Preparation method and application of core-shell structure lithium-rich manganese-based precursor for oxidizing pinning Mn ions

Abstract

The invention discloses a preparation method and application of a core-shell structure lithium-rich manganese-based precursor for oxidizing pinning Mn ions. The preparation method comprises the following steps: preparing a first nickel-manganese mixed salt solution and a second nickel-manganese mixed salt solution; the concentrations of metal salts in the two nickel-manganese mixed salt solutions are 1-3 mol / L, but the nickel-manganese proportions are different; preparing a precipitator and a complexing agent; under the condition of nitrogen atmosphere protection, a first nickel-manganese mixed salt solution, a precipitant and a complexing agent are introduced to form a base solution, and a first-stage co-precipitation reaction is carried out; then introducing a second nickel-manganese mixed salt solution, carrying out a second-stage coprecipitation reaction in a nitrogen atmosphere, after the reaction is carried out for 20-50 hours, changing the atmosphere into compressed air, continuing the reaction, and after the reaction is carried out for 13-43 hours, stopping the reaction to obtain a coprecipitation product; and carrying out centrifugation, washing and vacuum drying on the coprecipitation product to obtain the lithium-rich manganese-based precursor with the core-shell structure. The core-shell structure is good in stability and can inhibit surface side reactions, so that better electrochemical performance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries, and in particular to a preparation method and application of a core-shell structured lithium-rich manganese-based precursor for oxidatively pinning Mn ions. Background Art

[0002] Due to the explosive growth in demand for high-energy-density lithium-ion batteries, lithium-rich manganese-based materials have been vigorously developed. However, during the charging process, a large amount of Ni is exposed on the surface of the positive electrode material. 4+ Highly reactive reactions with the electrolyte occur, resulting in rapid capacity degradation. Various strategies have been designed to alleviate this problem, among which surface coatings or doping with low-cost metal elements (e.g., Mg, Al, and Ti) can improve material stability. Despite the above benefits, they hinder lithium ion diffusion and reduce conductivity, resulting in a decrease in capacity.

[0003] The core-shell structure (generally a nickel-rich core and a manganese-rich shell) is explored as a special structure. The presence of a less active shell can effectively alleviate the adverse interfacial reactions on the surface. At the same time, as an active material coating, it can minimize capacity loss and ensure cycle stability. However, during the sintering process of the mixture of the core-shell structure precursor and the lithium source, the components of the core and shell diffuse with each other, making it difficult to maintain the designed core-shell structure.

[0004] Therefore, how to solve the above-mentioned deficiencies in the prior art has become a subject to be studied and solved by the present invention. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method and application of a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions, comprising:

[0008] Step 1, preparing a first nickel-manganese mixed salt solution, wherein the molar ratio of metal elements in the first nickel-manganese mixed salt solution is Ni:Mn=x:y, wherein x+y=1, and x≥0.6;

[0009] preparing a second nickel-manganese mixed salt solution, wherein the molar ratio of metal elements in the second nickel-manganese mixed salt solution is Ni:Mn=x1:y1, wherein x1+y1=1, and y1≥0.7;

[0010] The concentration of the metal salt in the first nickel-manganese mixed salt solution and the second nickel-manganese mixed salt solution is 1-3 mol / L;

[0011] preparing a precipitant, wherein the precipitant is an alkaline solution, wherein the alkaline substance in the alkaline solution comprises one or more of sodium hydroxide and potassium hydroxide, with a mass fraction of 30 to 40%;

[0012] preparing a complexing agent, which is one or more of oxalic acid, ammonia water, citric acid, sodium citrate, and sodium oxalate solution, with a concentration of 8 to 15 g / L;

[0013] Step 2: Under the protection of nitrogen atmosphere, pure water, the first nickel-manganese mixed salt solution, the precipitant and the complexing agent are introduced into the reactor to form a base liquid, and a first stage of coprecipitation reaction is performed;

[0014] Step 3: Keep introducing the precipitant and the complexing agent, stop introducing the first nickel-manganese mixed salt solution, introduce the second nickel-manganese mixed salt solution instead, and carry out the second stage of coprecipitation reaction under a nitrogen atmosphere. After reacting for 20 to 50 hours, change the atmosphere of the reaction system to compressed air, continue the reaction, and after reacting for 13 to 43 hours, stop the reaction to obtain a coprecipitation product.

