An oxygen vacancy surface-doped manganese-based lithium supplementing agent, a preparation method and application thereof

Abstract

The application provides an oxygen vacancy surface doped manganese-based lithium supplementing agent, a preparation method and application thereof, and belongs to the field of lithium ion battery lithium supplementing materials. The manganese-based lithium supplementing agent is treated by using a plasma treatment method, the concentration, depth and gradient distribution of oxygen vacancies on the surface of the manganese-based lithium supplementing agent are controlled by adjusting the type of gas, plasma power, treatment temperature and treatment time, the surface stability of the lithium supplementing agent is improved by controlling the surface doping of oxygen vacancies, and the surface oxygen precipitation and surface side reactions are inhibited. The preparation method is simple and low in cost, the physicochemical properties of the manganese-based lithium supplementing agent can be effectively improved, and the manganese-based lithium supplementing agent has important application prospects in lithium ion batteries.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium ion battery lithium supplement materials, in particular to an oxygen vacancy surface doped manganese-based lithium supplement agent and a preparation method and application thereof. BACKGROUND

[0002] Lithium ion batteries have been widely used in consumer electronics, electric vehicles and mobile energy storage, etc., and have promoted the development of related fields. At present, new fields and new industries based on high-performance lithium ion batteries are booming, including unmanned aerial vehicles / electric aircraft, robots and intelligent energy storage, etc., which are expected to form a new industrial blue ocean. These applications have put forward higher requirements for the performance of lithium ion batteries, including energy density, cycle life and safety, etc. Therefore, it is urgent to develop key materials and key strategies that can significantly improve the electrochemical performance of lithium ion batteries.

[0003] Among many schemes, lithium supplement is an effective strategy, which can supplement the irreversible lithium ion loss of lithium ion batteries in formation and work, especially compensate for the lithium ions consumed by the formation of solid-state-electrolyte interface phase (SEI) in the negative electrode, thus on the one hand, it can improve the energy density of the battery, on the other hand, it can improve the cycle life of the battery. Lithium supplement strategy can be divided into negative electrode lithium supplement and positive electrode lithium supplement. Lithium metal foil, lithium powder or electrochemical lithium supplement are often used for negative electrode lithium supplement, which has the disadvantages of difficult control of lithium supplement amount, unsafe process, high cost, etc.; compared with the above, positive electrode lithium supplement can add positive electrode lithium supplement agent in the homogenate process of positive electrode preparation. The positive electrode lithium supplement agent is a compound with high lithium content, and the addition amount of the positive electrode lithium supplement agent can be adjusted to realize precise lithium supplement, which is simple to operate, safe and low in cost, and has important application prospect and broad market potential.

[0004] Among many lithium supplement agents, the composite lithium manganese oxide xLi6MnO4·(1-x)LiMnO2(0.3≤x≤1) formed by reverse fluorite Li6MnO4 and layered LiMnO2 has the advantages of outstanding high first charge capacity (>600 mAh / g), low first discharge capacity (<100 mAh / g), low cost and environmental friendliness, etc., and is an important positive electrode lithium supplement agent. However, the manganese-based lithium supplement agent still has many problems, including serious gas production, large electrochemical polarization and significant surface side reaction, etc., which seriously affect the electrochemical performance of the battery. Therefore, how to solve the problems of serious gas production, large electrochemical polarization and significant surface side reaction of the manganese-based lithium supplement agent, and improve the air stability and electrochemical performance of the manganese-based lithium supplement agent, has become a technical problem to be solved in the field. SUMMARY

[0005] The application aims to provide an oxygen vacancy surface doped manganese-based lithium supplement agent, a preparation method and application thereof.

[0006] In order to achieve the above-mentioned application purposes, the application provides the following technical solutions.

