Fast ion conductor coated manganese-based lithium supplement agent as well as preparation method and application thereof

Abstract

The invention provides a fast ion conductor coated manganese-based lithium supplement agent as well as a preparation method and application thereof, and belongs to the field of lithium supplement materials of lithium ion batteries. According to the invention, the fast ion conductor is used as a coating material, so that the manganese-based lithium supplement agent can be protected, and the transmission of lithium ions on the interface of the lithium supplement agent can be ensured; the fast ion conductor has the characteristics of high air stability and low possibility of being oxidized, and the surface of the manganese-based lithium supplement agent is modified by adopting the fast ion conductor with a nano size, so that a nano-scale modified thin layer can be formed, a tight heterogeneous interface is formed, the transmission of lithium ions on the interface of the lithium supplement agent is facilitated, and the passing of other impurities can be avoided; therefore, the rate capability, the electrochemical stability and the air stability of the manganese-based lithium supplement agent are improved, and the manganese dissolution phenomenon and the electrochemical polarization of the manganese-based lithium supplement agent are reduced.

Description

Technical Field

[0001] The present invention relates to the field of lithium-ion battery lithium-replenishing materials, and in particular to a fast ion conductor-coated manganese-based lithium-replenishing agent, and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries often have problems such as low energy density, low first-cycle coulombic efficiency, poor cycle stability, and poor rate performance, which affect their practical applications. For example, in lithium iron phosphate-based lithium-ion batteries, the formation of a solid electrolyte interface phase (SEI) makes it impossible for some lithium ions to be reversibly embedded back into the lithium iron phosphate positive electrode, resulting in low battery energy density and attenuated cycle performance. Adding a lithium replenisher to the positive electrode material or positive electrode sheet can compensate for the irreversible loss of lithium ions and improve the electrochemical performance of the battery. The positive electrode lithium replenishment method is easy to operate, and precise lithium replenishment can be achieved by adjusting the amount of lithium replenisher added. It has important application prospects and has received widespread attention from the industry.

[0003] Among various lithium supplements, composite lithium supplements based on anti-fluorite Li6MnO4, especially composite or mixed lithium manganese oxides xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1) formed by Li6MnO4 and layered LiMnO2, have outstanding advantages such as high first-cycle charging capacity, low reversible capacity, low cost and environmental friendliness, and are excellent positive electrode lithium supplements for lithium-ion batteries. However, xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1) type manganese-based lithium supplements still have many problems, including severe electrochemical polarization, poor rate performance, poor electrochemical / air stability and severe manganese dissolution. Among them, poor rate performance will lead to poor battery fast charging performance, poor electrochemical stability will lead to problems such as easy battery flatulence, and poor air stability will lead to poor storage resistance of the material, which will greatly limit the application of the battery.

[0004] Therefore, in view of the above-mentioned problems such as poor rate performance leading to poor fast charging performance of the battery, poor electrochemical stability leading to easy flatulence of the battery, and poor air stability leading to the material's inability to be stored, how to improve the rate performance and stability of manganese-based lithium supplements has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0005] The object of the present invention is to provide a fast ion conductor coated manganese-based lithium supplement agent and a preparation method and application thereof. The fast ion conductor coated manganese-based lithium supplement agent provided by the present invention has good electrochemical stability and air stability, and can also improve the cycle stability of lithium ion batteries.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The invention provides a fast ion conductor coated manganese-based lithium supplement agent, comprising a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent; the median particle size of the fast ion conductor is 1-100nm.

[0008] Preferably, the chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.3-1.

[0009] Preferably, the fast ion conductor includes any one or more of an oxide-based fast ion conductor, a chloride-based fast ion conductor and a sulfide-based fast ion conductor.

