Quenching solution, method for manufacturing surface-stabilized lithium-rich manganese-based positive electrode material, and secondary battery

Abstract

Disclosed are a quenching solution, a method for manufacturing a surface-stabilized Li-rich manganese-based positive electrode material, and a secondary battery. The quenching solution contains a solvent, a lithium hydroxide or lithium salt, a reducing agent, and a phosphate, and the Li-rich manganese-based positive electrode material is treated by a quenching method in the quenching solution, thereby improving the initial coulombic efficiency and cyclic stability of the battery and alleviating voltage decay.

Description

Method for manufacturing a surface-stabilized lithium-rich manganese-based cathode material and a secondary battery

[0001] This application claims the benefit of priority to Chinese Patent Application No. 202410509387.7, filed April 25, 2024, Korean Patent Application No. 10-2025-0007474, filed January 17, 2025, and Korean Patent Application No. 10-2025-0049409, filed April 16, 2025, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to the field of battery materials, and more particularly, to a method for manufacturing a quenching solution, a surface-stabilized Li-rich manganese cathode material, and a secondary battery.

[0003] Lithium-ion batteries have high platform voltage, low self-discharge, and relatively long cycle life, making them widely used in various fields such as electronic devices, electric vehicles, and energy storage systems. Cathode materials are a key component of lithium-ion batteries, directly affecting the battery's energy density, safety performance, and cycle performance. However, conventional cathode materials include lithium cobalt oxide, lithium manganese oxide, ternary cathodes, and lithium iron phosphate cathodes, and the specific capacities of these materials still need to be improved. Lithium-rich manganese-based cathode materials are currently being discovered as lithium-ion battery cathodes with relatively high specific capacities, reaching over 300 mAh / g. Furthermore, these materials also boast low raw material costs and environmental friendliness, indicating great development prospects and application value.

[0004] Li-rich manganese-based cathode materials have the advantage of high specific capacity, but they have the following problems in practical application: first, the initial Coulombic efficiency is low; second, the cycling performance is poor; and third, the voltage decay is severe during the cycling process. The initial charging process of Li-rich manganese-based cathode materials can be divided into two stages. The first stage is when the voltage is below 4.5 V, the delithiation process mainly occurs on LiMnO2, and this process is similar to the initial charging process of conventional ternary cathode materials by performing charge compensation through electron loss oxidation of transition metal cations. The second stage is when the voltage is higher than 4.5 V, the lithium layer and transition metal layer delithiate lithium ions together, and the charge compensation is mainly performed through the oxidation reaction of oxygen anions. The lithium delithiation of the transition metal layer and the electron loss oxidation of oxygen cause the collapse of the original structure, and after the oxygen ions are oxidized, they are easily delithiated from the structure in the form of oxygen gas on the surface. During the subsequent discharge process, the lithium ions cannot completely return to the crystal lattice of the Li-rich manganese cathode material during the discharge process due to the evolution of oxygen gas and the collapse of the original structure, which reduces the initial charge-discharge efficiency. To exhibit high-capacity characteristics, the Li-rich manganese cathode material must be located within a wider charge-discharge voltage window. When in a highly charged state, the transition metal in the valence state of the material is highly oxidizable and easily causes side reactions with the electrolyte, which irreversibly transforms the crystal structure of the material from a layered phase to a spinel phase, and the interfacial film deteriorates, resulting in capacity decay and an increase in interfacial impedance. At the same time, the dissolution of transition metal ions at the electrode / electrolyte interface during the charge-discharge process is also an important cause of the deterioration of the cycle performance of the material. The voltage decay problem of the Li-rich manganese cathode material is relatively obvious in the first few weeks and gradually slows down thereafter.It is widely known that the phase change of the material structure caused by the irreversible release of oxygen during the current reaction is the main cause of the voltage decay, and after the oxygen is released, lithium ions are inserted back into the positive electrode structure during the discharge process, and when the oxygen is lost, the transition metal has no choice but to accept electrons to balance the charge state, and after the transition metal accepts electrons, the potential of the material decreases, and the voltage of the entire material also decreases, and since oxygen gas is continuously released during the entire battery cycle, the potential of the material continuously decreases.

[0005] Current solutions to these problems primarily include surface coating, bulk doping, surface modification, and particle nano-fabrication. However, these existing technologies still fail to effectively address the low initial Coulombic efficiency, severe voltage decay, and poor cycle performance of Li-rich manganese-based cathodes.

[0006] (Patent Document 1) KR 10-2024-0043755 A "Lithium-rich nickel manganese oxide battery cathode material and method"

[0007] The present invention provides a method for manufacturing a Li-rich manganese cathode material with a quenching solution and a surface-stabilized treatment, and its application to overcome the problems of the prior art. By treating a Li-rich manganese cathode material using a quenching solution, the material exhibits a relatively high initial Coulombic efficiency, while simultaneously improving the material's cycle life and alleviating voltage decay.

[0008] In a first aspect, the present application provides a pickling liquid.

[0009] In some embodiments, the quenching solution comprises a solvent, lithium hydroxide or a lithium salt, a reducing agent, and a phosphate.