[0007] The application provides a preparation method of an oxygen vacancy surface doped manganese-based lithium supplement agent, comprising the following steps:

[0008] The atmosphere of the plasma treatment comprises any one or more of N2, Ar, H2, NH3, He, O2 and CH4, the pressure of the plasma treatment is 1-1000 Pa, the temperature of the plasma treatment is 25-600 DEG C, and the time of the plasma treatment is 0.1-120 min.

[0009] Preferably, the chemical formula of the manganese-based lithium supplement agent is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.3-1.

[0010] Preferably, the atmosphere of the plasma treatment is a mixed atmosphere of Ar and H2, and the volume ratio of Ar to H2 in the mixed atmosphere of Ar and H2 is (90-95):(5-10).

[0011] Preferably, the pressure of the plasma treatment is 10-100 Pa.

[0012] Preferably, the temperature of the plasma treatment is 25-300 DEG C.

[0013] Preferably, the time of the plasma treatment is 20-60 min.

[0014] Preferably, the power of the plasma treatment is 10-1000 W.

[0015] The application provides an oxygen vacancy surface doped manganese-based lithium supplement agent prepared by the preparation method.

[0016] The application provides an application of the oxygen vacancy surface doped manganese-based lithium supplement agent in a lithium ion battery.

[0017] Preferably, the application is in the form of mixing the oxygen vacancy surface doped manganese-based lithium supplement agent and a positive electrode material, then preparing a positive electrode sheet, and finally assembling a lithium battery by using the positive electrode sheet; the amount of the oxygen vacancy surface doped manganese-based lithium supplement agent is 0.1-10% of the mass of the positive electrode material.

[0018] The application provides a preparation method of oxygen vacancy surface doped manganese-based lithium supplementing agent, comprising the following steps: subjecting the manganese-based lithium supplementing agent to plasma treatment to obtain the oxygen vacancy surface doped manganese-based lithium supplementing agent; the atmosphere of the plasma treatment comprises any one or more of N2, Ar, H2, NH3, He, O2 and CH4, the pressure of the plasma treatment is 1-1000 Pa, the temperature of the plasma treatment is 25-600 DEG C, and the time of the plasma treatment is 0.1-120 min. The manganese-based lithium supplementing agent is treated by the plasma treatment method, the concentration, depth and gradient distribution of the oxygen vacancy on the surface of the manganese-based lithium supplementing agent are controlled by adjusting the gas type, plasma power, treatment temperature and treatment time, the surface stability of the lithium supplementing agent is improved by the controllable oxygen vacancy surface doping, the surface oxygen precipitation and surface side reaction are inhibited, the preparation method is simple and low in cost, the physicochemical properties of the manganese-based lithium supplementing agent can be effectively improved, and the manganese-based lithium supplementing agent has important application prospects in lithium ion batteries. The results of the embodiments show that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplementing agent provided by the application is 5-35%, the oxygen vacancy depth is 3-30 nm, and the oxygen vacancy is gradient distributed on the surface; the discharge voltage of a 100 mAh level lithium ion soft package battery prepared by using the oxygen vacancy surface doped manganese-based lithium supplementing agent is 2-4.8 V, the first circle charging specific capacity is 837 mAh / g, the first circle discharge specific capacity is 60 mAh / g, and the first circle coulombic efficiency is 7.2%; a 100 mAh level lithium ion soft package battery is prepared by using the oxygen vacancy surface doped manganese-based lithium supplementing agent after one month, the discharge voltage is 2-4.8 V, the first circle charging specific capacity is 798 mAh / g, the first circle discharge specific capacity is 54 mAh / g, and the first circle coulombic efficiency is 6.8%; the electrochemical performances of the two are very close, and the charging specific capacities can be effectively exerted, which indicates that the oxygen vacancy surface doping method of the application effectively improves the air stability of the manganese-based lithium supplementing agent, and the interface oxygen precipitation and interface side reaction are significantly inhibited. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The preparation method of the oxygen vacancy surface doped manganese-based lithium supplementing agent provided by the application is shown in the flow chart.

