Manganese-based oxide / carbon material composite lithium supplement agent and preparation method and application thereof

Abstract

The invention provides a manganese-based oxide / carbon material composite lithium supplement agent and a preparation method and application thereof, and belongs to the field of lithium battery materials. By introducing a certain amount of the carbon material into the manganese-based oxide lithium supplement agent, the composite lithium supplement agent can have lower polarization than the manganese-based oxide lithium supplement agent, and can release higher specific capacity under the same charging cut-off voltage, so that the composite lithium supplement agent is more easily applicable to most positive electrode materials, and the application range of the composite lithium supplement agent is widened. And the introduction of carbon can also improve the stability of the composite lithium supplement agent, so that the composite lithium supplement agent is easier to store, and large-scale popularization and application in the industry are facilitated. The result of the embodiment shows that the manganese-based oxide lithium supplement agent and the carbon material in the manganese-based oxide / carbon material composite lithium supplement agent provided by the invention are uniformly mixed, the discharge voltage of the composite lithium supplement agent is less than 4.5 V, the electrochemical polarization of the manganese-based lithium supplement agent is reduced, the lithium supplement specific capacity of the composite lithium supplement agent is not influenced, and the storage stability is better.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery materials, and in particular to a manganese-based oxide / carbon material composite lithium supplement and a preparation method and application thereof. Background Art

[0002] In order to compensate for the irreversible loss of lithium ions in lithium-ion batteries during the cycle (such as participating in the formation of solid electrolyte interface phase (SEI)), thereby improving the battery's long-cycle stability and energy density and other performance, researchers have proposed a lithium replenishment strategy. Among them, negative electrode lithium replenishment often adopts physical contact lithium replenishment, electrochemical lithium replenishment and chemical lithium replenishment methods, and often uses highly reducing lithium replenishers, such as lithium sheets, lithium powder, butyl lithium and naphthalene lithium, etc., which have problems such as poor controllability, difficulty in amplification and poor safety. In comparison, positive electrode lithium replenishment is mainly achieved by adding a small amount of positive electrode lithium replenisher to the slurry during the homogenization process. This method is not only simple to operate, but also can achieve precise lithium replenishment by adjusting the amount of lithium replenisher added. It is a lithium replenishment method with great application prospects.

[0003] The development of high-performance lithium replenishers is the key to the positive electrode lithium replenishment strategy. However, the commonly used lithium replenishers such as Li5FeO4, Li2C2O4, Li2O, Li3N, etc. often have problems such as low first-cycle lithium desorption capacity, high cost, easy gas production and storage difficulties, which are difficult to meet the actual needs of lithium replenishment in the positive electrode of lithium-ion batteries. Manganese-based oxide lithium replenishers based on manganese elements have begun to gradually replace other lithium replenishers due to their diverse structures and significant low-cost advantages. Among them, the theoretical lithium desorption capacity of Li6MnO4 with an inverse fluorite structure is 1001mAh / g, but pure phase Li6MnO4 is difficult to prepare. Composite lithium replenishers based on Li6MnO4, such as the composite material xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1) formed by inverse fluorite Li6MnO4 and layered LiMnO2, are relatively simple to synthesize and have a lithium replenishment capacity similar to that of pure phase Li6MnO4. However, due to the presence of multiple phases and complex interfaces in xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1), and the poor conductivity of anti-fluorite Li6MnO4 and layered LiMnO2, xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1) is severely polarized in electrochemical reactions and can only effectively release capacity above 4.6V, making it difficult to apply to most positive electrode materials. In addition, the xLi6MnO4·(1-x)LiMnO2 (0.3≤x≤1) composite material also has problems such as poor stability, which makes it difficult to store, severely limiting its industrial production.

[0004] Therefore, how to reduce the electrochemical polarization of manganese-based composite lithium supplements and improve their stability has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The object of the present invention is to provide a manganese-based oxide / carbon material composite lithium supplement and a preparation method and application thereof. The manganese-based oxide / carbon material composite lithium supplement provided by the present invention has lower electrochemical polarization and better storage stability.

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

[0007] The present invention provides a manganese-based oxide / carbon material composite lithium supplement, which is composited from a carbon material and a manganese-based oxide lithium supplement; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material / carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material / carbon material precursor is 0.5-30% of the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement.