[0010] Preferably, the oxide-based fast ion conductor comprises LATP (Li 1.3 Al 0.3 Ti 1.7 P3O 12 )、LAGP(Li 1.5 Al 0.5 Ge 1.5 P3O 12 )、LLZO(Li7La3Zr2O 12 )、LLTO(Li 0.48 La 0.505 TiO3), LLZTO(Li 6.5 Ln3Z 1.5 Ta 0.5 O 12 )、LLZNO(Li 6.5 Ln3Z 1.5 Nb 0.5 O 12 )、Li5La3B2O 12 , LiTaO3 and LiNbO3 or more.

[0011] Preferably, the chloride-based fast ion conductor is Li3InCl6.

[0012] Preferably, the sulfide-based fast ion conductor is Li 10 GeP2S.

[0013] Preferably, the mass of the fast ion conductor is 0.05-5% of the mass of the manganese-based lithium supplement agent.

[0014] The present invention provides a method for preparing a fast ion conductor coated manganese-based lithium supplement agent described in the above technical scheme, comprising: mixing a manganese-based lithium supplement agent and a fast ion conductor and then performing high-speed mechanical fusion to obtain a fast ion conductor coated manganese-based lithium supplement agent; the rotation speed of the high-speed mechanical fusion is 1500 to 8000 rpm, and the time of the high-speed mechanical fusion is 5 to 60 minutes.

[0015] Preferably, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is an oxidizing atmosphere or an inert atmosphere.

[0016] The present invention provides the use of the fast ion conductor coated manganese-based lithium replenisher described in the above technical solution or the fast ion conductor coated manganese-based lithium replenisher prepared by the preparation method described in the above technical solution in replenishing lithium in positive electrode materials of lithium ion batteries.

[0017] The present invention provides a fast ion conductor coated manganese-based lithium supplement, comprising a manganese-based lithium supplement and a fast ion conductor coated on the surface of the manganese-based lithium supplement; the median particle size of the fast ion conductor is 1 to 100 nm. The present invention uses a fast ion conductor as a coating material to protect the manganese-based lithium supplement while ensuring the transmission of lithium ions at the interface of the lithium supplement; the fast ion conductor has the characteristics of high air stability and not being easily oxidized. The surface of the manganese-based lithium supplement is modified by a nano-sized fast ion conductor to form a nano-scale modified thin layer and a tight heterogeneous interface, which is beneficial to the transmission of lithium ions at the interface of the lithium supplement and can avoid the passage of other impurities, thereby improving the rate performance, electrochemical stability and air stability of the manganese-based lithium supplement, and reducing the manganese dissolution phenomenon and the electrochemical polarization of the manganese-based lithium supplement. The results of the embodiments show that after the fast ion conductor coated manganese-based lithium supplement agent provided by the present invention is placed for one month, its XRD pattern is basically unchanged, and it has good electrochemical stability and air stability. The prepared 100mAh lithium ion soft-pack battery is compared with the lithium ion battery without the fast ion conductor coated manganese-based lithium supplement agent. The initial capacity of the battery is slightly improved, and after 500 cycles of cycle performance testing, the decline is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The XRD pattern of the fast ion conductor coated with the manganese-based lithium supplement agent prepared in Example 1 of the present invention and after being placed for one month;

[0019] Figure 2 The cycling performance of 100mAh lithium-ion soft-pack batteries prepared in Application Example 1 and Comparative Application Example 1 is compared. DETAILED DESCRIPTION

[0020] The invention provides a fast ion conductor coated manganese-based lithium supplement agent, comprising a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent; the median particle size of the fast ion conductor is 1-100nm.

[0021] In the present invention, the chemical formula of the manganese-based lithium supplement is preferably xLi6MnO4·(1-x)LiMnO2; the x is 0.3-1, preferably 0.4-0.9, more preferably 0.5-0.8, and further preferably 0.6-0.7; the crystal structure of the manganese-based lithium supplement is preferably a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the particle size of the lithium-rich manganese-based positive electrode material is preferably 0.2-20 μm.