[0020] Figure 2 The charge-discharge curves of the 100 mAh level lithium ion soft package batteries prepared in application example 1 and application example 2 of the application are shown. DETAILED DESCRIPTION

[0021] The application provides a preparation method of oxygen vacancy surface doped manganese-based lithium supplementing agent, comprising the following steps: subjecting the manganese-based lithium supplementing agent to plasma treatment to obtain the oxygen vacancy surface doped manganese-based lithium supplementing agent;

[0022] The atmosphere of the plasma treatment includes any one or more of N2, Ar, H2, NH3, He, O2 and CH4, the pressure of the plasma treatment is 1-1000 Pa, the temperature of the plasma treatment is 25-600 DEG C, and the time of the plasma treatment is 0.1-120 min.

[0023] In the application, the chemical formula of the manganese-based lithium supplementing agent 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 supplementing agent is preferably 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 preferably 0.2-20 μm. The application does not have special limitation on the specific source of the manganese-based lithium supplementing agent, and a commercially available product known to those skilled in the art or a preparation method known to those skilled in the art can be used.

[0024] In the application, the plasma treatment is preferably performed in a plasma treatment instrument. The application does not have special limitation on the specific model and source of the plasma treatment instrument, and a plasma treatment instrument known to those skilled in the art can be used.

[0025] In the application, the atmosphere of the plasma treatment includes any one or more of N2, Ar, H2, NH3, He, O2 and CH4, and is preferably a mixed atmosphere of Ar and H2; the volume ratio of Ar to H2 in the mixed atmosphere of Ar and H2 is preferably (90-95):(5-10), and more preferably 95:5. The application can improve the oxygen vacancy concentration on the surface of the manganese-based lithium supplementing agent by controlling the atmosphere of the plasma treatment.

[0026] In the application, the pressure of the plasma treatment is 1-1000 Pa. The application can improve the oxygen vacancy depth on the surface of the manganese-based lithium supplementing agent by controlling the atmosphere of the plasma treatment.

[0027] As an embodiment of the application, the pressure of the plasma treatment can be 1 Pa, 5 Pa, 10 Pa, 20 Pa, 50 Pa, 80 Pa, 100 Pa, 150 Pa, 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa, 800 Pa, 900 Pa or 1000 Pa.

[0028] In the application, the temperature of the plasma treatment is 25-600 DEG C. The application can control the oxygen vacancy concentration on the surface of the manganese-based lithium supplementing agent by controlling the temperature of the plasma treatment.

[0029] As an embodiment of the present application, the temperature of the plasma treatment can be 25℃, 50℃, 100℃, 150℃, 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃ or 600℃.

[0030] In the present application, the time of the plasma treatment is 0.1-120 min. By controlling the time of the plasma treatment, the present application can control the depth of the oxygen vacancy on the surface of the manganese-based lithium supplement agent.

[0031] As an embodiment of the present application, the time of the plasma treatment can be 0.1 min, 1 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min.

[0032] In the present application, the power of the plasma treatment is preferably 10-1000 W. By controlling the power of the plasma treatment, the present application can ensure that the temperature of the plasma treatment is within the desired range, thereby further controlling the depth of the oxygen vacancy on the surface of the manganese-based lithium supplement agent.

[0033] As an embodiment of the present application, the power of the plasma treatment can be 10 W, 20 W, 50 W, 100 W, 150 W, 200 W, 250 W, 300 W, 350 W, 400 W, 450 W, 500 W, 550 W, 600 W, 650 W, 700 W, 750 W, 800 W, 850 W, 900 W, 950 W or 1000 W.

[0034] In the present application, the manganese-based lithium supplement agent is preferably rotated during the plasma treatment. The present application does not have special limitations on the rotating speed, which can be set according to the technical common sense of those skilled in the art. By rotating the manganese-based lithium supplement agent during the plasma treatment, the present application can make the treatment of the manganese-based lithium supplement agent more uniform.

