A lithium-rich manganese-based material and a method for preparing the same

Abstract

The application discloses a lithium-rich manganese-based material and a preparation method thereof, which is used for reducing the specific surface area of the lithium-rich manganese-based material without affecting the kinetic performance of the lithium-rich manganese-based material. The chemical formula of the lithium-rich manganese-based material is Li 1+x Ni a Co b Mn c M d O 2+x‑e N e ; wherein, 0.25≤x≤0.4, a+b+c+d=1, 0.28≤a≤0.34, 0.005≤b≤0.08, 0.58≤c≤0.68, 0≤d≤0.02, 0≤e≤0.06; M and N are doping elements, M is selected from at least one of Ta, Nb, Ti, Fe, Sb, Al, Mg, Na, K; N is selected from at least one of P, S and F.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery positive electrode materials, and particularly relates to a lithium-rich manganese-based material and a preparation method thereof. BACKGROUND

[0002] In order to improve the endurance of an electric vehicle, improving the energy density of a single battery cell is an effective method. Among them, the lithium-rich manganese-based material has been widely studied and applied to battery positive electrode materials due to its high energy density, excellent thermal safety performance and low cost.

[0003] At present, the lithium-rich manganese-based material is mainly synthesized by a coprecipitation combined with solid-phase sintering method. The precursor prepared by coprecipitation has two kinds. One is a transition metal hydroxide, and the other is a carbonate. Compared with the transition metal hydroxide, the lithium-rich manganese-based material prepared by taking the carbonate as the precursor has the advantages of large specific surface area and many internal voids. Therefore, the lithium-rich manganese-based material corresponding to the carbonate precursor has more superior kinetic performance: high discharge capacity and better rate performance. However, the above-mentioned advantages of morphology also bring the following disadvantages to the lithium-rich manganese-based material: the large specific surface area causes the material to easily absorb moisture in the environment and be damp, thereby increasing the processing procedure and quality control cost (for example, drying before use or storing in a vacuum environment). Moreover, the internal voids also cause the problem of low tap density of the lithium-rich manganese-based material, resulting in low energy density of the battery composed of the lithium-rich manganese-based material. SUMMARY

[0004] The application provides a lithium-rich manganese-based material and a preparation method thereof, so as to reduce the specific surface area of the lithium-rich manganese-based material without affecting the kinetic performance of the lithium-rich manganese-based material.

[0005] In a first aspect, the application provides a lithium-rich manganese-based material, the chemical formula of the lithium-rich manganese-based material is Li 1+ x Ni a Co b Mn c M d O 2+x-e N e ; wherein,

[0006] 0.25≤x≤0.4, a+b+c+d=1, 0.28≤a≤0.34, 0.005≤b≤0.08, 0.58≤c≤0.68, 0≤d≤0.02, 0≤e≤0.06; M and N are doping elements, M is selected from at least one of Ta, Nb, Ti, Fe, Sb, Al, Mg, Na, K; N is selected from at least one of P, S and F.

[0007] The lithium-rich manganese-based material with the stoichiometric ratio can be used as a positive active material to prepare a lithium ion battery with high energy density, high coulomb efficiency and high stability.

[0008] In a possible implementation, the specific surface area of the lithium-rich manganese-based material is 2.0-4.0 m 2 / g.

[0009] In the prior art, the specific surface area of the lithium-rich manganese-based material is usually 4.0-8.0 m 2 / g, and the specific surface area of the lithium-rich manganese-based material provided in the present application is 2.0-4.0 m 2 / g, which avoids the problem that the lithium-rich manganese-based material is severely damaged due to side reactions between the lithium-rich manganese-based material and the electrolyte when the lithium-rich manganese-based material is used as a battery positive material, especially as a lithium battery positive material, thereby reducing the battery life. At the same time, the lithium-rich manganese-based material with the specific surface area ensures that the kinetic performance of the lithium-rich manganese-based material as a battery positive material does not decrease significantly, thereby ensuring the capacity and rate performance of the corresponding battery.

[0010] In a possible implementation, the lithium-rich manganese-based material is formed by agglomeration of a plurality of primary particles, and the lithium-rich manganese-based material has a secondary spherical morphology.

[0011] In a possible implementation, the average particle size of the primary particles is 150-300 nm, and the average particle size of the secondary spheres is 6000 nm-11000 nm.

[0012] In a possible implementation, the tap density of the lithium-rich manganese-based material is 2.2-2.6 g / cm 3 .

[0013] In the prior art, the tap density of the lithium-rich manganese-based material (with a specific surface area of 2.0-4.0 m 2 / g) as a battery positive material is 2.5-2.65 g / cm 3 , and the tap density of the lithium-rich manganese-based material provided in the present application is 2.2-2.6 g / cm 3 , which ensures that the corresponding tap density of the lithium-rich manganese-based material as a battery positive material is higher than 2.8 g / cm 3 , thereby effectively improving the energy density of the battery by increasing the content of active material per unit volume on the battery positive electrode.

[0014] In a second aspect, the present application provides a method for preparing the lithium-rich manganese-based material as described in the first aspect and any possible implementation, comprising:

[0015] performing a first sintering treatment on a mixture of a nickel-cobalt-manganese transition metal carbonate and a lithium source to obtain a first intermediate composition; and

[0016] a second sintering treatment is performed after the first sintering treatment;

[0017] wherein the sintering temperature of the second sintering treatment is higher than the sintering temperature of the first sintering treatment, and the average heating rate of the second sintering treatment for heating to the sintering temperature is lower than the average heating rate of the first sintering treatment for heating to the sintering temperature,

[0018] wherein when the lithium-rich manganese-based material contains the doping elements M and / or N, the method further comprises a step of adding a doping element source to the first intermediate composition, and the sintering object of the second sintering treatment is a mixture of the first intermediate composition and the doping element source;

[0019] when the lithium-rich manganese-based material does not contain the doping elements, the object of the second sintering treatment is the first intermediate composition.

[0020] The method for preparing a lithium-rich manganese-based material provided in the present application ensures that, during the crystallization process, the crystal phase has sufficient time to grow in the direction of the lowest surface energy of the system at each temperature, by setting the average heating rate in the second sintering treatment to be lower than the average heating rate in the first sintering treatment, thereby effectively reducing the specific surface area of the lithium-rich manganese-based material. At the same time, by means of the first sintering treatment and the second sintering treatment, the thermal decomposition reaction and the crystal phase formation process are carried out in a segmented manner, i.e., in the first sintering treatment and the second sintering treatment, respectively, thereby avoiding the simultaneous occurrence of the thermal decomposition reaction and the crystal phase formation, which would cause the gas oxides produced by the thermal decomposition reaction to impact the growing crystal phase, resulting in the appearance of internal pores in the crystal phase, and further leading to the problems of excessively large specific surface area and low tap density.

[0021] In one possible implementation, the average heating rate of the first sintering treatment is 5-10℃ / min.

[0022] In the present application, by setting the average heating rate in the first sintering treatment, the precursor (i.e., the nickel-cobalt-manganese transition metal carbonate) is ensured to be fully and rapidly thermally decomposed, so that the gases such as carbon dioxide and water vapor fully and rapidly escape, thereby avoiding the problems of poor crystal phase density growth due to incomplete thermal decomposition in the first thermal treatment and the slow escape of gases during the second sintering treatment, and the increase of internal voids in the lithium-rich manganese-based material and further increase of the specific surface area.

[0023] In one possible implementation, the sintering temperatures of the multiple-stage sintering treatment in the second sintering treatment are sequentially increased.

[0024] In one possible implementation, in each stage of the multiple-stage sintering treatment, the average heating rate for heating to the corresponding sintering temperature is sequentially decreased.

[0025] In a possible implementation, the second sintering treatment is a two-stage or three-stage sintering treatment.

[0026] In a possible implementation, the doping element source is at least one of a Ta source, a Nb source, a Ti source, a Fe source, a Sb source, an Al source, a Mg source, a Na source, a K source, a P source, an S source, and a F source.

