Single-crystal lithium-rich manganese-based positive electrode material, preparation method thereof and lithium battery

Abstract

This invention provides a single-crystal lithium-rich manganese-based cathode material, its preparation method, and a lithium battery. The preparation method of the single-crystal lithium-rich manganese-based cathode material includes: mixing a low-cobalt hydroxide precursor and / or a cobalt-free hydroxide precursor with a lithium source and LiNO3, followed by a two-step sintering process to obtain the single-crystal lithium-rich manganese-based cathode material; the two-step sintering includes sequentially performing a first sintering and a second sintering, wherein the temperature of the first sintering is 920℃~980℃, and the temperature of the second sintering is 860℃~900℃. The preparation method of the single-crystal lithium-rich manganese-based cathode material provided by this invention, by using a hydroxide precursor and a two-step sintering process assisted by dual lithium source molten salt, obtains a low-cobalt and / or cobalt-free single-crystal lithium-rich manganese-based cathode material with fewer surface defects, lower residual alkali content, stronger crystallinity, and stronger structural stability without relying on high cobalt content.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and relates to a single-crystal lithium-rich manganese-based cathode material, in particular to a single-crystal lithium-rich manganese-based cathode material, a preparation method thereof, and a lithium battery. Background Art

[0002] With the popularization of environmental protection concepts, various countries have gradually phased out fossil energy and shifted to renewable energy such as wind energy and water energy to promote sustainable development. However, the supply of wind energy and water energy is unstable. Coupled with the popularization of new energy vehicles and electronic products, the demand for high-efficiency energy storage devices has become increasingly urgent. Lithium-ion batteries (LIBs) have been widely used and developed due to their high energy density, strong scalability, stable cycling, etc., and are used in everything from small devices to new energy vehicles and even energy storage systems.

[0003] Currently, the capacity of lithium-ion batteries is mainly limited by the cathode material. It is particularly important to develop cathode materials with higher specific capacity and wider voltage window. Among them, the lithium-rich manganese-based cathode material xLi2MnO3·(1-x)LiMO2 (where 0 < x < 1, M = Ni, Co, Mn, etc.) has attracted the attention of scientists and engineers around the world due to its ultra-high specific capacity (250 mAh / g), wide voltage window (2.0 V - 4.8 V), low cost, and high safety.

[0004] However, the lithium-rich manganese-based cathode material still has some defects. On the one hand, at voltages higher than 4.5 V, the lithium-rich manganese-based cathode material will cause irreversible oxygen release on the material surface due to the activation of Li2MnO3, resulting in problems such as low initial Coulomb efficiency, poor cycling stability, poor rate performance, and voltage attenuation of the lithium-rich manganese-based material; on the other hand, the traditional lithium-rich manganese-based material generally has a secondary spherical particle morphology formed by the aggregation of primary particles. This morphology is likely to exacerbate the side reaction between the lithium-rich manganese-based material and the electrolyte during the electrochemical cycling process, leading to volume change and crack generation, thereby further reducing the cycling performance of the material.

[0005] Single-crystal lithium-rich manganese-based materials are discrete primary particles, which can effectively relieve the micro-stress and micro-strain caused by the structural changes of grains during cycling, and thus avoid the entry of electrolyte into micro-cracks to generate side reactions, improving the structural stability and cycling life of the material. In addition, due to the scarcity, high price, and toxicity of cobalt element resources, developing low-cobalt / cobalt-free lithium-rich manganese-based cathode materials with low cost, more environmental protection, and stronger performance can not only reduce the production cost of batteries but also meet the requirements of the global lithium battery industry for green and sustainable development. Therefore, developing low-cobalt / cobalt-free single-crystal lithium-rich manganese-based cathode materials has good prospects.

[0006] However, the preparation process of single-crystalline lithium-rich manganese-based cathode materials in the prior art relies on high-temperature long-time sintering or molten salt washing treatment, which is likely to cause problems such as surface defects, excessive residual alkali content, and uneven particle size distribution. Additionally, in the low-cobalt / cobalt-free system, due to the lack of the structural support effect of cobalt elements, there are generally problems of poor crystallinity and insufficient structural stability. Moreover, in the existing preparation processes, when preparing single-crystalline lithium-rich manganese-based cathode materials, the phenomenon of irreversible phase transformation from the layered structure to the spinel or rock salt phase is relatively prominent, resulting in insufficient structural stability of the obtained single-crystalline lithium-rich manganese-based cathode materials, severely restricting their commercial application process.

[0007] For example, CN121484052A discloses a cobalt-free single-crystalline lithium-rich manganese-based cathode material, its preparation method and application, belonging to the technical field of lithium-ion battery cathode materials. The chemical formula of the cobalt-free single-crystalline lithium-rich manganese-based cathode material disclosed in this document is Li x Ni y Mn z O2; where 1.1 ≤ x ≤ 1.5, 0.2 ≤ y ≤ 0.5, 0.4 ≤ z ≤ 0.8. This document uses a precursor and lithium salt for ball milling, and then prepares a submicron cobalt-free single-crystalline lithium-rich manganese-based cathode material by high-temperature solid-phase sintering method.