[0010] In some embodiments, the solvent is pure water, or other liquid that is advantageous in dissolving lithium hydroxide or a lithium salt, a reducing agent, or a phosphate and does not cause a side reaction with lithium hydroxide or a lithium salt, a reducing agent, or a phosphate.

[0011] In some embodiments, the lithium salt is a soluble lithium salt, which may be selected from an organic lithium salt or an inorganic lithium salt. The organic lithium salt may be selected from one or more of lithium trifluoromethanesulfonate, lithium bisoxalate borate, and lithium bis(trifluoromethanesulphonyl)imide; and the inorganic lithium salt may be selected from one or more of lithium nitrate, lithium hexafluorophosphate, lithium acetate, lithium sulfide, and lithium perchlorate. Preferably, lithium hydroxide or a soluble inorganic lithium salt is used.

[0012] In some embodiments, the reducing agent is a substance having relatively strong reducing properties, which may be selected from a metal hydride, a vitamin, or citric acid. Here, the metal hydride may be selected from one or more of lithium aluminum hydride (LiAlH4), potassium borohydride (KBH4), sodium borohydride (NaBH4), and lithium borohydride (LiBH4); and the vitamin may be selected from one or more of vitamin A, vitamin C, and vitamin E. Preferably, the reducing agent of the present application is selected from a metal hydride. More preferably, the reducing agent is selected from lithium aluminum hydride.

[0013] In some embodiments, the phosphate is a phosphate having relatively high solubility, and may be selected from monophosphate, diphosphate, or orthophosphate. Here, the monophosphate may be selected from one or more of ammonium phosphate, sodium phosphate, and potassium phosphate; here, the diphosphate may be selected from sodium phosphate, potassium phosphate, and ammonium phosphate; and the orthophosphate may be selected from one or more of sodium phosphate, potassium phosphate, and ammonium phosphate. Preferably, the phosphate is selected from monophosphate.

[0014] In some embodiments, the amount of lithium hydroxide or lithium salt added is 0.02 to 0.1 mol / L based on lithium ion concentration.

[0015] In some embodiments, the amount of reducing agent added is 3.0% to 15.0% of the solvent mass.

[0016] In some embodiments, the amount of phosphate added is 0.5% to 2.0% of the solvent mass.

[0017] Preferably, the quenching liquid further comprises a solid electrolyte.

[0018] In some embodiments, the solid electrolyte may be selected from one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), and polyethylene oxide (PEO).

[0019] In some embodiments, the amount of the solid electrolyte added is 0.5% to 2.0% of the solvent mass.

[0020] In a second aspect, the present application provides a method for manufacturing a surface-stabilized Li-rich manganese-based cathode material.

[0021] In some embodiments, the manufacturing method comprises a step of quenching a primary sintered material of a Li-rich manganese-based cathode material in a quenching solution according to the first aspect.

[0022] In some embodiments, the primary sintered material of the Li-rich manganese-based cathode material is a material having a basic activity performance obtained by mixing a Li-rich manganese-based precursor material and lithium hydroxide or a lithium salt and solid-phase sintering. Specifically, the chemical formula of the primary sintered material of the Li-rich manganese-based cathode material is xLi2MnO3·(1-x)LiMO2, where 0.6 <x<0.8이고, M는 Ni, Co, Mn, Al, Zr, Cr, Y, Nb, Ta, La, W, Mg 중 한 종류 또는 여러 종류이다.

[0023] In some embodiments, the molar ratio of lithium ions to other metals in the mixture of the Li-rich manganese precursor material and lithium hydroxide or lithium salt is 1.2 to 1.4.

[0024] In some embodiments, the solid-state sintering temperature of the primary sintered material of the Li-rich manganese-based cathode material is 800 to 850°C.

[0025] In some embodiments, the quenching process comprises heating the primary sintered material of the Li-rich manganese-based cathode material to 150 to 300°C and then pouring it into a quenching solution and cooling it, wherein the temperature difference is greater than 100°C. Preferably, the temperature of the quenching solution is room temperature or 10 to 30°C.

[0026] In some embodiments, the mass ratio of the primary sintered material of the Li-rich manganese-based cathode material and the quenching liquid is 1:(1 to 3). In some embodiments, in order to improve the quenching effect, the primary sintered material of the Li-rich manganese-based cathode material is heated to 150 to 300°C and then kept at room temperature for 2 to 5 hours.

[0027] Furthermore, the material after quenching and cooling is filtered and dried to obtain a dried pretreated material.

[0028] In some embodiments, the drying temperature is 100 to 150°C and the drying time is 5 to 10 h.

[0029] Furthermore, secondary sintering is performed on the pretreated material, the sintering temperature is 300 to 500°C, and the sintering time is 5 to 15 h.

[0030] In a third aspect, the present application provides a secondary battery including a surface-stabilized Li-rich manganese-based cathode material obtained by the manufacturing method provided in the second aspect of the present application.

[0031] As a beneficial effect of the present invention,

[0032] First, rapid quenching can cause a phase change on the material surface to form a spinel-like structure layer on the surface, thereby improving the mobility of ions and the electrical conductivity of electrons, and improving the specific capacity and cycle stability of the material; The appropriate combination of quenching liquid components can alleviate the adaptability problem caused by rapid temperature drop and large structural change during the quenching process, and at the same time meet the purpose of improving performance; By adding a small amount of lithium hydroxide or lithium salt to the quenching liquid, it can adjust the balance of the lithium content on the material surface, effectively compensate for the surface lithium loss of the material during the quenching process, and further alleviate the voltage attenuation of the material caused by lithium loss.

