Composite modified lithium manganate positive electrode material as well as preparation method and application thereof

Abstract

The invention belongs to the field of battery materials, and particularly discloses a composite modified lithium manganate positive electrode material and a preparation method and application thereof.The positive electrode material comprises a core and a coating layer, and the coating layer coats at least part of the surface of the core; the core is made of a LiMn2O4 material, the coating layer comprises a LiMxMn2-xO4 material and a ZnMn2O4 material, M is any one or more than two of Zn, Fe and Ni, and x is more than or equal to 0.1 and less than or equal to 0.4. The composite coating structure provided by the invention forms a synergistic system of nuclear layer ion transmission, coating layer structure support and electron conduction, the structural stability under high magnification is guaranteed through the coating layer, the electron transmission efficiency is improved, meanwhile, the coating layer material does not cause increase of lithium ion transmission resistance, the capacity loss and polarization are reduced, and the performance of the lithium ion battery is improved. And the electrochemical performance of the battery at high rate is further improved.

Description

Technical Field

[0001] This invention belongs to the field of battery materials, and relates to a cathode material, specifically a composite modified lithium manganese oxide cathode material and its preparation method and application. Background Technology

[0002] LiMn2O4 cathode material has become one of the most promising cathode materials for lithium-ion batteries due to its advantages such as low cost, high energy density, no pollution, good safety, and abundant resources. However, the rate performance of LiMn2O4 is limited by the lithium-ion transport rate in the bulk phase and at the interface. The core reason is that its bulk diffusion is slow and the interface migration resistance is high, which cannot meet the requirements of high current for rapid ion transport at high rates.

[0003] From a bulk perspective, although the spinel structure of LiMn2O4 provides a diffusion path for lithium ions (8a→16c→8a), the effective cross-section of this channel is small, and the presence of Mn in the lattice is also a concern. 3+ / Mn 4+ Electrostatic repulsion will increase Li + The migration barrier leads to the Li in LiMn2O4 + The phase diffusion rate is much lower than that of cathode materials like LiCoO2. Meanwhile, during cycling, Li... + The intercalation / deintercalation of particles causes grain cracks that sever diffusion channels. The drastic changes in lattice parameters induced by phase transitions further compress channel space, exacerbating bulk transport bottlenecks. From an interfacial perspective, electrolyte decomposition during cycling forms a poorly conductive SEI film on the LiMn2O4 surface. This film thickens with each cycle, leading to micropore blockage and prolonging the LiMn2O4 transport time. + Migration paths are disrupted and resistance is increased; at high rates, large currents also accelerate particle volume deformation, causing the particles to peel off from the interface with the conductive agent and binder, forming contact gaps and cutting off ion transport paths. At the same time, local high current density will exacerbate the excessive decomposition of the electrolyte, producing more impedance substances and worsening the interface migration environment.

[0004] In high-magnification scenarios, a large amount of Li + The need for embedding / de-embedding, coupled with the low transport efficiency of the bulk phase and interface, creates a supply-demand imbalance. During charging, the Li on the positive electrode surface... + Due to slow transmission and excessive consumption, the voltage rises rapidly to the cutoff voltage, resulting in a reduction in the amount of lithium stripped; during discharge, Li + Unable to reach the active site in time, Li on the negative electrode side + It can only be consumed through side reactions, ultimately resulting in a sharp decrease in capacity and increased voltage polarization. That is, the transport efficiency of the two key links of bulk diffusion and interfacial migration in LiMn2O4 cannot match the demand for rapid ion transport under high current at high rates. Summary of the Invention

[0005] In view of the defects and deficiencies of the existing technology, the present invention provides, firstly, a composite modified lithium manganese oxide cathode material; secondly, a method for preparing the composite modified lithium manganese oxide cathode material; and thirdly, a battery.

[0006] In a first aspect, the present invention provides a composite modified lithium manganese oxide cathode material, comprising a core and a coating layer, wherein the coating layer covers at least a portion of the surface of the core; The core is LiMn2O4 material, and the coating layer includes LiMn2O4. x Mn 2-x O4 material and ZnMn2O4 material, wherein M is any one or more of Zn, Fe, and Ni, and 0.1≤x≤0.4.