[0015] Step 4: Centrifuge, wash and vacuum dry the coprecipitated product to obtain a core-shell structured lithium-rich manganese-based precursor.

[0016] According to a further technical solution, the metal salts in the first nickel-manganese mixed salt solution and the second nickel-manganese mixed salt solution both include any one of sulfate, nitrate or chloride, or a combination of at least two of them.

[0017] In a further technical solution, in step 2 and step 3, the flow rate of the complexing agent is 0.13-0.16 Kg / h; the flow rate of the precipitating agent is such that the pH of the coprecipitation reaction is maintained at 10-11; the temperature of the coprecipitation reaction is 35-70° C. In step 2, the flow rate of the first nickel-manganese mixed salt solution is 60-100 mol / h; in step 3, the flow rate of the second nickel-manganese mixed salt solution is 60-100 mol / h.

[0018] According to a further technical solution, the coprecipitation reaction is carried out under stirring at a speed of 200 to 600 r / min.

[0019] According to a further technical solution, the reaction time of the first stage is 15 to 20 hours, and the reaction time of the second stage is 45 to 65 hours.

[0020] According to a further technical solution, in step 4, solid-liquid separation is achieved by suction filtration and centrifugation in sequence; the temperature of the vacuum drying is 100-150°C.

[0021] Furthermore, the present invention also discloses a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions, which is prepared by the method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions. The chemical formula of the core-shell structure lithium-rich manganese-based precursor is Mn a M b (OH)2, wherein M is a transition metal element, 0.4<a<1, 0<b<1, and a+b=1;

[0022] M metal is Ni and / or Co.

[0023] Furthermore, the present invention also discloses a core-shell structure lithium-rich manganese-based positive electrode material with oxidized pinned Mn ions, which is prepared from the core-shell structure lithium-rich manganese-based precursor with oxidized pinned Mn ions.

[0024] The words “include,” “including,” and “have” used in this document are open-ended terms, meaning including but not limited to.

[0025] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0026] The working principle and advantages of the present invention are as follows:

[0027] The present invention effectively inhibits the mutual diffusion between the core and shell components by manipulating the oxidation state of manganese (Mn) during the synthesis of the precursor. The oxidation of Mn in the precursor shell can effectively inhibit the diffusion of Mn during the calcination process. That is, by changing the atmosphere of the reactor and oxidizing the manganese ions, the manganese ions are pinned in place during the subsequent calcination process and will not diffuse at will, thereby retaining the core-shell structure, enhancing the stability of the structure, inhibiting surface side reactions, and obtaining better electrochemical performance. Specifically:

[0028] On the one hand, the present invention synthesizes a core-shell structured lithium-rich manganese-based precursor material by changing the ratio of nickel and manganese in the nickel-manganese mixed salt solution of the co-precipitation reaction at different stages. The material includes a nickel-rich core and a manganese-rich shell. After further preparing the positive electrode material, the special core-shell structure can weaken the side reactions on the surface of the material, thereby improving the electrochemical properties of the lithium-rich manganese-based positive electrode material.

[0029] On the other hand, the preparation method provided by the present invention has a first stage for the preparation of a nickel-rich core. After the first stage, based on the original preparation, the ratio of the nickel-manganese mixed salt solution is further converted (from the first nickel-manganese mixed salt solution to the second nickel-manganese mixed salt solution). After the designed reaction time is reached, the atmosphere of the reactor is replaced to carry out a second stage of co-precipitation reaction to obtain a lithium-rich manganese-based precursor material with a manganese-rich shell coating a nickel-rich core. The preparation method is simple, does not require a complicated preparation process, and is suitable for large-scale production.