[0033] In addition, by reducing the material surface using a reducing agent during the quenching process, surface oxygen vacancies can be built, which on the one hand can improve the mobility and electronic conductivity of surface lithium ions and enhance the specific capacity of the battery, and on the other hand can effectively improve the initial Coulombic efficiency of the material by reducing the oxygen release during the battery charge / discharge process and alleviating the problem of gas generation due to side reactions.

[0034] In addition, phosphate has good lithium ion conductivity and electronic conductivity, and as a kind of restoring agent, it can enter the crystal structure of the material surface during the quenching process, delay the phase change of the material during the cycle charge / discharge process, improve the cycle stability of the material, cooperate with the reducing agent to improve the initial coulombic efficiency of the battery, and cooperate with lithium hydroxide or lithium salt to alleviate the voltage decay during the cycle charge / discharge process of the battery.

[0035] Furthermore, the solid electrolyte exhibits excellent ionic conductivity and can be uniformly and stably coated on the surface of the material through quenching, while simultaneously reducing side reactions between the cathode material and the electrolyte. Therefore, the surface-stabilized Li-rich manganese cathode material exhibits relatively high initial Coulombic efficiency and excellent cycle stability.

[0036] Hereinafter, in order to more clearly explain the technical solution according to the embodiment of the present invention, drawings necessary for use in explaining the embodiment or the prior art are briefly introduced. The drawings described below are only some embodiments of the present invention, and it is obvious that a person skilled in the art can obtain other drawings based on these drawings without conducting progressive work.

[0037] Figure 1 is an XRD diagram of Example 1 and Comparative Example 5.

[0038] Figure 2 is an SEM drawing of Example 1 and Comparative Example 1.

[0039] FIG. 3 is a diagram comparing the discharge specific capacity at 100 cycles of long cycle performance of Li-rich manganese-based cathode materials manufactured in Examples 1 to 3 and Comparative Examples 1, 2, and 4.

[0040] Figure 4 is a diagram showing the voltage decay trend in the 100-cycle long cycle performance of the Li-rich manganese cathode materials manufactured in Example 1 and Comparative Example 3.

[0041] Figure 5 is a drawing showing the expansion situation of Example 1 and Comparative Example 4.

[0042] Hereinafter, in order to facilitate understanding of the present invention, the present invention will be described more comprehensively and examples of the present invention will be presented, but the scope of the present invention is not limited thereto.

[0043] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in this application is for the purpose of describing specific embodiments only and is not intended to be limiting of this application; and the terms “comprising” and “having” and any variations thereof in the specification and claims of this application and the brief description of the drawings above are intended to encompass a non-exclusive inclusion.

[0044] References to "an embodiment" in this application indicate that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of each phrase in the specification does not necessarily imply that all embodiments are identical, nor are they exclusive, independent, or alternative embodiments compared to other embodiments. Those skilled in the art should understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.

[0045] In the description of the present application, the term “several kinds” means two or more kinds (including two kinds), similarly, “several sets” means two or more sets (including two sets), and “at least one kind” means one or more kinds (including one kind, two kinds, three kinds, etc.).

[0046] In a first aspect, the present application provides a quenching solution. The quenching solution comprises a solvent, lithium hydroxide or a lithium salt, a reducing agent, and a phosphate.

[0047] Here, by adding lithium hydroxide or lithium salt to the quenching solution, the surface lithium loss of the material during the quenching process can be effectively compensated for, and further, the voltage decay of the material due to lithium loss can be alleviated. The reducing agent reduces the surface of the material to create surface oxygen vacancies, which on the one hand can improve the mobility and electronic conductivity of surface lithium ions and enhance the specific capacity of the battery. On the other hand, it can effectively improve the initial coulombic efficiency of the material by reducing the oxygen evolution during the battery charge and discharge process and alleviating the problem of gas generation due to side reactions. Phosphate has good lithium ion conductivity and electronic conductivity, and as a kind of restoring agent, it can enter the crystal structure of the material surface during the quenching process, delay the phase change of the material during the cycle charge and discharge process, and improve the cycle stability of the material.

[0048] During the quenching process, the structural support of phosphate overcomes the instability of the material surface structure caused by the formation of oxygen vacancies in the reducing agent, and simultaneously, together with the reducing agent, improves the initial coulombic efficiency of the battery, and together with lithium hydroxide or lithium salt, alleviates voltage decay during the battery cycle charge / discharge process. Therefore, by quenching the Li-rich manganese-based cathode material using the above quenching solution, the initial coulombic efficiency and cycle stability of the material can be effectively improved, and voltage decay can be alleviated.

[0049] In some embodiments, the solvent is pure or another liquid that is advantageous in dissolving lithium hydroxide or a lithium salt, a reducing agent, or a phosphate and does not cause a side reaction with lithium hydroxide or a lithium salt, a reducing agent, or a phosphate.