[0022] In the present invention, the fast ion conductor preferably includes any one or more of an oxide-based fast ion conductor, a chloride-based fast ion conductor and a sulfide-based fast ion conductor; the oxide-based fast ion conductor preferably includes LATP (Li 1.3 Al 0.3 Ti 1.7 P3O 12 )、LAGP(Li 1.5 Al 0.5 Ge 1.5 P3O 12 )、LLZO(Li7La3Zr2O 12 )、LLTO(Li 0.48 La 0.505 TiO3), LLZTO(Li 6.5 Ln3Z 1.5 Ta 0.5 O 12 )、LLZNO(Li 6.5 Ln3Z 1.5 Nb 0.5 O 12 )、Li5La3B2O 12 , LiTaO3 and LiNbO3; the chloride-based fast ion conductor is preferably Li3InCl6; the sulfide-based fast ion conductor is preferably Li 10 GeP2S. The present invention adopts the fast ion conductor, which has the characteristics of high air stability and not easy to be oxidized, so that after coating the manganese-based lithium supplement agent, the electrochemical stability and air stability of the manganese-based lithium supplement agent can be significantly improved.

[0023] In the present invention, the mass of the fast ion conductor is preferably 0.05-5% of the mass of the manganese-based lithium supplement. By controlling the amount of the fast ion conductor, the present invention can not only form a good coating on the manganese-based lithium supplement, thereby improving its electrochemical stability and air stability, but also avoid the coating layer being too thick to affect the transmission of lithium ions at the interface of the lithium supplement.

[0024] As an embodiment of the present invention, the mass of the fast ion conductor can be 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5% of the mass of the manganese-based lithium supplement.

[0025] In the present invention, the median particle size of the fast ion conductor is 1 to 100 nm. The present invention uses a nano-sized fast ion conductor to modify the surface of the manganese-based lithium supplement agent, which can form a nano-scale modified thin layer and a compact heterogeneous interface, which is beneficial to the transmission of lithium ions at the interface of the lithium supplement agent and can avoid the passage of other impurities, thereby improving the rate performance, electrochemical stability and air stability of the manganese-based lithium supplement agent, and reducing the manganese dissolution phenomenon and the electrochemical polarization of the manganese-based lithium supplement agent.

[0026] As an embodiment of the present invention, the median particle size of the fast ion conductor may be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm.

[0027] The present invention adopts a fast ion conductor as a coating material, which can protect the manganese-based lithium supplement and ensure the transmission of lithium ions at the interface of the lithium supplement. The fast ion conductor has the characteristics of high air stability and not being easily oxidized. The surface of the manganese-based lithium supplement is modified by a nano-sized fast ion conductor to form a nano-scale modified thin layer and a compact heterogeneous interface, which is beneficial to the transmission of lithium ions at the interface of the lithium supplement and can avoid the passage of other impurities, thereby improving the rate performance, electrochemical stability and air stability of the manganese-based lithium supplement, and reducing the manganese dissolution phenomenon and the electrochemical polarization of the manganese-based lithium supplement.

[0028] The present invention also provides a method for preparing the fast ion conductor coated manganese-based lithium supplement agent described in the above technical scheme, comprising: mixing the manganese-based lithium supplement agent and the fast ion conductor and performing high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the rotation speed of the high-speed mechanical fusion is 1500 to 8000 rpm, and the time of the high-speed mechanical fusion is 5 to 60 minutes.

[0029] The present invention has no special limitation on the specific sources of the manganese-based lithium supplement and the fast ion conductor. Commercially available products familiar to those skilled in the art or known methods can be used for preparation, as long as the chemical formula and size of the manganese-based lithium supplement and the fast ion conductor meet the requirements.

[0030] In the present invention, the mixing and high-speed mechanical fusion are preferably performed in a mechanical fusion high-mixer. The present invention has no particular limitation on the specific model and source of the mechanical fusion high-mixer, and a commercially available mechanical fusion high-mixer well known to those skilled in the art can be used.