[0007] Preferably, the particle surface of the composite modified lithium manganese oxide cathode material has a polyhedral morphology.

[0008] Preferably, the particle size of the composite modified lithium manganese oxide cathode material is 100~300nm.

[0009] Secondly, the present invention provides a method for preparing a composite modified lithium manganese oxide cathode material, comprising: ball milling and mixing LiMn2O4 material, LiMn2O4 material, and LiMn2O4 material. x Mn 2-x O4 material and ZnMn2O4 material are sintered in air or an oxygen-containing atmosphere to obtain the product; wherein M is one or more of Zn, Fe, and Ni, and 0.1≤x≤0.4.

[0010] Preferably, the ball milling speed is 300-1000 r / min; the ball milling time is 0.5-5 h.

[0011] Preferably, LiMn2O4 material, LiM x Mn 2-x The mass ratio of O4 material to ZnMn2O4 material is 1:(0.01-0.04):(0.01-0.04).

[0012] Preferably, the sintering temperature is 500-700℃ and the sintering time is 0.5-2h.

[0013] Preferably, LiM x Mn 2-x The preparation method of O4 material is as follows: manganese dioxide, metal M oxide and lithium source are mixed by ball milling, and then sintered in air or oxygen-containing atmosphere to obtain the material.

[0014] Further optimization involves a ball milling speed of 300-1000 r / min and a ball milling time of 0.5-5 h.

[0015] Further preferred, the metal M oxide is any one or more of zinc oxide, ferrous oxide, and nickel oxide.

[0016] Further optimization is made by selecting one or more of lithium hydroxide, lithium acetate, and lithium nitrate as the lithium source.

[0017] Further preferred options include manganese dioxide, M in metal M oxide, and LiM. x Mn 2-x The stoichiometry of the O4 material is consistent, and the molar ratio of lithium in the lithium source is LiM. x Mn 2-x The stoichiometry of O4 material is 1 to 1.06 times that of O4 material.

[0018] Further optimization involves a sintering temperature of 880-1000℃ and a sintering time of 8-16h.

[0019] Preferably, the ZnMn2O4 material is prepared by ball milling manganese dioxide and zinc source, followed by sintering in air or an oxygen-containing atmosphere.

[0020] Further optimization involves a ball milling speed of 300-1000 r / min and a ball milling time of 0.5-5 h.

[0021] Further preferred, the zinc source is any one or more of zinc oxide, zinc acetate, and zinc nitrate.

[0022] Further optimization is achieved by ensuring that the manganese in the manganese dioxide and the zinc in the zinc source have the same stoichiometric ratio as the manganese dioxide and zinc source.

[0023] Further optimization involves a sintering temperature of 700-900℃ and a sintering time of 4-12h.

[0024] Thirdly, the present invention provides a battery comprising the above-described composite modified lithium manganese oxide cathode material or the composite modified lithium manganese oxide cathode material prepared by the above-described preparation method.

[0025] Compared with the prior art, one or more technical solutions provided by the present invention have at least one of the following beneficial effects: (1) The composite coating structure provided by this invention forms a core layer for ion transport, a ZnMn2O4 structural support, and a LiM x Mn 2-x The synergistic system of O4 electron conduction ensures structural stability at high magnification through the coating layer, and ZnMn2O4 and LiM x Mn 2-xAll three—O4, LiMn2O4, and LiMn2O4—have spinel-type crystal structures with high lattice matching, enabling tight coating and preserving the structural continuity of the Li+ diffusion channels. This prevents an increase in lithium-ion transport resistance, reduces capacity loss and polarization, and further enhances the electrochemical performance of the battery at high rates.