[0050] In some embodiments, the lithium salt is a soluble lithium salt, which may be selected from an organic lithium salt or an inorganic lithium salt. The organic lithium salt may be selected from one or more of lithium trifluoromethanesulfonate, lithium bisoxalate borate, and lithium bis(trifluoromethanesulphonyl)imide; and the inorganic lithium salt may be selected from one or more of lithium nitrate, lithium hexafluorophosphate, lithium acetate, lithium sulfide, and lithium perchlorate. Preferably, when lithium hydroxide or a soluble inorganic lithium salt is used, it is advantageous in reducing complexation during the quenching process and promoting lithium migration and anchorage to the surface of the primary sintered body of the Li-rich manganese-based cathode material.

[0051] In some embodiments, the reducing agent is a substance having relatively strong reducing properties, which may be selected from a metal hydride, a vitamin, or citric acid. Here, the metal hydride may be selected from one or more of lithium aluminum hydride (LiAlH4), potassium borohydride (KBH4), sodium borohydride (NaBH4), and lithium borohydride (LiBH4); and the vitamin may be selected from one or more of vitamin A, vitamin C, and vitamin E. Preferably, the reducing agent of the present application is selected from a metal hydride. More preferably, the reducing agent of the present application is selected from lithium aluminum hydride. Metal hydrides have a stronger defect-building ability for Li-rich manganese-based cathode materials, and at the same time, they can supplement a small amount of active metal, which is advantageous for the structural stability of the surface phase change process of the first sintered body of Li-rich manganese-based cathode materials.

[0052] In some embodiments, the phosphate is a phosphate having relatively high solubility, and may be selected from monophosphate, diphosphate, or orthophosphate. Here, the monophosphate may be selected from one or more of ammonium phosphate, sodium phosphate, and potassium phosphate; here, the diphosphate may be selected from sodium phosphate, potassium phosphate, and ammonium phosphate; and the orthophosphate may be selected from one or more of sodium phosphate, potassium phosphate, and ammonium phosphate. Preferably, the phosphate of the present application is selected from monophosphate, and can provide higher reactive activity during rapid quenching.

[0053] In some embodiments, the amount of lithium hydroxide or lithium salt added is 0.02 to 0.1 mol / L based on the lithium ion concentration. The lithium salt can play a good role in controlling the lithium content on the surface of the positive electrode material within the concentration range. If the concentration is too high, the residual alkali on the surface of the material may aggravate the side reaction that deteriorates the material, and if the concentration is too low, the structural lithium desorption due to lithium loss on the surface of the material may not be compensated for.

[0054] In some embodiments, the amount of the reducing agent added is 3.0% to 15.0% of the solvent mass. The reducing agent concentration within this range can effectively control the material surface structure. If the concentration is too high, the discharge specific capacity of the material may decrease, and if the concentration is too low, the problem of gas generation due to side reactions may not be effectively alleviated.

[0055] In some embodiments, the amount of the phosphate added is 0.5% to 2.0% of the solvent mass. The phosphate concentration within this range can favorably maintain the crystal structure of the material surface layer.

[0056] Preferably, the quenching solution further comprises a solid electrolyte. The solid electrolyte is different from the lithium salt.

[0057] Solid electrolytes exhibit excellent ionic conductivity. Through quenching and secondary sintering, the solid electrolyte is uniformly and stably coated on the surface of the material. This enhances the ionic conductivity of the phase-change layer on the surface of the Li-rich manganese cathode material and reduces side reactions between the cathode material and the electrolyte. Therefore, adding a solid electrolyte to the quenching solution can further improve the cycle stability of the material.

[0058] In some embodiments, the solid electrolyte may be selected from one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), and polyethylene oxide (PEO).

[0059] In some embodiments, the amount of the solid electrolyte added is 0.5% to 2.0% of the solvent mass. Within this range, the solid electrolyte can form a good ion conducting network.

[0060] In a second aspect, the present application provides a method for manufacturing a surface-stabilized Li-rich manganese-based cathode material.

[0061] In some embodiments, the manufacturing method comprises a step of quenching a primary sintered body of a Li-rich manganese-based cathode material in a quenching solution according to the first aspect.

[0062] In some embodiments, the primary sintered material of the Li-rich manganese-based cathode material is a material having a basic cathode activity performance obtained by mixing a Li-rich manganese-based precursor material and lithium hydroxide or a lithium salt and solid-phase sintering. The Li-rich manganese-based precursor material is a precursor material used in the production of the Li-rich manganese-based cathode material and may be selected from manganese-containing metal compounds. Specifically, the chemical formula of the primary sintered material of the Li-rich manganese-based cathode material is xLi2MnO3·(1-x)LiMO2, where 0.6 <x<0.8이고, M는 Ni, Co, Mn, Al, Zr, Cr, Y, Nb, Ta, La, W, Mg 중 한 종류 또는 여러 종류이다.

[0063] In some embodiments, the molar ratio of lithium ions to other metals in the mixture of the Li-rich manganese precursor material and lithium hydroxide or lithium salt is 1.2 to 1.4.

[0064] In some embodiments, the solid-state sintering temperature of the primary sintered material of the Li-rich manganese-based cathode material is 800 to 850°C.

[0065] In some embodiments, the quenching process comprises heating the primary sintered material of the Li-rich manganese-based cathode material to 150 to 300°C and then pouring it into a quenching solution and cooling it, wherein the temperature difference is greater than 100°C. Preferably, the temperature of the quenching solution is room temperature or 10 to 30°C.

