Lithium-rich manganese-based lithium ion battery and preparation method thereof

Abstract

The invention discloses a lithium-rich manganese-based lithium ion battery and a preparation method thereof, the lithium ion battery comprises a positive electrode, a negative electrode and an electrolyte, the positive electrode comprises a collector electrode and a positive electrode material uniformly deposited on the surface of the collector electrode, and the positive electrode material comprises a positive electrode active material, a conductive agent and a binder which are uniformly mixed; the positive electrode active material comprises a layered lithium-manganese-rich positive electrode material and a lithium heteropolyacid coating layer coating the surface of the layered lithium-manganese-rich positive electrode material in situ; according to the lithium ion battery disclosed by the invention, layered lithium-rich manganese modified by heteropoly acid and salt thereof is taken as a positive electrode active material, so that the lithium ion battery has excellent cycling stability, and has an extremely high capacity retention ratio which can reach 100% at most after being circulated for 400 times under the high current density of 200 milliampere / g; and meanwhile, better voltage holding ratio and rate capability are realized. The preparation process still uses the traditional coating process, and no additional modification step is needed.

Description

A lithium-rich manganese-based lithium-ion battery and its preparation method Technical Field

[0001] This invention relates to the technical field of secondary batteries, and more particularly to a lithium-rich manganese-based lithium-ion battery and its preparation method. Background Technology

[0002] Lithium-ion batteries, with their advantages of high energy density, low self-discharge, long cycle life, and environmental friendliness, have become dominant in electrochemical energy storage devices and are widely used in smartphones, computers, power batteries, and energy storage batteries. Over the past decade, lithium-ion batteries have experienced rapid commercialization and large-scale development, especially in the new energy vehicle sector, where huge market demand has directly driven the booming power battery industry. As a key component of lithium-ion batteries, cathode materials play a crucial role in battery performance and energy density. However, currently, commercially widely used layered oxide cathode materials (such as LiCoO2 and ternary materials LiNi)... 1 / 3 Co 1 / 3 Mn 1 / 3 The actual specific capacity of cathode materials such as O2 is basically limited to within 150 mAh / g; the theoretical specific capacities of spinel-structured LiMn2O4 and polyanionic LiFePO4 cathode materials are only 148 mAh / g and 170 mAh / g, respectively, and the capacities achievable in practical applications are even lower. The capacity levels of these commercially available cathode materials are far from meeting the core performance requirements of high-energy-density lithium-ion batteries for cathode materials. Therefore, cathode materials have become a core bottleneck restricting further improvements in the performance of lithium-ion batteries.

[0003] Layered lithium-rich manganese oxide cathode materials, with their high specific capacity (over 280 mAh / g) and high energy density (over 1000 Wh / kg), are considered ideal candidates for next-generation lithium-ion battery cathode materials. A typical layered lithium-rich manganese oxide cathode material has the basic composition xLi₂MnO₃·(1-x)LiTMO₂ (0≤x≤1), where TM is selected from one or a mixture of several of Ni, Co, Mn, Cr, Fe, Al, Nb, Mo, and Ru. However, layered lithium-rich manganese oxide cathode materials also have many problems that need to be solved. Their poor cycle stability, low initial coulombic efficiency, voltage decay during cycling, and poor rate performance severely restrict their practical application. Furthermore, due to the scarcity and high price of Co resources, cobalt-free lithium-rich manganese oxide cathodes can further reduce costs. Compared to traditional Co-containing lithium-rich manganese oxide cathode materials, cobalt-free lithium-rich manganese oxide cathode materials show a slight decrease in both capacity and rate performance. Solving these problems is the key to the commercialization of cobalt-free lithium-rich manganese oxide cathode materials.

[0004] Over the past few decades, researchers have conducted extensive studies on suppressing oxygen release and other issues mentioned above, proposing modification strategies including elemental doping, surface coating, and structural design. Among various modification strategies, surface coating is one of the most effective and widely used modification methods in the field of lithium-rich manganese-based oxide cathode materials. Compared with other modification strategies, surface coating technology has unique advantages: while bulk doping can regulate the intrinsic electronic structure of materials, it may sacrifice specific capacity; structural design often requires complex synthesis processes; while surface coating technology can directly protect the weak interface between the electrode and the electrolyte without losing the inherent high specific capacity characteristics of the matrix material. In surface coating technology, electrochemically inert coatings (such as MgAl2O4, KBO2, Al2O3, etc.) can act as a physical protective barrier, blocking undesirable side reactions between the electrolyte and the active material and inhibiting the dissolution of transition metals; in contrast, electrochemically active coatings, especially lithium-ion conductive coatings (such as Li3PO4, LiZr2(PO4)3, Nd... 0.6 Sr 0.4 CoO3 and other materials can promote lithium-ion transport and optimize the electrochemical kinetics of lithium-rich manganese-based oxide cathode materials. However, traditional coating techniques usually require additional preparation steps, which not only increases the complexity of the process but also increases the material preparation cost.