[0027] In a possible implementation, the Ta source is Ta2O5, the Nb source is Nb2O5, the Ti source is TiO2, the Fe source is FePO4 and / or Fe2O3, the Sb source is Sb2O3 and / or Sb2O5, the Al source is Al2O3 and / or Al(OH)3, the Mg source is MgO and / or Mg(OH)2, the Na source is NaOH, Na2S and / or Na2CO3, the K source is KOH and / or K2S, the P source is NH4H2PO4, Li3PO4, H3PO4 and / or FePO4, the S source is Na2S and / or K2S, and the F source is NaF, LiF, KF and / or NH4F.

[0028] In a third aspect, the present application provides a battery positive electrode, comprising the lithium-rich manganese-based material according to the first aspect and any possible implementation, and the lithium-rich manganese-based material prepared by the preparation method according to the second aspect and any possible implementation.

[0029] In a fourth aspect, the present application provides a battery pack, comprising at least one battery monomer; wherein,

[0030] The positive electrode of the battery monomer comprises the lithium-rich manganese-based material according to the first aspect and any possible implementation, and the lithium-rich manganese-based material prepared by the preparation method according to the second aspect and any possible implementation. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The electron microscope image of the lithium-rich manganese-based material in the synthesis example 2 provided by the embodiments of the present application;

[0032] Figure 2 The i-v graph of the first circle charge-discharge of the lithium battery in the device example 2 provided by the embodiments of the present application;

[0033] Figure 3 The electron microscope image of the lithium-rich manganese-based material in the synthesis example 4 provided by the embodiments of the present application;

[0034] Figure 4 The i-v graph of the first circle charge-discharge of the lithium battery in the device example 4 provided by the embodiments of the present application;

[0035] Figure 5The electron microscope image of the lithium-rich manganese-based material in synthesis example 7 provided by the embodiments of the present application;

[0036] Figure 6 The i-v graph of the first cycle charge-discharge of the lithium battery in device example 7 provided by the embodiments of the present application;

[0037] Figure 7 The electron microscope image of the lithium-rich manganese-based material in synthesis example 9 provided by the embodiments of the present application;

[0038] Figure 8 The i-v graph of the first cycle charge-discharge of the lithium battery in device example 9 provided by the embodiments of the present application;

[0039] Figure 9 The electron microscope image of the lithium-rich manganese-based material in synthesis comparative example 3 provided by the embodiments of the present application;

[0040] Figure 10 The i-v graph of the first cycle charge-discharge of the lithium battery in device comparative example 3 provided by the embodiments of the present application;

[0041] Figure 11 The electron microscope image of the lithium-rich manganese-based material in synthesis comparative example 6 provided by the embodiments of the present application;

[0042] Figure 12 The i-v graph of the first cycle charge-discharge of the lithium battery in device comparative example 6 provided by the embodiments of the present application;

[0043] Figure 13 The electron microscope image of the lithium-rich manganese-based material in synthesis comparative example 8 provided by the embodiments of the present application;

[0044] Figure 14 The i-v graph of the first cycle charge-discharge of the lithium battery in device comparative example 8 provided by the embodiments of the present application. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of the embodiments of the present application, the following first explains the professional terms used in the embodiments of the present application:

[0046] Tap density: the mass per unit volume of the powder in the container measured after the powder is vibrated under specified conditions. The vibration indicates that the powder is shaken to destroy the voids therein, so as to reach the limit bulk density.

[0047] Compacted density: the density of the positive / negative material after the positive / negative material is rolled on the electrode sheet. The higher the compacted density, the higher the capacity and energy density of the battery. The expression of the compacted density is compacted density = area density / (thickness of the electrode sheet after rolling - thickness of the current collector).

[0048] Specific surface area: the total area possessed by the unit mass of material.

[0049] Initial coulombic efficiency: One of the performance indicators for quantifying the performance of a lithium-ion battery anode material, defined as the ratio of the discharge capacity to the charge capacity of a lithium-ion battery in the first charge-discharge cycle.

[0050] Battery capacity: The amount of electricity discharged by a battery under certain conditions (discharge rate, temperature, terminal voltage, etc.) (can be tested by JS-150D), i.e. the capacity of the battery, usually in units of ampere-hours (abbreviated as A·H, 1 A·H = 3600 C).

[0051] Energy density: Refers to the energy released by a battery per unit mass or per unit volume, i.e. volumetric energy density or mass energy density. Both energy density and power density are variables. After multiple uses of a battery, the energy density will decrease (the battery capacity will decrease), and the power density will also decrease.

[0052] The terms used in the following examples are only for the purpose of describing specific embodiments and are not intended to be limiting to the present application. As used in the specification and the appended claims, the singular forms "a," "an" and "the" are intended to include both singular and plural forms, e.g. "a" or "one" unless the context clearly indicates otherwise.

[0053] Reference to "one embodiment" or "some embodiments" or "one implementation" or "some implementations" described in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. Thus, the appearances of the phrases "in one embodiment" or "in some embodiments" or "in one implementation" or "in some implementations" in various places in the specification are not necessarily all referring to the same embodiment, but can refer to one or more but not all embodiments, unless otherwise indicated by the context. The terms "including," "containing," "having," and variations thereof mean "including but not limited to," unless expressly specified otherwise.

[0054] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be described in further detail below with reference to the accompanying drawings.

[0055] The chemical formula of the lithium-rich manganese-based material is:

[0056] Li 1+x Ni a Co b Mn c M d O 2+x-e N e .

[0057] Wherein, 0.25≤x≤0.4, a+b+c+d=1, 0.28≤a≤0.34, 0.005≤b≤0.08, 0.58≤c≤0.68, 0≤d≤0.02, 0≤e≤0.06; M and N are doping elements, M is selected from at least one of Ta, Nb, Ti, Fe, Sb, Al, Mg, Na, K; N is selected from at least one of P, S, F.

[0058] The specific surface area of the above-mentioned lithium-rich manganese-based material is 2.0-4.0m 2 / g.

[0059] In the prior art, the specific surface area of the lithium-rich manganese-based material is usually 4.0-8.0m 2 / g. The specific surface area of 2.0-4.0m 2 / g of the lithium-rich manganese-based material not only slows down the side reaction of the lithium-rich manganese-based material with the electrolyte when the lithium-rich manganese-based material is used as a positive electrode material, but also ensures that the kinetic performance of the lithium-rich manganese-based material is almost unaffected, thereby ensuring that the discharge capacity, the initial coulombic efficiency and the stability of the battery when the lithium-rich manganese-based material is used as a positive electrode of the battery.

[0060] Further, the lithium-rich manganese-based material has a lithium (Li) content of 0.25-0.40, which can ensure that the battery capacity is improved when the lithium-rich manganese-based material is used as an electrode material. The nickel (Ni) content of more than 0.28 can ensure that the battery composed of the lithium-rich manganese-based material as an electrode material has high energy density and excellent cycle stability. The nickel content of less than 0.34 and the cobalt (Co) content of less than 0.08 can ensure that the content of Ni 4+ on the surface of the material is low when the lithium-rich manganese-based material is used as an electrode material, and the oxidation and decomposition of the electrolyte due to the high activity of Ni 4+ is slowed down, thereby reducing the deterioration speed of the performance of the battery cell. At the same time, the cobalt content of more than 0.005 is beneficial to the activation of the manganese-rich Li2MnO3 phase of the lithium-rich manganese-based positive electrode material, thereby improving the kinetic performance of the lithium-rich manganese-based material and stabilizing the electrochemical performance of the lithium-rich manganese-based material, thereby ensuring the stability of the performance of the lithium-rich manganese-based material in mass production. At the same time, compared with the cobalt-free carbonate or other cobalt-free systems, the decomposition temperature of the cobalt-containing carbonate as a precursor is lower, so that the sintering temperature of the lithium-rich manganese-based material can be lowered to reduce the sintering power, thereby effectively reducing the preparation difficulty and saving the preparation cost.