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

[0009] Preferably, the carbon material includes any one or more of graphite, hard carbon, soft carbon, carbon nanotubes, graphene, Ketjen black, SuperP carbon black and activated carbon; the carbon material precursor includes any one or more of sucrose, glucose, citric acid, lactic acid, polydopamine, tannic acid, succinic acid, oleic acid and tannic acid.

[0010] The present invention provides a method for preparing the manganese-based oxide / carbon material composite lithium supplement agent described in the above technical solution, comprising the following steps:

[0011] (1) mixing a carbon material / carbon material precursor and a manganese-based oxide lithium supplement agent to obtain a solid mixture;

[0012] (2) Sintering the solid mixture obtained in step (1) to obtain a manganese-based oxide / carbon material composite lithium supplement.

[0013] Preferably, the carbon material / carbon material precursor and the manganese-based oxide lithium supplement agent are mixed in the step (1) as follows: in an argon atmosphere glove box, the carbon material / carbon material precursor and the manganese-based oxide lithium supplement agent are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is dried to obtain a solid mixture.

[0014] Preferably, the solvent includes any one or more of anhydrous ethanol, isopropanol, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide and dimethylformamide; the ratio of the mass of the solvent to the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement is (2-6):1.

[0015] Preferably, the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is (8-12):1, the rotation speed of the ball mill is 80-300 rpm, and the ball milling time is 0.5-5 h.

[0016] Preferably, the mass percentage of the carbon material / carbon material precursor in the solid mixture in step (1) is 0.5-30%.

[0017] Preferably, the sintering holding temperature in step (2) is 200-900°C, the sintering holding time is 1-100h, the heating rate to the sintering holding temperature is 1-10°C / min, the sintering atmosphere is an inert atmosphere, and the gas flow rate of the inert atmosphere is ≤50m / min. 3 / h.

[0018] The present invention provides the manganese-based oxide / carbon material composite lithium replenisher described in the above technical solution or the use of the manganese-based oxide / carbon material composite lithium replenisher described in the above technical solution in replenishing lithium of positive electrode materials of lithium-ion batteries.

[0019] The present invention provides a manganese-based oxide / carbon material composite lithium supplement, which is composited by a carbon material and a manganese-based oxide lithium supplement; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material / carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material / carbon material precursor is 0.5-30% of the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement. The present invention uses a manganese-based oxide lithium supplement as a matrix material of the composite lithium supplement, which is relatively simple to synthesize and has a lithium supplement specific capacity similar to that of pure phase Li6MnO4, which can reduce production difficulty and preparation cost; by introducing a certain amount of carbon material into the manganese-based oxide lithium supplement, the composite lithium supplement can have a lower polarization than the manganese-based oxide lithium supplement, and can release a higher specific capacity at the same charging cut-off voltage, so that the composite lithium supplement is more easily applicable to most positive electrode materials, and the introduction of carbon can also improve the stability of the composite lithium supplement, making it easier to store, which is conducive to its large-scale promotion and application in industry. The results of the embodiments show that the manganese-based oxide / carbon material composite lithium supplement provided by the present invention has a uniform mixture of the manganese-based oxide lithium supplement and the carbon material, and the discharge voltage of the composite lithium supplement is less than 4.5 V, which can reduce the electrochemical polarization of the manganese-based lithium supplement. At the same time, compared with the manganese-based oxide lithium supplement, the lithium supplement specific capacity of the manganese-based oxide / carbon material composite lithium supplement is not affected, and the storage stability is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the morphology of the manganese-based oxide / carbon material composite lithium supplement prepared in Example 1;

[0021] Figure 2This is the Raman spectrum of the manganese-based oxide / carbon material composite lithium supplement prepared in Example 1;

[0022] Figure 3 The charge and discharge curves of the manganese-based oxide / carbon material composite lithium supplement prepared in Example 1 and the manganese-based oxide lithium supplement provided in Comparative Example 1. DETAILED DESCRIPTION

[0023] The present invention provides a manganese-based oxide / carbon material composite lithium supplement, which is composited from a carbon material and a manganese-based oxide lithium supplement; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material / carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material / carbon material precursor is 0.5-30% of the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement.