[0035] The present application adopts the plasma treatment method to treat the manganese-based lithium supplement agent, realizes the controllable construction of the oxygen vacancy concentration, depth and gradient distribution on the surface of the manganese-based lithium supplement agent by adjusting the gas type, plasma power, treatment temperature and treatment time, suppresses the surface oxygen precipitation and surface side reaction through the controllable oxygen vacancy surface doping, and improves the surface stability of the lithium supplement agent.

[0036] The preparation method flow chart of the oxygen vacancy surface doped manganese-based lithium supplement agent provided by the present application is shown in Figure 1 Figure 1 ​It can be seen that the preparation method provided by the present application is simple and low in cost, and can effectively improve the physicochemical properties of the manganese-based lithium supplement, and has important application prospects in lithium ion batteries.

[0037] The present application also provides the oxygen vacancy surface doped manganese-based lithium supplement prepared by the preparation method.

[0038] In the present application, the oxygen vacancy surface doped manganese-based lithium supplement preferably has oxygen vacancies; the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplement is preferably 0.01-30%; the oxygen vacancy depth of the oxygen vacancy surface doped manganese-based lithium supplement is preferably 1-50 nm; and the oxygen vacancies of the oxygen vacancy surface doped manganese-based lithium supplement preferably present a gradient distribution decreasing from the surface to the inside.

[0039] The present application also provides the application of the oxygen vacancy surface doped manganese-based lithium supplement in lithium ion batteries.

[0040] In the present application, the application mode preferably comprises mixing the oxygen vacancy surface doped manganese-based lithium supplement and a positive electrode material, preparing a positive electrode sheet, and assembling a lithium battery with the positive electrode sheet.

[0041] In the present application, the positive electrode material preferably comprises any one or more of lithium iron phosphate, lithium manganese iron phosphate, ternary layered oxides and lithium-rich layered oxides.

[0042] In the present application, the amount of the oxygen vacancy surface doped manganese-based lithium supplement is preferably 0.1-10% of the mass of the positive electrode material.

[0043] In the present application, the amount of the oxygen vacancy surface doped manganese-based lithium supplement can be 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% of the mass of the positive electrode material.

[0044] The present application does not have special limitations on the specific operation of assembling the lithium battery with the positive electrode sheet, and any method for assembling a lithium battery known to those skilled in the art can be used.

[0045] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0046] Embodiment 1

[0047] A preparation method of the oxygen vacancy surface doped manganese-based lithium supplement agent is as follows:

[0048] (1) Put the manganese-based lithium supplement agent into a sample bottle, and then put the sample bottle into a chamber of a plasma treatment instrument, and then introduce a plasma treatment atmosphere into the chamber and vacuumize to a required plasma treatment pressure; the chemical formula of the manganese-based lithium supplement agent is xLi6MnO4·(1-x)LiMnO2, x is 0.5; the crystal structure of the manganese-based lithium supplement agent is a composite structure formed by inverse fluorite type Li6MnO4 and layered LiMnO2; the particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm; the plasma treatment atmosphere is a mixed atmosphere of Ar and H2, wherein the volume ratio of Ar to H2 is 95:5, and the plasma treatment pressure is 10 Pa;

[0049] (2) Turn on the plasma treatment instrument in the step (1), so that the temperature of the chamber of the plasma treatment instrument reaches the plasma treatment temperature 25℃, and at the same time, the sample bottle is rotated, then the plasma treatment power is controlled to be 100 W, the manganese-based lithium supplement agent is treated by plasma for 20 min, finally the plasma treatment instrument is turned off, air is introduced into the chamber to restore the atmospheric pressure, the chamber is opened to collect the solid material, and the oxygen vacancy surface doped manganese-based lithium supplement agent is obtained.

[0050] The oxygen vacancy surface doped manganese-based lithium supplement agent prepared in Example 1 is subjected to XPS depth analysis test, and the results show that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplement agent is 20%, the oxygen vacancy depth is 25 nm, and the oxygen vacancy is a surface gradient distribution.