[0030] In summary, the NiMn core-shell structure of the present invention utilizes a nickel-rich core with high energy density, while adopting a manganese-rich shell to enhance interface stability by suppressing adverse reactions with the electrolyte. This method improves cycle stability. However, during the synthesis process, the mutual diffusion of Mn ions between the core and the shell remains a major challenge. The present invention proposes a simple method to solve the problem of mutual diffusion of manganese in core-shell positive electrode materials. Studies have shown that partial oxidation of the precursor in the synthesis stage effectively enhances the oxidation of Mn. The scheme of the present invention successfully suppresses the mutual diffusion of manganese during the subsequent calcination process, thereby retaining the core-shell structure of the final positive electrode material. This optimized structure mitigates interfacial reactions and improves electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attached Figure 1 This is a SEM image of the lithium-rich manganese-based precursor prepared in Example 1 of the present invention;

[0032] Attached Figure 2 This is a SEM image of the lithium-rich manganese-based precursor prepared in Example 2 of the present invention;

[0033] Attached Figure 3 This is a SEM image of the lithium-rich manganese-based precursor prepared in Example 3 of the present invention;

[0034] Attached Figure 4 This is a SEM image of the lithium-rich manganese-based precursor prepared in Example 4 of the present invention;

[0035] Attached Figure 5 This is a SEM image of a lithium-rich manganese-based precursor prepared in Comparative Example 1 of the present invention;

[0036] Attached Figure 6 This is a SEM image of a lithium-rich manganese-based precursor prepared in Comparative Example 2 of the present invention;

[0037] Attached Figure 7 The electrochemical performance diagram of Example 1 of the present invention and Comparative Examples 1 and 2 after 100 cycles at 1C. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0039] The present invention will be clearly described below with drawings and detailed descriptions. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0040] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0041] Example 1

[0042] This embodiment provides a core-shell structured lithium-rich manganese-based precursor material, wherein the lithium-rich manganese-based precursor material comprises a nickel-rich core and a manganese-rich shell layer; the chemical formula of the lithium-rich manganese-based precursor material is Ni 0.35 Mn 0.65 (OH)2.

[0043] The preparation method of the lithium-rich manganese-based precursor material is as follows:

[0044] According to the stoichiometric ratio of Ni:Mn=60:40, a 2 mol / L mixed salt solution was prepared;

[0045] According to the stoichiometric ratio of Ni:Mn=30:70, a 2 mol / L mixed salt solution 2 was prepared;

[0046] The mixed salt solution 1, the precipitant sodium hydroxide solution, and the complexing agent ammonia solution were added to the bottom liquid of the reactor (pH value was 11-12, and the temperature was controlled at 35-70°C) in a nitrogen atmosphere, and stirred continuously at a speed of 600r / min to maintain the pH of the reaction system at 10-11 for the first stage of coprecipitation reaction. After the reaction for 15 hours, the mixed salt solution 2 was switched to continue the reaction, and the second stage of coprecipitation reaction was carried out. After the reaction for 20 hours, the reaction system atmosphere was switched to compressed air, and the reaction was continued for 43 hours to terminate the reaction. After washing, vacuum drying, and sieving, Ni 0.35 Mn 0.65 (OH)2 spherical lithium-rich manganese-based precursor material (see Figure 1 ).

[0047] This embodiment 1 also provides a lithium-rich manganese-based positive electrode material, which is prepared from the precursor material prepared above, and the specific preparation method is as follows:

[0048] The obtained precursor material was mixed with LiOH in a stoichiometric ratio of Me:Li=1:1.3, and the temperature was raised to 800°C. After being kept at this temperature for 10 hours, the mixture was cooled in the furnace to obtain a core-shell structured lithium-rich manganese-based positive electrode material.