[0061] Please refer to Figure 1 , Figure 3 , Figure 5 , Figure 7 , Figure 9 , Figure 11 , Figure 13 . For example Figure 1 , Figure 3 ,Figure 5 、 Figure 7 、 Figure 9 、 Figure 11 、 Figure 13 As shown in FIG. 1, the lithium-rich manganese-based material is formed by agglomeration of a plurality of primary particles, forming a secondary spherical morphology. The morphology of these primary particles is irregular or quasi-spherical.

[0062] Further, the average particle size of the primary particles of the lithium-rich manganese-based material is 150-300 nm, and the average particle size of the secondary spheres is 6.0-11.0 μm, i.e. 6000-11000 nm. In fact, the secondary sphere size is high, and the particle size can be obtained by a particle size analyzer: 6.0≤D50≤11.0, 0.8≤(D90-D10) / D50≤1.5.

[0063] In yet another embodiment of the present application, the tap density of the lithium-rich manganese-based positive electrode material is 2.2-2.6 g / cm 3 In the prior art, the lithium-rich manganese-based material (specific surface area of 2.0-4.0 m 2 / g) as a battery positive electrode material has a tap density of 2.5-2.65 g / cm 3 / g. The lithium-rich manganese-based material provided in the embodiments of the present application has a tap density of 2.2-2.6 g / cm 3 , which can ensure that the corresponding tap density is higher than 2.8 g / cm 3 when used as a battery positive electrode material, thereby effectively improving the energy density of the battery by increasing the content of active material per unit volume on the battery positive electrode.

[0064] Further, when the specific surface area of the electrode material is too low, the kinetic performance of the electrode material will be reduced; when the specific surface area of the electrode material is too high, the electrode surface will react with the electrolyte, reducing the rate performance of the electrode material. The present application proposes a lithium-rich manganese-based material to reduce the specific surface area of the lithium-rich manganese-based material without affecting the kinetic performance of the lithium-rich manganese-based material, in view of the problem in the prior art that the specific surface area of the lithium-rich manganese-based material is large, causing the lithium-rich manganese-based material to react with the electrolyte when used as a battery positive electrode (e.g. lithium battery positive electrode), affecting the performance of the battery. Therefore, the present application provides a preparation method of a lithium-rich manganese-based material, which comprises a first sintering treatment and a second sintering treatment with gradually decreasing heating rate and increasing sintering temperature. That is, by controlling the sintering temperature and heating rate of the first sintering treatment and the second sintering treatment to control the nucleation and crystal growth process of the lithium-rich manganese-based crystal phase, a lithium-rich manganese-based material with appropriate surface area and high tap density is prepared; and when the lithium-rich manganese-based material contains a doping element, the preparation method controls the addition of the doping element source between the first sintering treatment and the second sintering treatment to avoid the influence of the doping element on the nucleation of the crystal phase.

[0065] The preparation method of the lithium-rich manganese-based material provided in the present application is described in detail as follows:

[0066] First, a nickel cobalt manganese transition metal carbonate is prepared based on a coprecipitation method. Then, based on a stoichiometric ratio, the nickel cobalt manganese transition metal carbonate is mixed with a lithium source as a precursor to obtain a first intermediate mixture; wherein the lithium source is lithium carbonate and / or lithium hydroxide. Generally, an excess of lithium source is added in the first sintering process to avoid partial lithium source escaping in the form of gas in the second sintering process, resulting in the final obtained lithium-rich manganese-based material with a lithium content lower than the stoichiometric number. Next, the first intermediate mixture is subjected to a first sintering process to obtain a first intermediate composition; wherein the first sintering process indicates heating the first intermediate mixture until a sintering temperature based on a first average heating rate. Finally, when the lithium-rich manganese-based material contains doping elements M and / or N, a step of adding a doping element source to the first intermediate composition is also included, and the sintering object of the second sintering process is the mixture of the first intermediate composition and the doping element source. When the lithium-rich manganese-based material does not contain the doping elements, the object of the second sintering process is the first intermediate composition. That is, when the lithium-rich manganese-based material does not contain doping elements, the first intermediate composition is subjected to a second sintering process to obtain the lithium-rich manganese-based material. Wherein the second sintering process indicates heating the first intermediate composition until a sintering temperature based on an average heating rate. The sintering temperature of the above-mentioned second sintering process is higher than the sintering temperature of the first sintering process, and the average heating rate in the second sintering process is lower than the first average heating rate.

[0067] In the embodiments of the present application, the average heating rate in the second sintering process is lower than the first average heating rate in the first sintering process, which is beneficial to the crystal growth in the direction of the lowest surface energy of the system during the second sintering process. In fact, the second sintering process can further be provided with multiple sintering stages, and the average heating rate gradually decreases as the temperature increases, so that the crystal phase always has sufficient time to grow, and the specific surface area of the final product, the lithium-rich manganese-based material, is more superior (2.0-4.0 m 2 / g). In the embodiments of the present application, the method for determining the average heating rate in any sintering process includes but is not limited to the following embodiments provided:

[0068] (I) Within the temperature change range of the corresponding heat treatment process, the current heating rate is obtained every preset time, and the average value is determined by taking the heating rates at multiple preset times.

[0069] (II) Within the temperature change range of the corresponding heat treatment process, the heating rate at the preset temperature is determined every time the preset temperature is reached. The average value is determined by taking the heating rates at a set number of preset temperatures within the temperature change range.

[0070] Specifically, the way of determining the first intermediate composition as a complete oxide so that the thermal decomposition of the gas oxide does not occur in the second heat treatment can be to compare the mass of the first intermediate composition with a mixture of the nickel-cobalt-manganese transition metal carbonate and the lithium source to determine whether the mixture is completely thermally decomposed.

[0071] Further, the average heating rate of the first heat treatment can be 5°C / min or higher. In the embodiments of the present application, by setting the average heating rate of the first heat treatment, it can be ensured that the thermal decomposition reaction of the carbonate and the lithium source is fully carried out in the first sintering process, so that the gas oxide is fully escaped, i.e., the obtained carbon dioxide (CO2) and water vapor are oxidized, avoiding the influence of the gas escaping due to incomplete thermal decomposition of the precursor - nickel-cobalt-manganese transition metal carbonate in the second sintering process.

[0072] Further, in the lithium-rich manganese-based preparation method provided in the embodiments of the present application, if the lithium-rich manganese-based material contains a doping element source, the doping element source is added after the first intermediate composition is obtained. Therefore, the sintering object of the second sintering process is a mixture of the first intermediate composition and the doping element source. The method of adding the doping source after the first intermediate composition is obtained can effectively reduce the influence of the doping element on the crystal nucleation process of the lithium-rich manganese-based material, and can support the above-mentioned layered crystal structure, which helps to stabilize the layered crystal structure. At the same time, after the doping element source is mixed with the first intermediate composition, it can migrate in the subsequent sintering process, i.e., the second sintering process, so that the doping element is uniformly distributed in the above-mentioned layered crystal structure in the second sintering process, thereby further stabilizing the layered crystal structure.

[0073] In the embodiments of the present application, the sintering process is actually divided into the first sintering process and the second sintering process by the addition of the doping element source. Therefore, the number of segments of the first sintering process and the second sintering process is not limited. In the embodiments of the present application, the first sintering process is preferably set to one segment to ensure that the nickel-cobalt-manganese metal carbonate and the lithium source are fully thermally decomposed. The reactions in the first sintering process and the reactions in the second sintering process are described below. Wherein, TM represents different combinations of different transition metals, and x represents the amount of lithium (also in terms of molar ratio).

[0074] TMCO3→TMO+CO2 (1);

[0075] Li2CO3→Li2O+CO2 (2);

[0076] LiOH·H2O→LiOH+H2O (3);

[0077] LiOH→Li2O+H2O (4);

[0078] TMO + (1 + x) / 2Li2O + (1 + x) / 4O2→ Li 1+x TMO 2+x (5);

[0079] The above formulae (1)-(4) correspond to the first sintering process. Among them, formula (1) is an expression of thermal decomposition of the carbonate in the first sintering process, and formulae (2)-(4) are expressions of thermal decomposition of the lithium source in the first sintering process. Formula (5) corresponds to the second sintering process, in which the reaction between the transition metal oxide and the lithium oxide is mainly carried out.