[0051] Example 2

[0052] A preparation method of the oxygen vacancy surface doped manganese-based lithium supplement agent is as follows:

[0053] (1) Put the manganese-based lithium supplement agent into a sample bottle, and then put the sample bottle into a chamber of a plasma treatment instrument, and then introduce a plasma treatment atmosphere into the chamber and vacuumize to a required plasma treatment pressure; the chemical formula of the manganese-based lithium supplement agent is xLi6MnO4·(1-x)LiMnO2, x is 0.5; the crystal structure of the manganese-based lithium supplement agent is a composite structure formed by inverse fluorite type Li6MnO4 and layered LiMnO2; the particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm; the plasma treatment atmosphere is a mixed atmosphere of Ar and H2, wherein the volume ratio of Ar to H2 is 95:5, and the plasma treatment pressure is 10 Pa;

[0054] (2) turn on the plasma processing instrument in step (1), make the temperature of the chamber of the plasma processing instrument reach the temperature 25℃ of plasma processing, at the same time make the sample bottle rotate, then control the power of plasma processing to be 100W, plasma process the manganese-based lithium supplementing agent for 5min, finally close the plasma processing instrument, introduce air into the chamber to restore atmospheric pressure, open the chamber to collect solid materials, and obtain the oxygen vacancy surface doped manganese-based lithium supplementing agent.

[0055] The oxygen vacancy surface doped manganese-based lithium supplementing agent prepared in Example 2 is subjected to XPS depth analysis test, and the result shows that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplementing agent is 10%, the oxygen vacancy depth is 10nm, and the oxygen vacancy is surface gradient distribution.

[0056] Example 3

[0057] A preparation method of an oxygen vacancy surface doped manganese-based lithium supplementing agent is as follows:

[0058] (1) put the manganese-based lithium supplementing agent into a sample bottle, then put the sample bottle into the chamber of a plasma processing instrument, then introduce a plasma processing atmosphere into the chamber and vacuumize to a required plasma processing pressure; the chemical formula of the manganese-based lithium supplementing agent is xLi6MnO4·(1-x)LiMnO2, and x is 0.5; the crystal structure of the manganese-based lithium supplementing agent is a composite structure formed by inverse fluorite type Li6MnO4 and layered LiMnO2; the particle size of the lithium-rich manganese-based positive electrode material is 0.2-20μm; the plasma processing atmosphere is Ar, and the plasma processing pressure is 100Pa;

[0059] (2) turn on the plasma processing instrument in step (1), make the temperature of the chamber of the plasma processing instrument reach the temperature 100℃ of plasma processing at a heating rate of 1℃ / min, at the same time make the sample bottle rotate, then control the power of plasma processing to be 100W, plasma process the manganese-based lithium supplementing agent for 5min, finally close the plasma processing instrument, introduce air into the chamber to restore atmospheric pressure, open the chamber to collect solid materials, and obtain the oxygen vacancy surface doped manganese-based lithium supplementing agent.

[0060] The oxygen vacancy surface doped manganese-based lithium supplementing agent prepared in Example 3 is subjected to XPS depth analysis test, and the result shows that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplementing agent is 30%, the oxygen vacancy depth is 30nm, and the oxygen vacancy is surface gradient distribution.

[0061] Example 4

[0062] A preparation method of an oxygen vacancy surface doped manganese-based lithium supplementing agent is as follows:

[0063] (1) Put the manganese-based lithium supplement into a sample bottle, and then put the sample bottle into a chamber of a plasma treatment instrument, and then introduce a plasma treatment atmosphere into the chamber and vacuumize to a required plasma treatment pressure; the chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, x is 0.5; the crystal structure of the manganese-based lithium supplement is a composite structure formed by inverse fluorite Li6MnO4 and layered LiMnO2; the particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm; the plasma treatment atmosphere is N2, and the plasma treatment pressure is 20 Pa;

[0064] (2) Turn on the plasma treatment instrument in the step (1), so that the temperature of the chamber of the plasma treatment instrument reaches a plasma treatment temperature of 50°C at a temperature increasing rate of 1°C / min, and at the same time, the sample bottle is rotated, then the plasma treatment power is controlled to be 20 W, the manganese-based lithium supplement is plasma treated for 5 min, finally the plasma treatment instrument is turned off, air is introduced into the chamber to restore the atmospheric pressure, the chamber is opened to collect the solid material, and the oxygen vacancy surface doped manganese-based lithium supplement is obtained.

