Lithium-rich manganese-based positive electrode material and preparation method therefor, positive electrode and battery

Abstract

The present application relates to the technical field of battery materials, and discloses a lithium-rich manganese-based positive electrode material and a preparation method therefor, a positive electrode and a battery. The preparation method comprises: mixing and sintering a lithium source and a lithium-rich manganese-based precursor, with a ratio of the molar amount of lithium to the total molar amount of metals in the precursor being (1-1.05)+x:1, wherein the lithium-rich manganese-based precursor is at least one of MnxM1-x(OH)a, MnxM1-xOb and MnxM1-x(CO3)c, where 0.05≤x＜0.50; the lithium source is diffused to form lithium-rich Li2MnO3 during the sintering process, and the remaining metal M forms a high-ion-conductivity channel structure in an Mn-deficient state; and the metal M is selected from at least one of Ni, Co, Al, Ti, Mg, Zr, Nb, Cr, Fe, Se, Ru, Sb, Ir, Sn, Y, Sr, W, Mo and V. The preparation method is simple, and can prepare a positive electrode material with a good rate capability and a high charging and discharging rate.

Description

Lithium-rich manganese-based positive electrode material, preparation method thereof, positive electrode and battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to application number 2024103385245 filed with the China Patent Office on March 22, 2024, entitled “Lithium-rich manganese-based positive electrode material, preparation method thereof, positive electrode and battery”, the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present application relates to the technical field of battery materials, and in particular to a lithium-rich manganese-based positive electrode material and a preparation method thereof, a positive electrode, and a battery. Background Art

[0004] Lithium-rich manganese-based cathode materials are an important material for lithium-ion batteries, offering high specific capacity and low cost. However, due to the limited diffusion of lithium ions in these materials, their rate performance is poor. Furthermore, direct contact with the electrolyte can easily lead to side reactions, resulting in unstable material structure, unstable cycling, rapid voltage drop, and low initial efficiency.

[0005] Several solutions have been proposed to improve the rate performance of lithium-rich manganese-based cathode materials. For example, surface coating or doping with other elements can improve the material's conductivity and increase ion diffusion rate, as described in patents CN116639740A and CN115548290A. Furthermore, as proposed in patent CN110364713B, conductive additives such as carbon nanotubes can be used to enhance the material's conductivity.

[0006] However, existing technologies present several challenges. For example, improving electronic conductivity through surface coating or doping, as well as the use of specialized conductive additives, often introduces additional preparation steps, increasing production costs. Furthermore, existing approaches struggle to simultaneously balance capacity, initial efficiency, and cycling stability, making it difficult to simultaneously improve these multiple properties.

[0007] In view of this, this application is hereby filed.

[0008] Summary of the Invention

[0009] The purpose of this application is to provide a preparation method of a lithium-rich manganese-based positive electrode material, a lithium-rich manganese-based positive electrode material, a positive electrode and a battery.

[0010] This application is implemented as follows:

[0011] In a first aspect, the present application provides a method for preparing a lithium-rich manganese-based positive electrode material, comprising:

[0012] The lithium source and the lithium-rich manganese precursor are mixed and sintered in a ratio of the molar amount of lithium to the molar amount of the total metal in the precursor of (1 to 1.05) + x:1. The lithium-rich manganese precursor is Mn x M 1-x (OH) a 、Mn x M 1-x O b and Mn x M 1-x (CO3) c At least one of the following, wherein 0.05≤x<0.50, and the values ​​of a, b and c are such that the corresponding chemical formula valence is zero;

[0013] During the sintering process, the lithium source diffuses to form lithium-rich Li2MnO3, and the remaining metal M forms a high ion conductivity channel structure in the Mn-deficient state;

[0014] The metal M is selected from at least one of Ni, Co, Al, Ti, Mg, Zr, Nb, Cr, Fe, Se, Ru, Sb, Ir, Sn, Y, Sr, W, Mo and V.

[0015] In an optional embodiment, the content of the Mn element in the Mn-deficient high ion conductance channel structure accounts for 0 to 10% of the molar amount of the metal element in the Mn-deficient high ion conductance channel structure.

[0016] In an optional embodiment, the value of x ranges from 0.1 to 0.48;

[0017] In an optional embodiment, the mixed sintering method includes:

[0018] After the precursor and the lithium source are evenly mixed, the temperature is raised to 300-600° C. in an air or oxygen atmosphere and kept warm for 3-8 hours; then the temperature is raised to 700-1000° C. and kept warm for 9-16 hours.

[0019] In an optional embodiment, the precursor and the lithium source are mixed uniformly by ball milling or jar milling.