[0024] In the present invention, the carbon material preferably includes any one or more of graphite, hard carbon, soft carbon, carbon nanotubes, graphene, Ketjen black, SuperP carbon black and activated carbon; the carbon material precursor preferably includes any one or more of sucrose, glucose, citric acid, lactic acid, polydopamine, tannic acid, succinic acid, oleic acid and tannic acid. The present invention introduces a certain amount of carbon material into the manganese-based oxide lithium supplement, so that the composite lithium supplement has lower polarization than the manganese-based oxide lithium supplement, can release higher specific capacity at the same charge cut-off voltage, and can also make the composite lithium supplement have better storage stability.

[0025] As an embodiment of the present invention, the mass of the carbon material / carbon material precursor can be 0.5%, 1%, 2%, 5%, 8%, 10%, 15%, 20%, 25% or 30% of the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement.

[0026] In the present invention, the chemical formula of the manganese-based oxide lithium supplement is preferably xLi6MnO4·(1-x)LiMnO2; the x is 0.3 to 1, preferably 0.4 to 0.9, more preferably 0.5 to 0.8, and further preferably 0.6 to 0.7; the crystal structure of the manganese-based oxide lithium supplement is preferably a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2.

[0027] The present invention adopts xLi6MnO4·(1-x)LiMnO2 manganese-based oxide lithium supplement as the base material of the composite lithium supplement, which is relatively simple to synthesize and has a lithium supplement specific capacity similar to that of pure phase Li6MnO4, thereby reducing the production difficulty and the preparation cost. By introducing a certain amount of carbon material into the manganese-based oxide lithium supplement, the composite lithium supplement can have a lower polarization than the manganese-based oxide lithium supplement, and can release a higher specific capacity at the same charging cut-off voltage, thereby making the composite lithium supplement more suitable for most positive electrode materials, and the introduction of carbon can also improve the stability of the composite lithium supplement, making it easier to store, which is beneficial to its large-scale promotion and application in industry.

[0028] The present invention also provides a method for preparing the manganese-based oxide / carbon material composite lithium supplement agent described in the above technical solution, comprising the following steps:

[0029] (1) mixing a carbon material / carbon material precursor and a manganese-based oxide lithium supplement agent to obtain a solid mixture;

[0030] (2) Sintering the solid mixture obtained in step (1) to obtain a manganese-based oxide / carbon material composite lithium supplement.

[0031] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art.

[0032] The present invention mixes the carbon material / carbon material precursor and the manganese-based oxide lithium supplement agent to obtain a solid mixture.

[0033] In the present invention, the carbon material preferably includes any one or more of graphite, hard carbon, soft carbon, carbon nanotubes, graphene, Ketjen black, SuperP carbon black and activated carbon; the carbon material precursor preferably includes any one or more of sucrose, glucose, citric acid, lactic acid, polydopamine, tannic acid, succinic acid, oleic acid and tannic acid. The present invention can provide sufficient carbon and reduce the introduction of impurities by using the above-mentioned carbon material / carbon material precursor as raw materials.

[0034] In the present invention, the chemical formula of the manganese-based oxide lithium supplement is preferably xLi6MnO4·(1-x)LiMnO2; the x is 0.3 to 1, preferably 0.4 to 0.9, more preferably 0.5 to 0.8, and further preferably 0.6 to 0.7; the crystal structure of the manganese-based oxide lithium supplement is preferably a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2.

[0035] In the present invention, the carbon material / carbon material precursor and the manganese-based oxide lithium supplement are preferably mixed in the following manner: in an argon atmosphere glove box, the carbon material / carbon material precursor and the manganese-based oxide lithium supplement are added to a ball mill, then a solvent is added, the ball mill is sealed and taken out, and the ball mill is installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is dried to obtain a solid mixture. The present invention is conducive to making the carbon material / carbon material precursor and the manganese-based oxide lithium supplement more uniformly mixed by mixing the raw materials in a solvent and then ball milling.

[0036] The present invention has no particular limitation on the specific model and source of the argon atmosphere glove box, and a commercially available argon atmosphere glove box known to those skilled in the art can be used. The present invention mixes the raw materials in an argon atmosphere glove box to reduce the introduction of impurities.

[0037] The present invention has no particular limitation on the specific model of the ball mill, and a commercially available ball mill well known to those skilled in the art can be used.

[0038] In the present invention, the solvent preferably includes any one or more of anhydrous ethanol, isopropanol, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide and dimethylformamide. In the present invention, the ratio of the mass of the solvent to the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement is preferably (2-6):1, more preferably (4-5):1. The present invention is conducive to the full dispersion of the raw materials by controlling the amount of the solvent.