[0065] The oxygen vacancy surface doped manganese-based lithium supplement prepared in Example 4 is subjected to XPS depth analysis test, and the result shows that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplement is 5%, the oxygen vacancy depth is 5 nm, and the oxygen vacancy is a surface gradient distribution.

[0066] Example 5

[0067] A preparation method of an oxygen vacancy surface doped manganese-based lithium supplement is as follows:

[0068] (1) Put the manganese-based lithium supplement into a sample bottle, and then put the sample bottle into a chamber of a plasma treatment instrument, and then introduce a plasma treatment atmosphere into the chamber and vacuumize to a required plasma treatment pressure; the chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, x is 0.5; the crystal structure of the manganese-based lithium supplement is a composite structure formed by inverse fluorite Li6MnO4 and layered LiMnO2; the particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm; the plasma treatment atmosphere is H2, and the plasma treatment pressure is 20 Pa;

[0069] (2) Turn on the plasma treatment instrument in the step (1), so that the temperature of the chamber of the plasma treatment instrument reaches a plasma treatment temperature of 80°C at a temperature increasing rate of 1°C / min, and at the same time, the sample bottle is rotated, then the plasma treatment power is controlled to be 5 W, the manganese-based lithium supplement is plasma treated for 1 min, finally the plasma treatment instrument is turned off, air is introduced into the chamber to restore the atmospheric pressure, the chamber is opened to collect the solid material, and the oxygen vacancy surface doped manganese-based lithium supplement is obtained.

[0070] The XPS depth analysis test of the oxygen vacancy surface doped manganese-based lithium supplement agent prepared in Example 5 shows that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplement agent is 6%, the oxygen vacancy depth is 3 nm, and the oxygen vacancy is a surface gradient distribution.

[0071] Example 6

[0072] A preparation method of an oxygen vacancy surface doped manganese-based lithium supplement agent is as follows:

[0073] (1) Put the manganese-based lithium supplement agent into a sample bottle, then put the sample bottle into a chamber of a plasma treatment instrument, then introduce a plasma treatment atmosphere into the chamber and vacuumize to a required plasma treatment pressure; the chemical formula of the manganese-based lithium supplement agent is xLi6MnO4·(1-x)LiMnO2, x is 0.5; the crystal structure of the manganese-based lithium supplement agent is a composite structure formed by inverse fluorite type Li6MnO4 and layered LiMnO2; the particle size of the lithium-rich manganese-based positive electrode material is 0.2-20 μm; the plasma treatment atmosphere is CH4, and the plasma treatment pressure is 20 Pa;

[0074] (2) Turn on the plasma treatment instrument in the step (1), so that the temperature of the chamber of the plasma treatment instrument reaches a plasma treatment temperature of 300℃ at a temperature increasing rate of 2℃ / min, while rotating the sample bottle, then control the plasma treatment power to be 5 W, plasma treat the manganese-based lithium supplement agent for 10 min, finally turn off the plasma treatment instrument, introduce air into the chamber to restore the atmospheric pressure, open the chamber to collect the solid material, and obtain the oxygen vacancy surface doped manganese-based lithium supplement agent.

[0075] The XPS depth analysis test of the oxygen vacancy surface doped manganese-based lithium supplement agent prepared in Example 6 shows that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplement agent is 25%, the oxygen vacancy depth is 30 nm, and the oxygen vacancy is a surface gradient distribution.