[0008] For example, CN118039848A discloses a lithium-rich manganese-based cathode material. The chemical formula of the lithium-rich manganese-based cathode material is xLi2MnO3·(1 - x)LiNi a Mn b O2·Co c , where 0 < x < 1, 0 < a < 1, 0 < b < 1, 0 < c < 0.1, and a + b = 1. This document prepares a cobalt-free lithium-rich manganese-based precursor by coprecipitation method. Through multiple spray drying processes, nano cobalt particles are evenly bonded and coated on the surface of the lithium-rich manganese-based precursor. Selective laser melting is used to melt the cobalt nanoparticles and thermally erode the grain boundaries of the primary particles of the precursor, enabling cobalt elements to be doped into the lattice of the lithium-rich manganese-based precursor and allowing the excess cobalt nanoparticles to graft onto the surface of the precursor after cooling. At the same time, micron-sized secondary particles (aggregates of primary particles) are separated into nano-sized primary particles, achieving the single crystallization of the precursor.

[0009] It can be seen that the preparation methods of single-crystalline lithium-rich manganese-based cathode materials disclosed in the prior art all have certain defects, such as problems of surface defects and high residual alkali content, poor crystallinity and insufficient structural stability in the prepared low-cobalt or cobalt-free single-crystalline lithium-rich manganese-based cathode materials, resulting in the first Coulomb efficiency, rate performance, and cycle stability of the single-crystalline lithium-rich manganese-based cathode materials not meeting the requirements of practical applications. Therefore, it is crucial to develop and design a new type of single-crystalline lithium-rich manganese-based cathode material, its preparation method, and lithium batteries. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a single-crystal lithium-rich manganese-based cathode material, its preparation method, and a lithium battery. The preparation method of the single-crystal lithium-rich manganese-based cathode material provided by the present invention utilizes a hydroxide precursor and a two-step sintering process assisted by dual lithium source molten salt. This process yields a low-cobalt and / or cobalt-free single-crystal lithium-rich manganese-based cathode material with fewer surface defects, lower residual alkali content, stronger crystallinity, and stronger structural stability without relying on high cobalt content. Therefore, the single-crystal lithium-rich manganese-based cathode material obtained by the aforementioned method exhibits superior initial coulombic efficiency, rate performance, and cycle stability.

[0011] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a single-crystal lithium-rich manganese-based cathode material, wherein the single-crystal lithium-rich manganese-based cathode material includes low-cobalt single-crystal lithium-rich manganese-based cathode material and / or cobalt-free single-crystal lithium-rich manganese-based cathode material, and the preparation method includes: A single-crystal lithium-rich manganese-based cathode material is obtained by mixing a low-cobalt hydroxide precursor and / or a cobalt-free hydroxide precursor with a lithium source and LiNO3 and then sintering them in two steps. The two-step sintering includes performing a first sintering and a second sintering in sequence. The temperature of the first sintering is 920℃~980℃, and the temperature of the second sintering is 860℃~900℃.

[0012] In this invention, the temperature of the first sintering is 920℃~980℃, for example, it can be 920℃, 930℃, 940℃, 950℃, 960℃, 970℃ or 980℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] In this invention, the second sintering temperature is 860℃~900℃, for example, it can be 860℃, 865℃, 870℃, 875℃, 880℃, 885℃, 890℃, 895℃ or 900℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] The preparation method provided by this invention employs a dual lithium source system composed of a lithium source and LiNO3. LiNO3 also serves as an auxiliary molten salt. The low melting point of LiNO3 allows it to form a eutectic liquid phase with the lithium source, which is beneficial for atomically uniform mixing of the precursor and the lithium source and helps reduce surface defects. Furthermore, the molten salt phase formed by LiNO3 uniformly encapsulates the precursor particles, limiting particle agglomeration and guiding directional crystal growth, thereby achieving full single-crystalization. Additionally, the decomposition products of LiNO3 are only Li2O and volatile gases, with no solid impurities remaining, completely eliminating the need for subsequent water washing. This facilitates the production of single-crystal lithium-rich manganese-based cathode materials with low residual alkali content, thereby improving the rate performance and cycle stability of the obtained single-crystal lithium-rich manganese-based cathode material.

[0015] The preparation method provided by this invention uses a hydroxide precursor and a two-step sintering process. Because the hydroxide precursor has a low decomposition temperature and high reactivity, and its temperature matches that of the molten salt liquid phase formed by LiNO3, it is conducive to the growth of crystals along a preferred orientation, avoiding the formation of secondary particles and grain boundaries. Finally, a single-crystal lithium-rich manganese-based cathode material with strong crystallinity, uniform particle dispersion and no grain boundaries is obtained, thereby improving the rate performance and cycle stability of the obtained single-crystal lithium-rich manganese-based cathode material.

[0016] The preparation method of this invention uses a low-cobalt hydroxide precursor and / or a cobalt-free hydroxide precursor, without relying on the structural stabilizing effect of high cobalt elements. It utilizes the sufficient oxygen partial pressure released by the decomposition of LiNO3 during in-situ sintering to suppress the lattice oxygen release and the irreversible structural transformation from layered phase to spinel phase in the single-crystal lithium-rich manganese-based cathode material, thereby improving structural stability and alleviating the voltage decay problem of single-crystal lithium-rich manganese-based cathode material during cycling, thus improving cycle stability.

[0017] In summary, the preparation method provided by this invention, by employing a hydroxide precursor and a two-step sintering process assisted by dual lithium source molten salt, yields low-cobalt and / or cobalt-free single-crystal lithium-rich manganese-based cathode materials with fewer surface defects, lower residual alkali content, stronger crystallinity, and stronger structural stability without relying on high cobalt content. Therefore, the single-crystal lithium-rich manganese-based cathode materials obtained by the preparation method exhibit superior initial coulombic efficiency, rate performance, and cycle stability. In addition, the preparation method is simple, has low requirements for equipment and environment, and has good prospects for large-scale application.