[0039] In the present invention, the grinding balls used in the ball mill are preferably steel balls; the ball-to-material ratio of the ball mill is preferably (8-12):1, more preferably 10:1; the rotation speed of the ball mill is preferably 80-300 rpm, more preferably 100-200 rpm; the time of the ball mill is preferably 0.5-5 hours, more preferably 2-4 hours. The present invention can make the carbon material / carbon material precursor and the manganese-based oxide lithium supplement agent mixed more uniformly by controlling the parameters of the ball mill.

[0040] In the present invention, the drying method is preferably to perform vacuum filtration and vacuum drying on the mixed solution in sequence. The present invention has no special limitation on the vacuum degree during the vacuum filtration and vacuum drying, and it is determined according to the technical common sense of those skilled in the art, as long as the introduction of impurities can be avoided. The present invention has no special limitation on the specific operation of the vacuum filtration, and the vacuum filtration well known to those skilled in the art can be used to separate the solid and the liquid. In the present invention, the vacuum drying is preferably carried out in a vacuum oven. The present invention has no special limitation on the specific source of the vacuum oven, and a commercially available vacuum oven well known to those skilled in the art can be used. The present invention can avoid the introduction of impurities by filtering and drying in a vacuum.

[0041] In the present invention, the mass percentage of the carbon material / carbon material precursor in the solid mixture is preferably 0.5-30%. By controlling the amount of the carbon material / carbon material precursor in the solid mixture, the present invention can ensure that the carbon content in the prepared manganese-based oxide / carbon material composite lithium supplement meets the requirements.

[0042] As an embodiment of the present invention, the mass percentage of the carbon material / carbon material precursor in the solid mixture can be 0.5%, 1%, 2%, 5%, 8%, 10%, 15%, 20%, 25% or 30%.

[0043] After obtaining the solid mixture, the present invention sintered the solid mixture to obtain a manganese-based oxide / carbon material composite lithium supplement.

[0044] In the present invention, the sintering is preferably carried out in a tube furnace. The present invention has no particular limitation on the specific model and source of the tube furnace, and a commercially available tube furnace well known to those skilled in the art can be used.

[0045] In the present invention, the sintering holding temperature is preferably 200-900°C; the sintering holding time is preferably 1-100h; the heating rate to the sintering holding temperature is preferably 1-10°C / min; the sintering atmosphere is preferably an inert atmosphere; the inert atmosphere preferably includes nitrogen and / or argon; the gas flow rate of the inert atmosphere is preferably ≤50m / min. 3 / h. The present invention can avoid the introduction of impurities in the air by sintering in an inert atmosphere; by controlling the sintering temperature and time, the carbon material precursor can be decomposed into carbon material at high temperature, and the carbon material and the manganese-based oxide lithium supplement can form a relatively dense structure, thereby realizing the composite of the carbon material and the manganese-based oxide lithium supplement.

[0046] As an embodiment of the present invention, the sintering insulation temperature may be 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or 900°C; the sintering insulation time may be 1h, 5h, 10h, 20h, 30h, 40h, 50h, 60h, 70h, 80h, 90h or 100h; the heating rate to the sintering insulation temperature may 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; the gas flow rate of the inert atmosphere may be 5m / s. 3 / h、10m 3 / h、15m 3 / h、20m 3 / h、25m 3 / h、30m 3 / h、35m 3 / h、40m 3 / h、45m 3 / h or 50m 3 / h.

[0047] The invention can be prepared by mixing a carbon material / carbon material precursor and a manganese-based oxide lithium supplement agent and then sintering them. The preparation method is simple, has low requirements on equipment in the preparation process, can reduce costs, and is conducive to large-scale industrial production and promotion.

[0048] The present invention also provides the use of the manganese-based oxide / carbon material composite lithium replenisher described in the above technical solution or the manganese-based oxide / carbon material composite lithium replenisher prepared by the preparation method described in the above technical solution in replenishing lithium in positive electrode materials of lithium-ion batteries.

[0049] In the present invention, the application method is preferably: mixing the manganese-based oxide / carbon material composite lithium supplement and the positive electrode material, then preparing a positive electrode sheet, and finally assembling the positive electrode sheet into a lithium-ion battery.

[0050] In the present invention, the positive electrode material preferably includes any one of lithium iron phosphate, lithium iron manganese phosphate, ternary layered oxide and lithium-rich layered oxide. The present invention has no particular limitation on the specific source of the positive electrode material, and commercially available positive electrode materials known to those skilled in the art can be used.