[0066] Rapid quenching can induce a phase change on the surface of a material, thereby creating a spinel-like structure layer on the surface, thereby improving the mobility of ions and the electrical conductivity of electrons, and improving the specific capacity and cycle stability of the material.

[0067] In some embodiments, the mass ratio of the primary sintering material of the Li-rich manganese-based cathode material and the quenching solution is 1:(1 to 3). An appropriate mixing ratio is advantageous for sufficient quenching and reduces waste of the quenching solution.

[0068] In some embodiments, to enhance the quenching effect, the primary sintered material of the Li-rich manganese cathode material is heated to 150 to 300°C and then kept at room temperature for 2 to 5 h.

[0069] In some embodiments, the time interval from taking out the primary sintered material of the Li-rich manganese-based cathode material after heating until adding it to the quenching liquid is less than 5 min, preferably, the time interval is less than 1 min, and it is preferable that the quenching liquid be in a continuously stirred state during the quenching process, the stirring rotation speed is greater than 250 r / min, and the stirring time is 5 to 30 min. This is advantageous for the uniformity of each component in the quenching liquid and the uniformity of the temperature distribution.

[0070] Furthermore, the material after quenching and cooling is filtered and dried to obtain a dried pretreated material.

[0071] In some embodiments, the drying temperature is 100 to 150°C and the drying time is 5 to 10 h.

[0072] Furthermore, secondary sintering is performed on the pretreated material, with a sintering temperature of 300 to 500°C and a sintering time of 5 to 15 hours. By performing secondary sintering, the coating layer can be distributed more uniformly and stably on the surface of the material.

[0073] In a third aspect, the present application provides a secondary battery including a surface-stabilized Li-rich manganese-based cathode material obtained by the manufacturing method provided in the second aspect of the present application.

[0074] In some embodiments, the secondary battery includes a positive electrode sheet, a negative electrode sheet, and a separator. During the battery charging and discharging process, active ions are inserted and deintercalated back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte serves to conduct ions between the positive electrode sheet and the negative electrode sheet. The separator is installed between the positive electrode sheet and the negative electrode sheet, and primarily serves to prevent short circuits between the positive and negative electrodes, while allowing ions to pass through.

[0075] In some embodiments, the positive electrode sheet comprises a current collector and a positive electrode active layer bonded to the current collector. Here, the positive electrode active layer comprises a surface-stabilized Li-rich manganese-based positive electrode material obtained by the manufacturing method provided in the second aspect of the present application.

[0076] In some embodiments, the current collector of the positive electrode sheet, also called a positive electrode current collector, may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet.

[0077] In some embodiments, the negative electrode sheet includes a current collector and a negative electrode active layer combined with the current collector. The current collector of the negative electrode sheet, also called a negative electrode current collector, may be a metal foil sheet or a composite current collector. The negative electrode active material of the negative electrode active layer includes at least one type of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, etc.

[0078] Hereinafter, examples of this application will be described. The examples described below are illustrative and are intended solely to aid in the interpretation of this application and should not be construed as limiting the scope of this application. If specific techniques or conditions are not specified in the examples, the techniques or conditions described in literature within the technical field or in the product description will be followed. If the manufacturer of a reagent or device used is not specified, all are commercially available products.

[0079] Example 1

[0080] Weigh 500g of room temperature pure water to use as a solvent, and weigh 1g of lithium hydroxide, 15g of citric acid, 5g of monobasic ammonium phosphate, and 5g of LATP, respectively, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0081] According to the molar ratio of Li / Me (Me: other metals except Li) = 1.33, Ni 0.35 Mn 0.65 1000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0082] Example 2

[0083] After selecting different insulation temperatures with reference to Example 1, quenching is performed, and the detailed technical plan is as follows.

[0084] Weigh 500g of room temperature pure water to use as a solvent, and weigh 1g of lithium hydroxide, 15g of citric acid, 5g of monobasic ammonium phosphate, and 5g of LATP, respectively, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0085] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 300℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0086] Example 3

[0087] Referring to Example 1, different contents of phosphate and solid electrolyte are selected, and the specific method is as follows.

[0088] Weigh 500g of room temperature pure water to use as a solvent, and weigh 1g of lithium hydroxide, 15g of citric acid, 2.5g of monobasic ammonium phosphate, and 10g of LATP, respectively, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0089] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0090] Example 4

[0091] Different types and contents of lithium salts are selected with reference to Example 1, and the specific method is as follows.

[0092] Weigh 500g of room temperature pure water to use as a solvent, and weigh 2g of lithium nitrate, 15g of citric acid, 5g of monobasic ammonium phosphate, and 5g of LATP, respectively, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0093] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0094] Example 5

[0095] Referring to Example 1, different reducing agents and different reducing agent contents are selected, and the specific method is as follows.

[0096] Weigh 500g of room temperature pure water to use as a solvent, and weigh 1g of lithium hydroxide, 20g of NaBH, 5g of monobasic ammonium phosphate, and 5g of LATP, respectively, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0097] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0098] Example 6

[0099] Referring to Example 1, a solid electrolyte is not used, and the specific method is as follows.

