Metal element doped manganese-based lithium supplementing agent and preparation method and application thereof

Abstract

The invention provides a metal element doped manganese-based lithium supplement agent and a preparation method and application thereof, and belongs to the field of lithium batteries. The invention provides a metal element doped manganese-based lithium supplement agent. The metal element doped manganese-based lithium supplement agent comprises a manganese-based lithium supplement agent and metal elements doped in the manganese-based lithium supplement agent, the metal element is connected with oxygen in the manganese-based lithium supplementing agent through a chemical bond; the manganese-based lithium supplement agent comprises a composite lithium manganese oxide formed by antifluorite type Li6MnO4 and layered LiMnO2; the average chemical composition of the composite lithium manganese oxide is xLi < 6 > MnO < 4 >. (1-x) LiMnO < 2 > (x is more than or equal to 0.3 and less than or equal to 1). Metal elements and oxygen elements are connected through strong chemical bonds, lattice oxygen of the manganese-based lithium supplement agent can be effectively stabilized, so that gas production and manganese dissolution of the lithium supplement agent are inhibited, polarization of the manganese-based lithium supplement agent is reduced, and the manganese-based lithium supplement agent can be applied to lithium supplement of the positive electrode side of a lithium ion battery and is beneficial to improvement of the energy density and long cycle life of the lithium ion battery.

Description

Technical Field

[0001] The present invention relates to the field of lithium batteries, and in particular to a metal element doped manganese-based lithium supplement agent and a preparation method and application thereof. Background Art

[0002] With the continuous advancement of transportation electrification and large-scale energy storage, the current electrochemical performance of lithium-ion batteries has become increasingly difficult to meet the needs of rapid development, and there is an urgent need to significantly improve the key performance of lithium-ion batteries, such as energy density and long cycle life.

[0003] Lithium supplementation on the positive electrode side is an effective method for optimizing battery performance and has received great attention from the battery industry in recent years. Adding a lithium supplement to the positive electrode material or positive electrode sheet can compensate for the irreversible lithium ion loss of lithium-ion batteries during the charge and discharge process, make up for the lithium ions consumed by the formation of the solid electrolyte-interface phase (SEI), and improve the battery energy density and long cycle performance. The positive electrode lithium supplement generally needs to release lithium ions during the first cycle of charging to compensate for the irreversible lithium ion loss. Therefore, the requirements for the positive electrode lithium supplement include: (1) high first cycle charge capacity, at least higher than the positive electrode material itself, otherwise the battery energy density will be reduced; (2) low first cycle discharge capacity, that is, lithium ions do not need to be embedded back into the lithium supplement, which also corresponds to a low first cycle coulomb efficiency; (3) suitable or low charging voltage, which means that the lithium supplement can release lithium ions more easily. Among the many lithium supplements, the composite lithium manganese oxide Li6MnO4·(1-x)LiMnO2 (0.3≤x≤1) formed by anti-fluorite Li6MnO4 and layered LiMnO2 has outstanding advantages such as high first-cycle charging capacity (>600mAh / g), low first-cycle discharge capacity (<100mAh / g), low cost, and environmental friendliness. It is an excellent positive electrode lithium supplement for lithium-ion batteries. However, this manganese-based lithium supplement still has many problems, including severe gas production, significant manganese dissolution, and large electrochemical polarization. Therefore, it is urgent to modify this type of manganese-based lithium supplement to meet the needs of practical applications. Summary of the invention

[0004] The present invention provides a metal element doped manganese-based lithium supplement agent, a preparation method and an application thereof. The metal element doped manganese-based lithium supplement agent of the present invention can inhibit the gas production and manganese dissolution of the lithium supplement agent, and reduce the polarization of the manganese-based lithium supplement agent.

[0005] The present invention provides a metal element doped manganese-based lithium supplement, comprising a manganese-based lithium supplement and a metal element doped in the manganese-based lithium supplement; the metal element is connected to oxygen in the manganese-based lithium supplement through a chemical bond;

[0006] The manganese-based lithium supplement comprises a composite lithium manganese oxide formed by anti-fluorite Li6MnO4 and layered LiMnO2;

[0007] The average chemical composition of the composite lithium manganese oxide is xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1).