[0051] In the present invention, the amount of the manganese-based oxide / carbon material composite lithium replenisher is preferably 0.1-10% of the mass of the positive electrode material. The present invention can achieve a good lithium replenishment effect on the positive electrode material by controlling the amount of the composite lithium replenisher.

[0052] As an embodiment of the present invention, the amount of the manganese-based oxide / carbon material composite lithium supplement can be 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% of the mass of the positive electrode material.

[0053] The present invention has no particular limitation on the specific operation of the mixing, as long as the manganese-based oxide / carbon material composite lithium supplement and the positive electrode material can be mixed evenly.

[0054] The present invention has no special limitation on the specific operation of preparing the positive electrode sheet, and the operation of preparing the positive electrode sheet well known to those skilled in the art can be adopted.

[0055] The present invention has no special limitation on the specific operation of assembling the positive electrode sheets into a lithium-ion battery, and the operation of assembling a lithium-ion battery well known to those skilled in the art can be adopted.

[0056] 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.

[0057] Example 1

[0058] A manganese-based oxide / carbon material composite lithium supplement, which is composited with a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material is 5% of the total mass of the carbon material and the manganese-based oxide lithium supplement;

[0059] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0060] (1) In an argon atmosphere glove box, a carbon material and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material is Super P carbon black, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, and the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is anhydrous ethanol, and the ratio of the mass of the solvent to the total mass of the carbon material and the manganese-based oxide lithium supplement is 4:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 100 rpm, and the ball milling time is 2 hours; the mass percentage of the carbon material in the solid mixture is 5%;

[0061] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it, and finally naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 500° C., the sintering insulation time is 10 h, and the heating rate to the sintering insulation temperature is 2° C. / min; the gas flow rate of the nitrogen is 5 m / s. 3 / h.

[0062] Figure 1Schematic diagram of the morphology of the manganese-based oxide / carbon material composite lithium supplement prepared in Example 1. Figure 1 It can be seen that in the manganese-based oxide / carbon material composite lithium supplement provided by the present invention, the carbon material and the manganese-based oxide lithium supplement are uniformly mixed together.

[0063] Figure 2 This is the Raman spectrum of the manganese-based oxide / carbon material composite lithium supplement prepared in Example 1. Figure 2 It can be seen that in the composite lithium supplement, the carbon material has a good graphitization effect after high-temperature sintering.

[0064] Example 2

[0065] A manganese-based oxide / carbon material composite lithium supplement, which is composited with a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material is 5% of the total mass of the carbon material and the manganese-based oxide lithium supplement;

[0066] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0067] (1) In an argon atmosphere glove box, a carbon material and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material is carbon nanotubes, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is N-methylpyrrolidone, and the ratio of the mass of the solvent to the total mass of the carbon material and the manganese-based oxide lithium supplement is 3:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 4 hours; the mass percentage of the carbon material in the solid mixture is 5%;

[0068] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it. Finally, naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 600° C., the sintering insulation time is 5 h, and the heating rate to the sintering insulation temperature is 1° C. / min; the gas flow rate of the nitrogen is 10 m / s. 3 / h.

[0069] Example 3

[0070] A manganese-based oxide / carbon material composite lithium supplement, which is composited with a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material is 5% of the total mass of the carbon material and the manganese-based oxide lithium supplement;

[0071] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0072] (1) In an argon atmosphere glove box, a carbon material and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material is graphene oxide, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is N-methylpyrrolidone, and the ratio of the mass of the solvent to the total mass of the carbon material and the manganese-based oxide lithium supplement is 3:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 5 hours; the mass percentage of the carbon material in the solid mixture is 5%;

[0073] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it. Finally, naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 600° C., the sintering insulation time is 5 h, and the heating rate to the sintering insulation temperature is 1° C. / min; the gas flow rate of the nitrogen is 10 m / s. 3 / h.

[0074] Example 4

[0075] A manganese-based oxide / carbon material composite lithium supplement, which is composited with a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material is 5% of the total mass of the carbon material and the manganese-based oxide lithium supplement;

[0076] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0077] (1) In an argon atmosphere glove box, a carbon material and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material is graphite, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is N-methylpyrrolidone, and the ratio of the mass of the solvent to the total mass of the carbon material and the manganese-based oxide lithium supplement is 2:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 150 rpm, and the ball milling time is 4 hours; the mass percentage of the carbon material in the solid mixture is 5%;

[0078] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it, and finally naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 700° C., the sintering insulation time is 4 hours, and the heating rate to the sintering insulation temperature is 2° C. / min; the gas flow rate of the nitrogen is 10 m / s. 3 / h.