[0018] Preferably, the chemical formula of the low-cobalt hydroxide precursor is Mn. a Ni b Co c Al 1-a-b-c (OH)2, of which 0.5 <a<0.7,0.25<b<0.40,0.04<c<0.07。

[0019] In the present invention, 0.5 < a < 0.7. The value of a can be, for example, 0.51, 0.52, 0.54, 0.56, 0.58, 0.60, 0.62, 0.64, 0.66, 0.68 or 0.69, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0020] In the present invention, 0.25 < b < 0.40. The value of b can be, for example, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38 or 0.39, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0021] In the present invention, 0.04 < c < 0.07. The value of c can be, for example, 0.042, 0.044, 0.046, 0.048, 0.050, 0.052, 0.054, 0.056, 0.058, 0.060, 0.062, 0.064, 0.066 or 0.068, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0022] Preferably, the chemical formula of the cobalt-free hydroxide precursor is Mn x Ni 1-x (OH)2, where 0.5 < x < 0.7.

[0023] In the present invention, 0.5 < x < 0.7. The value of x can be, for example, 0.51, 0.52, 0.54, 0.56, 0.58, 0.60, 0.62, 0.64, 0.66, 0.68 or 0.69, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0024] Preferably, the lithium source includes any one or a combination of at least two of LiOH, Li2CO3 or LiCl. Typical but non-limiting combinations include the combination of LiOH and Li2CO3, the combination of Li2CO3 and LiCl, the combination of LiOH and LiCl, or the combination of LiOH, Li2CO3 and LiCl.

[0025] Preferably, in the mixing, the molar ratio of the lithium source to LiNO3 is (3 - 5):6. It can be, for example, 3:6, 3.2:6, 3.4:6, 3.6:6, 3.8:6, 4:6, 4.2:6, 4.4:6, 4.6:6, 4.8:6 or 5:6, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0026] Preferably, in the mixture, the ratio of the total molar amount of Li in the lithium source and LiNO3 to the total molar amount of transition metals in the low-cobalt hydroxide precursor and / or cobalt-free hydroxide precursor is (1.45~1.60):1, for example, it can be 1.45:1, 1.46:1, 1.47:1, 1.48:1, 1.49:1, 1.50:1, 1.51:1, 1.52:1, 1.53:1, 1.54:1, 1.55:1, 1.56:1, 1.57:1, 1.58:1, 1.59:1 or 1.60:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] The preparation method provided by this invention achieves a balance between crystallinity, cation mixing degree, initial coulombic efficiency and cycle stability by controlling the ratio of the total molar amount of Li in the lithium source and LiNO3 to the total molar amount of transition metals in the low-cobalt hydroxide precursor and / or cobalt-free hydroxide precursor during mixing.

[0028] Preferably, the mixing is carried out in a mixer.

[0029] Preferably, the first sintering time is 9h to 10h, for example, it can be 9.0h, 9.1h, 9.2h, 9.3h, 9.4h, 9.5h, 9.6h, 9.7h, 9.8h, 9.9h or 10.0h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] Preferably, the second sintering time is 1.5h to 2.5h, for example, it can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h or 2.5h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] Preferably, the two-step sintering further includes heating before the first sintering, wherein the heating rate is 1℃ / min to 10℃ / min, for example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0032] Preferably, the two-step sintering further includes cooling between the first sintering and the second sintering, wherein the cooling rate is 1℃ / min to 10℃ / min and the heating rate is 1℃ / min to 10℃ / min, for example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min or 10℃ / min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0033] Preferably, after the second sintering, the process further includes: naturally cooling to room temperature for later use.

[0034] Preferably, the preparation method further includes: pre-sintering before mixing to obtain low-cobalt precursor oxide and / or cobalt-free precursor oxide.

[0035] In this invention, if pre-sintering is performed before mixing, the resulting low-cobalt precursor oxide and / or cobalt-free precursor oxide are mixed with a lithium source and LiNO3. Since pre-sintering does not change the molar amount of lithium in the low-cobalt hydroxide precursor and / or cobalt-free hydroxide precursor, the ratio of the total molar amount of Li in the lithium source and LiNO3 to the total molar amount of transition metals in the low-cobalt hydroxide precursor and / or cobalt-free hydroxide precursor is controlled to be (1.45~1.60):1, which is equivalent to controlling the ratio of the total molar amount of Li in the lithium source and LiNO3 to the total molar amount of transition metals in the low-cobalt precursor oxide and / or cobalt-free precursor oxide to be (1.45~1.60):1.

[0036] Preferably, the pre-sintering temperature is 500℃~650℃ and the time is 3h~8h.

[0037] In this invention, the pre-sintering temperature is 500℃~650℃, for example, it can be 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, 620℃, 630℃, 640℃ or 650℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] In this invention, the pre-sintering time is 3h to 8h, for example, it can be 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, pre-sintering temperature rise is also included before the pre-sintering. The rate of the pre-sintering temperature rise is 1 °C / min to 10 °C / min, and the rate of the temperature rise is 1 °C / min to 10 °C / min. For example, it can be 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, 8 °C / min, 9 °C / min or 10 °C / min, but it is not limited to the listed values. Other unlisted values within this numerical range are equally applicable. The end temperature is the temperature of the pre-sintering.

[0040] Preferably, between the pre-sintering and the mixing, it also includes: standby after natural cooling to room temperature.