[0008] Preferably, the metal element includes one or more of Al, Mg, Ti, Co, Ni, Fe, Cu, V, Ti, Cr, Nb, Ta, W, Mo, Zn, Ru, Rh, Ir and Pt.

[0009] Preferably, the amount of the metal element is 0.01 to 5% of the amount of the manganese element.

[0010] The present invention also provides a method for preparing the metal element doped manganese-based lithium supplement agent described in the above technical solution, comprising the following steps:

[0011] Mixing a manganese-based lithium supplement agent with a compound containing a metal element to obtain a manganese-based lithium supplement agent coated with the compound containing the metal element;

[0012] The manganese-based lithium supplement agent coated with the metal element-containing compound is subjected to heat treatment, and the metal element migrates into the bulk phase of the manganese-based lithium supplement agent to obtain the metal element-doped manganese-based lithium supplement agent.

[0013] Preferably, the compound containing the metal element includes one or more of an oxide corresponding to the metal element, a hydroxide corresponding to the metal element, a phosphate corresponding to the metal element, a carbonate corresponding to the metal element, an acetate corresponding to the metal element, and an oxalate corresponding to the metal element.

[0014] Preferably, the particle size of the manganese-based lithium supplement agent is 0.1 to 10 μm, and the particle size of the compound containing the metal element is 1 to 100 nm.

[0015] Preferably, the mixing is carried out in a high-speed mixer, the rotation speed of the blades in the high-speed mixer is 200-4000 rpm; the mixing temperature is 10-30° C., and the mixing time is 2-60 min.

[0016] Preferably, the heat treatment temperature is 300-1000° C., and the insulation time is 1-100 h.

[0017] Preferably, the heating rate to the heat treatment temperature is 1 to 10° C. / min.

[0018] The present invention also provides the use of the metal element doped manganese-based lithium supplement agent described in the above technical solution or the metal element doped manganese-based lithium supplement agent prepared by the preparation method described in the above technical solution in a lithium battery.

[0019] The metal element in the metal element-doped manganese-based lithium supplementer of the present invention is connected to the oxygen element through a strong chemical bond, which can effectively stabilize the lattice oxygen of the manganese-based lithium supplementer, thereby inhibiting the gas production and manganese dissolution of the lithium supplementer, and reducing the polarization of the manganese-based lithium supplementer. It can be applied to lithium supplementation on the positive electrode side of lithium ion batteries, which is beneficial to improving the energy density and long cycle life of lithium ion batteries.

[0020] The preparation method of the metal element doped manganese-based lithium supplement agent of the present invention is simple and easy to scale up, and can be practically applied in the lithium ion battery industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart of preparing a metal element doped manganese-based lithium supplement agent in an embodiment;

[0022] Figure 2 DEMS test results of Co-doped manganese-based lithium supplement agent in Example 1;

[0023] Figure 3 The first cycle charge and discharge curves of the soft-pack battery without adding lithium supplement and adding the manganese-based lithium supplement of Example 1. DETAILED DESCRIPTION

[0024] The present invention provides a metal element doped manganese-based lithium supplement, comprising a manganese-based lithium supplement and a metal element doped in the manganese-based lithium supplement; the metal element is connected to oxygen in the manganese-based lithium supplement through a chemical bond;

[0025] The manganese-based lithium supplement comprises a composite lithium manganese oxide formed by anti-fluorite Li6MnO4 and layered LiMnO2;

[0026] The average chemical composition of the composite lithium manganese oxide is xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1).

[0027] In the present invention, the amount of the metal element is preferably 0.01-5% of the amount of the manganese element. In a specific embodiment of the present invention, the amount of the metal element can be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5% of the amount of the manganese element. The metal element preferably includes one or more of Al, Mg, Ti, Co, Ni, Fe, Cu, V, Ti, Cr, Nb, Ta, W, Mo, Zn, Ru, Rh, Ir and Pt.