[0079] Example 5

[0080] A manganese-based oxide / carbon material composite lithium supplement, which is composited by a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing a carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material precursor is 10% of the total mass of the carbon material precursor and the manganese-based oxide lithium supplement;

[0081] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0082] (1) In an argon atmosphere glove box, a carbon material precursor and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material precursor is tannic acid, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, and the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is anhydrous ethanol, and the ratio of the mass of the solvent to the total mass of the carbon material precursor and the manganese-based oxide lithium supplement is 3:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 0.5 h; the mass percentage of the carbon material precursor in the solid mixture is 10%;

[0083] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it, and finally naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 600° C., the sintering insulation time is 10 h, and the heating rate to the sintering insulation temperature is 2° C. / min; the gas flow rate of the nitrogen is 5 m / s. 3 / h.

[0084] Example 6

[0085] A manganese-based oxide / carbon material composite lithium supplement, which is composited by a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing a carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material precursor is 15% of the total mass of the carbon material precursor and the manganese-based oxide lithium supplement;

[0086] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0087] (1) In an argon atmosphere glove box, a carbon material precursor and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material precursor is citric acid, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, and the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is tetrahydrofuran, and the ratio of the mass of the solvent to the total mass of the carbon material precursor and the manganese-based oxide lithium supplement is 3:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 0.5 h; the mass percentage of the carbon material precursor in the solid mixture is 15%;

[0088] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it. Finally, naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 650° C., the sintering insulation time is 20 h, and the heating rate to the sintering insulation temperature is 2° C. / min; the gas flow rate of the nitrogen is 5 m / s. 3 / h.

[0089] Example 7

[0090] A manganese-based oxide / carbon material composite lithium supplement, which is composited by a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing a carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material precursor is 10% of the total mass of the carbon material precursor and the manganese-based oxide lithium supplement;

[0091] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0092] (1) In an argon atmosphere glove box, a carbon material precursor and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material precursor is sucrose, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, and the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is isopropanol, and the ratio of the mass of the solvent to the total mass of the carbon material precursor and the manganese-based oxide lithium supplement is 3:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 0.5 h; the mass percentage of the carbon material precursor in the solid mixture is 10%;

[0093] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it. Finally, naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 700° C., the sintering insulation time is 20 h, and the heating rate to the sintering insulation temperature is 1° C. / min; the gas flow rate of the nitrogen is 10 m / s. 3 / h.

[0094] Example 8

[0095] A manganese-based oxide / carbon material composite lithium supplement, which is composited by a carbon material and a manganese-based oxide lithium supplement; the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9; the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2; the carbon material and the manganese-based oxide lithium supplement are composited by mixing a carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material precursor is 12% of the total mass of the carbon material precursor and the manganese-based oxide lithium supplement;

[0096] The preparation method of the manganese-based oxide / carbon material composite lithium supplement agent is as follows:

[0097] (1) In an argon atmosphere glove box, a carbon material precursor and a manganese-based oxide lithium supplement are added to a ball mill, and then a solvent is added, the ball mill is sealed and taken out, and installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is vacuum filtered and vacuum dried in a vacuum oven to obtain a solid mixture; the carbon material precursor is polydopamine, the chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9, and the crystal structure of the manganese-based oxide lithium supplement is a composite structure formed by anti-fluorite Li6MnO4 and layered LiMnO2, the solvent is isopropanol, and the ratio of the mass of the solvent to the total mass of the carbon material precursor and the manganese-based oxide lithium supplement is 3:1; the grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is 10:1, the rotation speed of the ball mill is 200 rpm, and the ball milling time is 0.5 h; the mass percentage of the carbon material precursor in the solid mixture is 12%;

[0098] (2) placing the solid mixture obtained in step (1) in a tube furnace, sealing it, introducing nitrogen, and then sintering it. Finally, naturally cooling it to room temperature to obtain a manganese-based oxide / carbon material composite lithium supplement; the sintering insulation temperature is 700° C., the sintering insulation time is 20 h, and the heating rate to the sintering insulation temperature is 1° C. / min; the gas flow rate of the nitrogen is 10 m / s. 3 / h.