[0041] Preferably, the preparation method also includes: grinding and drying are sequentially carried out after the two-step sintering.

[0042] In a second aspect, the present invention provides a single-crystal lithium-rich manganese-based cathode material, which is obtained by the preparation method described in the first aspect.

[0043] Preferably, the chemical formula of the low-cobalt single-crystal lithium-rich manganese-based cathode material is Li z Mn a Ni b Co c Al 1-a-b-c O2, where 1.45 < z < 1.60, 0.5 < a < 0.7, 0.25 < b < 0.40, 0.04 < c < 0.07.

[0044] In the present invention, 1.45 < z < 1.60. The value of z can be, for example, 1.46, 1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58 or 1.59, but it is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0045] In the present invention, 0.5 < a < 0.7. The value of a can be, for example, 0.51, 0.52, 0.54, 0.56, 0.58, 0.60, 0.62, 0.64, 0.66, 0.68 or 0.69, but it is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0046] In the present invention, 0.25 < b < 0.40. The value of b can be, for example, 0.26, 0.28, 0.30, 0.32, 0.34, 0.36, 0.38 or 0.39, but it is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0047] In the present invention, 0.04 < c < 0.07. The value of c can be, for example, 0.041, 0.042, 0.044, 0.046, 0.048, 0.050, 0.052, 0.054, 0.056, 0.058, 0.060, 0.062, 0.064, 0.066 or 0.068, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0048] Preferably, the chemical formula of the cobalt-free single-crystal lithium-rich manganese-based cathode material is Li y Mn x Ni 1-x O2, where 1.45 < y < 1.60 and 0.5 < x < 0.7.

[0049] In the present invention, 1.45 < y < 1.60. The value of y can be, for example, 1.46, 1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58 or 1.59, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0050] In the present invention, 0.04 < c < 0.07. The value of c can be, for example, 0.041, 0.042, 0.044, 0.046, 0.048, 0.050, 0.052, 0.054, 0.056, 0.058, 0.060, 0.062, 0.064, 0.066 or 0.068, but is not limited to the listed values. Other unlisted values within this numerical range are equally applicable.

[0051] In a third aspect, the present invention provides a lithium battery, which includes the single-crystal lithium-rich manganese-based cathode material described in the second aspect.

[0052] The numerical ranges described in the present invention not only include the above-listed point values, but also any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the described ranges.

[0053] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method provided by the present invention adopts a dual lithium source system composed of lithium source and LiNO3. At the same time, LiNO3 also serves as an auxiliary molten salt. The low melting point of LiNO3 can form a eutectic liquid phase with the lithium source, which is conducive to the atomic-level uniform mixing of the precursor and the lithium source and to reducing surface defects. In addition, the molten salt liquid phase formed by LiNO3 will uniformly encapsulate the precursor particles, restrict the agglomeration between particles and guide the directional growth of crystals, thereby achieving full single crystallization. In addition, the decomposition products of LiNO3 are only Li2O and volatile gases, with no solid impurities remaining, completely eliminating the need for subsequent water washing steps, which is conducive to obtaining single crystal lithium-rich manganese-based cathode materials with low residual alkali content, thereby improving the rate performance and cycle stability of the obtained single crystal lithium-rich manganese-based cathode materials. (2) The preparation method provided by the present invention selects hydroxide precursor and combines it with a two-step sintering process. Since the hydroxide precursor has a low decomposition temperature and high reactivity, it matches the temperature of the molten salt liquid phase formed by LiNO3. Therefore, it is conducive to the growth of crystal along the preferred orientation, avoiding the formation of secondary particles and grain boundaries. Finally, a single crystal lithium-rich manganese-based cathode material with strong crystallinity, uniform particle dispersion and no grain boundaries is obtained, thereby improving the rate performance and cycle stability of the obtained single crystal lithium-rich manganese-based cathode material. (3) The preparation method of the present invention uses a low cobalt hydroxide precursor and / or a cobalt-free hydroxide precursor, without relying on the structural stabilizing effect of high cobalt elements. It utilizes the sufficient oxygen partial pressure released by the decomposition of LiNO3 during in-situ sintering to suppress the release of lattice oxygen and the irreversible structural transformation of the layered phase to the spinel phase in the single-crystal lithium-rich manganese-based cathode material, thereby improving the structural stability and alleviating the voltage decay problem of the single-crystal lithium-rich manganese-based cathode material during cycling, thus improving the cycling stability. (4) The preparation method provided by the present invention, by using a hydroxide precursor and a two-step sintering process assisted by dual lithium source molten salt, obtains a low-cobalt and / or cobalt-free single-crystal lithium-rich manganese-based cathode material with fewer surface defects, lower residual alkali content, stronger crystallinity and stronger structural stability without relying on high cobalt content; therefore, the single-crystal lithium-rich manganese-based cathode material obtained by the preparation method exhibits better first coulombic efficiency, rate performance and cycle stability; in addition, the preparation method has a simple process, low requirements for equipment and environment, and has good prospects for large-scale application. Detailed Implementation

[0054] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0055] The "range" disclosed in this invention can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. This type of range definition can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be arbitrarily combined, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for specific parameters, it is understood that ranges of 60~110 and 80~120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this invention, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2~10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0056] In this invention, "a combination of at least two" refers to a quantity greater than or equal to two, unless otherwise specified. For example, "any combination of one or at least two" means one or more or more items. It can be understood that when referring to "a combination of at least two," it refers to any suitable combination of multiple items, that is, a combination of "at least two" items carried out in a manner that does not conflict with and enables the implementation of this invention.