[0080] In yet another embodiment of the present application, by controlling the average heating rate in the first sintering process to be 5-10℃ / min, the rapid thermal decomposition of the carbonate and the lithium source is ensured, so that in the first sintering process, the rapid heating promotes the rapid generation and volatilization of CO2 and water vapor (H2O), which can effectively avoid the impact of the generation and volatilization of CO2 and water vapor on the inside of the lithium-rich manganese-based material during the second sintering process, forming pores, affecting the growth of crystal density, and increasing the specific surface area of the lithium-rich manganese-based material.

[0081] At the same time, in order to ensure that the nickel-cobalt-manganese transition metal carbonate is fully thermally decomposed in the first sintering process and does not affect the growth of the crystal phase in the second sintering process, the sintering temperature and sintering time of the first sintering process can be set.

[0082] For example, the sintering temperature of the first thermal treatment can be set to 400-600℃, and the holding time is 2-6h. At this time, the second thermal treatment can include 1 sintering temperature (800-900℃), and the corresponding holding time is 10-20h, and the heating rate is 0.5-2℃ / min.

[0083] For example, the sintering temperature of the first sintering process can be 350-500℃, and the holding time is 2-6h. At this time, the second thermal treatment can include 2 sintering temperatures, the first sintering temperature is between 500-700℃, and the second sintering temperature is between 800-900℃, the holding time corresponding to the first sintering temperature is 1-5h, and the heating rate is 2-4℃ / min; the holding time corresponding to the second sintering temperature is 10-20h, and the heating rate is 0.5-2℃ / min.

[0084] For example, the first sintering temperature in the first sintering process is 300-400℃, and the holding time is 2-6h. At this time, the second sintering process can include three sintering temperatures: the first sintering temperature is 400-600℃, and the corresponding holding time is 1-5h, and the heating rate is 3-5℃ / min; the second sintering temperature is 600-800℃, and the holding time is 1-5h, and the heating rate is 2-4℃ / min; the third sintering temperature is 800-900℃, and the holding time is 10-20h, and the heating rate is 0.5-2℃ / min.

[0085] The lithium-rich manganese-based material in the embodiments of the present application will be further explained and described below in combination with specific examples and comparative examples.

[0086] Synthesis Example 1

[0087] Synthesis Example 1 provides a lithium-rich manganese-based material with the chemical formula Li 1.25 Ni 0.28 Co 0.04 Mn 0.66 Nb 0.01 Al 0.01 O 2.23 F 0.02 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0088] Step S1, based on the stoichiometric ratio in the above formula, mix the nickel-cobalt-manganese transition metal carbonate as a precursor with an excess of 5% lithium hydroxide (i.e. the molar content is (1.25+0.05=)1.30 compared to other components) to uniformity to obtain a first intermediate mixture.

[0089] Step S2, the first sintering process is performed on the first intermediate mixture: the first average heating rate is 5℃ / min, and the holding time is 5h after the temperature is raised to the first sintering temperature 500℃. After the holding time, the temperature is lowered until room temperature to obtain a first intermediate composition.

[0090] Step S3, based on the stoichiometric ratio in the above formula, take the first intermediate composition and grind it together with Nb2O5, Al(OH)3, and LiF, and mix it uniformly to obtain a second intermediate mixture.

[0091] Step S4, the second sintering process is performed on the second intermediate mixture: the second average heating rate is 2℃ / min, and the holding time is 12h after the temperature is raised to the second sintering temperature 850℃. After the holding time, the temperature is lowered until room temperature to obtain a lithium-rich manganese-based material with the chemical formula Li 1.25 Ni 0.28 Co 0.04 Mn 0.66 Nb 0.01 Al 0.01 O 2.23 F 0.02Lithium-rich manganese-based materials.

[0092] The specific surface area of ​​this lithium-rich manganese-based material is 3.83 m². 2 / g, tap density is 2.26g / cm³ 3 .

[0093] Synthesis Example 2

[0094] Synthesis Example 2 provides a chemical formula Li 1.4 Ni 0.34 Co 0.01 Mn 0.63 Ta 0.01 Mg 0.01 O 2.38 P 0.02 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0095] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is used as a precursor and mixed with an excess of 5% lithium carbonate (i.e., the molar content is (1.40 + 0.05 =) 1.45 compared to other components) until homogeneous to obtain a first intermediate mixture.

[0096] Step S2 involves performing a first sintering treatment on the first intermediate mixture: the first average heating rate is 6°C / min, and the mixture is held at the first sintering temperature of 600°C. After holding for 4 hours, the mixture is cooled down to room temperature to obtain the first intermediate composition.

[0097] Step S3: Based on the stoichiometric ratio in the above chemical formula, the first intermediate composition is ground together with Ta2O5, MgO and Li3PO4 and mixed evenly to obtain the second intermediate mixture.

[0098] Step S4: Perform a second sintering treatment on the second intermediate mixture: the second average heating rate is 1.5℃ / min, and the mixture is held at the second sintering temperature of 900℃ for 10 hours. Then, it is cooled to room temperature to obtain the product with the chemical formula Li. 1.4 Ni 0.34 Co 0.01 Mn 0.63 Ta 0.01 Mg 0.01 O 2.38 P 0.02 Lithium-rich manganese-based materials.

[0099] The specific surface area of ​​this lithium-rich manganese-based material is 3.22 m². 2 / g, tap density is 2.31g / cm³ 3 .

[0100] Synthesis Example 3

[0101] Synthesis Example 3 provides a lithium-rich manganese-based material with a chemical formula of Li 1.33 Ni 0.33 Co 0.08 Mn 0.58 Ti 0.01 O 2.33 , specific preparation steps of which are as follows:

[0102] Step S1, based on the stoichiometric ratio in the above chemical formula, mix the nickel-cobalt-manganese transition metal carbonate as a precursor with excess 3% carbon lithium (i.e. the molar content is (1.33+0.03=) 1.36 compared to other components) to uniformity to obtain a first intermediate mixture.

[0103] Step S2, perform a first sintering treatment on the first intermediate mixture: the first average heating rate is 8℃ / min, and wait to heat to a first sintering temperature of 480℃ for heat preservation. After the heat preservation time reaches 3h, cool down until room temperature to obtain a first intermediate composition.

[0104] Step S3, based on the stoichiometric ratio in the above chemical formula, grind the first intermediate composition together with TiO2 and mix uniformly to obtain a second intermediate mixture.

[0105] Step S4, perform a second sintering treatment on the second intermediate mixture: the second average heating rate is 2℃ / min, and wait to heat to a second sintering temperature of 830℃ for heat preservation. After the heat preservation time reaches 14h, cool down until room temperature to obtain a lithium-rich manganese-based material with a chemical formula of Li 1.33 Ni 0.33 Co 0.08 Mn 0.58 Ti 0.01 O 2.33 .

[0106] The specific surface area of the lithium-rich manganese-based material is 3.65m 2 / g, and the tap density is 2.28g / cm 3 .

[0107] Synthesis Example 4

[0108] Synthesis Example 4 provides a lithium-rich manganese-based material with a chemical formula of Li 1.35 Ni 0.29 Co 0.01 Mn 0.68 Ti 0.01 Mg 0.01 O 2.33 F 0.01 P 0.01 , specific preparation steps of which are as follows:

[0109] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is used as a precursor and mixed with an excess of 3% lithium carbonate until homogeneous to obtain a first intermediate mixture.

[0110] Step S2: Perform a first sintering treatment on the first intermediate mixture: The first average heating rate is 8°C / min, and the mixture is held at the first sintering temperature of 400°C. After holding for 3 hours, the mixture is cooled down to room temperature to obtain the first intermediate composition.

[0111] Step S3: Based on the stoichiometric ratio in the above chemical formula, the first intermediate composition is ground together with TiO2, MgO, LiF and NH4H2PO4 and mixed evenly to obtain the second intermediate mixture.