[0099] Comparative Example 1

[0100] A manganese-based oxide lithium supplement has a chemical formula of xLi6MnO4·(1-x)LiMnO2, wherein x is 0.9.

[0101] The charge and discharge performance of the manganese-based oxide / carbon material composite lithium supplement prepared in Example 1 and the manganese-based oxide lithium supplement provided in Comparative Example 1 were tested using conventional button cell tests with the same parameters. The obtained charge and discharge curves are shown in FIG. Figure 3 As shown. Figure 3 It can be seen that the discharge voltage of the manganese-based oxide / carbon material composite lithium supplement provided by the present invention is significantly reduced, indicating that the present invention can reduce the electrochemical polarization of the manganese-based lithium supplement by introducing carbon material. At the same time, compared with the manganese-based oxide lithium supplement, the lithium supplement specific capacity of the manganese-based oxide / carbon material composite lithium supplement of the present invention is not affected, and the stability is better.

[0102] 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 manganese-based oxide / carbon material composite lithium supplement, which is composed of a carbon material and a manganese-based oxide lithium supplement; the carbon material and the manganese-based oxide lithium supplement are composited by mixing the carbon material / carbon material precursor and the manganese-based oxide lithium supplement and then sintering; the mass of the carbon material / carbon material precursor is 0.5 to 30% of the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement.

2. The manganese-based oxide / carbon material composite lithium supplement according to claim 1, characterized in that: The chemical formula of the manganese-based oxide lithium supplement is xLi6MnO4·(1-x)LiMnO2, where x is 0.3-1.

3. The manganese-based oxide / carbon material composite lithium supplement according to claim 1, characterized in that: The carbon material includes any one or more of graphite, hard carbon, soft carbon, carbon nanotubes, graphene, Ketjen black, SuperP carbon black and activated carbon; the carbon material precursor includes any one or more of sucrose, glucose, citric acid, lactic acid, polydopamine, tannic acid, succinic acid, oleic acid and tannic acid.

4. The method for preparing the manganese-based oxide / carbon material composite lithium supplement according to any one of claims 1 to 3, comprising the following steps: (1) mixing a carbon material / carbon material precursor and a manganese-based oxide lithium supplement agent to obtain a solid mixture; (2) Sintering the solid mixture obtained in step (1) to obtain a manganese-based oxide / carbon material composite lithium supplement.

5. The preparation method according to claim 4, characterized in that: The carbon material / carbon material precursor and the manganese-based oxide lithium supplement agent are mixed in the step (1) as follows: in an argon atmosphere glove box, the carbon material / carbon material precursor and the manganese-based oxide lithium supplement agent are added into a ball mill, then a solvent is added, the ball mill is sealed and taken out, and the ball mill is installed in a ball mill for ball milling to obtain a mixed solution, and then the mixed solution is dried to obtain a solid mixture.

6. The preparation method according to claim 5, characterized in that: The solvent includes any one or more of anhydrous ethanol, isopropanol, tetrahydrofuran, N-methylpyrrolidone, dimethyl sulfoxide and dimethylformamide; the ratio of the mass of the solvent to the total mass of the carbon material / carbon material precursor and the manganese-based oxide lithium supplement is (2-6):

1.

7. The preparation method according to claim 5, characterized in that: The grinding balls used in the ball mill are steel balls, the ball-to-material ratio of the ball mill is (8-12):1, the rotation speed of the ball mill is 80-300 rpm, and the ball milling time is 0.5-5 hours.

8. The preparation method according to claim 4, characterized in that: In the step (1), the mass percentage of the carbon material / carbon material precursor in the solid mixture is 0.5-30%.

9. The preparation method according to claim 4, characterized in that: In the step (2), the sintering holding temperature is 200-900° C., the sintering holding time is 1-100 h, the heating rate to the sintering holding temperature is 1-10° C. / min, the sintering atmosphere is an inert atmosphere, and the gas flow rate of the inert atmosphere is ≤50 m / s. 3 / h.

10. Use of the manganese-based oxide / carbon material composite lithium replenisher according to any one of claims 1 to 3 or the manganese-based oxide / carbon material composite lithium replenisher according to any one of claims 4 to 9 in replenishing lithium in positive electrode materials of lithium-ion batteries.

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