[0026] (2) In the coating layer, LiM x Mn 2-x The M metal in O4 material is a +2 valence metal, which increases the valence state of Mn element, higher than the average valence state of Mn element in LiMn2O4 cathode material. In contrast, the Mn in ZnMn2O4 material is a +3 valence metal. These two different valence states of Mn element in the surface layer can effectively suppress the Jahn-Teller effect of Mn element in LiMn2O4 cathode material, suppress the dissolution of the main manganese element, and thus effectively improve the structural stability and electrochemical reversibility of lithium manganese oxide.

[0027] (3) The preparation process provided by the present invention is simple, easy to operate, and easy to scale up for production. Attached Figure Description

[0028] Figure 1 Here is a SEM image of the cathode material prepared in Example 1; Figure 2 TEM image of the cathode material prepared in Example 1; Figure 3 The cycling curve test diagrams are of batteries assembled from the cathode materials prepared in Examples 1-3 and Comparative Examples 1-3. Detailed Implementation

[0029] The present invention provides the following specific technical solutions.

[0030] In a first aspect, the present invention provides a composite modified lithium manganese oxide cathode material, comprising a core and a coating layer, wherein the coating layer covers at least a portion of the surface of the core; The core is LiMn2O4 material, and the coating layer includes LiMn2O4. x Mn 2-x O4 material and ZnMn2O4 material, wherein M is any one or more of Zn, Fe, and Ni, and 0.1≤x≤0.4.

[0031] Research has found that LiM x Mn 2-x O4 materials have optimized lattice structures through doping with element M. The introduction of M can suppress ion transport channel blockage caused by lattice collapse during high-rate charge and discharge. The dense structure of ZnMn2O4 can isolate the electrolyte, strengthen the protection of the core layer, reduce SEI film thickness caused by electrolyte decomposition, and avoid high-resistance SEI films hindering ion transport. Furthermore, LiM...x Mn 2-x The M metal in the O4 material is a +2 valence metal, thus increasing the valence state of Mn to a higher level than that in the LiMn2O4 cathode material. In contrast, the Mn in the ZnMn2O4 material is a +3 valence metal. This constructs a dual-valence Mn synergistic regulation mechanism, fundamentally suppressing Mn enrichment and the Jahn-Teller effect in the LiMn2O4 cathode material. Compared to single coating layers that only achieve physical isolation or single-structure stabilization, this invention provides a more thorough inhibition of manganese dissolution, synergistically improving the material's structural stability and electrochemical reversibility. Simultaneously, ZnMn2O4 and LiMn2O4... x Mn 2-x All three crystal types—O4, LiMn2O4, and LiMn2O4—have spinel-type crystal structures with high lattice matching, enabling tight coating of Li. + The structural continuity of the diffusion channels is not disrupted. The channel size of ZnMn2O4 is similar to that of LiMn2O4, while that of Li... + It can quickly penetrate the interface between the matrix and the outer layer; LiM x Mn 2-x By fine-tuning the lattice parameters of O4 through doping with M elements (Zn, Fe, Ni), the channels can be further widened or the ion migration energy barrier can be reduced, making the ion diffusion coefficient of the coated structure an order of magnitude higher than that of single LiMn2O4, and maintaining efficient ion transport even at high rates.

[0032] The core layer of the cathode material provides ion transport, while the coating layer provides structural support and electronic conduction. Furthermore, the coating layer does not affect the lithium-ion transport capacity, ultimately improving the synergistic transport efficiency of ions and electrons at high rates, reducing capacity loss and polarization, and enhancing the electrochemical performance of the battery at high rates.

[0033] Preferably, the surface morphology of the composite modified lithium manganese oxide cathode material is spherical or near-spherical.

[0034] Preferably, the particle size of the composite modified lithium manganese oxide cathode material is 100~300nm.

[0035] Secondly, the present invention provides a method for preparing a composite modified lithium manganese oxide cathode material, comprising: ball milling and mixing LiMn2O4 material, LiMn2O4 material, and LiMn2O4 material. x Mn 2-x O4 material and ZnMn2O4 material are sintered in an oxygen-containing atmosphere to obtain the product; wherein M is one or more of Zn, Fe, and Ni, and 0.1≤x≤0.4.