[0100] Weigh 500g of room temperature pure water to use as a solvent, weigh 1g of lithium hydroxide, 15g of citric acid, and 5g of monobasic ammonium phosphate, respectively, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0101] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0102] Comparative Example 1

[0103] Refer to Example 1, no pickling liquid is used, and the specific method is as follows.

[0104] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.65 1000g of CO3 Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; after cooling, it is placed in a furnace for secondary sintering (sintering temperature 300℃, sintering time 8h), and after taking it out of the furnace, it is sieved to obtain a Li-rich manganese cathode material.

[0105] Comparative Example 2

[0106] Refer to Example 1, no phosphate is used, and the specific method is as follows.

[0107] Weigh 500g of room temperature pure water to use as a solvent, weigh 1g of lithium hydroxide, 15g of citric acid, and 5g of LATP, add to the pure water, stir for 10 minutes, and dissolve to obtain the required pickling solution.

[0108] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.65 1000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0109] Comparative Example 3

[0110] Referring to Example 1, lithium hydroxide or lithium salt is not used, and the specific method is as follows.

[0111] Weigh 500g of room temperature pure water to use as a solvent, weigh 15g of citric acid, 5g of monobasic ammonium phosphate, and 5g of LATP, add to the pure water, stir for 10 minutes, and dissolve to obtain the required pickling solution.

[0112] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0113] Comparative Example 4

[0114] Refer to Example 1, no reducing agent is used, and the specific method is as follows.

[0115] Weigh 500g of room temperature pure water to use as a solvent, weigh 1g of lithium hydroxide, 5g of monobasic ammonium phosphate, and 5g of LATP, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0116] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese cathode material; Take 500g of the primary sintered material of the Li-rich manganese-based cathode material, put the primary sintered material of the cathode in a bowl, put it in a furnace and heat it (heating temperature 200℃, sintering time 3h), after the sintering is complete, the material is directly discharged and poured into a quenching liquid to perform quenching, stirred for 10 min to ensure that the quenching liquid and the material are sufficiently mixed, filtered and dried (drying temperature 100℃, drying time 5h), and after drying, put the material back in a bowl, put it in a furnace and sinter it (sintering temperature 300℃, sintering time 8h), take it out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0117] Comparative Example 5

[0118] Refer to Example 1, do not perform pickling, and the specific method is as follows.

[0119] Weigh 500g of room temperature pure water to use as a solvent, and weigh 1g of lithium hydroxide, 15g of citric acid, 5g of monobasic ammonium phosphate, and 5g of LATP, respectively, add to the pure water, stir for 10 minutes, and dissolve to obtain the required quenching solution.

[0120] According to the molar ratio of Li / Me=1.33, Ni 0.35 Mn 0.651000g of CO3Li-rich manganese precursor and 405g of lithium carbonate are weighed and mixed, and after uniform mixing, solid-phase sintering (sintering temperature 820℃) is performed to obtain a primary sintered material of a Li-rich manganese-based cathode material; 500g of the primary sintered material of a Li-rich manganese-based cathode material is taken, added to the prepared quenching liquid, stirred for 10 min to ensure sufficient mixing of the quenching liquid and the material, filtered, dried (drying temperature 100℃, drying time 5h), and after drying, the material is put back into a bowl, placed in a furnace, and sintered (sintering temperature 300℃, sintering time 8h), and then taken out of the furnace and sieved to obtain a Li-rich manganese-based cathode material.

[0121] To further verify whether the electrochemical performance of the surface-stabilized Li-rich manganese-based cathode material described in the present invention was improved, lithium ion batteries were manufactured using the Li-rich manganese-based cathode materials manufactured in the examples and comparative examples, and their performances were tested.

[0122] Manufacturing method: Test sample: Mix the challenge agent SP: Adhesive PVDF in a mass ratio of 90:5:5, add an appropriate amount of N-vinylpyrrolidone as a solvent, mix this to form a uniform slurry, coat aluminum foil, vacuum dry and roll to manufacture a positive electrode sheet, use metallic lithium as a negative electrode, mix 1 mol / L lithium hexafluorophosphate (LiPF6) and a three-component mixed solvent of ethylene carbonate (EC): dimethyl carbonate (DMC): methyl ethyl carbonate (EMC) = 1:1:1 (v / v) to form an electrolyte, use a polypropylene microporous membrane as a separator, and assemble it into a CR2032 button cell in a glove box filled with an inert gas.

[0123] The CR2032 button cell batteries manufactured in the above examples and comparative examples are subjected to an initial coulomb efficiency charge / discharge test and a cycle performance test, respectively.

[0124] (1) Adopt 25℃ room temperature test, the first cycle test voltage is 2.5 to 4.8V, the nominal capacity is 270mAh / g, the current density is 0.1C, and the test method is used to calibrate the charge / discharge capacity and initial coulomb efficiency of the first cycle of the material.

[0125] (2) Adopt 25℃ room temperature test, the first cycle test voltage is 2.5 to 4.6V, the nominal capacity is 270mAh / g, the current density is 1.0C, and the cycle retention rate and voltage decay performance of the material are corrected after 100 cycles.