[0020] In an optional embodiment, the lithium source is selected from at least one of lithium carbonate and lithium hydroxide.

[0021] In a second aspect, the present application provides a lithium-rich manganese-based positive electrode material, which is prepared using the preparation method of any of the aforementioned embodiments.

[0022] In a third aspect, the present application provides a positive electrode, the raw materials for preparing the positive electrode include the lithium-rich manganese-based positive electrode material as described in the aforementioned embodiment.

[0023] In a fourth aspect, the present application provides a battery comprising a positive electrode as described in the aforementioned embodiment.

[0024] This application has the following beneficial effects:

[0025] The preparation method provided by the present application has a molar amount of manganese in the selected precursor in the range of 0.05≤x<0.50. Compared with the existing lithium-rich manganese precursor, its proportion is small. During the sintering process, a three-dimensional manganese-deficient high ion conductivity channel can be formed in the agglomerated structure of the lithium-rich manganese-based positive electrode material. The formation of this channel greatly improves the problem of poor rate performance of the lithium-rich manganese-based positive electrode material and improves the charge and discharge rate of the battery. The formed high ion conductivity channel structure in the Mn-deficient state also reduces the direct contact between the lithium-rich manganese-based material and the electrolyte, thereby improving the stability of the structure. The preparation method provided by the present application is simple and can be sintered in one time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0027] FIG1 is an XRD diffraction pattern of Example 1 compared with Comparative Example 1;

[0028] FIG2 is a partially enlarged XRD diffraction pattern of Example 1 compared with Comparative Example 1;

[0029] FIG3 is a graph showing the charge-withdrawal rate performance in the voltage range of 2-4.4V after activation of the lithium-rich manganese structure at above 4.5V in comparison with Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0031] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0032] The lithium-rich manganese-based positive electrode material and its preparation method provided in the embodiments of the present application are described in detail below.

[0033] The method for preparing the lithium-rich manganese-based positive electrode material provided in the embodiment of the present application includes:

[0034] The lithium source and the lithium-rich manganese precursor are mixed and sintered in a ratio of the molar amount of lithium to the molar amount of the total metal in the precursor of (1-1.05) + x:1. The lithium-rich manganese precursor is Mnx M 1-x (OH) a 、Mn x M 1-x O b and Mn x M 1-x (CO3) c At least one of the following, wherein 0.05≤x<0.50, and the values ​​of a, b and c are such that the corresponding chemical formula valence is zero;

[0035] During the sintering process, the lithium source diffuses to form lithium-rich Li2MnO3, and the remaining metal M forms a high ion conductivity channel structure in the Mn-deficient state;

[0036] The metal M is selected from at least one of Ni, Co, Al, Ti, Mg, Zr, Nb, Cr, Fe, Se, Ru, Sb, Ir, Sn, Y, Sr, W, Mo and V.

[0037] The preparation method of the lithium-rich manganese-based positive electrode material provided in the embodiment of the present application, the molar amount of manganese in the selected precursor is in the range of 0.05≤x<0.50 (for example, 0.05, 0.1, 0.2, 0.3, 0.4, 0.48, 0.49 or 0.499), which is smaller than the existing lithium-rich manganese precursor. During the sintering process, a three-dimensional manganese-deficient high ion conductivity channel can be formed in the agglomerated structure of the lithium-rich manganese-based positive electrode material. The formation of this channel greatly improves the problem of poor rate performance of the lithium-rich manganese-based positive electrode material and improves the charge and discharge rate of the battery. The formed high ion conductivity channel structure in the Mn-deficient state also reduces the direct contact between the lithium-rich manganese-based material and the electrolyte, thereby improving the stability of the structure. The preparation method provided by the present application is simple and can be sintered in one time.

[0038] Preferably, in order to ensure that the lithium-rich manganese-based positive electrode material has better performance, x is 0.1 to 0.48 (eg, 0.1, 0.2, 0.3, 0.4 or 0.48).

[0039] Furthermore, the preparation method is specifically as follows:

[0040] S1, mixed

[0041] The lithium-rich manganese-based precursor and the lithium source are uniformly mixed. Specifically, the uniform mixing is achieved by, for example, ball milling or pot milling. It should be noted that other mechanical mixing methods that can achieve uniform mixing of the two are also feasible.

[0042] Optionally, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide, lithium nitrate, lithium acetate and lithium oxide.

[0043] S2. Sintering

[0044] After the precursor and the lithium source are evenly mixed, the temperature is raised to 300-600°C (e.g., 300°C, 400°C, 500°C, or 600°C) in air or oxygen atmosphere and kept warm for 3-8h (e.g., 3h, 4h, 5h, 6h, or 8h); then the temperature is raised to 700-1000°C (700°C, 800°C, 900°C, or 1000°C) and kept warm for 9-16h (9h, 12h, or 16h).