[0031] In the present invention, the mixing method is preferably low-speed blending; the low-speed blending is preferably single low-speed blending or step-by-step low-speed blending.

[0032] In the present invention, the rotation speed of the single low-speed blending is preferably 200-1500rpm; the time of the single low-speed blending is preferably 2-20min. As an embodiment of the present invention, the rotation speed of the single low-speed blending can be 200rpm, 300rpm, 400rpm, 500rpm, 600rpm, 700rpm, 800rpm, 900rpm, 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm or 1500rpm; the time of the single low-speed blending can be 2min, 3min, 5min, 8min, 10min, 12min, 15min, 18min or 20min.

[0033] In the present invention, the rotation speed of the step-by-step low-speed blending is preferably 200-1500rpm; the starting rotation speed of the step-by-step low-speed blending is preferably 200-500rpm; the final rotation speed of the step-by-step low-speed blending is preferably 1000-1500rpm; the rotation speed of the step-by-step low-speed blending shows a step-by-step upward trend within the range of 200-1500rpm; the time of the step-by-step low-speed blending is preferably 2-20min. The present invention has no special limitation on the step-by-step increase in the rotation speed within the range of 200-1500rpm of the step-by-step low-speed blending, as long as the starting rotation speed, final rotation speed and time of the step-by-step low-speed blending meet the requirements. As an embodiment of the present invention, the starting speed of the step low-speed blending can be 200rpm, 300rpm, 400rpm or 500rpm; the final speed of the step low-speed blending can be 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm or 1500rpm; the time of the step low-speed blending can be 2min, 3min, 5min, 8min, 10min, 12min, 15min, 18min or 20min. As an embodiment of the present invention, the step low-speed blending can be first blended at 400rpm for 2min, then blended at 800rpm for 2min, and finally blended at 1200rpm for 2min.

[0034] In the present invention, the temperature of the low-speed blending is preferably room temperature; the atmosphere of the low-speed blending is preferably an oxidizing atmosphere or an inert atmosphere.

[0035] In the present invention, when the fast ion conductor is an oxide-based fast ion conductor, the atmosphere of the low-speed blending is preferably an oxidizing atmosphere; the oxidizing atmosphere is preferably a mixed gas of oxygen and nitrogen, air or oxygen. The present invention can avoid the introduction of impurities into the oxide-based fast ion conductor by performing low-speed blending in an oxidizing atmosphere.

[0036] In the present invention, when the fast ion conductor is a chloride-based fast ion conductor or a sulfide-based fast ion conductor, the atmosphere for the low-speed blending is preferably an inert atmosphere; the inert atmosphere preferably includes any one or more of argon, nitrogen and helium. The present invention can avoid the introduction of impurities such as oxygen into the chloride-based fast ion conductor or the sulfide-based fast ion conductor during the mixing process by performing low-speed blending in an inert atmosphere.

[0037] The present invention adopts a single low-speed blending or a step-by-step low-speed blending method to achieve preliminary uniform mixing of the manganese-based lithium supplement and the fast ion conductor, thereby laying a foundation for subsequent high-speed mechanical fusion.

[0038] In the present invention, the rotation speed of the high-speed mechanical fusion is 1500-8000rpm; the time of the high-speed mechanical fusion is 5-60min. The present invention adopts the high-speed mechanical fusion method and controls its rotation speed and time. During the fusion process, a higher rotation speed will activate the surface of the material, thereby making it better combined, which is conducive to the coating of the fast ion conductor on the surface of the manganese-based lithium supplement.

[0039] As an embodiment of the present invention, the rotation speed of the high-speed mechanical fusion can be 1500rpm, 2000rpm, 2500rpm, 3000rpm, 3500rpm, 4000rpm, 4500rpm, 5000rpm, 5500rpm, 6000rpm, 6500rpm, 7000rpm, 7500rpm or 8000rpm; the time of the high-speed mechanical fusion can be 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min or 60min.