[0112] Step S4: Perform a second sintering treatment on the second intermediate mixture: the second average heating rate is 2℃ / min, and the mixture is held at the second sintering temperature of 800℃. After holding for 15 hours, the mixture is cooled to room temperature to obtain the product with the chemical formula Li. 1.35 Ni 0.29 Co 0.01 Mn 0.68 Ti 0.01 Mg 0.01 O 2.33 F 0.01 P 0.01 Lithium-rich manganese-based materials.

[0113] The specific surface area of ​​this lithium-rich manganese-based material is 3.59 m². 2 / g, tap density is 2.24g / cm³ 3 .

[0114] Synthesis Example 5

[0115] Synthesis Example 5 provides a chemical formula of Li 1.38 Ni 0.28 Co 0.03 Mn 0.68 Sb 0.01 O 2.36 F 0.02 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0116] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is used as a precursor and mixed with an excess of 3% lithium hydroxide until homogeneous to obtain a first intermediate mixture.

[0117] Step S2: Perform a first sintering treatment on the first intermediate mixture: the first average heating rate is 6℃ / min, and the mixture is held at the first sintering temperature of 450℃. After holding for 4 hours, the mixture is cooled down to room temperature to obtain the first intermediate composition.

[0118] Step S3, based on the stoichiometric ratio in the above formula, grind the first intermediate composition with Sb2O3, NH4F together and mix uniformly to obtain a second intermediate mixture.

[0119] Step S4, perform a second sintering treatment on the second intermediate mixture: the second average heating rate is 4℃ / min, and when the temperature is raised to the second sintering temperature 660℃, keep warm. After the warm-keeping time reaches 2h, continue to raise the temperature at a third average heating rate of 1℃ / min, and keep warm at a third sintering temperature 865℃. After the warm-keeping time reaches 12h, cool down until room temperature, to obtain a lithium-rich manganese-based material with the formula Li 1.38 Ni 0.28 Co 0.03 Mn 0.68 Sb 0.01 O 2.36 F 0.02 .

[0120] The specific surface area of the lithium-rich manganese-based material is 3.26m 2 / g, and the tap density is 2.43g / cm 3 .

[0121] Synthesis Example 6

[0122] Synthesis Example 6 provides a lithium-rich manganese-based material with the formula Li 1.34 Ni 0.32 Co 0.08 Mn 0.58 Ti 0.005 Al 0.01 Mg 0.005 O 2.32 F 0.02 , and the specific preparation steps of the lithium-rich manganese-based material are as follows:

[0123] Step S1, based on the stoichiometric ratio in the above formula, mix the nickel-cobalt-manganese transition metal carbonate as a precursor with excess 1% lithium carbonate to be uniform to obtain a first intermediate mixture.

[0124] Step S2, perform a first sintering treatment on the first intermediate mixture: the first average heating rate is 8℃ / min, and when the temperature is raised to the first sintering temperature 480℃, keep warm. After the warm-keeping time reaches 3h, cool down until room temperature to obtain a first intermediate composition.

[0125] Step S3, based on the stoichiometric ratio in the above formula, grind the first intermediate composition with TiO2, MgO, Al(OH)3, LiF together and mix uniformly to obtain a second intermediate mixture.

[0126] Step S4, a second sintering treatment is performed on the second intermediate mixture: the second average heating rate is 3℃ / min, and the temperature is kept at the second sintering temperature 630℃. After the temperature is kept for 2h, the temperature is continuously increased at the third average heating rate of 2℃ / min, and the temperature is kept at the third sintering temperature 800℃. After the temperature is kept for 12h, the temperature is decreased until room temperature, and a lithium-rich manganese-based material with the chemical formula of Li 1.34 Ni 0.32 Co 0.08 Mn 0.58 Ti 0.005 Al 0.01 Mg 0.005 O 2.32 F 0.02 is obtained.

[0127] The specific surface area of the lithium-rich manganese-based material is 2.96m 2 / g, and the tap density is 2.26g / cm 3 .

[0128] Synthesis Example 7

[0129] Synthesis Example 7 provides a lithium-rich manganese-based material with the chemical formula of Li 1.3 Ni 0.33 Co 0.06 Mn 0.59 K 0.02 O 2.29 S 0.01 , and the specific preparation steps of the lithium-rich manganese-based material are as follows:

[0130] Step S1, based on the stoichiometric ratio in the above chemical formula, a nickel-cobalt-manganese transition metal carbonate is mixed with excess 4% lithium carbonate as a precursor to obtain a first intermediate mixture.

[0131] Step S2, a first sintering treatment is performed on the first intermediate mixture: the first average heating rate is 6℃ / min, and the temperature is kept at the first sintering temperature 420℃. After the temperature is kept for 4h, the temperature is decreased until room temperature, and a first intermediate composition is obtained.

[0132] Step S3, based on the stoichiometric ratio in the above chemical formula, the first intermediate composition is taken and ground together with Nb2O5 and K2S, and is mixed uniformly to obtain a second intermediate mixture.

[0133] Step S4, a second sintering treatment is performed on the second intermediate mixture: the second average heating rate is 4℃ / min, and the temperature is kept at the second sintering temperature 660℃. After the temperature is kept for 2h, the temperature is continuously increased at the third average heating rate of 1℃ / min, and the temperature is kept at the third sintering temperature 900℃. After the temperature is kept for 10h, the temperature is decreased until room temperature, and a lithium-rich manganese-based material with the chemical formula of Li 1.3Ni 0.33 Co 0.06 Mn 0.59 K 0.02 O 2.29 S 0.01 Li

[0134] The specific surface area of the lithium-rich manganese-based material is 2.89m 2 / g, and the tap density is 2.36g / cm 3 .

[0135] Synthesis Example 8

[0136] Synthesis Example 8 provides a lithium-rich manganese-based material with the chemical formula of Li 1.28 Ni 0.34 Co 0.01 Mn 0.64 Nb 0.01 O 2.27 F 0.01 , and the specific preparation steps of the lithium-rich manganese-based material are as follows:

[0137] Step S1, based on the stoichiometric ratio in the above chemical formula, mix the nickel-cobalt-manganese transition metal carbonate as a precursor with excess 2% lithium carbonate to be uniform to obtain a first intermediate mixture.

[0138] Step S2, the first sintering treatment is carried out for the first intermediate mixture: the first average heating rate is 8℃ / min, and the temperature is kept at the first sintering temperature 300℃. After the holding time reaches 4h, the temperature is lowered until room temperature to obtain a first intermediate composition.

[0139] Step S3, based on the stoichiometric ratio in the above chemical formula, take the first intermediate composition and grind it together with Nb2O5, LiF, and mix it uniformly to obtain a second intermediate mixture.

[0140] Step S4, the second sintering treatment is carried out for the second intermediate mixture: the second average heating rate is 4℃ / min, and the temperature is kept at the second sintering temperature 600℃. After the holding time reaches 2h, continue to heat at a third average heating rate of 3℃ / min, and keep the temperature at a third sintering temperature 700℃. After the holding time reaches 2h, continue to heat at a fourth average heating rate of 2℃ / min, and keep the temperature at a fourth sintering temperature 865℃. After the holding time reaches 12h, the temperature is lowered until room temperature to obtain a lithium-rich manganese-based material with the chemical formula of Li 1.28 Ni 0.34 Co 0.01 Mn 0.64 Nb 0.01 O 2.27 F 0.01 .

[0141] The lithium-rich manganese-based material has a specific surface area of 2.58 m 2 / g, and a tap density of 2.33 g / cm 3 .

[0142] Synthesis Example 9

[0143] Synthesis Example 9 provides a lithium-rich manganese-based material of the chemical formula Li 1.4 Ni 0.28 Co 0.02 Mn 0.68 Na 0.02 O 2.39 S 0.01 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0144] Step S1, based on the stoichiometric ratio in the above chemical formula, mix the nickel-cobalt-manganese transition metal carbonate as a precursor with an excess of 2% lithium carbonate to be uniform, to obtain a first intermediate mixture.

[0145] Step S2, the first sintering treatment is carried out for the first intermediate mixture: the first average heating rate is 10°C / min, and the temperature is kept at the first sintering temperature of 380°C. After the holding time reaches 6h, the temperature is lowered until room temperature, to obtain a first intermediate composition.