[0028] The present invention also provides a method for preparing the metal element doped manganese-based lithium supplement agent described in the above technical solution, comprising the following steps:

[0029] Mixing a manganese-based lithium supplement agent with a compound containing a metal element to obtain a manganese-based lithium supplement agent coated with the compound containing the metal element;

[0030] The manganese-based lithium supplement agent coated with the metal element-containing compound is subjected to heat treatment, and the metal element migrates into the bulk phase of the manganese-based lithium supplement agent to obtain the metal element-doped manganese-based lithium supplement agent.

[0031] The invention mixes a manganese-based lithium supplement agent with a compound containing a metal element to obtain a manganese-based lithium supplement agent coated with the compound containing the metal element.

[0032] In the present invention, the particle size of the manganese-based lithium supplement agent is preferably 0.1-10 μm. In a specific embodiment of the present invention, the particle size of the manganese-based lithium supplement agent may be 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm; the particle size of the compound containing metal elements is preferably 1-100 nm. In a specific embodiment of the present invention, the particle size of the compound containing metal elements may be 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0033] In the present invention, the compound containing metal elements preferably includes one or more of oxides corresponding to the metal elements, hydroxides corresponding to the metal elements, phosphates corresponding to the metal elements, carbonates corresponding to the metal elements, acetates corresponding to the metal elements and oxalates corresponding to the metal elements. In a specific embodiment of the present invention, the compound containing metal elements may be oxides corresponding to the metal elements.

[0034] In the present invention, the mixing is preferably carried out in a high mixer, and the rotation speed of the blade in the high mixer is preferably 200-4000rpm. In a specific embodiment of the present invention, the rotation speed of the blade in the high mixer may be 200rpm, 500rpm, 1000rpm, 1500rpm, 2000rpm, 2500rpm, 3000rpm, 3500rpm or 4000rpm; the mixing temperature is preferably 10-30°C, and the time is preferably 2-60min. In a specific embodiment of the present invention, the mixing temperature may be 10°C, 20°C or 30°C; and the time may be 2min, 10min, 20min, 30min, 40min, 50min or 60min.

[0035] During the mixing, the metal compound nanoparticles act as a doping source and are coated on the surface of the manganese-based lithium supplement due to electrostatic adsorption.

[0036] After obtaining the manganese-based lithium supplement agent coated with the compound containing metal elements, the present invention heat treats the manganese-based lithium supplement agent coated with the compound containing metal elements, and the metal elements migrate into the bulk phase of the manganese-based lithium supplement agent to obtain the metal element-doped manganese-based lithium supplement agent.

[0037] In the present invention, the temperature of the heat treatment is preferably 300-1000°C, and the holding time is preferably 1-100h. In a specific embodiment of the present invention, the temperature of the heat treatment can be 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C or 1000°C, and the time can be 1h, 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h or 100h.

[0038] In the present invention, the heating rate to the temperature of the heat treatment is preferably 1 to 10°C / min. In a specific embodiment of the present invention, the heating rate can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min.

[0039] In the present invention, the atmosphere of the heat treatment preferably includes an air atmosphere, an oxygen atmosphere, a nitrogen atmosphere, or an argon atmosphere.

[0040] The present invention also provides the use of the metal element doped manganese-based lithium supplement agent described in the above technical solution or the metal element doped manganese-based lithium supplement agent prepared by the preparation method described in the above technical solution in a lithium battery.

[0041] Figure 1 The flow chart of the preparation of metal element doped manganese-based lithium supplement agent for example is as follows: the manganese-based lithium supplement agent and the compound (nanoparticles) containing the metal element are highly mixed to form a nanoparticle-coated manganese-based lithium supplement agent, and then the nanoparticle-coated manganese-based lithium supplement agent is heat-treated to obtain the metal element doped manganese-based lithium supplement agent.