[0040] In the present invention, the temperature of the high-speed mechanical fusion is preferably room temperature; the atmosphere of the high-speed mechanical fusion is preferably an oxidizing atmosphere or an inert atmosphere.

[0041] In the present invention, when the fast ion conductor is an oxide-based fast ion conductor, the atmosphere of the high-speed mechanical fusion is preferably an oxidizing atmosphere; the oxidizing atmosphere is preferably a mixed gas of oxygen and nitrogen, air or oxygen. The present invention can avoid the introduction of impurities into the oxide-based fast ion conductor by performing high-speed mechanical fusion in an oxidizing atmosphere.

[0042] In the present invention, when the fast ion conductor is a chloride-based fast ion conductor or a sulfide-based fast ion conductor, the atmosphere of the high-speed mechanical fusion is preferably an inert atmosphere; the inert atmosphere preferably includes any one or more of argon, nitrogen and helium. The present invention can avoid the introduction of impurities such as oxygen into the chloride-based fast ion conductor or the sulfide-based fast ion conductor during the mixing process by performing high-speed mechanical fusion in an inert atmosphere.

[0043] The preparation method provided by the present invention is simple and easy to realize mass production, and no other equipment is required during the preparation process, so the cost is lower, which is conducive to improving the market competitiveness of the product.

[0044] The present invention also provides the use of the fast ion conductor coated manganese-based lithium replenisher described in the above technical solution or the fast ion conductor coated manganese-based lithium replenisher prepared by the preparation method described in the above technical solution in replenishing lithium in positive electrode materials of lithium ion batteries.

[0045] The present invention has no particular limitation on the specific manner of the application, and it can be referenced in a manner familiar to those skilled in the art.

[0046] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1

[0048] A fast ion conductor coated manganese-based lithium supplement agent, comprising: a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent;

[0049] The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.5. The crystal structure of the manganese-based lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2. The particle size of the lithium-rich manganese-based positive electrode material is 0.2 to 20 μm. The fast ion conductor is Li 1.3 Al 0.3 Ti 1.7 P3O 12 , the median particle size of the fast ion conductor is 5 nm; the mass of the fast ion conductor is 0.5% of the mass of the manganese-based lithium supplement agent;

[0050] The preparation method of the fast ion conductor coated manganese-based lithium supplement agent is as follows: the manganese-based lithium supplement agent and the fast ion conductor are blended at a low speed in a mechanical fusion high mixer, and then subjected to high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the rotation speed of the low-speed blending is 600 rpm, the time of the low-speed blending is 5 minutes, the temperature of the low-speed blending is room temperature, and the atmosphere of the low-speed blending is air; the rotation speed of the high-speed mechanical fusion is 4000 rpm, the time of the high-speed mechanical fusion is 30 minutes, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is air.

[0051] Example 2

[0052] A fast ion conductor coated manganese-based lithium supplement agent, comprising: a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent;

[0053] The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.5. The crystal structure of the manganese-based lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2. The particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm. The fast ion conductor is Li7La3Zr2O 12 , the median particle size of the fast ion conductor is 8 nm; the mass of the fast ion conductor is 0.5% of the mass of the manganese-based lithium supplement agent;

[0054] The preparation method of the fast ion conductor coated manganese-based lithium supplement agent is as follows: the manganese-based lithium supplement agent and the fast ion conductor are blended at a low speed in a mechanical fusion high mixer, and then subjected to high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the rotation speed of the low-speed blending is 800 rpm, the time of the low-speed blending is 3 minutes, the temperature of the low-speed blending is room temperature, and the atmosphere of the low-speed blending is air; the rotation speed of the high-speed mechanical fusion is 4500 rpm, the time of the high-speed mechanical fusion is 25 minutes, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is air.