[0126] The cycle life and voltage decay are calculated as follows:

[0127] Cycle maintenance rate = capacity of the 100th cycle ÷ capacity of the first cycle × 100%

[0128] Voltage decay = platform voltage of the first cycle - platform voltage of the 100th cycle

[0129] The test results are shown in Table 1.

[0130] Serial numberCharge capacity (mAh / g)Discharge capacity (mAh / g)Initial efficiency (%)100 cycle retention (%)100 cycle voltage decay (mV)Example 1319.49281.8388.2197.35101Example 2317.52281.3088.5597.42102Example 3320.21283.5888.5697.30101Example 4318.47281.9488.5397.68105Example 5319.28281.9688.3197.19100Example 6322.53284.9888.3695.83105Comparative example 1325.43264.2281.1994.65128Comparative Example 2320.01276.9986.5593.56117Comparative Example 3319.72274.2885.7997.51155Comparative Example 4318.94270.7084.8695.92108Comparative Example 5304.18265.6387.3294.77112

[0131] As can be verified from the data results of Examples 1 to 6 and Comparative Example 1, the primary sintered material of the Li-rich manganese-based cathode material can improve the initial coulombic efficiency and cycle stability of the battery and alleviate battery attenuation after quenching in the quenching solution. Figure 2 is an SEM drawing of Example 1 and Comparative Example 1. As can be seen from the comparison, after the material has been quenched in the quenching solution, the surface primary particles show a special structure in which the surface primary particles are converted from a lateral arrangement to a radial arrangement. This structure can effectively improve the initial efficiency of the material through the infiltration of the electrolyte and the desorption of lithium ions. At the same time, the solid electrolyte coated on the surface of the secondary particles of the material after quenching can be observed. The solid electrolyte can isolate the positive electrode particle surface and the electrolyte during the cycling process, thereby reducing the side reactions of the material. The present invention jointly promotes the comprehensive improvement and stability of the material performance after quenching by utilizing the synergistic effect of each component in the quenching solution. As can be seen by combining Comparative Examples 1 to 4, the materials quenched using some of the quenching liquid components (Comparative Examples 2 to 4) cannot predict the improvement effect on battery performance, and compared to the untreated material (Comparative Example 1), can only achieve limited improvement (Comparative Example 4), and even the battery performance may deteriorate further (Comparative Examples 2 and 3). This shows that it is difficult to comprehensively improve the initial coulombic efficiency and cycle stability of the battery and alleviate the voltage decay by using only some of the quenching liquid components. As can be verified from the data results of Examples 1 to 6 and Comparative Example 3 and the cycle voltage decay curve of FIG. 4, adding lithium hydroxide or a lithium salt to the quenching liquid can effectively compensate for the surface lithium loss of the material during the quenching process, and further alleviate the voltage decay of the material due to the lithium loss.One of the main causes is that, during the quenching process, the loss of surface lithium causes structural lithium to migrate from the structure to the surface, forming a new lithium-containing surface layer; the charge imbalance caused by the loss of structural lithium is compensated for by the loss of electrons from the transition metal; during the battery charging process, the inherent electron loss of the transition metal accelerates the oxidation-reduction of oxygen anions, which are used for charge compensation, thereby aggravating the phase change and voltage attenuation of the material.

[0132] The reducing agent can build up surface oxygen vacancies, and on the one hand, can improve the mobility and electronic conductivity of surface lithium ions, and on the other hand, can reduce oxygen evolution during the battery charge / discharge process and alleviate the problem of gas generation due to side reactions. As can be seen from the expansion state diagrams of Example 1 and Comparative Example 4 illustrated in FIG. 5, after adding the reducing agent to the quenching solution, the problem of gas generation of the material was significantly alleviated. As can be verified from the data results of Examples 1 to 6 and Comparative Example 4 and the comparative diagram of discharge specific capacity under long-cycle performance illustrated in FIG. 3, adding a reducing agent to the quenching solution can improve the discharge specific capacity of the battery, thereby improving the initial Coulombic efficiency.

[0133] Phosphate can enter the crystal structure of the material surface during the quenching process and slow down the phase change of the material during the cycle charge-discharge process. As can be verified from the data results of Examples 1 to 6 and Comparative Example 2 and the comparative discharge capacity diagram under long-cycle performance shown in FIG. 3, adding phosphate to the quenching solution can effectively improve the cycle stability of the battery. As can be verified by comparing the data results of Comparative Examples 2, 3, and 4, phosphate, together with a reducing agent, can improve the initial coulombic efficiency of the battery and, together with a lithium salt, can alleviate the voltage decay during the cycle charge-discharge process of the battery.

[0134] As can be seen from the XRD diagrams of Example 1 and Comparative Example 5 in FIG. 1, the Li-rich manganese-based cathode material shows a small peak (spinel-like phase peak in the arrowed area shown in FIG. 1) between 15 and 16° after the quenching treatment, and the peak position of the 003 peak shifts to a small angle, and the XRD peak value shifts to a small angle, which means that the lattice constant increases. As can be verified from the data results of Examples 1 to 5 and Comparative Example 5, rapid quenching can improve the specific capacity and cycle stability of the material by causing a phase change on the surface of the material to form a single layer of spinel-like structure on the surface.