[0036] The preparation method is specifically as follows: Step 1, Preparation of LiM x Mn 2-xO4 material is obtained by ball milling manganese dioxide, metal M oxide and lithium source, and sintering in an oxygen-containing atmosphere; Step 2: Prepare ZnMn2O4 material by ball milling manganese dioxide and zinc source, and sintering in an oxygen-containing atmosphere. Step 3, Coating: Ball milling mixed LiMn2O4 material, LiM x Mn 2-x O4 material and ZnMn2O4 material are sintered in an oxygen-containing atmosphere to obtain the final product.

[0037] In actual production processes, LiM x Mn 2-x O4 and ZnMn2O4 materials can be prepared by the above methods, or commercially available LiMnO4 materials can be used. x Mn 2-x The composite modified lithium manganese oxide cathode material is prepared by directly mixing O4 material and ZnMn2O4 material with LiMn2O4 material, ball milling and coating, and sintering.

[0038] Preferably, in step 1, the ball milling speed is 300-1000 r / min; the ball milling time is 0.5-5 h.

[0039] Preferably, in step 1, the metal M oxide is any one or more of zinc oxide, ferrous oxide, and nickel oxide.

[0040] Preferably, in step 1, the lithium source is one or more of lithium hydroxide, lithium acetate, and lithium nitrate.

[0041] Preferably, in step 1, the manganese dioxide, the M in the metal M oxide, and LiM x Mn 2-x The stoichiometry of the O4 material is consistent, and the molar ratio of lithium in the lithium source is LiM. x Mn 2-x The stoichiometry of O4 material is 1 to 1.06 times that of O4 material.

[0042] Research has shown that lithium is prone to volatilization loss during roasting. By adding an appropriate excess of lithium source, the proportion of lithium in the target product can be ensured to meet the stoichiometric requirements.

[0043] Preferably, in step 1, the sintering temperature is 880-1000℃ and the sintering time is 8-16h.

[0044] Preferably, in step 2, the zinc source is any one or more of zinc oxide, zinc acetate, and zinc nitrate.

[0045] Preferably, in step 2, the stoichiometric ratio of manganese in manganese dioxide and zinc in the zinc source is consistent with that of manganese dioxide and zinc source.

[0046] Preferably, in step 2, the sintering temperature is 700-900℃ and the sintering time is 4-12h.

[0047] Preferably, in step 3, the ball milling speed is 300-1000 r / min; the ball milling time is 0.5-5 h.

[0048] Preferably, in step 3, LiMn2O4 material, LiM x Mn 2-x The mass ratio of O4 material to ZnMn2O4 material is 1:(0.01-0.04):(0.01-0.04).

[0049] Research has shown that a low coating ratio allows for precise control of the coating layer thickness, ensuring the formation of a thin yet dense modified layer. On one hand, this thickness completely covers the surface of the LiMn2O4 particles, physically isolating the electrolyte from direct contact with the active material; on the other hand, the thin coating layer does not excessively increase the Li content. + The migration path length is reduced to avoid a significant increase in ion transport resistance, ensuring Li2O2 performance at high rates. + It can quickly cross the interface between the modified layer and the bulk phase, maintaining good rate performance. The two modified materials form a main-auxiliary synergistic structure with LiMn2O4, maximizing the complementary functions. The two modified materials are matched in equal proportions, and the total proportion is controllable, which can simultaneously enhance the two core requirements of ion transport and structural stability, avoiding performance deviations caused by the functional shortcomings of a single modified material.

[0050] Preferably, in step 3, the sintering temperature is 500-700℃ and the sintering time is 0.5-2h.