[0042] The metal element doped manganese-based lithium supplement agent provided by the present invention and its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0043] Example 1

[0044] In air, dry manganese-based oxide lithium supplement (0.1-5 μm) 0.9Li6MnO4·0.1LiMnO2 and Co3O4 nanoparticles are placed in a high-speed mixer. The molar ratio of Co element to Mn element is 2%, and the median particle size D50 of Co3O4 nanoparticles is 10 nm.

[0045] At room temperature, the manganese-based oxide lithium supplement and Co3O4 nanoparticles were mixed at a blade speed of 2000 rpm for 10 minutes. After standing, the solid material was collected to obtain the manganese-based lithium supplement coated with Co3O4 nanoparticles.

[0046] The manganese-based lithium supplement agent coated with Co3O4 nanoparticles is placed in a tubular furnace, heated to 800°C at a heating rate of 2°C / min in an air atmosphere, and then kept at 800°C for 24 hours, and then naturally cooled to room temperature to obtain a Co element doped manganese-based lithium supplement agent.

[0047] Figure 2 This is the DEMS test result of the Co-doped manganese-based lithium supplement agent in Example 1.

[0048] Depend on Figure 2 It can be seen that the release of O2 is significantly inhibited during the electrochemical process of Co-doped manganese-based lithium supplement.

[0049] The manganese-based lithium supplement agent, the conductive agent, the binder and the lithium iron phosphate are homogenized together by a homogenizer to obtain a positive electrode slurry; wherein the mass of the manganese-based lithium supplement agent is 2% of the total mass of the conductive agent, the binder, the lithium iron phosphate and the manganese-based lithium supplement agent, the conductive agent superP carbon is 2.5% of the total mass of the conductive agent, the binder, the lithium iron phosphate and the manganese-based lithium supplement agent, and the binder PVDF is 2.5% of the total mass of the conductive agent, the binder, the lithium iron phosphate and the manganese-based lithium supplement agent; the positive electrode slurry is coated on an aluminum current collector by a coating machine to prepare a positive electrode plate; a 100mAh lithium-ion soft-pack battery is assembled with the above-mentioned positive electrode plate and the graphite negative electrode plate, and the N / P ratio is 1.1, and liquid injection, formation and testing are performed.

[0050] Figure 3 The first cycle charge and discharge curves of the soft-pack battery without adding lithium supplement (wherein the mass of lithium iron phosphate is 95% of the total mass of the conductive agent, binder and lithium iron phosphate, the conductive agent superP carbon is 2.5% of the total mass of the conductive agent, binder and lithium iron phosphate, and the binder PVDF is the conductive agent, binder and lithium iron phosphate) and with adding the manganese-based lithium supplement in Example 1.

[0051] Depend on Figure 3 It can be seen that after adding the lithium supplement, the first cycle coulomb efficiency of the battery increased from 79.7% (comparative example) to 85.2%.

[0052] Example 2

[0053] In air, dry manganese-based oxide lithium supplement (0.1-5 μm) 0.9Li6MnO4·0.1LiMnO2 and Al2O3 nanoparticles are placed in a high-speed mixer, respectively. The molar ratio of Al element to Mn element is 1%, and the median particle size D50 of Al2O3 nanoparticles is 5 nm.

[0054] At room temperature, the manganese-based oxide lithium supplement and Al2O3 nanoparticles were mixed at a blade speed of 1800 rpm for 15 minutes. After standing, the solid material was collected to obtain the manganese-based lithium supplement coated with Al2O3 nanoparticles.

[0055] The manganese-based lithium supplement agent coated with Al2O3 nanoparticles is placed in a tubular furnace and heated to 850°C at a heating rate of 5°C / min in an air atmosphere. It is then kept at 850°C for 24 hours and then naturally cooled to room temperature to obtain an Al-doped manganese-based lithium supplement agent.

[0056] Example 3

[0057] In the air, dry manganese-based oxide lithium supplement (0.1-5 μm) 0.9Li6MnO4·0.1LiMnO2 and RuO2 nanoparticles are placed in a high-speed mixer. The molar ratio of Ru element to Mn element is 0.5%, and the median particle size D50 of RuO2 nanoparticles is 10 nm.

