabricated in Examples 1-4 and Comparative Example 1 were respectively mixed with Li 10 GeP2S 12 The sulfide electrolyte was ground and mixed evenly at a mass ratio of 7:3 to prepare a composite cathode powder. Li was weighed... 10 GeP2S 12100g of sulfide electrolyte was placed in a solid-state battery mold and molded under a pressure of 10MPa. The negative electrode was a Li-In alloy. During battery assembly, 10mg of composite positive electrode powder was weighed and assembled in the following order: composite stainless steel sheet - negative electrode - electrolyte - composite positive electrode - stainless steel sheet. The battery was then extruded under a pressure of 15MPa and finally secured with screws. The assembly process was carried out in an argon-filled glove box. Electrical performance testing was also conducted in a glove box using a Newway battery testing system at 35°C, with a test voltage range of 2.1–3.68V. The initial discharge capacity, efficiency, and 100-cycle capacity retention were tested, and the results are listed in Table 1.

[0059] Table 1 Electrical performance test data

[0060]

[0061] As can be seen from the data in Table 1, compared with Comparative Example 1, the NCMA quaternary cathode materials in Examples 1 to 5 have better capacity and cycle life. This is mainly because the residual lithium is eliminated through a chemical reaction after the Zr(HPO4)2·H2O coating, which improves the conductivity of the interface between the NCMA quaternary cathode material and the sulfide electrolyte. On the other hand, the coating layer effectively prevents the side reactions that occur when the high-nickel layered oxide comes into direct contact with the sulfide, thereby improving the specific capacity of the material. At the same time, the radial structure effectively prevents internal cracking of the cathode material, suppresses contact failure, and improves the cycle performance of the material.

[0062] This invention utilizes the characteristic of Zr(HPO4)2·H2O coating to eliminate residual lithium through a chemical reaction, thereby improving the ion transport properties of the material surface and effectively enhancing its electrochemical performance. Based on the characteristic that Zr(HPO4)2·H2O can form a stable and uniform coating layer on the material surface, fluidized bed coating and high-temperature solid-state methods are used to generate the coating layer, solving the problem of poor interfacial compatibility between NCMA and sulfide electrolytes. Using Zr(HPO4)2·H2O as a coating layer can simultaneously introduce both Zr and P elements, and the material is uniformly dispersed during the preparation process, resulting in low cost and allowing for mass production suitable for industrial manufacturing.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an NCMA quaternary cathode material, characterized in that, Includes the following steps: Step 1: Prepare NCMA precursor using co-precipitation method; Step 2: Radial NCMA quaternary cathode material is prepared by solid-phase one-time calcination; Step 3: The prepared radial NCMA quaternary cathode material is subjected to acid phosphate attachment and secondary calcination to obtain the radial NCMA quaternary cathode material after acid phosphate attachment. The acidic phosphate is Zr(HPO4)2·H2O; Step 2 specifically involves: mixing the NCMA precursor with LiOH and a directional growth inducer to obtain a mixture; subjecting the mixture to a first calcination to obtain a material after one calcination; cooling and pulverizing the first calcined material to obtain a radial NCMA quaternary cathode material with a particle size of 6–20 μm; the molar ratio of the NCMA precursor, LiOH, and directional growth inducer is 1: 1–1.06: 0.001–0.

01.

2. The method for preparing the NCMA quaternary cathode material according to claim 1, characterized in that, The chemical formula of the NCMA quaternary cathode material is LiNi. w Co x Mn y Al z O2, where 0.88≤w≤0.95, 0.03≤x≤0.06, 0.01≤y≤0.03, 0.01≤z≤0.03, and w+x+y+z=1.

3. The method for preparing the NCMA quaternary cathode material according to claim 1, characterized in that, The mass ratio of the NCMA quaternary cathode material to the acid phosphate is 0.001 to 0.05:

1.

4. The method for preparing the NCMA quaternary cathode material according to claim 1, characterized in that, The thickness of the coating layer of the radial NCMA quaternary cathode material is 10–50 nm.

5. The method for preparing the NCMA quaternary cathode material according to claim 1, characterized in that, In step 3, the temperature of the second roasting is 400-600℃, the time of the second roasting is 5-10 hours, and the second roasting is carried out in an oxygen atmosphere.

6. The method for preparing the NCMA quaternary cathode material according to claim 1, characterized in that, The directional growth inducer is WO3.

7. The method for preparing the NCMA quaternary cathode material according to claim 1, characterized in that, The mixing is a dry mixing process. The temperature of the first calcination is 700-850℃, the time of the first calcination is 10-20 hours, and the first calcination is carried out in an oxygen atmosphere.

8. The NCMA quaternary cathode material prepared by the preparation method according to any one of claims 1-7.

9. An all-solid-state battery, characterized in that, The NCMA quaternary cathode material of claim 8 is used.

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