[0045] During the entire sintering process, the lithium source diffuses and lithium-rich Li2MnO3 is formed in situ, and the remaining metal M forms a Mn-deficient high ion conductivity channel structure LiMO2, which is equivalent to forming a high ion conductivity three-dimensional channel around the low conductivity and high gram capacity lithium-rich manganese Li2MnO3, so that the final lithium-rich manganese-based positive electrode material exhibits excellent overall performance.

[0046] Furthermore, the prepared Mn-deficient high ion conductance channel structure (LiMO2) may contain a small amount of Mn element, and the Mn element content accounts for 0-10% of the molar amount of the metal elements in the Mn-deficient high ion conductance channel structure, and can exhibit significantly excellent performance.

[0047] The lithium-rich manganese-based positive electrode material provided in the embodiments of the present application is prepared using the preparation method provided in the embodiments of the present application.

[0048] The positive electrode provided in the embodiment of the present application is prepared from raw materials including the lithium-rich manganese-based positive electrode material provided in the embodiment of the present application.

[0049] The battery provided in the embodiment of the present application includes the positive electrode provided in the embodiment of the present application.

[0050] Example 1

[0051] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, specifically:

[0052] Lithium-rich manganese-based precursor: Mn 0.4 Ni 0.5 Co 0.1 (OH)2; lithium source: lithium hydroxide.

[0053] The lithium hydroxide and the lithium-rich manganese-based precursor are mixed and ball-milled at a molar ratio of lithium to metal elements in the precursor of 1.43:1 to obtain two separate and evenly mixed mixtures;

[0054] The mixed material was placed in a sintering device, air was introduced into the device, the temperature was raised to 500°C, and sintered for 5 hours, then the temperature was raised to 800°C, and sintered for 10 hours.

[0055] A lithium-rich manganese-based positive electrode material is obtained, in which the Mn element content in the high ion conductivity channel structure accounts for 1.5% of the total molar amount of metal elements in the structure.

[0056] Example 2

[0057] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, specifically:

[0058] Lithium-rich manganese-based precursor: Mn 0.1 Ni 0.8 Co 0.05 Al 0.05 (OH)2; lithium source: lithium carbonate.

[0059] The lithium carbonate and the lithium-rich manganese-based precursor are mixed and ball-milled at a molar ratio of lithium to metal elements in the precursor of 1.15:1 to obtain two separate and evenly mixed mixtures;

[0060] The mixed material was placed in a sintering device, air was introduced into the device, the temperature was raised to 500°C, and sintered for 6 hours, then the temperature was raised to 850°C, and sintered for 12 hours.

[0061] A lithium-rich manganese-based positive electrode material was obtained, in which the Mn element content in the high ion conductivity channel structure accounted for 2.1% of the total molar amount of metal elements in the structure.

[0062] Example 3

[0063] This embodiment provides a method for preparing a lithium-rich manganese-based positive electrode material, specifically:

[0064] Lithium-rich manganese-based precursor: Mn 0.48 Ni 0.4 Al 0.1 Zr 0.02 (OH)2; lithium source: lithium carbonate.

[0065] The lithium hydroxide and the lithium-rich manganese-based precursor are mixed and ball-milled at a molar ratio of lithium to metal elements in the precursor of 1.5:1 to obtain two separate and evenly mixed mixtures;

[0066] The mixed material was placed in a sintering device, air was introduced into the device, the temperature was raised to 600°C, and sintered for 8 hours, then the temperature was raised to 900°C, and sintered for 9 hours.

[0067] A lithium-rich manganese-based positive electrode material is obtained, in which the Mn element content in the high ion conductivity channel structure accounts for 4% of the total molar amount of metal elements in the structure.

[0068] Example 4

[0069] This embodiment is basically the same as embodiment 1, except that: the lithium-rich manganese-based precursor: Mn 0.4 Ni 0.6 (OH)2.

[0070] Example 5

[0071] This embodiment is basically the same as embodiment 1, except that: the lithium-rich manganese-based precursor: Mn 0.2 Ni 0.6 Co 0.2 CO3.

[0072] Comparative Example 1

[0073] This comparative example is basically the same as Example 1, except that: the lithium-rich manganese-based precursor: Mn 0.6 Ni 0.3 Co 0.1 (OH)2.

[0074] Comparative Example 2

[0075] This comparative example is basically the same as Example 1, except that: the lithium-rich manganese-based precursor: Mn 0.65 Ni 0.35 (OH)2.