[0076] Example 7

[0077] A preparation method of an oxygen vacancy surface doped manganese-based lithium supplement agent is as follows:

[0078] (1) Put the manganese-based lithium supplement into a sample bottle, and then put the sample bottle into a chamber of a plasma processing instrument, and then introduce a plasma processing atmosphere into the chamber and vacuumize to a desired plasma processing pressure; the manganese-based lithium supplement has a chemical formula of xLi6MnO4·(1-x)LiMnO2, x is 0.5; the manganese-based lithium supplement has a composite structure formed by an inverse fluorite Li6MnO4 and a layered LiMnO2; the lithium-rich manganese-based positive electrode material has a particle size of 0.2-20 μm; the plasma processing atmosphere is CH4, and the plasma processing pressure is 30 Pa;

[0079] (2) Turn on the plasma processing instrument in the step (1), so that the temperature of the chamber of the plasma processing instrument reaches a plasma processing temperature of 300℃ at a temperature increasing rate of 2℃ / min, and the sample bottle is rotated, and then the plasma processing power is controlled to be 50 W, the manganese-based lithium supplement is plasma processed for 10 min, and finally the plasma processing instrument is turned off, air is introduced into the chamber to restore the atmospheric pressure, the chamber is opened to collect the solid material, and the oxygen vacancy surface doped manganese-based lithium supplement is obtained.

[0080] The oxygen vacancy surface doped manganese-based lithium supplement prepared in the step (1) is subjected to XPS in-depth analysis test, and the result shows that the surface oxygen vacancy concentration of the oxygen vacancy surface doped manganese-based lithium supplement is 35%, the oxygen vacancy depth is 30 nm, and the oxygen vacancy is a surface gradient distribution.

[0081] The oxygen vacancy surface-doped manganese-based lithium supplementing agent prepared in Examples 1-7 is analyzed. As can be seen from the comparison between Example 1 and Example 2, when the plasma treatment time is changed from 20 min to 5 min, the surface oxygen vacancy concentration and the oxygen vacancy depth of the oxygen vacancy surface-doped manganese-based lithium supplementing agent both show a downward trend, but the oxygen vacancies are surface gradient distribution, indicating that by controlling the plasma treatment time, the surface oxygen vacancy concentration and the oxygen vacancy depth of the oxygen vacancy surface-doped manganese-based lithium supplementing agent can be regulated. As can be seen from the comparison between Example 2 and Example 3, when the plasma treatment pressure and temperature are increased, the surface oxygen vacancy concentration and the oxygen vacancy depth of the oxygen vacancy surface-doped manganese-based lithium supplementing agent are both significantly improved, indicating that controlling the plasma treatment pressure and temperature can regulate the surface oxygen vacancy concentration and the oxygen vacancy depth of the oxygen vacancy surface-doped manganese-based lithium supplementing agent. As can be seen from the comparison between Example 4 and Example 5, under the condition that the plasma treatment pressure and time are unchanged, the higher the plasma treatment temperature, the higher the oxygen vacancy concentration, and the higher the plasma treatment power, the higher the oxygen vacancy depth. In Examples 6-7, by appropriately increasing the plasma treatment pressure and power while keeping other conditions unchanged, the surface oxygen vacancy concentration of the oxygen vacancy surface-doped manganese-based lithium supplementing agent is improved, while the oxygen vacancy depth does not change, indicating that controlling the plasma treatment pressure and power can regulate the surface oxygen vacancy concentration of the oxygen vacancy surface-doped manganese-based lithium supplementing agent. As can be seen from Examples 1-7, by regulating the gas type, plasma power, treatment temperature and treatment time, the present application can achieve controllable construction of the surface oxygen vacancy concentration, depth and gradient distribution of the manganese-based lithium supplementing agent.