[0005] In existing technologies, there are studies on surface modification of cathode materials using heteropoly acids such as phosphomolybdic acid. For example, the paper with DOI 10.1016 / j.nanoen.2021.106901, entitled "Constructing a stable interfacial phase on single-crystalline Ni-rich cathode via chemical reaction with phosphomolybdic acid", discloses a method for surface modification of single-crystal high-nickel ternary cathode material LiNi using phosphomolybdic acid. 0.8 Co 0.1 Mn 0.1 The surface treatment method using O2 requires calcination at 600℃ in an oxygen atmosphere for 5 hours after surface treatment, ultimately forming a rock salt phase and lithium-ion conductor Li4MoO5 on the material surface. The modified cathode material has an initial discharge capacity of 206 mAh / g at a 0.1C rate, and after 200 cycles at room temperature, 0.5C rate, and a voltage range of 3~4.3 V, the capacity retention rate is 92%.

[0006] Another paper, with DOI 10.1021 / acs.energyfuels.3c02219, titled "Ion-Exchanged Phosphomolybdic Acid Interfacial Modification Enhances the Electrochemical Performance of LiNi",... 0.9 Mn 0.1 The literature "O2" discloses the preparation of phosphomolybdic acid products with different Li⁺ exchange capacities by adjusting the amount of lithium carbonate solution added, mixing it with phosphomolybdic acid solution, and then dehydrating it. At the same time, using nickel manganese hydroxide and lithium hydroxide as raw materials, the cathode material NM91 was synthesized through a two-step calcination process of ball milling, drying, and oxygen atmosphere. The modified material has an initial discharge capacity of 216.6 mAh / g at 0.1C rate, and a capacity retention rate of 84.8% after 100 cycles at 1C rate and a voltage range of 2.8~4.5 V. Moreover, its rate performance is better than that of the unmodified original NM91 material.

[0007] The core idea of ​​the aforementioned existing technologies is to utilize the acidity and Li⁺ / H⁺ exchange properties of phosphomolybdic acid, combined with subsequent high-temperature calcination or multi-step roasting to form a surface coating layer, thereby improving the cycle stability and rate performance of ternary materials. However, this type of method has significant limitations: First, it must rely on high-temperature calcination / roasting steps, resulting in cumbersome processes and a surge in energy consumption, which is not conducive to large-scale commercial production; second, it fails to fully exploit the inherent advantages of the unique Keggin-type structure of phosphomolybdate, limiting the modification effect; third, it only targets ternary materials and does not address the modification needs of high-capacity lithium-rich manganese materials. As a core candidate material for next-generation high-energy-density lithium-ion batteries, lithium-rich manganese materials urgently need to solve problems such as poor cycle stability and voltage decay, and existing technologies cannot provide suitable solutions. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention discloses a lithium-rich manganese-based lithium-ion battery. Layered lithium-rich manganese modified with heteropolyacids and their salts is used as the positive electrode active material, exhibiting excellent cycle stability. At a high current density of 200 mA / g, it maintains extremely high capacity retention after 400 cycles, reaching up to 100%. Simultaneously, it also demonstrates good voltage retention and rate performance. The preparation process still utilizes traditional coating techniques, requiring no additional modification steps.

[0009] The specific technical solution is as follows:

[0010] A lithium-manganese-based lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises a current collector and a positive electrode material uniformly deposited on the surface of the current collector:

[0011] The cathode material includes a uniformly mixed cathode active material, a conductive agent, and a binder. The cathode active material includes a layered lithium-rich manganese cathode material and a lithium heteropolyacid coating layer in situ coated on the surface of the layered lithium-rich manganese cathode material.