[0051] Research has revealed that temperature is the core driving factor, with the medium-low temperature range of 500-700℃ being the optimal temperature range for Li. + Zn 2+ Ni 2+ The interfacial diffusion of key ions provides sufficient impetus, promoting a tight bond between the coating layer and the LiMn2O4 matrix, while avoiding problems such as Li source volatilization, impurity phase formation, and grain coarsening caused by high temperatures. Temperature-controlled material selection ensures a uniform and dense coating layer with better lattice matching with the core LiMn2O4, effectively reducing interfacial impedance changes during charge and discharge. This significantly improves the material's cycle stability under high-rate conditions, with a cycle capacity retention rate far exceeding that of single inverse spinel materials or single LiMn2O4. x Mn 2-x The modification effect of O4 coating.

[0052] Thirdly, the present invention provides a battery comprising the above-described composite modified lithium manganese oxide cathode material or the composite modified lithium manganese oxide cathode material prepared by the above-described preparation method.

[0053] To make the technical problems, technical solutions and technical advantages of the present invention clearer, a detailed description will be given below with reference to specific examples. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0054] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0055] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0056] Example 1: A method for preparing a composite modified lithium manganese oxide cathode material includes the following steps: Step 1: 0.18 mol MnO, 0.02 mol ZnO, and 0.105 mol LiOH were ball-milled at 500 r / min for 2 h, and then sintered at 950 °C for 10 h in air to prepare LiZn. 0.2 Mn 1.8 O4 material: 0.2 mol MnO and 0.1 mol ZnO were ball-milled together at a speed of 500 r / min for 2 h, and then sintered at 750 °C for 8 h in air atmosphere to prepare ZnMn2O4 material.

[0057] Step 2: Ball mill and mix 10g LiMn2O4 material and 0.2g LiZn 0.2 Mn 1.8 O4 material and 0.2g ZnMn2O4 material were ball-milled at 500r / min for 2h to obtain a mixed powder. The powder was then sintered at 550℃ for 1h in air to obtain solid particles of LiZn. 0.2 Mn 1.8 O4 / ZnMn2O4@LiMn2O4 cathode material.

[0058] Comparative Example 1: The sample of Comparative Example 1 was the LiMn2O4 material used in Example 1, and it was not coated or composited.

[0059] Comparative Example 2: A method for preparing a composite modified lithium manganese oxide cathode material includes: ball milling 10g of LiMn2O4 material from the same batch as in Example 1 with 0.4g of ZnMn2O4 material prepared in Example 1, the ball milling speed being 500r / min and the ball milling time being 2h, to obtain a mixed powder, which is then sintered at 550℃ for 1h in air atmosphere, and the resulting solid particles are ZnMn2O4@LiMn2O4 cathode material.

[0060] Comparative Example 3: A method for preparing a composite modified lithium manganese oxide cathode material includes: mixing 10g of LiMn2O4 material from the same batch as in Example 1 with 0.4g of LiZn prepared in Example 1. 0.2 Mn 1.8 O4 material was ball-milled at 500 r / min for 2 h to obtain a mixed powder. This powder was then sintered at 550 °C for 1 h in air to obtain solid particles of LiZn. 0.2 Mn 1.8 O4@LiMn2O4 cathode material.

[0061] Example 2: A method for preparing a composite modified lithium manganese oxide cathode material includes the following steps: Step 1: 0.19 mol MnO, 0.01 mol FeO, and 0.105 mol LiOH were ball-milled at 300 r / min for 4 h, and then sintered at 880 °C for 16 h in air to prepare LiFe. 0.1 Mn 1.9 O4 material: 0.2 mol MnO and 0.1 mol ZnO were ball-milled together at a speed of 300 r / min for 4 h, and then sintered at 700 °C for 12 h in air atmosphere to prepare ZnMn2O4 material.

[0062] Step 2: Ball mill and mix 10g LiMn2O4 material and 0.1g LiZn 0.2 Mn 1.8 O4 material was mixed with 0.1 g ZnMn2O4 and ball-milled at 300 r / min for 5 h to obtain a mixed powder. This powder was then sintered at 550℃ for 1 h in air to obtain solid particles of LiFe. 0.1 Mn 1.9 O4 / ZnMn2O4@LiMn2O4 cathode material.