[0058] At room temperature, the manganese-based oxide lithium supplement and RuO2 nanoparticles were mixed at a blade speed of 2200 rpm for 25 minutes. After standing, the solid material was collected to obtain the manganese-based lithium supplement coated with RuO2 nanoparticles.

[0059] The manganese-based lithium supplement agent coated with RuO2 nanoparticles is placed in a tubular furnace and heated to 820°C at a heating rate of 2°C / min in an air atmosphere. It is then kept at 820°C for 40 hours and then naturally cooled to room temperature to obtain a Ru-doped manganese-based lithium supplement agent.

[0060] Example 4

[0061] In air, dry manganese-based oxide lithium supplement (0.1-5 μm) 0.9Li6MnO4·0.1LiMnO2 and (CH3COO)2Ni·4H2O nanoparticles were placed in a high-speed mixer. The molar ratio of Ni element to Mn element was 3%, and the median particle size D50 of (CH3COO)2Ni·4H2O nanoparticles was 20 nm.

[0062] At room temperature, the manganese-based oxide lithium supplement and (CH3COO)2Ni·4H2O nanoparticles were mixed at a blade speed of 1500 rpm for 15 minutes. After standing, the solid material was collected to obtain a manganese-based lithium supplement coated with (CH3COO)2Ni·4H2O nanoparticles.

[0063] The manganese-based lithium supplement agent coated with (CH3COO)2Ni·4H2O nanoparticles was placed in a tubular furnace and heated to 850°C at a heating rate of 2°C / min under an Ar atmosphere. The temperature was then kept at 850°C for 36 hours and then naturally cooled to room temperature to obtain a Ni-doped manganese-based lithium supplement agent.

[0064] Example 5

[0065] In the air, dry manganese-based oxide lithium supplement (0.1-5 μm) 0.9Li6MnO4·0.1LiMnO2 and Fe(OH)3 nanoparticles are placed in a high-speed mixer. The molar ratio of Fe element to Mn element is 4%, and the median particle size D50 of Fe(OH)3 nanoparticles is 20 nm.

[0066] At room temperature, the manganese-based oxide lithium supplement and Fe(OH)3 nanoparticles were mixed at a blade speed of 2000 rpm for 20 minutes. After standing, the solid material was collected to obtain a manganese-based lithium supplement coated with Fe(OH)3 nanoparticles.

[0067] The manganese-based lithium supplement agent coated with Fe(OH)3 nanoparticles was placed in a tubular furnace and heated to 900°C at a heating rate of 2°C / min under a N2 atmosphere. It was then kept at 900°C for 20 hours and then naturally cooled to room temperature to obtain an Fe-doped manganese-based lithium supplement agent.

[0068] Example 6

[0069] In air, dry manganese-based oxide lithium supplement (0.1-5 μm) 0.9Li6MnO4·0.1LiMnO2 and Mg(OH)2 nanoparticles are placed in a high-speed mixer. The molar ratio of Mg element to Mn element is 2%, and the median particle size D50 of Mg(OH)2 nanoparticles is 50 nm.

[0070] At room temperature, the manganese-based oxide lithium supplement and Mg(OH)2 nanoparticles were mixed at a blade speed of 2000 rpm for 20 minutes. After standing, the solid material was collected to obtain a manganese-based lithium supplement coated with Mg(OH)2 nanoparticles.

[0071] The manganese-based lithium supplement agent coated with Mg(OH)2 nanoparticles is placed in a tubular furnace and heated to 900°C at a heating rate of 2°C / min in an air atmosphere. It is then kept at 900°C for 20 hours and then naturally cooled to room temperature to obtain a Mg-doped manganese-based lithium supplement agent.

[0072] Example 7

[0073] In the air, dry manganese-based oxide lithium supplement (0.1-5 μm) 0.9Li6MnO4·0.1LiMnO2 and Cr(NO3)3 nanoparticles are placed in a high-speed mixer. The molar ratio of Cr element to Mn element is 0.5%, and the median particle size D50 of Cr(NO3)3 nanoparticles is 10 nm.