[0082] Application Example 1

[0083] The oxygen vacancy surface-doped manganese-based lithium supplementing agent prepared in Example 1 is prepared into a 100 mAh-level lithium ion soft-pack battery, and the specific steps are as follows:

[0084] 1) The oxygen vacancy surface-doped manganese-based lithium supplementing agent and the lithium iron phosphate positive electrode material are uniformly grinded together by using a homogenizer, the solvent is NMP, and a positive electrode slurry with a solid content of 50 wt.% is obtained. Then, the positive electrode slurry is coated on an aluminum current collector by using a coating machine to obtain a positive electrode sheet, and the area density of the positive electrode sheet is 20 mg / cm 2 ; wherein the amount of the oxygen vacancy surface-doped manganese-based lithium supplementing agent is 2% of the mass of the lithium iron phosphate positive electrode material;

[0085] 2) The positive electrode sheet obtained in step 1) and a graphite negative electrode sheet are assembled into a 100 mAh-level lithium ion soft-pack battery, and the N / P ratio is 1.1. Then, the battery is sequentially subjected to liquid injection, formation and testing.

[0086] Application Example 2

[0087] The oxygen vacancy surface doped manganese-based lithiu m supplementing agent prepared in Example 1 was placed in an air environment at room temperature for one month, and then was prepared into a 100 mAh level lithium ion soft package battery in the same manner as in Preparation Method and Application Example 1.

[0088] The performance of the 100 mAh level lithium ion soft package batteries provided in Application Example 1 and Application Example 2 was tested, and the test voltage during the test was 2-4.8 V, and the results obtained are shown in Table 1 and Table 2, respectively: Figure 1

[0089] Table 1 Performance of the 100 mAh level lithium ion soft package batteries prepared in Application Example 1 and Application Example 2

[0090] Performance Initial charge specific capacity mAh / g Initial discharge specific capacity mAh / g Corresponding initial coulombic efficiency / % Application Example 1 837 60 7.2 Application Example 2 798 54 6.8

[0091] As can be seen from Table 1, the freshly prepared oxygen vacancy surface doped manganese-based lithium supplementing agent and the oxygen vacancy surface doped manganese-based lithium supplementing agent placed in an air environment at room temperature for one month have very close electrochemical performances, and the charge specific capacity of both can be effectively exerted, indicating that the oxygen vacancy surface doping strategy effectively improves the air stability of the manganese-based lithium supplementing agent, and the interface oxygen evolution and the interface side reaction are significantly inhibited.

[0092] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.​

Claims

1. A method for preparing a manganese-based lithium supplement agent with oxygen vacancy surface doping, comprising: Plasma treatment of manganese-based lithium supplementers yields oxygen vacancy-doped manganese-based lithium supplementers. The chemical formula of the manganese-based lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.3~0.9; The plasma treatment atmosphere includes any one of N2, Ar, H2, NH3, He, O2 and CH4 or a mixture of Ar and H2. The volume ratio of Ar to H2 in the Ar and H2 mixture is (90~95):(5~10). The plasma treatment pressure is 1~1000 Pa, the plasma treatment temperature is 25~600℃, and the plasma treatment time is 0.1~120 min.

2. The preparation method according to claim 1, characterized in that, The pressure of the plasma treatment is 10~100 Pa.

3. The preparation method according to claim 1, characterized in that, The plasma treatment temperature is 25~300℃.

4. The preparation method according to claim 1, characterized in that, The plasma treatment time is 20-60 minutes.

5. The preparation method according to claim 1, characterized in that, The power of the plasma treatment is 10~1000W.

6. The oxygen vacancy surface-doped manganese-based lithium replenisher prepared by the preparation method according to any one of claims 1 to 5.

7. The application of the oxygen vacancy surface-doped manganese-based lithium replenishing agent according to claim 6 in lithium-ion batteries.

8. The application according to claim 7, characterized in that, The application method involves mixing the oxygen vacancy surface doped with a manganese-based lithium supplement agent with the cathode material, then preparing a cathode electrode sheet, and finally assembling the cathode electrode sheet into a lithium battery; the amount of the oxygen vacancy surface doped with the manganese-based lithium supplement agent is 0.1~10% of the mass of the cathode material.

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