[0063] Example 3: A method for preparing a composite modified lithium manganese oxide cathode material includes the following steps: Step 1: 0.15 mol MnO, 0.05 mol NiO, and 0.106 mol LiOH were ball-milled at 800 r / min for 1 h, and then sintered at 1000 °C for 8 h in air to prepare LiNi. 0.5 Mn 1.5 O4 material: 0.2 mol MnO and 0.1 mol ZnO were ball-milled together at a speed of 800 r / min for 1 h, and then sintered at 900 °C for 4 h in air atmosphere to prepare ZnMn2O4 material.

[0064] Step 2: Ball mill and mix 10g LiMn2O4 material and 0.4g LiZn 0.2 Mn 1.8 O4 material was mixed with 0.4 g ZnMn2O4 and ball-milled at 1000 r / min for 0.5 h to obtain a mixed powder. This powder was then sintered at 700℃ for 0.5 h in air to obtain solid particles of LiNi. 0.5 Mn 1.5 O4 / ZnMn2O4@LiMn2O4 cathode material.

[0065] Figure 1 Here is a SEM image of the cathode material prepared in Example 1. Figure 1 It can be seen that the cathode material has a polyhedral morphology and a loose, porous flocculent / clustered structure on its surface.

[0066] Figure 2 This is a TEM image of the cathode material prepared in Example 1. Figure 2 It can be seen that the core material obtained in Example 1 is LiMn2O4, LiMn2O4 and LiZn 0.2 Mn 1.8 O4 co-forms the coating layer. Clear lattice fringes are visible in all regions of the image, indicating the presence of LiMn2O4, LiMn2O4, and LiZn. 0.2 Mn 1.8 O4 is entirely crystalline with no obvious amorphous regions, proving that the sintering process effectively promoted crystal growth. The interfaces between different regions show no obvious gaps or defects, indicating good bonding between the coating layer and the substrate / coating layer material.

[0067] The positive electrode materials obtained in Examples 1-3 and Comparative Examples 1-3 were weighed and ground according to a mass ratio of positive electrode material: conductive graphite: PVDF of 8:1:1. Then, an appropriate amount of N-methylpyrrolidone (NMP) was added, and grinding and stirring were continued to form a uniform slurry. The slurry was then uniformly coated onto aluminum foil using a mold to a thickness of 200 μm, and placed in a drying oven at 90°C for 10 hours. The coated foil was then cut into 12 mm diameter discs. Using the discs as the positive electrode and lithium foil as the negative electrode, the electrolyte consisted of a solvent and LiPF6, with a LiPF6 concentration of 1 mol / L. The electrolyte solvent was a mixture of EC, DEC, and DMC in a volume ratio of 1:1:1. The batteries were assembled in a glove box according to the coin cell assembly sequence.

[0068] The assembled batteries were subjected to performance testing. After being left to stand overnight, the batteries were placed in a LAND2001CT battery test chamber for charge-discharge testing. The tests were conducted at 25°C, 2C, and a cycle voltage of 2.7-4.2V, with 100 cycles. Figure 3 The cycling curve test diagrams are of batteries assembled from the cathode materials prepared in Examples 1-3 and Comparative Examples 1-3.

[0069] Depend on Figure 3 As can be seen, Examples 1, 2, and 3 still maintain a gradual capacity decay at high rates (2C). The "synergistic protection" of the two-component coating provided by this invention not only suppresses capacity decay during conventional cycling but also adapts to structural stress and ion transport requirements at high rates, thus maintaining excellent cycling stability under 2C conditions. Comparative Example 1 (pure LiMn2O4) exhibits extremely rapid capacity decay at high rates, indicating that the Jahn-Teller distortion and interfacial side reactions are more significant in unmodified LiMn2O4 during high-rate cycling, making it unable to adapt to the high-rate charge-discharge stress. At 2C rates, the coating structure improves ion diffusion efficiency, allowing Li... + It can transmit rapidly, thereby reducing capacity loss. As shown in the figure, the specific capacity of Example 1 is always much higher than that of Comparative Example 1, which proves that it can still maintain efficient ion transmission at high rates.