[0049] Example 2

[0050] This embodiment provides a core-shell structured lithium-rich manganese-based precursor material, wherein the lithium-rich manganese-based precursor material comprises a nickel-rich core and a manganese-rich shell layer; the chemical formula of the lithium-rich manganese-based precursor material is Ni 0.35 Mn 0.65 (OH)2.

[0051] The preparation method of the lithium-rich manganese-based precursor material is as follows:

[0052] According to the stoichiometric ratio of Ni:Mn=60:40, a 2 mol / L mixed salt solution was prepared;

[0053] According to the stoichiometric ratio of Ni:Mn=30:70, a 2 mol / L mixed salt solution 2 was prepared;

[0054] The mixed salt solution 1, the precipitant sodium hydroxide solution, and the complexing agent ammonia solution were added to the bottom liquid of the reactor (pH value was 11-12, and the temperature was controlled at 35-70°C) in a nitrogen atmosphere, and stirred continuously at a speed of 600r / min to maintain the pH of the reaction system at 10-11 for the first stage of coprecipitation reaction. After the reaction for 15 hours, the mixed salt solution 2 was switched to continue the reaction, and the second stage of coprecipitation reaction was carried out. After the reaction for 30 hours, the reaction system atmosphere was switched to compressed air, and the reaction was continued for 33 hours to terminate the reaction. After washing, vacuum drying, and sieving, Ni 0.35 Mn 0.65 (OH)2 spherical lithium-rich manganese-based precursor material (see Figure 2 ).

[0055] This embodiment 2 also provides a lithium-rich manganese-based positive electrode material, which is prepared from the precursor material prepared above, and the specific preparation method is as follows:

[0056] The obtained precursor material was mixed with LiOH in a stoichiometric ratio of Me:Li=1:1.3, and the temperature was raised to 800°C. After being kept at this temperature for 10 hours, the mixture was cooled with the furnace to obtain a coated lithium-rich manganese-based positive electrode material.

[0057] Example 3

[0058] This embodiment provides a core-shell structured lithium-rich manganese-based precursor material, wherein the lithium-rich manganese-based precursor material comprises a nickel-rich core and a manganese-rich shell layer; the chemical formula of the lithium-rich manganese-based precursor material is Ni 0.35 Mn 0.65 (OH)2.

[0059] The preparation method of the lithium-rich manganese-based precursor material is as follows:

[0060] According to the stoichiometric ratio of Ni:Mn=60:40, a 2 mol / L mixed salt solution was prepared;

[0061] According to the stoichiometric ratio of Ni:Mn=30:70, a 2 mol / L mixed salt solution 2 was prepared;

[0062] The mixed salt solution 1, the precipitant sodium hydroxide solution, and the complexing agent ammonia solution were added to the bottom liquid of the reactor (pH value was 11-12, and the temperature was controlled at 35-70°C) in a nitrogen atmosphere, and stirred continuously at a speed of 600r / min to maintain the pH of the reaction system at 10-11 for the first stage of coprecipitation reaction. After the reaction for 15 hours, the mixed salt solution 2 was switched to continue the reaction, and the second stage of coprecipitation reaction was carried out. After the reaction for 40 hours, the reaction system atmosphere was switched to compressed air, and the reaction was continued for 23 hours to terminate the reaction. After washing, vacuum drying, and sieving, Ni 0.35 Mn 0.65 (OH)2 spherical lithium-rich manganese-based precursor material (see Figure 3 ).

[0063] This embodiment 3 also provides a lithium-rich manganese-based positive electrode material, which is prepared from the precursor material prepared above, and the specific preparation method is as follows:

[0064] The obtained precursor material was mixed with LiOH in a stoichiometric ratio of Me:Li=1:1.3, and the temperature was raised to 800°C. After being kept at this temperature for 10 hours, the mixture was cooled in the furnace to obtain a core-shell structured lithium-rich manganese-based positive electrode material.