[0012] The lithium heteropolyacid coating layer has one or more of the following general formulas (1) to (3);

[0013] (1);

[0014] (2);

[0015] (3);

[0016] In the formula, n is selected from integers from 3 to 5, and is specifically determined by the valence of the central atom X;

[0017] m is selected from integers from 6 to 8, and is specifically determined by the valence of the central atom Y;

[0018] p is selected from integers from 6 to 8, and is specifically determined by the valence of the central atom Z;

[0019] X, Y, and Z are central atoms, independently selected from one or more of P, Si, Ge, and B;

[0020] M, N, and P are coordinating atoms, independently selected from one or more of Mo, W, and V.

[0021] This invention is the first to propose using a layered lithium-rich manganese cathode material in situ coated with lithium heteropolyacid as the cathode active material for preparing cathodes for lithium-ion batteries. By coating the layered lithium-rich manganese cathode material with lithium heteropolyacid, the cycle stability, voltage retention, and rate performance of the cathode can be effectively improved, especially the improvement in cycle stability is extremely significant. Through comprehensive characterization of various properties of this cathode, the following inferences are made regarding its working principle:

[0022] Firstly, the in-situ coating of lithium heteropolyacids reduces the direct contact between the lithium-rich manganese cathode material and the electrolyte, thereby reducing the dissolution of transition metals in the lithium-rich manganese cathode material in the electrolyte and increasing the stability of the composition of the lithium-rich manganese cathode material.

[0023] Secondly, the in-situ formed heteropolyacid lithium has both high lithium-ion conductivity and structural compatibility. As a fast lithium-ion conductor, it can effectively reduce the lithium-ion migration energy barrier. At the same time, its in-situ bonding with the surface of lithium-rich manganese-based materials can avoid the obstruction of the transmission channel, thereby significantly improving the high-rate charge-discharge capability and cycle stability of the material.

[0024] Furthermore, the acidity of heteropolyacids and their salts can interact with lithium-rich manganese materials, inducing the formation of numerous oxygen vacancies in situ on their surface. These oxygen vacancies can both improve ion transport efficiency and reduce oxygen evolution. Specifically, the heteropolyacid ions can be selected from phosphomolybdate ([PMo) ions). 12 O 40 ] 3- ), silicotungstate ([SiW) 12 O 40 ] 4- ), phosphotungstate ([PW) 12 O 40 ] 3- ), Phosphovanadate ([PV 12 O 40 ] 4- The mainstream Keggin-type heteropolyacid anions, such as ), have Mo as their central metal ion. 6+ W 6+ V 5+ Equal valence state M n+ During the charging phase, the lattice oxygen (O) in the lithium-rich manganese material... 2- It is oxidized to generate peroxide ions (O2). 2- ), synchronously driving M in heteropolyacids n+ Restored to the low valence state M (n-x)+ (x=1 or 2, i.e., M per mole) n+ (Gaining 1-2 moles of electrons); the synchronous electron transfer between the two can achieve efficient charge compensation, which promotes O2... 2- The selective generation of O2 can suppress its irreversible decomposition into O2, and the generated O2 2- It can be obtained by interacting with reduced M species (such as Mo) 5+ W 5+ / W 4+ V 4+ / V 3+ The coordination effect of O2 is bound by the interface. During the discharge phase, O2 2- Reduced to lattice oxygen (O) 2- Synchronous drive M (n-x)+ Re-oxidized to M n+ This completes a reversible redox cycle. Furthermore, M in heteropolyacids... n + / M (n-x)+ The reversible redox pairs formed by (x=1 or 2) can further significantly improve the cycling performance of the material and greatly suppress the release of oxygen during cycling.

[0025] Through the synergistic effect of the above-mentioned multiple factors, the stability of the crystal structure of lithium-rich manganese cathode material is greatly improved, and the capacity and voltage decay during cycling is reduced. This greatly improves the cycle stability, voltage retention rate and rate performance of the cathode, especially the cycle stability at high rates and the high capacity at ultra-high rates.

[0026] Preferably, the lithium heteropolyacid coating layer is selected from... and / or ;

[0027] Experiments have shown that when the lithium heteropolyacid coating layer is selected from... When the prepared lithium-ion battery exhibits superior cycle stability at high rates; when the lithium heteropolyacid coating layer is selected from... When prepared, the lithium-ion battery has a higher initial capacity at high rates.

[0028] Preferably, the thickness of the lithium heteropolyacid coating layer is 1~50 nm; more preferably 3~10 nm.