[0146] Step S3, based on the stoichiometric ratio in the above chemical formula, take the first intermediate composition and grind it with Na2S, and mix it uniformly, to obtain a second intermediate mixture.

[0147] Step S4, the second sintering treatment is carried out for the second intermediate mixture: the second average heating rate is 3°C / min, and the temperature is kept at the second sintering temperature of 400°C. After the holding time reaches 2h, continue to heat at a third average heating rate of 2°C / min, and keep the temperature at a third sintering temperature of 600°C. After the holding time reaches 4h, continue to heat at a fourth average heating rate of 0.5°C / min, and keep the temperature at a fourth sintering temperature of 900°C. After the holding time reaches 10h, the temperature is lowered until room temperature, to obtain a lithium-rich manganese-based material of the chemical formula Li 1.4 Ni 0.28 Co 0.02 Mn 0.68 Na 0.02 O 2.39 S 0.01 .

[0148] The lithium-rich manganese-based material has a specific surface area of 2.65 m 2 / g, and a tap density of 2.38 g / cm 3 .

[0149] Synthesis Example 10

[0150] Synthesis Example 10 provides a lithium-rich manganese-based material of the chemical formula Li 1.35 Ni 0.30 Co 0.06 Mn 0.62 Ta 0.01 Fe 0.01 O 2.34 P 0.01 , specific preparation steps of which are as follows:

[0151] Step S1, based on the stoichiometric ratio in the above chemical formula, mix the nickel-cobalt-manganese transition metal carbonate as a precursor with excess 2% lithium carbonate to be uniform, to obtain a first intermediate mixture.

[0152] Step S2, the first sintering treatment is carried out for the first intermediate mixture: the first average heating rate is 5℃ / min, and the temperature is kept at the first sintering temperature 300℃. After the holding time reaches 6h, the temperature is lowered until room temperature, to obtain a first intermediate composition.

[0153] Step S3, based on the stoichiometric ratio in the above chemical formula, grind the first intermediate composition together with Ta2O5, FePO4, and mix uniformly, to obtain a second intermediate mixture.

[0154] Step S4, the second sintering treatment is carried out for the second intermediate mixture: the second average heating rate is 3℃ / min, and the temperature is kept at the second sintering temperature 600℃. After the holding time reaches 2h, continue to heat at a third average heating rate of 2℃ / min, and keep the temperature at a third sintering temperature 715℃. After the holding time reaches 4h, continue to heat at a fourth average heating rate of 1℃ / min, and keep the temperature at a fourth sintering temperature 800℃. After the holding time reaches 15h, the temperature is lowered until room temperature, to obtain a lithium-rich manganese-based material of the chemical formula Li 1.35 Ni 0.30 Co 0.06 Mn 0.62 Ta 0.01 Fe 0.01 O 2.34 P 0.01 .

[0155] The specific surface area of the lithium-rich manganese-based material is 2.39m 2 / g, and the tap density is 2.29g / cm 3 .

[0156] Synthesis Example 11

[0157] Synthesis Example 11 provides a lithium-rich manganese-based material of the chemical formula Li 1.33 Ni 0.33 Co 0.08 Mn 0.59 O 2.33Li 1.25 N i0.28 Co 0.04 Mn 0.66 Nb 0.01 Al 0.01 O 2.23 F 0.02 rich lithium manganese-based material, the specific preparation steps of which are as follows:

[0158] Step S1, based on the stoichiometric ratio in the above chemical formula, a nickel-cobalt-manganese transition metal carbonate is taken as a precursor and mixed with excess 3% lithium carbonate (i.e. the molar content is (1.33+0.03=) 1.36 compared with other components) to be uniform, to obtain a first intermediate mixture.

[0159] Step S2, the first intermediate mixture is subjected to a first sintering treatment: the first average heating rate is 8℃ / min, and the temperature is raised to the first sintering temperature 480℃ and kept for a while. After the holding time reaches 3h, the temperature is lowered until room temperature, to obtain a first intermediate composition.

[0160] Step S3, the first intermediate mixture is subjected to a second sintering treatment: the second average heating rate is 2℃ / min, and the temperature is raised to the second sintering temperature 830℃ and kept for a while. After the holding time reaches 14h, the temperature is lowered until room temperature, to obtain a lithium-rich manganese-based material of the chemical formula Li 1.33 Ni 0.33 Co 0.08 Mn 0.59 O 2.33 .

[0161] The specific surface area of the lithium-rich manganese-based material is 3.65m 2 / g, and the tap density is 2.28g / cm 3 .

[0162] Synthesis Comparative Example 1

[0163] Comparative Example 1 provides a lithium-rich manganese-based material of the chemical formula Li 1.25 N i0.28 Co 0.04 Mn 0.66 Nb 0.01 Al 0.01 O 2.23 F 0.02 , the specific preparation steps of which are as follows:

[0164] Step S1, based on the stoichiometric ratio in the above chemical formula, a nickel-cobalt-manganese transition metal carbonate is taken as a precursor, and is ground together with excess 5% lithium hydroxide, Nb2O5, Al(OH)3, and LiF, and is mixed uniformly to obtain a first intermediate mixture.

[0165] Step S2, the first intermediate mixture is subjected to a first sintering treatment: the first average heating rate is 2℃ / min, and the temperature is raised to the first sintering temperature 500℃ and kept for a while. After the holding time reaches 5h, the temperature is lowered until room temperature, to obtain a first intermediate composition.

[0166] Step S3, a second sintering treatment is performed on the first intermediate composition: the average heating rate is 2℃ / min, and the temperature is kept at the second sintering temperature 850℃. After the temperature is kept for 12h, the temperature is decreased until room temperature, and a lithium-rich manganese-based material with the chemical formula of Li 1.2 5N i0.28 Co 0.04 Mn 0.66 Nb 0.01 Al 0.01 O 2.23 F 0.02 is obtained.

[0167] The specific surface area of the lithium-rich manganese-based material is 6.36m 2 / g, and the tap density is 1.95g / cm 3 .

[0168] Synthesis Comparative Example 2

[0169] Comparative Example 2 provides a lithium-rich manganese-based material with the chemical formula of Li 1.25 Ni 0.28 Co 0.04 Mn 0.66 Nb 0.01 Al 0.01 O 2.23 F 0.02 , and the specific preparation steps of the lithium-rich manganese-based material are as follows:

[0170] Step S1, based on the stoichiometric ratio in the above chemical formula, take the nickel-cobalt-manganese transition metal carbonate as the precursor, grind it together with excess 5% lithium hydroxide, Nb2O5, Al(OH)3, and LiF, and mix them uniformly to obtain a first intermediate mixture.

[0171] Step S2, a first sintering treatment is performed on the first intermediate mixture: the first average heating rate is 10℃ / min, and the temperature is kept at the first sintering temperature 500℃. After the temperature is kept for 5h, the temperature is decreased until room temperature, and a first intermediate composition is obtained.

[0172] Step S3, a second sintering treatment is performed on the first intermediate composition: the second average heating rate is 10℃ / min, and the temperature is kept at the second sintering temperature 850℃. After the temperature is kept for 12h, the temperature is decreased until room temperature, and a lithium-rich manganese-based material with the chemical formula of Li 1.25 Ni 0.28 Co 0.04 Mn 0.66 Nb 0.01 Al 0.01 O 2.23 F 0.02 is obtained.

[0173] The lithium-rich manganese-based material has a specific surface area of 5.52 m 2 / g, and a tap density of 2.03 g / cm 3 .

[0174] Synthesis Comparative Example 3

[0175] Comparative Example 3 provides a lithium-rich manganese-based material of the chemical formula Li 1.34 Ni 0.32 Co 0.08 Mn 0.58 Ti 0.005 Al 0.01 Mg 0.005 O 2.32 F 0.02 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0176] Step S1, based on the stoichiometric ratio in the above chemical formula, take the nickel-cobalt-manganese transition metal carbonate as the precursor, grind it together with excess 1% lithium carbonate, TiO2, MgO, Al(OH)3, and LiF, and mix them uniformly to obtain a first intermediate mixture.