[0055] Example 3

[0056] A fast ion conductor coated manganese-based lithium supplement agent, comprising: a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent;

[0057] The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.5. The crystal structure of the manganese-based lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2. The particle size of the lithium-rich manganese-based positive electrode material is 0.2 to 20 μm. The fast ion conductor is Li 1.5 Al 0.5 Ge 1.5 P3O 12, the median particle size of the fast ion conductor is 20 nm; the mass of the fast ion conductor is 2% of the mass of the manganese-based lithium supplement agent;

[0058] The preparation method of the fast ion conductor coated manganese-based lithium supplement agent is as follows: the manganese-based lithium supplement agent and the fast ion conductor are blended at a low speed in a mechanical fusion high mixer, and then subjected to high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the low-speed blending is first blended at 400 rpm for 2 minutes, and then blended at 800 rpm for 2 minutes, the temperature of the low-speed blending is room temperature, and the atmosphere of the low-speed blending is air; the rotation speed of the high-speed mechanical fusion is 3000 rpm, the time of the high-speed mechanical fusion is 50 minutes, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is air.

[0059] Example 4

[0060] A fast ion conductor coated manganese-based lithium supplement agent, comprising: a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent;

[0061] The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.5. The crystal structure of the manganese-based lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2. The particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm. The fast ion conductor is LiTaO3, and the median particle size of the fast ion conductor is 10 nm. The mass of the fast ion conductor is 1% of the mass of the manganese-based lithium supplement.

[0062] The preparation method of the fast ion conductor coated manganese-based lithium supplement agent is as follows: the manganese-based lithium supplement agent and the fast ion conductor are blended at a low speed in a mechanical fusion high mixer, and then subjected to high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the low-speed blending is first blended at 400 rpm for 2 minutes, and then blended at 800 rpm for 2 minutes, the temperature of the low-speed blending is room temperature, and the atmosphere of the low-speed blending is air; the rotation speed of the high-speed mechanical fusion is 4000 rpm, the time of the high-speed mechanical fusion is 30 minutes, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is air.

[0063] Example 5

[0064] A fast ion conductor coated manganese-based lithium supplement agent, comprising: a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent;

[0065] The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.5. The crystal structure of the manganese-based lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2. The particle size of the lithium-rich manganese-based positive electrode material is 0.2 to 20 μm. The fast ion conductor is Li 1.5 Al 0.5 Ge 1.5 P3O 12 and Li7La3Zr2O 12 , Li 1.5 Al 0.5 Ge 1.5 P3O 12 The median particle size is 20nm, Li7La3Zr2O 12 The median particle size is 5 nm; the fast ion conductor Li 1.5 Al 0.5 Ge 1.5 P3O 12 The mass of Li7La3Zr2O is 0.5% of the mass of manganese-based lithium supplement. 12 The mass is 0.5% of the mass of the manganese-based lithium supplement;

[0066] The preparation method of the fast ion conductor coated manganese-based lithium supplement agent is as follows: the manganese-based lithium supplement agent and the fast ion conductor are blended at a low speed in a mechanical fusion high mixer, and then subjected to high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the low-speed blending is first blended at 400 rpm for 2 minutes, and then blended at 800 rpm for 2 minutes, the temperature of the low-speed blending is room temperature, and the atmosphere of the low-speed blending is air; the rotation speed of the high-speed mechanical fusion is 3000 rpm, the time of the high-speed mechanical fusion is 50 minutes, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is air.