[0029] Further optimization:

[0030] The lithium heteropolyacid coating layer is selected from... ;

[0031] The thickness of the lithium heteropolyacid coating layer is 5~7 nm;

[0032] The lithium-ion battery prepared under further optimized conditions can achieve 100% capacity retention after 400 cycles at a high current density of 200 mA / g; it also has good voltage retention and rate performance.

[0033] This invention also discloses a method for preparing the above-mentioned lithium-rich manganese-based lithium-ion battery, comprising:

[0034] (1) A slurry is prepared by mixing layered lithium-rich manganese cathode material, heteropoly acid and its salt, conductive agent, binder and solvent;

[0035] (2) The slurry is coated onto the current collector, and then dried and pressed to prepare the positive electrode;

[0036] (3) The positive electrode, negative electrode and electrolyte are assembled to obtain a lithium-ion battery.

[0037] This preparation method is a conventional coating process in the field, which involves blending layered lithium-rich manganese cathode material, heteropolyacids and their salts with other raw materials, followed by a coating process. The protons (H) in the heteropolyacid molecules... + ), cations in heteropolyacids (such as NH4), + ) and lithium ions (Li) in layered lithium-rich manganese-based cathode materials + A substitution reaction occurs, with some or all of the components being replaced by Li.+ The process involves substitution, ultimately forming an in-situ coating of lithium heteropolyacid lithium on the surface of the layered lithium-rich manganese cathode material, followed by drying and pressing. This preparation process does not alter the composition and structure of the layered lithium-rich manganese cathode material, requires only one step, does not add electrode preparation steps, does not increase additional preparation costs, is simple to operate, and offers strong controllability in material preparation, making it fully suitable for industrial production requirements.

[0038] In step (1):

[0039] Preferably, the heteropolyacid and its salts comprise heteropolyacids and / or ammonium salts of heteropolyacids;

[0040] Preferably, the heteropolyacids and their salts are selected from one or more of the Keggin, Dawson, and Anderson types;

[0041] The general formula for Keggin-type heteropolyacids is: The general formula for Keggin-type heteropolyacid ammonium salts is: In the formula, n is an integer from 3 to 5, specifically determined by the valence of the central atom X; X is the central atom, selected from one or more of P, Si, Ge, and B; M is the coordinating atom, selected from one or more of Mo, W, and V; preferably, X is selected from P and / or Si, and M is selected from Mo and / or W.

[0042] The general formula for Dawson-type heteropolyacids is: The general formula for Dawson-type heteropolyacid ammonium salts is In the formula, m is selected from an integer from 6 to 8, specifically determined by the valence of the central atom Y; Y is the central atom, selected from one or more of P, Si, Ge, and B; N is the coordinating atom, selected from one or more of Mo, W, and V; preferably, Y is selected from P and / or Si, and N is selected from Mo and / or W.

[0043] The general formula for Anderson-type heteropolyacids is: The general formula for Anderson-type heteropolyacid ammonium salts is: In the formula, p is selected from an integer from 6 to 8, specifically determined by the valence of the central atom Z; Z is the central atom, selected from one or more of P, Si, Ge, and B; P is the coordinating atom, selected from one or more of Mo, W, and V; preferably, Z is selected from P and / or Si, and P is selected from Mo and / or W.

[0044] Further preferably, the heteropolyacid and its salt are selected from the Keggin type.

[0045] The general structural formula of the layered lithium-rich manganese cathode material is: In the formula, TM is selected from one or more of Ni, Co, Mn, Cr, Fe, Al, Nb, Mo, and Ru, and 0 ≤ x ≤ 1;

[0046] Preferably, the layered lithium-rich manganese cathode material is selected from Li 1.2 Mn 0.6 Ni 0.2 O2.

[0047] Preferably, the size of the layered lithium-rich manganese cathode material is selected from 50 nm to 50 μm, and more preferably nanoscale.

[0048] The conductive agent is selected from common types in the art, such as one or more of graphite, acetylene black, Super P, carbon nanotubes, graphene, and Ketjen black.

[0049] The adhesive is selected from common types in the art, such as one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene rubber, sodium carboxymethyl cellulose, and sodium alginate.

[0050] The solvent is selected from water, or a mixture of water and an organic solvent. The specific selection depends on the type of adhesive used.

[0051] Preferably, the organic solvent is selected from one or more of ethanol, N-methylpyrrolidone, and p-xylene.