[0177] Step S2, the first sintering treatment is performed on the first intermediate mixture: the first average heating rate is 2°C / min, and the temperature is kept at the first sintering temperature of 480°C. After the holding time reaches 3h, the temperature is lowered until room temperature to obtain a first intermediate composition.

[0178] Step S3, the second sintering treatment is performed on the first intermediate composition: the second average heating rate is 2°C / min, and the temperature is kept at the second sintering temperature of 630°C. After the holding time reaches 2h, the temperature is continuously raised at a third average heating rate of 2°C / min until the third sintering temperature of 800°C, and the temperature is kept at this temperature for 12h. After the holding time reaches 12h, the temperature is lowered until room temperature to obtain a lithium-rich manganese-based material of the chemical formula Li 1.34 Ni 0.32 Co 0.08 Mn 0.58 Ti 0.005 Al 0.01 Mg 0.005 O 2.32 F 0.02 .

[0179] The lithium-rich manganese-based material has a specific surface area of 5.38 m 2 / g, and a tap density of 2.02 g / cm 3 .

[0180] Synthesis Comparative Example 4

[0181] Comparative Example 4 provides a lithium-rich manganese-based material of the chemical formula Li 1.4 Ni 0.28 Co0.02 Mn 0.68 Na 0.02 O 2.39 S 0.01 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0182] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is taken as a precursor, ground together with excess 2% lithium carbonate and Na2S, and mixed evenly to obtain the first intermediate mixture.

[0183] Step S2: Perform a first sintering treatment on the first intermediate mixture: the first average heating rate is 10℃ / min, and the mixture is held at the first sintering temperature of 380℃. After holding for 6 hours, the mixture is cooled down to room temperature to obtain the first intermediate composition.

[0184] Step S3: Perform a second sintering treatment on the first intermediate composition: The second average heating rate is 10℃ / min, and the temperature is raised to the second sintering temperature of 400℃ and held. After holding for 2 hours, the temperature is increased at a third average heating rate of 10℃ / min until the third sintering temperature of 600℃ is reached and held for 4 hours. Then, the temperature is increased at a fourth average heating rate of 0.5℃ / min until the fourth sintering temperature of 900℃ is reached and held for 10 hours. After cooling to room temperature, the product with the chemical formula Li is obtained. 1.4 Ni 0.28 Co 0.02 Mn 0.68 Na 0.02 O 2.39 S 0.01 Lithium-rich manganese-based materials.

[0185] The specific surface area of ​​this lithium-rich manganese-based material is 4.65 m². 2 / g, tap density is 2.10g / cm³ 3 .

[0186] Synthetic Comparative Example 5

[0187] Comparative Example 5 provides a chemical formula of Li 1.5 Ni 0.25 Mn 0.75 O 2.5 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0188] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is used as a precursor and mixed with an excess of 3% lithium carbonate (i.e., the molar content is (1.5 + 0.03 =) 1.53 compared to other components) until homogeneous to obtain the first intermediate mixture.

[0189] Step S2: Perform a first sintering treatment on the first intermediate mixture: The first average heating rate is 8°C / min, and the mixture is heated to a first sintering temperature of 480°C and held at that temperature. After holding at that temperature for 3 hours, the mixture is cooled down to room temperature to obtain the first intermediate composition.

[0190] Step S3: Perform a second sintering treatment on the first intermediate mixture: the second average heating rate is 2℃ / min, and the mixture is held at the second sintering temperature of 830℃. After holding for 14 hours, the mixture is cooled to room temperature to obtain the chemical formula Li. 1.5 Ni 0.25 Mn 0.75 O 2.5 Lithium-rich manganese-based materials.

[0191] The specific surface area of ​​this lithium-rich manganese-based material is 3.56 m². 2 / g, tap density is 2.23g / cm³ 3 .

[0192] Synthetic Comparative Example 6

[0193] Comparative Example 6 provides a chemical formula of Li 1.2 Ni 0.32 Co 0.16 Mn 0.52 O 2.2 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0194] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is used as a precursor and mixed with an excess of 3% lithium carbonate (i.e., the molar content is (1.2 + 0.03 =) 1.23 compared to other components) until homogeneous to obtain the first intermediate mixture.

[0195] Step S2: Perform a first sintering treatment on the first intermediate mixture: The first average heating rate is 8°C / min, and the mixture is heated to a first sintering temperature of 480°C and held at that temperature. After holding at that temperature for 3 hours, the mixture is cooled down to room temperature to obtain the first intermediate composition.

[0196] Step S3: Perform a second sintering treatment on the first intermediate mixture: the second average heating rate is 2℃ / min, and the mixture is held at the second sintering temperature of 830℃. After holding for 14 hours, the mixture is cooled to room temperature to obtain the chemical formula Li. 1.2 Ni 0.32 Co 0.16 Mn 0.52 O 2.2 Lithium-rich manganese-based materials.

[0197] The specific surface area of ​​this lithium-rich manganese-based material is 3.66 m². 2 / g, tap density is 2.31g / cm³3 .

[0198] Synthetic Comparative Example 7

[0199] Comparative Example 7 provides a chemical formula of Li 1.35 Ni 0.30 Co 0.06 Mn 0.62 Ta 0.01 Fe 0.01 O 2.34 P 0.01 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0200] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is used as a precursor and mixed with an excess of 2% lithium carbonate until homogeneous to obtain a first intermediate mixture.

[0201] Step S2 involves performing a first sintering treatment on the first intermediate mixture: the first average heating rate is 5°C / min, and the mixture is held at the first sintering temperature of 300°C. After holding for 6 hours, the mixture is cooled down to room temperature to obtain the first intermediate composition.

[0202] Step S3: Based on the stoichiometric ratio in the above chemical formula, the first intermediate composition is ground together with Ta2O5 and FePO4 and mixed evenly to obtain the second intermediate mixture.

[0203] Step S4: Perform a second sintering treatment on the second intermediate mixture: The second average heating rate is 5℃ / min, and the mixture is heated to the second sintering temperature of 600℃ and held at that temperature. After holding for 2 hours, the temperature is increased again at a third average heating rate of 5℃ / min until the third sintering temperature of 715℃ is reached and held at that temperature. After holding for 4 hours, the temperature is increased again at a fourth average heating rate of 5℃ / min until the fourth sintering temperature of 800℃ is reached and held at that temperature. After holding for 15 hours, the mixture is cooled down to room temperature to obtain the chemical formula Li. 1.35 Ni 0.30 Co 0.06 Mn 0.62 Ta 0.01 Fe 0.01 O 2.34 P 0.01 Lithium-rich manganese-based materials.

[0204] The specific surface area of ​​this lithium-rich manganese-based material is 5.67 m². 2 / g, tap density is 1.96g / cm³ 3 .

[0205] Synthetic Comparative Example 8

[0206] Comparative Example 8 provides a chemical formula of Li1.33 Ni 0.33 Co 0.08 Mn 0.59 O 2.33 The specific preparation steps of the lithium-rich manganese-based material are as follows:

[0207] Step S1: Based on the stoichiometric ratio in the above chemical formula, nickel cobalt manganese transition metal carbonate is used as a precursor and mixed with an excess of 3% lithium carbonate (i.e., the molar content is (1.33+0.03=)1.36 compared to other components) until homogeneous to obtain a first intermediate mixture.

[0208] Step S2 involves a sintering treatment of the first intermediate mixture: the average heating rate is 5°C / min, and the temperature is raised to 830°C and held. After holding for 14 hours, the temperature is lowered to room temperature to obtain Li. 1.33 Ni 0.33 Co 0.08 Mn 0.59 O 2.33 Lithium-rich manganese-based materials.

[0209] The specific surface area of ​​this lithium-rich manganese-based material is 5.33 m². 2 / g, tap density is 2.11g / cm³ 3 .