[0074] At room temperature, the manganese-based oxide lithium supplement and Cr(NO3)3 nanoparticles were mixed at a blade speed of 1500 rpm for 40 minutes. After standing, the solid material was collected to obtain a manganese-based lithium supplement coated with Cr(NO3)3 nanoparticles.

[0075] The manganese-based lithium supplement agent coated with Cr(NO3)3 nanoparticles is placed in a tubular furnace and heated to 900°C at a heating rate of 3°C / min in an air atmosphere. It is then kept at 900°C for 24 hours and then naturally cooled to room temperature to obtain a Cr-doped manganese-based lithium supplement agent.

[0076] The method in Example 1 was used to test the first cycle coulombic efficiency of lithium ion batteries prepared with the manganese-based lithium supplement agents of Examples 2 to 7. The results are shown in Table 1.

[0077] Table 1 The first cycle coulombic efficiency of lithium ion batteries prepared with manganese-based lithium supplement agents of Examples 2 to 7

[0078] Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Coulomb efficiency / % 84.5％ 85.7％ 84.9％ 85.4％ 83.0％ 86.0％

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A metal element doped manganese-based lithium supplement, characterized in that: It comprises a manganese-based lithium supplement and a metal element doped in the manganese-based lithium supplement; the metal element is connected to oxygen in the manganese-based lithium supplement through a chemical bond; The manganese-based lithium supplement comprises a composite lithium manganese oxide formed by anti-fluorite Li6MnO4 and layered LiMnO2; The average chemical composition of the composite lithium manganese oxide is xLi6MnO4·(1-x)LiMnO2, 0.3≤x≤1.

2. The metal element doped manganese-based lithium supplement according to claim 1, characterized in that: The metal elements include one or more of Al, Mg, Ti, Co, Ni, Fe, Cu, V, Ti, Cr, Nb, Ta, W, Mo, Zn, Ru, Rh, Ir and Pt.

3. The metal element doped manganese-based lithium supplement according to claim 1 or 2, characterized in that: The amount of the metal element is 0.01 to 5% of the amount of the manganese element.

4. The method for preparing the metal element doped manganese-based lithium supplement agent according to any one of claims 1 to 3, characterized in that: The following steps are involved: Mixing a manganese-based lithium supplement agent with a compound containing a metal element to obtain a manganese-based lithium supplement agent coated with the compound containing the metal element; The manganese-based lithium supplement agent coated with the metal element-containing compound is subjected to heat treatment, and the metal element migrates into the bulk phase of the manganese-based lithium supplement agent to obtain the metal element-doped manganese-based lithium supplement agent.

5. The preparation method according to claim 4, characterized in that: The compound containing the metal element includes one or more of an oxide corresponding to the metal element, a hydroxide corresponding to the metal element, a phosphate corresponding to the metal element, a carbonate corresponding to the metal element, an acetate corresponding to the metal element, and an oxalate corresponding to the metal element.

6. The preparation method according to claim 4 or 5, characterized in that: The particle size of the manganese-based lithium supplement agent is 0.1 to 10 μm, and the particle size of the compound containing metal elements is 1 to 100 nm.

7. The preparation method according to claim 4, characterized in that: The mixing is carried out in a high-speed mixer, the rotation speed of the blade in the high-speed mixer is 200-4000 rpm; the mixing temperature is 10-30° C., and the mixing time is 2-60 min.

8. The preparation method according to claim 4, characterized in that: The heat treatment temperature is 300-1000° C., and the heat preservation time is 1-100 hours.

9. The preparation method according to claim 4 or 8, characterized in that: The heating rate to the heat treatment temperature is 1 to 10° C. / min.

10. Use of the metal element doped manganese-based lithium supplement agent according to any one of claims 1 to 3 or the metal element doped manganese-based lithium supplement agent prepared by the preparation method according to any one of claims 4 to 9 in lithium batteries.

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