[0052] Based on all raw materials excluding water as 100%, the raw material composition includes:

[0053] Layered lithium-rich manganese cathode materials account for 70-95%;

[0054] Heteropolyacids and their salts, 0.5-10%;

[0055] Conductive agent 1~20%;

[0056] Adhesive 1~15%;

[0057] Preferably, the mass percentage of heteropoly acids and their salts is 1-5%, based on 100% of all raw materials excluding water.

[0058] Further optimization reveals that the raw material composition includes:

[0059] Layered lithium-rich manganese cathode material: 80-85%;

[0060] Heteropolyacids and their salts 1-5%;

[0061] Conductive agent 1~20%;

[0062] Adhesive 1~15%;

[0063] The mixing is performed using common mixing methods in the art, such as ball milling, mechanical stirring, or magnetic stirring.

[0064] Preferably, the mass ratio of all raw materials except water to water is 1:(2~10). A slurry that is too thin or too thick is not conducive to coating. A further preferred ratio is 1:5.

[0065] The drying process is carried out at a temperature of 80~150℃.

[0066] The pressing process includes cold pressing or roller pressing, with a pressure of 5~40 MPa.

[0067] In step (2):

[0068] The current collector is selected from common types in the art, such as one or more of aluminum foil, carbon-coated aluminum foil, and nickel foil;

[0069] In step (3):

[0070] The negative electrode is selected from common types in the art, such as one or more of carbon negative electrodes, silicon-based negative electrodes, metal oxide negative electrodes, and lithium metal negative electrodes.

[0071] The electrolyte is also selected from common non-aqueous electrolytes in the art, including lithium salts and non-aqueous solvents. The lithium salt can be one or more of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), and lithium fluorohydroxysulfonate (LiC(SO2CF3)3). The non-aqueous solvent can be one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC).

[0072] Based on the above raw materials, further optimization is performed:

[0073] The heteropolyacids and their salts are selected from , , , One or more of the following;

[0074] Better:

[0075] The heteropolyacids and their salts are selected from and / or ;

[0076] Based on all raw materials excluding water as 100%, heteropoly acids and their salts account for 3% of the total mass.

[0077] With the continuous optimization of the types and contents of the above-mentioned raw materials, the prepared lithium-ion batteries have better cycle stability, voltage retention rate and rate performance.

[0078] Compared with the prior art, the present invention has the following beneficial effects:

[0079] This invention discloses a lithium-rich manganese-based lithium-ion battery, in which the positive electrode uses a layered lithium-rich manganese positive electrode material in situ coated with lithium heteropolyacid as the positive electrode active material. Experiments have shown that coating the layered lithium-rich manganese positive electrode material with lithium heteropolyacid can effectively improve the cycle stability, voltage retention rate and rate performance of the positive electrode, especially the improvement in cycle stability and rate performance is extremely significant. This lithium-ion battery can maintain a capacity retention rate of up to 100% after 400 cycles at a current density of 1C (1C = 200 mAh / g), and still has a capacity of 50 mAh / g at an ultra-high rate of 80C.

[0080] In the method for preparing a lithium-rich manganese-based lithium-ion battery disclosed in this invention, the preparation of the positive electrode is a conventional coating process in the art, which is formed in one step during the electrode preparation process. Taking advantage of the water solubility of heteropoly acids and their salts, they are uniformly distributed in the slurry with good dispersibility. After the electrode is dried, they become a uniform coating layer that coats the surface of the lithium-rich manganese positive electrode material. This preparation process does not add electrode preparation steps or additional preparation costs. It is simple to operate, has strong controllability in material preparation, and is fully suitable for industrial production requirements. Attached Figure Description

[0081] Figure 1 is a transmission electron microscope (TEM) image of the positive electrode material on the surface of the positive electrode sheet prepared in Example 1;

[0082] Figure 2 shows the energy spectrum of the positive electrode material on the surface of the positive electrode sheet prepared in Example 1;

[0083] Figure 3 shows the infrared spectrum of the cathode material prepared in Example 1;

[0084] Figure 4 shows the X-ray photoelectron spectrum (XPS) of oxygen on the surface of the positive electrode material prepared in Example 1.

[0085] Figure 5 shows the X-ray photoelectron spectroscopy (XPS) of P element on the surface of the positive electrode material prepared in Example 1 before cycling.