[0210] Device Examples 1-11, Device Comparative Examples 1-8

[0211] Device Examples 1-11 and Device Comparative Examples 1-8 were prepared using the lithium-rich manganese-based materials obtained in Synthetic Examples 1-11 and Synthetic Comparative Examples 1-8, respectively, to fabricate secondary batteries. The specific preparation methods are as follows:

[0212] Step S1: Mix the powdered lithium-rich manganese-based material with a conductive agent and a binder at a preset mass ratio to obtain a positive electrode mixture.

[0213] The conductive agent mentioned above can be Super-P conductive agent (i.e., small particle conductive black), the binder can be PVDF (i.e., polyvinylidene fluoride), and the corresponding preset mass ratio can be 92:4:4.

[0214] Step S2: Dissolve the positive electrode mixture in NMP solution (i.e., N-methylpyrrolidone solution) to form a slurry, and then coat the slurry onto aluminum foil.

[0215] Step S3: Place the aluminum foil coated with the slurry in a vacuum oven to dry at a temperature of 120°C for 12 hours.

[0216] Step S4: Dissolve 1 mol / L LiPF6 in an organic solvent containing EC (ethylene carbonate) and EMC (ethyl methyl carbonate) in a volume ratio of 3:7 to obtain an electrolyte.

[0217] In step S5, the dried aluminum foil is used as the positive electrode, and lithium metal is used as the negative electrode. The battery is assembled with the electrolyte in an argon atmosphere to obtain a coin cell CR2032 battery.

[0218] Based on steps S1-S5 above, the secondary batteries prepared in Comparative Examples 1-8 were synthesized using synthesis examples 1-11, and the following performance tests were performed. Please refer to [the relevant documentation]. Figure 2 , Figure 4 , Figure 6 , Figure 8 , Figure 10 , Figure 12 , Figure 14 and Table 1:

[0219] (1) Under constant current charge-discharge mode, with a current density of 50mA / g and a voltage window of 2.0-4.7, charge-discharge test was performed.

[0220] (2) Stability of the battery after 200 charge-discharge cycles (cycle capacity retention and cycle voltage retention) when the test current density is 250mA / g.

[0221] Table 1 shows the performance data of devices 1-11 and 1-8 corresponding to synthesis examples 1-11 and synthesis comparative examples 1-8. As shown in Table 1, for ease of reading, Table 1 summarizes the specific surface area and tap density of the lithium-rich manganese-based materials (i.e., cathode materials) of synthesis examples 1-11 and synthesis comparative examples 1-8 corresponding to device examples 1-11 and device comparative examples 1-8.

[0222] Table 1

[0223]

[0224]

[0225] As shown in the table above, the lithium-rich manganese-based materials synthesized in Examples 1-11 are lithium-rich manganese-based materials with low specific surface area and high tap density.

[0226] Further, comparing the performance data of the lithium-rich manganese-based materials in device examples 1-11 with device comparative examples 5-6, the lithium-rich manganese-based materials of device comparative examples 5-6 are prepared based on the preparation method provided in the present application. In fact, the preparation method of the lithium-rich manganese-based materials of device comparative examples 5-6 is the same as that of the lithium-rich manganese-based materials of device example 11, and thus the specific surface area and tap density of the lithium-rich manganese-based materials of device comparative examples 5-6 are similar to those of the lithium-rich manganese-based materials of device examples 1-11, but obviously the performance of device example 11 is superior to that of device comparative examples 5-6. Among them, the cycle life, i.e. the energy retention rate (energy retention rate, capacity retention rate) of device example 11 is superior to that of device comparative example 5, and the initial specific discharge capacity and the initial coulombic efficiency of device example 11 are superior to those of device comparative example 6.

[0227] Further, the battery performance of lithium ion in device examples 1-11 (prepared based on device examples 1-11) is superior to that of lithium ion in device comparative examples 1-8 (prepared based on device examples 1-8), i.e. in combination with the initial energy density and stability data, the volume energy density and the initial coulombic efficiency of the lithium ion battery in device examples 1-11 are superior to those of device comparative examples 1-8, and the stability, i.e. the voltage decay, and the capacity retention rate are also superior to those of device comparative examples 1-8.

[0228] With reference to the data in device comparative example 7, it can be seen that when the heating rate is not controlled during the preparation process, and the average heating rate is consistent during each sintering process, although the lithium-rich manganese-based material with the stoichiometric ratio provided in the present application can also be prepared, since the thermal decomposition of the precursor and the crystal phase formation occur at the same time, the lithium-rich manganese-based material has a high specific surface area and a low tap density, and thus the performance of the corresponding battery is poor.

[0229] With reference to the data in device comparative example 8, it can be seen that when the lithium-rich manganese-based material is prepared based on a sintering process, instead of the method provided in the present application including the first sintering process and the second sintering process, the specific surface area of the obtained lithium-rich manganese-based material is too high, the tap density is low, and the performance of the corresponding battery is poor. It can be seen that the lithium-rich manganese-based material provided in the present application has an appropriate specific surface area and a high tap density, and thus the comprehensive performance of the volume energy density, the initial coulombic efficiency, the cycle capacity retention rate and the cycle voltage retention rate of the corresponding battery is better.

[0230] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A lithium-rich manganese-based material, characterized in that, The chemical formula of the lithium-rich manganese-based material is: Li 1+x Ni a Co b Mr c M d O 2+x-e N e ; in, 0.25≤x≤0.4, a+b+c+d=1, 0.28≤a≤0.34, 0.005≤b≤0.08, 0.58≤c≤0.68, 0<d≤0.02, 0<e≤0.06; M and N are doping elements, M is selected from at least one of Ta, Nb, Ti, Fe, Sb, Al, Mg, Na, K; N is selected from at least one of P, S, F; The tap density of the lithium-rich manganese-based material is 2.2-2.6 g / cm³. 3 ; The specific surface area of ​​the lithium-rich manganese-based material is 2.0-4.0 m². 2 / g.

2. The lithium-rich manganese-based material as described in claim 1, characterized in that, The lithium-rich manganese-based material is composed of multiple primary particles aggregated together, and the morphology of the lithium-rich manganese-based material is a secondary sphere.

3. The lithium-rich manganese-based material as described in claim 2, characterized in that, The average particle size of the primary particles is 150-300 nm; the average particle size of the secondary spheres is 6000 nm-11000 nm.

4. A method for preparing the lithium-rich manganese-based material as described in any one of claims 1-3, characterized in that, include: A first sintering treatment was performed on a mixture of nickel-cobalt-manganese transition metal carbonate and a lithium source to obtain a first intermediate composition; as well as A second sintering process is performed after the first sintering process; In this process, the sintering temperature of the second sintering treatment is higher than that of the first sintering treatment, and the average heating rate to the sintering temperature in the second sintering treatment is lower than the average heating rate to the sintering temperature in the first sintering treatment. Wherein, when the lithium-rich manganese-based material contains doping elements M and / or N, the step of adding the doping element source to the first intermediate composition is further included, and the sintering object of the second sintering treatment is a mixture of the first intermediate composition and the doping element source. When the lithium-rich manganese-based material does not contain the doping element, the object of the second sintering treatment is the first intermediate composition.

5. The method as described in claim 4, characterized in that, The average heating rate of the first sintering treatment is 5℃ / min-10℃ / min.

6. The method as described in any one of claims 4 or 5, characterized in that, The sintering temperature of the multi-stage sintering process in the second sintering process increases sequentially.

7. The method as described in claim 6, characterized in that, In each of the multiple sintering processes, the average heating rate to the corresponding sintering temperature decreases sequentially.

8. The method as described in claim 7, characterized in that, The multi-stage sintering process is a 2-stage or 3-stage sintering process.

9. A battery positive electrode, characterized in that, Includes the lithium-rich manganese-based material as described in any one of claims 1-3 or the lithium-rich manganese-based material prepared by the method described in any one of claims 4-8.

10. A battery pack, characterized in that, Includes at least one battery cell; wherein, The positive electrode of the battery cell comprises the lithium-rich manganese-based material as described in any one of claims 1-3 or the lithium-rich manganese-based material prepared by the method described in any one of claims 4-8.

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