[0065] Example 4

[0066] This embodiment provides a core-shell structured lithium-rich manganese-based precursor material, wherein the lithium-rich manganese-based precursor material comprises a nickel-rich core and a manganese-rich shell layer; the chemical formula of the lithium-rich manganese-based precursor material is Ni 0.35 Mn 0.65 (OH)2.

[0067] The preparation method of the lithium-rich manganese-based precursor material is as follows:

[0068] According to the stoichiometric ratio of Ni:Mn=60:40, a 2 mol / L mixed salt solution was prepared;

[0069] According to the stoichiometric ratio of Ni:Mn=30:70, a 2 mol / L mixed salt solution 2 was prepared;

[0070] The mixed salt solution 1, the precipitant sodium hydroxide solution, and the complexing agent ammonia solution were added to the bottom liquid of the reactor (pH value was 11-12, and the temperature was controlled at 35-70°C) in a nitrogen atmosphere, and stirred continuously at a speed of 600r / min to maintain the pH of the reaction system at 10-11 for the first stage of coprecipitation reaction. After the reaction for 15 hours, the mixed salt solution 2 was switched to continue the reaction, and the second stage of coprecipitation reaction was carried out. After the reaction for 50 hours, the reaction system atmosphere was switched to compressed air, and the reaction was continued for 13 hours to terminate the reaction. After washing, vacuum drying, and sieving, Ni 0.35 Mn 0.65 (OH)2 spherical lithium-rich manganese-based precursor material (see Figure 4 ).

[0071] This embodiment also provides a lithium-rich manganese-based positive electrode material, which is prepared from the precursor material prepared above, and the specific preparation method is as follows:

[0072] The obtained precursor material was mixed with LiOH in a stoichiometric ratio of Me:Li=1:1.3, and the temperature was raised to 800°C. After being kept at this temperature for 10 hours, the mixture was cooled in the furnace to obtain a core-shell structured lithium-rich manganese-based positive electrode material.

[0073] Comparative Example 1

[0074] The difference between this comparative example 1 and Example 1 is that nitrogen protection is used during the two-stage reaction process of this comparative example 1, and the prepared precursor material is shown in Figure 5 .

[0075] Comparative Example 2

[0076] The difference between this comparative example 2 and example 1 is that the atmosphere in the first stage of this comparative example 2 is nitrogen, and the atmosphere in the second stage is compressed air. Figure 6 .

[0077] Table 1:

[0078]

[0079] From Table 1, we can conclude that:

[0080] From the data results of Example 1, Example 3, 4 and Comparative Example 1, it can be seen that in the present invention, the longer the nitrogen protection time during the coprecipitation reaction, that is, the lower the degree of oxidation of the material, the higher the tap density of the material, and the smaller the specific surface area, but this also reduces the number of active sites on the surface of the material, and further increase in the tap density brings certain difficulties to the subsequent sintering, thereby affecting the capacity of the material. More importantly, insufficient oxidation will lead to a certain degree of ion diffusion after sintering, thereby affecting the capacity and cycle stability of the material.

[0081] From the data results of Example 1 and Comparative Example 2, it can be seen that excessive oxidation during the material synthesis process will reduce the compaction density of the material. At the same time, a larger surface area will produce more side reactions, thereby affecting the energy density of the positive electrode material.

[0082] like Figure 7 As shown, it is the electrochemical performance diagram of Example 1 of the present invention and Comparative Examples 1 and 2 after 100 cycles at 1C. It can be seen from the figure that the electrochemical performance of Example 1 is better than that of Comparative Examples 1 and 2.

[0083] In summary, the preparation method provided by the present invention is the preparation of a nickel-rich core precursor matrix material in the first stage. After the first stage, on the basis of the original preparation, the nickel-manganese ratio of the nickel-manganese metal salt solution in the second stage is changed, and the reaction atmosphere is replaced after the target reaction time is reached. The coprecipitation reaction of the second stage is carried out to achieve the preparation of a lithium-rich manganese-based precursor material with a core-shell structure in which a manganese-rich shell is coated with a nickel-rich core. The preparation method of the present invention is simple, does not require a complicated preparation process, is suitable for large-scale production, and after further preparing the positive electrode material, the special core-shell structure improves the electrochemical properties of the lithium-rich manganese-based positive electrode material.