[0067] Example 6

[0068] A fast ion conductor coated manganese-based lithium supplement agent, comprising: a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent;

[0069] The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.5, and the crystal structure of the manganese-based lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, and the particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm; the fast ion conductor is LiTaO3 and LiNbO3, the median particle size of LiTaO3 is 10 nm, and the median particle size of LiNbO3 is 10 nm; the mass of LiTaO3 in the fast ion conductor is 0.3% of the mass of the manganese-based lithium supplement, and the mass of LiNbO3 is 0.3% of the mass of the manganese-based lithium supplement;

[0070] The preparation method of the fast ion conductor coated manganese-based lithium supplement agent is as follows: the manganese-based lithium supplement agent and the fast ion conductor are blended at a low speed in a mechanical fusion high mixer, and then subjected to high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the rotation speed of the low-speed blending is 800 rpm, the time of the low-speed blending is 5 minutes, the temperature of the low-speed blending is room temperature, and the atmosphere of the low-speed blending is air; the rotation speed of the high-speed mechanical fusion is 4500 rpm, the time of the high-speed mechanical fusion is 25 minutes, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is air.

[0071] Example 7

[0072] A fast ion conductor coated manganese-based lithium supplement agent, comprising: a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent;

[0073] The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.5. The crystal structure of the manganese-based lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2. The particle size of the lithium-rich manganese-based positive electrode material is 0.2 to 20 μm. The fast ion conductor is Li 10 GeP2S, the median particle size of the fast ion conductor is 30nm; the mass of the fast ion conductor is 5% of the mass of the manganese-based lithium supplement;

[0074] The preparation method of the fast ion conductor coated manganese-based lithium supplement agent is as follows: the manganese-based lithium supplement agent and the fast ion conductor are blended at a low speed in a mechanical fusion high mixer, and then subjected to high-speed mechanical fusion to obtain the fast ion conductor coated manganese-based lithium supplement agent; the rotation speed of the low-speed blending is 500 rpm, the time of the low-speed blending is 5 minutes, the temperature of the low-speed blending is room temperature, and the atmosphere of the low-speed blending is argon; the rotation speed of the high-speed mechanical fusion is 3000 rpm, the time of the high-speed mechanical fusion is 30 minutes, the temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is argon.

[0075] Application Example 1

[0076] The fast ion conductor prepared in Example 1 is coated with a manganese-based lithium supplement agent to prepare a 100 mAh lithium ion soft pack battery, and the specific steps are as follows:

[0077] 1) The fast ion conductor coated manganese-based lithium supplement agent and the lithium iron phosphate positive electrode material are homogenized by a homogenizer, and the solvent is NMP to obtain a positive electrode slurry with a solid content of 50wt.%, and then the positive electrode slurry is coated on the aluminum current collector by a coating machine to obtain a positive electrode sheet, and the surface density of the positive electrode sheet is 20mg / cm 2 ; The amount of the fast ion conductor coated manganese-based lithium supplement agent is 2% of the mass of the lithium iron phosphate positive electrode material;

[0078] 2) Assembling the positive electrode sheet obtained in step 1) and the graphite negative electrode sheet into a 100 mAh lithium-ion soft-pack battery with an N / P ratio of 1.1, and then performing liquid injection, formation and testing in sequence.

[0079] Application Example 2

[0080] The fast ion conductor prepared in Example 5 was coated with a manganese-based lithium supplement agent to prepare a 100 mAh lithium ion soft pack battery. Other operations were the same as those in Application Example 1.

[0081] Comparative application example 1

[0082] The preparation method of 100mAh lithium-ion soft pack battery is as follows:

[0083] 1) The lithium iron phosphate positive electrode material is homogenized by a homogenizer, and the solvent is NMP to obtain a positive electrode slurry with a solid content of 50wt.%, and then the positive electrode slurry is coated on the aluminum current collector by a coating machine to obtain a positive electrode sheet. The surface density of the positive electrode sheet is 20mg / cm 2 ;

[0084] 2) Assembling the positive electrode sheet obtained in step 1) and the graphite negative electrode sheet into a 100 mAh lithium-ion soft-pack battery with an N / P ratio of 1.1, and then performing liquid injection, formation and testing in sequence.