[0057] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0058] The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0059] Those skilled in the art will understand that the order in which the steps are written in the methods of the various embodiments does not imply a strict execution order. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), meaning that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0060] In this invention, open-ended technical features or solutions described using terms such as "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, A includes a1, a2, and a3. Unless otherwise specified, it may also include other members or exclude additional members. This can be considered as providing both technical features or solutions where "A is composed of a1, a2, and a3" or "A is selected from a1, a2, and a3," and technical features or solutions where "A includes not only a1, a2, and a3, but also other members."

[0061] In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" represents a group consisting of A, B, and "a combination of A and B". "Containing A and / or B" can mean "containing A, containing B, and containing A and B", or "containing A, containing B, or containing A and B", and can be appropriately understood according to the context.

[0062] In this invention, the terms "first aspect," "second aspect," "third aspect," "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," "fourth," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on the quantity.

[0063] In this invention, "room temperature" generally refers to 4℃~35℃, and can refer to 20℃±5℃. In some embodiments of this invention, room temperature refers to 20℃~30℃.

[0064] Example 1 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material, wherein the single-crystal lithium-rich manganese-based cathode material is a cobalt-free single-crystal lithium-rich manganese-based cathode material, and the preparation method includes: (1) The precursor was prepared by coprecipitation method. Powders of MnSO4·H2O and NiSO4·6H2O with a molar ratio of 60:40 were weighed and dissolved in deionized water to obtain a mixed solution with a total metal ion concentration of 2 mol / L. The temperature of the reactor was controlled at 55℃. After purging with N2 for 2 hours, the mixed solution, precipitant (4 mol / L NaOH solution), and complexing agent (1 mol / L NH3·H2O solution) were added to the reactor in a co-current manner. The pH was controlled at 9.5-10, and a stirring speed of 380 r / min and a nitrogen atmosphere were maintained throughout the reaction to carry out the co-precipitation reaction. After the reaction, the mixture was aged for 20 hours. After solid-liquid separation, the obtained co-precipitated product was washed and then placed in an oven to dry at 110℃ for 24 hours to obtain the cobalt-free hydroxide precursor (Mn). 0.6 Ni 0.4 (OH)2); (2) The cobalt-free hydroxide precursor obtained in step (1) is heated to 600°C at a rate of 3°C / min and then pre-sintered for 5 hours, and then naturally cooled to 25°C to obtain cobalt-free precursor oxide. (3) In a mixer, the cobalt-free precursor oxide obtained in step (2) is mixed with LiOH and LiNO3. During mixing, the molar ratio of LiOH to LiNO3 is controlled to be 4:6, and the ratio of the total molar amount of Li in LiOH and LiNO3 to the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide is 1.53:1 to obtain a mixture. (4) The mixture obtained in step (3) is heated to 950°C at a rate of 3°C / min and subjected to a first sintering for 10 hours, then cooled to 880°C at a rate of 3°C / min and subjected to a second sintering for 2 hours. After natural cooling to 25°C, it is then ground and dried sequentially to obtain a single-crystal lithium-rich manganese-based cathode material (Li). 1.23 Mn 0.6 Ni 0.4 O2).

[0065] Example 2 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material, wherein the single-crystal lithium-rich manganese-based cathode material is a cobalt-free single-crystal lithium-rich manganese-based cathode material, and the preparation method includes: (1) The precursor was prepared by coprecipitation method. Powders of MnSO4·H2O and NiSO4·6H2O with a molar ratio of 55:45 were weighed and dissolved in deionized water to obtain a mixed solution with a total metal ion concentration of 2 mol / L. The temperature of the reactor was controlled at 55℃. After purging with N2 for 2 hours, the mixed solution, precipitant (4 mol / L NaOH solution), and complexing agent (1 mol / L NH3·H2O solution) were added to the reactor in a co-current manner. The pH was controlled at 9.5-10, and a stirring speed of 380 r / min and a nitrogen atmosphere were maintained throughout the reaction to carry out the co-precipitation reaction. After the reaction, the mixture was aged for 20 hours. After solid-liquid separation, the obtained co-precipitated product was washed and then placed in an oven to dry at 110℃ for 24 hours to obtain the cobalt-free hydroxide precursor (Mn). 0.55 Ni 0.45 (OH)2); (2) The cobalt-free hydroxide precursor obtained in step (1) is heated to 500°C at a rate of 1°C / min and then pre-sintered for 8 hours, and then naturally cooled to 25°C to obtain cobalt-free precursor oxide. (3) In a mixer, the cobalt-free precursor oxide obtained in step (2) is mixed with Li2CO3 and LiNO3. During mixing, the molar ratio of Li2CO3 to LiNO3 is controlled to be (3~5):6, and the ratio of the total molar amount of Li in Li2CO3 and LiNO3 to the total molar amount of transition metal in the cobalt-free precursor oxide is 1.45:1, to obtain a mixture; (4) The mixture obtained in step (3) is heated to 980°C at a rate of 10°C / min and then sintered for 9 hours. After that, it is cooled to 900°C at a rate of 10°C / min and then sintered for 1.5 hours. After that, it is naturally cooled to 25°C and then ground and dried in sequence to obtain a single-crystal lithium-rich manganese-based cathode material.