[0076] Experimental Example 1

[0077] (1) The phase composition of the lithium-rich manganese-based positive electrode materials prepared in Example 1 and Comparative Example 1 was tested, and the XRD patterns shown in Figures 1 and 2 were obtained. It can be seen from Figures 1 and 2 that the lithium-rich manganese-based positive electrode material prepared in Example 1 is mainly composed of Li2MnO3 and LiMO2, showing that the diffraction peak position is significantly shifted, and the crystal interlayer spacing of the manganese-deficient high ion conductivity channel is reduced compared with the manganese-rich channel.

[0078] (2) The electrochemical properties of the lithium-rich manganese-based positive electrode materials prepared in each embodiment and comparative example were tested. The specific testing method is as follows:

[0079] A lithium-rich manganese-based cathode material, PVDF, and conductive carbon are mixed in a ratio of 8:1:1 to form a uniform slurry, which is then coated, dried, and punched out to form the positive electrode. Lithium metal is used as the negative electrode. A liquid electrolyte containing a lithium salt and a separator are added, and the mechanical parts are assembled to form a button-type half-cell.

[0080] At a rate of 0.1C, after activation above 4.5V, the rate performance was tested in the range of 2-4.4V, and the discharge capacity in grams is shown in Table 1.

[0081] Table 1 Electrochemical performance test results of lithium-rich manganese-based positive electrode materials prepared in various embodiments and comparative examples

[0082] As can be seen from Table 1, the lithium-rich manganese-based positive electrode materials prepared in each embodiment of the present application all have good rate discharge performance;

[0083] Comparing Example 1 with Comparative Examples 1 and 2, Example 1 has higher rate performance, which shows that a lithium-rich manganese-based positive electrode material with higher rate performance can be produced by using a precursor with a molar ratio of Mn element less than 0.5 as a raw material and sintering a high ion conductivity channel in a manganese-deficient state.

[0084] In summary, the preparation method of the lithium-rich manganese-based positive electrode material provided in the embodiment of the present application has a molar amount of manganese in the selected precursor in the range of 0.05≤x<0.50. Compared with the existing lithium-rich manganese precursor, its proportion is small. During the sintering process, a three-dimensional manganese-deficient high ion conductivity channel can be formed in the agglomerated structure of the lithium-rich manganese-based positive electrode material. The formation of this channel greatly improves the problem of poor rate performance of the lithium-rich manganese-based positive electrode material and improves the charge and discharge rate of the battery. The formed Mn-deficient high ion conductivity channel structure also reduces the direct contact between the lithium-rich manganese-based material and the electrolyte, thereby improving the stability of the structure.

[0085] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application. Industrial Applicability

[0086] The preparation method of the lithium-rich manganese-based positive electrode material provided in this application has a molar amount of manganese in the selected precursor in the range of 0.05≤x<0.50. Compared with the existing lithium-rich manganese precursor, its proportion is small. During the sintering process, a three-dimensional manganese-deficient high ion conductivity channel can be formed in the agglomerated structure of the lithium-rich manganese-based positive electrode material. The formation of this channel greatly improves the problem of poor rate performance of the lithium-rich manganese-based positive electrode material and improves the charge and discharge rate of the battery. The formed high ion conductivity channel structure in the Mn-deficient state also reduces the direct contact between the lithium-rich manganese-based material and the electrolyte, thereby improving the stability of the structure.

Claims

1. A method for preparing a lithium-rich manganese-based positive electrode material, characterized in that: include: The lithium source and the lithium-rich manganese precursor are mixed and sintered in a ratio of the molar amount of lithium to the molar amount of the total metal in the precursor of (1-1.05) + x:

1. The lithium-rich manganese precursor is Mn x M 1-x (OH) a 、Mn x M 1-x O b and Mn x M 1-x (CO3) c At least one of the following, wherein 0.05≤x<0.50, and the values ​​of a, b and c are such that the corresponding chemical formula valence is zero; During the sintering process, the lithium source diffuses to form lithium-rich Li2MnO3, and the remaining metal M forms a high ion conductivity channel structure in the Mn-deficient state; The metal M is selected from at least one of Ni, Co, Al, Ti, Mg, Zr, Nb, Cr, Fe, Se, Ru, Sb, Ir, Sn, Y, Sr, W, Mo and V.

2. The preparation method according to claim 1, characterized in that The lithium-rich manganese precursor is Mn 0.4 Ni 0.5 Co 0.1 (OH)2、Mn 0.1 Ni 0.8 Co 0.05 Al 0.05 (OH)2、Mn 0.48 Ni 0.4 Al 0.1 Zr 0.02 (OH)2、Mn 0.4 Ni 0.6 (OH)2 and Mn 0.2 Ni 0.6 Co 0.2 At least one of CO3.