[0070] The curves of Comparative Examples 2 and 3 still showed a significant decrease at 2C rate. A single coating layer is insufficient to simultaneously address both the "rapid lithium-ion insertion / extraction stress at high rates" and "interfacial side reactions." Therefore, the improvement effect of a single coating layer at high rates is weakened and still cannot meet the requirements for stable cycling.

[0071] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope of the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A composite modified lithium manganese oxide cathode material, characterized in that, It includes a core and a coating layer, the coating layer covering at least a portion of the surface of the core; the core is a LiMn2O4 material, and the coating layer includes LiMn2O4. x Mn 2-x O4 material and ZnMn2O4 material, wherein M is any one or more of Zn, Fe, and Ni, and 0.1≤x≤0.

4.

2. The composite modified lithium manganese oxide cathode material as described in claim 1, characterized in that, The surface of the composite modified lithium manganese oxide cathode material particles has a polyhedral morphology; the particle size of the composite modified lithium manganese oxide cathode material is 100~300nm.

3. A method for preparing a composite modified lithium manganese oxide cathode material, characterized in that, include: Ball milling mixed LiMn2O4 materials, LiM x Mn 2-x O4 material and ZnMn2O4 material are sintered in air or an oxygen-containing atmosphere to obtain the product; wherein M is one or more of Zn, Fe, and Ni, and 0.1≤x≤0.

4.

4. The preparation method of the composite modified lithium manganese oxide cathode material as described in claim 3, characterized in that, The ball milling speed is 300-1000 r / min; the ball milling time is 0.5-5 h; the sintering temperature is 500-700℃; and the sintering time is 0.5-2 h.

5. The method for preparing the composite modified lithium manganese oxide cathode material as described in claim 3 or 4, characterized in that, LiMn2O4 materials, LiM x Mn 2-x The mass ratio of O4 material to ZnMn2O4 material is 1:(0.01-0.04):(0.01-0.04).

6. The preparation method of the composite modified lithium manganese oxide cathode material as described in claim 3, characterized in that, LiM x Mn 2-x The preparation method of O4 material is as follows: manganese dioxide, metal M oxide and lithium source are mixed by ball milling, and then sintered in air or oxygen-containing atmosphere to obtain the material.

7. The method for preparing the composite modified lithium manganese oxide cathode material as described in claim 6, characterized in that, The ball milling speed is 300-1000 r / min; the ball milling time is 0.5-5 h; the metal M oxide is any one or more of zinc oxide, ferrous oxide, and nickel oxide; the lithium source is one or more of lithium hydroxide, lithium acetate, and lithium nitrate; manganese dioxide, M in the metal M oxide and LiM x Mn 2-x The stoichiometry of the O4 material is consistent, and the molar ratio of lithium in the lithium source is LiM. x Mn 2-x The stoichiometry of O4 material is 1 to 1.06 times; the sintering temperature is 880-1000℃, and the sintering time is 8-16h.

8. The method for preparing the composite modified lithium manganese oxide cathode material as described in claim 3, characterized in that, The preparation method of ZnMn2O4 material is as follows: manganese dioxide and zinc source are mixed by ball milling and sintered in air or oxygen-containing atmosphere to obtain the material.

9. The method for preparing the composite modified lithium manganese oxide cathode material as described in claim 8, characterized in that, The ball milling speed is 300-1000 r / min; the ball milling time is 0.5-5 h; the zinc source is any one or more of zinc oxide, zinc acetate, and zinc nitrate; the stoichiometric ratio of manganese in manganese dioxide and zinc in the zinc source is consistent with that of manganese dioxide and zinc source; the sintering temperature is 700-900℃ and the sintering time is 4-12 h.

10. A battery, characterized in that, The composite modified lithium manganese oxide cathode material according to any one of claims 1 to 2 or the composite modified lithium manganese oxide cathode material prepared by the preparation method according to any one of claims 3 to 9 is included.

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