[0066] Example 3 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material, wherein the single-crystal lithium-rich manganese-based cathode material is a cobalt-free single-crystal lithium-rich manganese-based cathode material, and the preparation method includes: (1) The precursor was prepared by co-precipitation method. Powders of MnSO4·H2O and NiSO4·6H2O with a molar ratio of 65:35 were weighed and dissolved in deionized water to obtain a mixed solution with a total metal ion concentration of 2 mol / L. The temperature of the reactor was controlled at 55℃. After purging with N2 for 2 hours, the mixed solution, precipitant (4 mol / L NaOH solution), and complexing agent (1 mol / L NH3·H2O solution) were added to the reactor in a parallel stream. The pH was controlled at 9.5~10, and a stirring speed of 380 r / min and a nitrogen atmosphere were maintained throughout the reaction to carry out the co-precipitation reaction. After the reaction, the mixture was aged for 20 hours. After solid-liquid separation, the obtained co-precipitated product was washed and then placed in an oven to dry at 110℃ for 24 hours to obtain cobalt-free single-crystal lithium-rich manganese-based cathode material (Mn). 0.65 Ni 0.35 (OH)2); (2) The cobalt-free hydroxide precursor obtained in step (1) is heated to 650°C at a rate of 10°C / min and then pre-sintered for 3 hours, and then naturally cooled to 25°C to obtain cobalt-free precursor oxide. (3) In a mixer, the cobalt-free precursor oxide obtained in step (2) is mixed with LiOH and LiNO3. During mixing, the molar ratio of LiOH to LiNO3 is controlled to be (3~5):6, and the ratio of the total molar amount of Li in LiOH and LiNO3 to the total molar amount of transition metal in the cobalt-free precursor oxide is 1.60:1, to obtain a mixture. (4) The mixture obtained in step (3) is heated to 920°C at a rate of 1°C / min and then sintered for 10 hours. After that, it is cooled to 860°C at a rate of 1°C / min and then sintered for 2.5 hours. After that, it is naturally cooled to 25°C and then ground and dried in sequence to obtain a single-crystal lithium-rich manganese-based cathode material.

[0067] Example 4 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material, wherein the single-crystal lithium-rich manganese-based cathode material is a low-cobalt single-crystal lithium-rich manganese-based cathode material, and the preparation method includes: (1) The precursor was prepared by coprecipitation method. Powders of MnSO4·H2O, NiSO4·6H2O, CoSO4·7H2O and Al2(SO4)3·18H2O with a molar ratio of 60:32:6:1 were weighed and dissolved in deionized water to obtain a mixed solution with a total metal ion concentration of 2 mol / L. The temperature of the reactor was controlled at 55℃. After purging with N2 for 2 hours, the mixed solution, precipitant (4 mol / L NaOH solution), and complexing agent (1 mol / L NH3·H2O solution) were added to the reactor in a co-current manner. The pH was controlled at 9.5-10, and a stirring speed of 380 r / min and an anaerobic environment were maintained throughout the reaction to carry out the co-precipitation reaction. After the reaction, the mixture was aged for 20 hours. After solid-liquid separation, the obtained co-precipitated product was washed and then placed in an oven to dry at 110℃ for 24 hours to obtain the low-cobalt hydroxide precursor (Mn). 0.6 Ni 0.32 Co 0.06 Al 0.02 (OH)2); (2) The low cobalt hydroxide precursor obtained in step (1) is heated to 600°C at a rate of 3°C / min and then pre-sintered for 5 hours, and then naturally cooled to 25°C to obtain the low cobalt precursor oxide. (3) In a mixer, the low cobalt precursor oxide obtained in step (2) is mixed with LiOH and LiNO3. During mixing, the molar ratio of LiOH to LiNO3 is controlled to be 4:6, and the ratio of the total molar amount of Li in LiOH and LiNO3 to the total molar amount of transition metals (Ni, Mn and Co) in the low cobalt precursor oxide is 1.53:1 to obtain a mixture. (4) The mixture obtained in step (3) is heated to 950°C at a rate of 3°C / min and subjected to a first sintering for 10 hours, then cooled to 880°C at a rate of 3°C / min and subjected to a second sintering for 2 hours. After natural cooling to 25°C, it is then ground and dried sequentially to obtain a single-crystal lithium-rich manganese-based cathode material (Li). 1.23 Mn 0.6 Ni 0.32 Co 0.06 Al 0.02 O2).

[0068] Example 5 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (3) of the preparation method, in which the ratio of the total molar amount of Li in LiOH and LiNO3 to the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide is controlled to be 1.52:1, all other steps are the same as in Example 1.

[0069] Example 6 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (3) of the preparation method, in which the ratio of the total molar amount of Li in LiOH and LiNO3 to the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide is controlled to be 1.54:1, all other steps are the same as in Example 1.

[0070] Example 7 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (3) of the preparation method, in which the ratio of the total molar amount of Li in LiOH and LiNO3 to the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide is controlled to be 1.30:1, all other steps are the same as in Example 1.

[0071] Example 8 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (3) of the preparation method, in which the ratio of the total molar amount of Li in LiOH and LiNO3 to the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide is controlled to be 1.75:1, all other steps are the same as in Example 1.

[0072] Example 9 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (3) of the preparation method, in which the molar ratio of LiOH to LiNO3 is controlled to be 2:6 during mixing, the rest is the same as in Example 1.

[0073] Example 10 This embodiment provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (3) of the preparation method, in which the molar ratio of LiOH to LiNO3 is controlled to be 6:6 during mixing, the rest is the same as in Example 1.