[0084] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions, characterized in that: include: Step 1, preparing a first nickel-manganese mixed salt solution, wherein the molar ratio of metal elements in the first nickel-manganese mixed salt solution is Ni:Mn=x:y, wherein x+y=1, and x≥0.6; preparing a second nickel-manganese mixed salt solution, wherein the molar ratio of metal elements in the second nickel-manganese mixed salt solution is Ni:Mn=x1:y1, wherein x1+y1=1, and y1≥0.7; The concentration of the metal salt in the first nickel-manganese mixed salt solution and the second nickel-manganese mixed salt solution is 1-3 mol / L; preparing a precipitant, wherein the precipitant is an alkaline solution, wherein the alkaline substance in the alkaline solution comprises one or more of sodium hydroxide and potassium hydroxide, with a mass fraction of 30-40%; preparing a complexing agent, wherein the complexing agent is one or more of oxalic acid, ammonia water, citric acid, sodium citrate, and sodium oxalate solution, and the concentration is 8-15 g / L; Step 2: Under the protection of nitrogen atmosphere, pure water, the first nickel-manganese mixed salt solution, the precipitant and the complexing agent are introduced into the reactor to form a base liquid, and a first stage of coprecipitation reaction is performed; Step 3: stop introducing the first nickel-manganese mixed salt solution, introduce the second nickel-manganese mixed salt solution instead, and carry out the second stage of coprecipitation reaction under a nitrogen atmosphere. After reacting for 20 to 50 hours, change the atmosphere of the reaction system to compressed air, continue the reaction, and after reacting for 13 to 43 hours, stop the reaction to obtain a coprecipitation product. Step 4: Centrifuge, wash and vacuum dry the coprecipitated product to obtain a core-shell structured lithium-rich manganese-based precursor.

2. The method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions according to claim 1, characterized in that: The metal salts in the first nickel-manganese mixed salt solution and the second nickel-manganese mixed salt solution include any one of sulfate, nitrate or chloride, or a combination of at least two of them.

3. The method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions according to claim 1, characterized in that: In step 2 and step 3, the flow rate of the complexing agent is 0.13-0.16 Kg / h; the flow rate of the precipitating agent is such that the pH of the coprecipitation reaction is maintained at 10-11; the temperature of the coprecipitation reaction is 35-70°C; In step 2, the flow rate of the first nickel-manganese mixed salt solution is 60-100 mol / h; in step 3, the flow rate of the second nickel-manganese mixed salt solution is 60-100 mol / h.

4. The method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions according to claim 1, characterized in that: The coprecipitation reaction is carried out under stirring conditions, and the stirring speed is 200-600 r / min.

5. The method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions according to claim 1, characterized in that: The reaction time of the first stage is 15-20 hours, and the reaction time of the second stage is 45-65 hours.

6. The method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions according to claim 1, characterized in that: In step 4, solid-liquid separation is achieved by suction filtration and centrifugation in sequence; the temperature of the vacuum drying is 100-150°C.

7. The method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions according to claim 1, characterized in that: The chemical formula of the prepared core-shell structure lithium-rich manganese-based precursor is Mn a M b (OH)2, wherein M is a transition metal element, 0.4<a<1, 0<b<1, and a+b=1.

8. The method for preparing a core-shell structure lithium-rich manganese-based precursor for oxidative pinning of Mn ions according to claim 7, characterized in that: M metal is Ni and / or Co.

9. A core-shell structured lithium-rich manganese-based positive electrode material with oxidative pinning of Mn ions, characterized in that: It is prepared from the core-shell structure lithium-rich manganese-based precursor with oxidized pinned Mn ions as described in claim 7 or 8.

Images