3. The preparation method according to claim 1, characterized in that The lithium-rich manganese precursor is Mn 0.4 Ni 0.5 Co 0.1 (OH)2、Mn 0.1 Ni 0.8 Co 0.05 Al 0.05 (OH)2、Mn 0.48 Ni 0.4 Al 0.1 Zr 0.02 (OH)2、Mn 0.4 Ni 0.6 (OH)2、Mn 0.3 Ni 0.5 Co 0.2 (OH)2、Mn 0.2 Ni 0.6 Co 0.2 (OH)2、Mn 0.1 Ni 0.8 Co 0.1 (OH)2、Mn 0.33 Ni 0.33 Co 0.33 (OH)2、Mn 0.4 Ni 0.5 Co 0.1 CO3、Mn 0.1 Ni 0.8 Co 0.05 Al 0.05 CO3、Mn 0.48 Ni 0.4 Al 0.1 Zr 0.02 CO3、Mn 0.4 Ni 0.6 CO3、Mn 0.2 Ni 0.6 Co 0.2 CO3、Mn 0.3 Ni 0.5 Co 0.2 CO3、Mn 0.2 Ni 0.6 Co 0.2 CO3、Mn 0.1 Ni 0.8 Co 0.1 CO3 and Mn 0.33 Ni 0.33 Co 0.33 At least one of CO3.

4. The preparation method according to claim 1, characterized in that The lithium-rich manganese precursor is Mn 0.4 Ni 0.5 Co 0.1 (OH)2、Mn 0.1 Ni 0.8 Co 0.05 Al 0.05 (OH)2、Mn 0.48 Ni 0.4 Al 0.1 Zr 0.02 (OH)2、Mn 0.4 Ni 0.6 (OH)2、Mn 0.3 Ni 0.5 Co 0.2 (OH)2、Mn 0.2 Ni 0.6 Co 0.2 (OH)2、Mn 0.1 Ni 0.8 Co 0.1 (OH)2、Mn 0.33 Ni 0.33 Co 0.33 (OH)2、Mn 0.4 Ni 0.5 Co 0.1 CO3、Mn 0.1 Ni 0.8 Co 0.05 Al 0.05 CO3、Mn 0.48 Ni 0.4 Al 0.1 Zr 0.02 CO3、Mn 0.4 Ni 0.6 CO3、Mn 0.2 Ni 0.6 Co 0.2 CO3、Mn 0.3 Ni 0.5 Co 0.2 CO3、Mn 0.2 Ni 0.6 Co 0.2 CO3、Mn 0.1 Ni 0.8 Co 0.1 CO3 or Mn 0.33 Ni 0.33 Co 0.33 CO3.

5. The preparation method according to any one of claims 1 to 4, characterized in that The content of the Mn element in the Mn-deficient high ion conductance channel structure accounts for 0 to 10% of the molar amount of the metal element in the Mn-deficient high ion conductance channel structure.

6. The preparation method according to claim 5, characterized in that The content of the Mn element in the Mn-deficient high ion conductance channel structure accounts for 1.5 to 4% of the molar amount of the metal element in the Mn-deficient high ion conductance channel structure.

7. The preparation method according to any one of claims 1 to 6, characterized in that Mixed sintering methods include: After the precursor and the lithium source are uniformly mixed, the temperature is raised to 300-600° C. in an air or oxygen atmosphere and kept warm for 3-8 hours; then the temperature is raised to 700-1000° C. and kept warm for 9-16 hours.

8. The preparation method according to claim 7, characterized in that The precursor and the lithium source are uniformly mixed by ball milling or pot milling.

9. The preparation method according to any one of claims 1 to 8, characterized in that The lithium source is selected from at least one of lithium carbonate, lithium hydroxide, lithium nitrate, lithium oxide and lithium acetate.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The value range of x is 0.1 to 0.

48.

11. A lithium-rich manganese-based positive electrode material, characterized in that: The method is as claimed in any one of claims 1 to 10.

12. A positive electrode, characterized in that The raw materials for its preparation include the lithium-rich manganese-based positive electrode material as claimed in claim 11.

13. A battery, characterized in that: Comprising the positive electrode as claimed in claim 12.

14. The battery according to claim 13, characterized in that The battery is a battery cell or a battery pack.

15. An electrical appliance, characterized in that: The power source is a battery as claimed in claim 13 or 14.

16. The electrical appliance according to claim 15, characterized in that The electrical appliance is an electric car.

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