[0074] Comparative Example 1 This comparative example provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for omitting the LiNO3 mixed in during the mixing process in step (3) of the preparation method, and controlling the ratio of the total molar amount of Li in LiOH to the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide to be 1.23:1, everything else is the same as in Example 1.

[0075] Comparative Example 2 This comparative example provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for omitting the LiNO3 mixed in during the mixing process in step (3) of the preparation method, and controlling the total molar amount of Li in LiOH by increasing the amount of LiOH, with the ratio of the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide being 1.53:1, the rest is the same as in Example 1.

[0076] Comparative Example 3 This comparative example provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for omitting the LiOH mixed in during the mixing process in step (3) of the preparation method, and controlling the total molar amount of Li in LiNO3 by increasing the amount of LiNO3, the ratio of the total molar amount of transition metals (Ni and Mn) in the cobalt-free precursor oxide is 1.53:1. All other aspects are the same as in Example 1.

[0077] Comparative Example 4 This comparative example provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (4) of the preparation method, in which the mixture obtained in step (3) is heated to 900°C and then subjected to a first sintering, the rest is the same as in Example 1.

[0078] Comparative Example 5 This comparative example provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (4) of the preparation method, in which the mixture obtained in step (3) is heated to 1020°C and then subjected to a first sintering, the rest is the same as in Example 1.

[0079] Comparative Example 6 This comparative example provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (4) of the preparation method, in which the temperature is lowered to 830°C after the first sintering and then a second sintering is performed, the rest are the same as in Example 1.

[0080] Comparative Example 7 This comparative example provides a method for preparing a single-crystal lithium-rich manganese-based cathode material. Except for step (4) of the preparation method, in which the temperature is lowered to 930°C after the first sintering and then a second sintering is performed, the rest are the same as in Example 1.

[0081] The monocrystalline lithium-rich manganese-based cathode material provided in the above embodiments and comparative examples was mixed with Super P conductive agent and polyvinylidene fluoride binder at a mass ratio of 8:1:1. N-methylpyrrolidone was added to prepare a uniform slurry, which was then coated onto a 12μm thick aluminum foil. After vacuum drying at 120℃ for 12h, the slurry was rolled to obtain a cathode sheet. Then, in an argon atmosphere glove box, a lithium metal sheet was used as the negative electrode sheet, Celgard 2400 was used as the separator, and a 1mol / L LiPF6 solution (the solvent being ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a volume ratio of 1:1:1) was used as the electrolyte to assemble a CR2032 coin cell. The constant current charge-discharge performance was tested using the Blue Battery Testing System. Before the test, the battery was activated for 3 cycles at a current density of 0.1C. Then, the voltage range was set to 2.0V~4.8V, and the battery was cycled for 200 cycles at a current density of 1C. The coulombic efficiency of the first cycle, the specific capacity of the first cycle at 1C rate, and the capacity retention rate after 200 cycles are shown in Table 1.

[0082] Table 1 From Table 1, we can obtain: (1) The single-crystal lithium-rich manganese-based cathode materials prepared by the preparation methods provided in Examples 1 to 6 of the present invention exhibit high first-cycle coulombic efficiency, high first-cycle discharge specific capacity and high capacity retention rate; it can be seen that the single-crystal lithium-rich manganese-based cathode materials also have superior first-cycle coulombic efficiency, rate performance and cycle stability. (2) By comparing Example 1 with Examples 7 and 8, it can be seen that in the mixture described in this invention, when the ratio of the total molar amount of Li in the lithium source and LiNO3 to the total molar amount of the transition metal in the low cobalt hydroxide precursor and / or cobalt-free hydroxide precursor is controlled to be (1.45~1.60):1, the single-crystal lithium-rich manganese-based cathode material exhibits better comprehensive performance. This is because when the total molar amount ratio is too low, it will lead to an increase in lithium vacancy defects, and when the ratio is too high, it will cause a surge in surface residual alkali and an aggravation of interfacial side reactions. (3) By comparing Example 1 with Examples 9 and 10, it can be seen that when the molar ratio of lithium source to LiNO3 is controlled at (3~5):6 in the mixture described in this invention, the single-crystal lithium-rich manganese-based cathode material exhibits better comprehensive performance. This is because when the proportion of LiNO3 is too low, it is impossible to form a sufficient amount of eutectic liquid phase, and the degree of single crystallization is insufficient; when the proportion of LiNO3 is too high, decomposition will lead to excessive gas production, which will result in a decrease in density, and excessive lithium will lead to an increase in residual alkali content. (4) By comparing Example 1 with Comparative Examples 1 to 7, it can be seen that the preparation method provided by the present invention adopts a dual lithium source system composed of lithium source and LiNO3. At the same time, LiNO3 also serves as an auxiliary molten salt. The low melting point of LiNO3 can form a low eutectic liquid phase with the lithium source, which is conducive to the atomic-level uniform mixing of the precursor and the lithium source and to reducing surface defects. In addition, the molten salt liquid phase formed by LiNO3 will uniformly encapsulate the precursor particles, restrict the agglomeration between particles and guide the directional growth of crystals, thereby achieving full single crystallization. In addition, the decomposition products of LiNO3 are only Li2O and volatile gases, with no solid impurities remaining, completely eliminating the need for subsequent water washing steps, which is conducive to obtaining single crystal lithium-rich manganese-based cathode materials with low residual alkali content, thereby improving the rate performance and cycle stability of the obtained single crystal lithium-rich manganese-based cathode materials. The preparation method provided by this invention uses a hydroxide precursor and a two-step sintering process. Because the hydroxide precursor has a low decomposition temperature and high reactivity, and its temperature matches that of the molten salt liquid phase formed by LiNO3, it is conducive to the growth of crystals along a preferred orientation and avoids the formation of secondary particles and grain boundaries. Finally, a single-crystal lithium-rich manganese-based cathode material with strong crystallinity, uniform particle dispersion and no grain boundaries is obtained, thereby improving the rate performance and cycle stability of the obtained single-crystal lithium-rich manganese-based cathode material. The preparation method of the present invention uses a low-cobalt hydroxide precursor and / or a cobalt-free hydroxide precursor, without relying on the structural stabilizing effect of high cobalt elements. It utilizes the sufficient oxygen partial pressure released by the decomposition of LiNO3 during in-situ sintering to suppress the lattice oxygen release and the irreversible structural transformation from layered phase to spinel phase in the single-crystal lithium-rich manganese-based cathode material, thereby improving structural stability and alleviating the voltage decay problem of single-crystal lithium-rich manganese-based cathode material during cycling, thus improving cycling stability. The preparation method provided by this invention, by using a hydroxide precursor and a two-step sintering process assisted by dual lithium source molten salt, yields low-cobalt and / or cobalt-free single-crystal lithium-rich manganese-based cathode materials with fewer surface defects, lower residual alkali content, stronger crystallinity, and stronger structural stability without relying on high cobalt content. Therefore, the single-crystal lithium-rich manganese-based cathode materials obtained by the preparation method exhibit superior initial coulombic efficiency, rate performance, and cycle stability. In addition, the preparation method is simple, has low requirements for equipment and environment, and has good prospects for large-scale application.