[0085] The fast ion conductor coated manganese-based lithium supplement prepared in Example 1 and the fast ion conductor coated manganese-based lithium supplement after being placed in air at room temperature for one month were tested using an X-ray diffractometer. The results are as follows: Figure 1 As shown. Figure 1 It can be seen that after the fast ion conductor coated manganese-based lithium supplement agent prepared in Example 1 was placed for one month, its XRD pattern remained basically unchanged, indicating that the fast ion conductor coated manganese-based lithium supplement agent provided by the present invention has good electrochemical stability and air stability.

[0086] The cycle performance of the 100mAh lithium-ion soft-pack battery prepared in Example 1 and Comparative Application Example 1 was tested, and the results were as follows: Figure 2 As shown. Figure 2 It can be seen that by adding the fast ion conductor coated manganese-based lithium supplement agent provided by the present invention into the positive electrode plate, the initial capacity of the 100mAh lithium ion soft-pack battery is slightly improved, and after 500 cycles of cycle performance test, the decline of the 100mAh lithium ion soft-pack battery with the addition of the fast ion conductor coated manganese-based lithium supplement agent is significantly reduced, indicating that the fast ion conductor coated manganese-based lithium supplement agent provided by the present invention can effectively improve the electrochemical performance of lithium ion batteries.

[0087] 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 fast ion conductor coated manganese-based lithium supplement agent, comprising a manganese-based lithium supplement agent and a fast ion conductor coated on the surface of the manganese-based lithium supplement agent; the median particle size of the fast ion conductor is 1 to 100 nm.

2. The fast ion conductor coated manganese-based lithium supplement according to claim 1, characterized in that: The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.3-1.

3. The fast ion conductor coated manganese-based lithium supplement according to claim 1, characterized in that: The fast ion conductor includes any one or more of an oxide-based fast ion conductor, a chloride-based fast ion conductor, and a sulfide-based fast ion conductor.

4. The fast ion conductor coated manganese-based lithium supplement according to claim 3, characterized in that: The oxide-based fast ion conductor includes LATP (Li 1.3 Al 0.3 Ti 1.7 P3O 12 )、LAGP(Li 1.5 Al 0.5 Ge 1.5 P3O 12 )、LLZO(Li7La3Zr2O 12 )、LLTO(Li 0.48 La 0.505 TiO3), LLZTO(Li 6.5 Ln3Z 1.5 Ta 0.5 O 12 )、LLZNO(Li 6.5 Ln3Z 1.5 Nb 0.5 O 12 )、Li5La3B2O 12 , LiTaO3 and LiNbO3 or more.

5. The fast ion conductor coated manganese-based lithium supplement according to claim 3, characterized in that: The chloride-based fast ion conductor is Li3InCl6.

6. The fast ion conductor coated manganese-based lithium supplement according to claim 3, characterized in that: The sulfide-based fast ion conductor is Li 10 GeP2S.

7. The fast ion conductor coated manganese-based lithium supplement according to claim 1, characterized in that: The mass of the fast ion conductor is 0.05-5% of the mass of the manganese-based lithium supplement agent.

8. The method for preparing the fast ion conductor coated manganese-based lithium supplement agent according to any one of claims 1 to 7, comprising: The manganese-based lithium supplement agent and the fast ion conductor are mixed and then subjected to high-speed mechanical fusion to obtain the fast ion conductor-coated manganese-based lithium supplement agent; the rotation speed of the high-speed mechanical fusion is 1500-8000rpm, and the time of the high-speed mechanical fusion is 5-60min.

9. The preparation method according to claim 8, characterized in that: The temperature of the high-speed mechanical fusion is room temperature, and the atmosphere of the high-speed mechanical fusion is an oxidizing atmosphere or an inert atmosphere.

10. Use of the fast ion conductor coated manganese-based lithium replenisher according to any one of claims 1 to 7 or the fast ion conductor coated manganese-based lithium replenisher prepared by the preparation method according to any one of claims 8 to 9 in replenishing lithium in positive electrode materials of lithium ion batteries.

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