[0135] By uniformly and stably coating the surface of the material through quenching, the solid electrolyte can reduce side reactions between the cathode material and the electrolyte. Comparing the data results of Examples 1 to 5 and Example 6 verifies that adding a solid electrolyte to the quenching solution can effectively improve the cycle stability of the material.

[0136] Above all, each of the above embodiments is only used to explain the technical solution of the present application and is not intended to limit it; although the present application has been described in detail with reference to each of the above embodiments, those skilled in the art can still modify the technical solution described in each of the above embodiments or make equivalent replacements for some or all of the technical features thereof; it should be understood that such modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution of each embodiment of the present application, and all of them should be included in the scope of the claims and specification of the present application. In particular, each of the technical features mentioned in each embodiment can be combined in any manner as long as the structure is not contradictory. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. In the pickling liquid, A quenching liquid characterized in that the above quenching liquid comprises a solvent, lithium hydroxide or lithium salt, a reducing agent, and a phosphate.

2. In paragraph 1, The solvent is pure or other liquid that is advantageous in dissolving lithium hydroxide or lithium salt, reducing agent, or phosphate and does not cause side reactions with lithium hydroxide or lithium salt, reducing agent, or phosphate; The lithium salt is an available lithium salt, selected from an organic lithium salt or an inorganic lithium salt, and the organic lithium salt is preferably selected from one or more kinds of lithium trifluoromethanesulfonate, lithium bisoxalate borate, and lithium bis(trifluoromethanesulphonyl)imide, and the inorganic lithium salt is preferably selected from one or more kinds of lithium nitrate, lithium hexafluorophosphate, lithium acetate, lithium sulfide, and lithium perchlorate; The reducing agent is selected from metal hydride, vitamin or citric acid, wherein the metal hydride is preferably selected from one or more of lithium aluminum hydride (LiAlH4), potassium borohydride (KBH4), sodium borohydride (NaBH4), and lithium borohydride (LiBH4), and the vitamin is preferably selected from one or more of vitamin A, vitamin C, and vitamin E. A quenching solution characterized in that the phosphate is selected from monobasic phosphate, dibasic phosphate or ortho phosphate, wherein the monobasic phosphate is preferably selected from one or more of ammonium phosphate, sodium phosphate and potassium phosphate, wherein the dibasic phosphate is preferably selected from sodium phosphate, potassium phosphate and ammonium phosphate, and the ortho phosphate is preferably selected from one or more of sodium phosphate, potassium phosphate and ammonium phosphate.

3. In paragraph 1, The amount of lithium hydroxide or lithium salt added is 0.02 to 0.1 mol / L based on the lithium ion concentration; The amount of the reducing agent added is 3.0% to 15.0% of the solvent mass; A quenching solution characterized in that the amount of the phosphate added is 0.5% to 2.0% of the solvent mass.

4. In paragraph 1, A quenching liquid characterized in that the above quenching liquid further comprises a solid electrolyte, and the solid electrolyte is preferably selected from one or more kinds of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanate (LLTO), and polyethylene oxide (PEO), and the amount of the solid electrolyte added is preferably 0.5% to 2.0% of the solvent mass.

5. In a method for manufacturing a surface-stabilized Li-rich manganese cathode material, A method for manufacturing a surface-stabilized Li-rich manganese cathode material, characterized in that the manufacturing method comprises a step of quenching a primary sintered material of a Li-rich manganese cathode material in the quenching solution according to any one of claims 1 to 4.

6. In paragraph 5, The first sintered material of the above Li-rich manganese-based cathode material is a material having basic cathode activity performance obtained by mixing a Li-rich manganese-based precursor material and lithium hydroxide or a lithium salt and solid-phase sintering, and preferably, the chemical formula of the first sintered material of the Li-rich manganese-based cathode material is xLi2MnO3·(1-x)LiMO2, where 0.6 <x<0.8이고, M는 Ni, Co, Mn, Al, Zr, Cr, Y, Nb, Ta, La, W, Mg 중 한 종류 또는 여러 종류이고, 바람직하게는, 상기 Li-rich 망간계 양극재의 1차 소결재의 고상 소결 온도는 800 내지 850℃인 것을 특징으로 하는 표면 안정화 처리된 Li-rich 망간계 양극재의 제조방법.

7. In paragraph 5, A method for manufacturing a surface-stabilized Li-rich manganese cathode material, characterized in that the mass ratio of the primary sintering material and the quenching liquid of the above Li-rich manganese cathode material is 1:(1 to 3).

8. In paragraph 5, A method for manufacturing a surface-stabilized Li-rich manganese cathode material, characterized in that the above-mentioned quenching process comprises heating a primary sintered material of a Li-rich manganese cathode material to 150 to 300°C and then pouring it into a quenching solution and cooling it, wherein the temperature difference is greater than 100°C, and preferably, the temperature of the quenching solution is room temperature or 10 to 30°C.

9. In paragraph 5, A method for manufacturing a surface-stabilized Li-rich manganese cathode material, characterized in that the material after quenching and cooling is filtered and dried to obtain a dried pretreated material, secondary sintering is performed on the pretreated material, the sintering temperature is 300 to 500°C, and the sintering time is 5 to 15 h. In the 10.2nd battery, A secondary battery characterized by comprising a surface-stabilized Li-rich manganese-based cathode material obtained by a manufacturing method according to any one of claims 5 to 9.

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