[0083] (5) By comparing Example 1 with Comparative Examples 4 to 7, it can be seen that in the preparation method of the present invention, when the first sintering temperature is 920℃~980℃ and the second sintering temperature is 860℃~900℃, the single crystal lithium-rich manganese-based cathode material exhibits better comprehensive performance. This is because when the first sintering temperature is too low, it will lead to insufficient crystallinity and insufficient single crystallization. When the first sintering temperature is too high, it will lead to abnormal grain growth and serious lithium volatilization. When the second sintering temperature is too low, it will be difficult to obtain a stable layered structure. When the second sintering temperature is too high, it will lead to a deterioration of the single crystal morphology of the single crystal lithium-rich manganese-based cathode material.

[0084] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a single-crystal lithium-rich manganese-based cathode material, characterized in that, The single-crystal lithium-rich manganese-based cathode material includes low-cobalt single-crystal lithium-rich manganese-based cathode material and / or cobalt-free single-crystal lithium-rich manganese-based cathode material, and the preparation method includes: A single-crystal lithium-rich manganese-based cathode material is obtained by mixing a low-cobalt hydroxide precursor and / or a cobalt-free hydroxide precursor with a lithium source and LiNO3 and then sintering them in two steps. The two-step sintering includes performing a first sintering and a second sintering in sequence. The temperature of the first sintering is 920℃~980℃, and the temperature of the second sintering is 860℃~900℃.

2. The production method according to claim 1, characterized by, The chemical formula of the low-cobalt hydroxide precursor is Mn. a Ni b Co c Al 1-a-b-c (OH)₂, of which 0.5 <a<0.7,0.25<b<0.40,0.04<c<0.07; and / or the cobalt-free hydroxide precursor has a chemical formula of Mn x Ni 1-x (OH)2, wherein 0.5 < x < 0.

7.

3. The preparation method according to claim 1, characterized in that, The lithium source includes any one or a combination of at least two of LiOH, Li2CO3, or LiCl.

4. The method of claim 1, wherein, In the mixture, the molar ratio of lithium source to LiNO3 is (3~5):6; And / or, in the mixture, the ratio of the total molar amount of Li in the lithium source and LiNO3 to the total molar amount of transition metals in the low-cobalt hydroxide precursor and / or cobalt-free hydroxide precursor is (1.45~1.60):

1.

5. The preparation method according to claim 1, characterized in that, The first sintering time is 9h~10h; And / or, the second sintering time is 1.5h to 2.5h.

6. The method of any one of claims 1 to 5, wherein the method further comprises the step of: The preparation method further includes: pre-sintering before mixing to obtain low-cobalt precursor oxides and / or cobalt-free precursor oxides.

7. The production method according to claim 6, wherein The pre-sintering temperature is 500℃~650℃, and the time is 3h~8h.

8. A single-crystalline lithium-rich manganese-based cathode material, characterized in that, The single-crystal lithium-rich manganese-based cathode material is obtained by the preparation method described in any one of claims 1 to 7. 9.The single-crystalline lithium-rich manganese-based cathode material of claim 8, wherein, The chemical formula of the low-cobalt single-crystal lithium-rich manganese-based cathode material is Li. z Mn a Ni b Co c Al 1-a-b-c O2, of which 1.45 <z<1.60,0.5<a<0.7,0.25<b<0.40,0.04<c<0.07; And / or, the chemical formula of the cobalt-free single-crystal lithium-rich manganese-based cathode material is Li y Mn x Ni 1-x O2, of which 1.45 <y<1.60,0.5<x<0.7。 10. A lithium battery, characterized by, The lithium battery includes the single-crystal lithium-rich manganese-based cathode material as described in claim 8 or 9.

Images