[0086] Figure 6 shows the X-ray photoelectron spectroscopy (XPS) of O on the surface of the cathode material prepared in Example 1 during (a) the first cycle; and (b) the X-ray photoelectron spectroscopy (XPS) of Mo during the first cycle. 6+ (c) Changes in relative content; Mo during the first cycle 5+ Changes in relative content;

[0087] Figure 7 shows the (a) initial charge-discharge curve, (b) 0.2C cycle performance curve, and (c) 1C cycle performance curve of the battery assembled in Example 1.

[0088] Figure 8 shows the median voltage decay curve of the battery assembled in Example 1;

[0089] Figure 9 shows the rate performance curve of the battery assembled in Example 1;

[0090] Figure 10 is a TEM image of the positive electrode material on the surface of the positive electrode sheet prepared in Example 2;

[0091] Figure 11 shows the following curves for the battery assembled in Example 2: (a) initial charge-discharge curve; (b) 0.2C cycle performance curve; (c) 1C cycle performance curve.

[0092] Figure 12 shows the median voltage decay curve of the battery assembled in Example 2;

[0093] Figure 13 shows the following curves for the battery assembled in Example 3: (a) initial charge-discharge curve; (b) 0.2C cycle performance curve; (c) 1C cycle performance curve.

[0094] Figure 14 shows the following curves for the battery assembled in Example 4: (a) initial charge-discharge curve; (b) 0.2C cycle performance curve; (c) 1C cycle performance curve.

[0095] Figure 15 shows the median voltage decay curve of the battery assembled in Example 4;

[0096] Figure 16 shows the rate performance curve of the battery assembled in Example 4;

[0097] Figure 17 shows the following curves for the battery assembled in Example 5: (a) initial charge-discharge curve; (b) 0.2C cycle performance curve; (c) 1C cycle performance curve.

[0098] Figure 18 shows the median voltage decay curve of the battery assembled in Example 5;

[0099] Figure 19 shows the (a) 1C cycle performance curve and (b) median voltage decay curve of the battery assembled in Example 6.

[0100] Figure 20 shows the (a) 1C cycle performance curve and (b) median voltage decay curve of the battery assembled in Example 7.

[0101] Figure 21 shows the X-ray photoelectron spectrum (XPS) of O on the surface of the positive electrode material prepared in Comparative Example 1.

[0102] Figure 22 shows the X-ray photoelectron spectrum (XPS) of O on the surface of the cathode material prepared in Comparative Example 1 during the first cycle.

[0103] Figure 23 shows the (a) initial charge-discharge curve, (b) 0.2C cycle performance curve, and (c) 1C cycle performance curve of the battery assembled in Comparative Example 1.

[0104] Figure 24 shows the median voltage decay curve of the battery assembled in Comparative Example 1;

[0105] Figure 25 shows the rate performance curve of the battery assembled in Comparative Example 1;

[0106] Figure 26 shows the 1C cycle performance curve of the battery assembled in Comparative Example 2. Detailed Implementation

[0107] To make the objectives, features, and advantages of this invention more apparent, further embodiments are provided below to illustrate the invention in detail. These embodiments are for illustrative purposes only and should not be construed as limiting the scope of protection of this invention. Any non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are within the scope of protection of this invention.

[0108] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0109] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0110] Example 1

[0111] The component used is Li 1.2 Mn 0.6 Ni 0.2 The lithium-rich manganese oxide cathode material, with a particle size of 200-300 nm, is composed of O2. This lithium-rich manganese oxide, conductive agent Super P, sodium carboxymethyl cellulose (CMC) aqueous binder, and phosphomolybdic acid (…). The raw materials were mixed in a mass ratio of 82:10:5:3, and deionized water was added as a solvent (the mass ratio of the total mass of raw materials to deionized water was 1:5). The mixture was magnetically stirred for 6 hours to obtain a slurry. The slurry was then evenly coated onto aluminum foil, vacuum dried at 120°C, and then pressed at 8 MPa to obtain a positive electrode sheet.

[0112] The electrochemical performance of the positive electrode prepared in this embodiment was characterized using a 2025 coin cell, assembled in an Ar-filled glove box with water and oxygen contents both less than 0.01 ppm. The positive electrode used was a Li metal sheet as both the reference and counter electrode, a Celgard-2400 separator, and a LiPF6 (1 mol / L) / EC+DEC+EMC (1:1:1) electrolyte. The test voltage window was 2.0–4.8 V, and the electrochemical performance of the battery was tested using a constant current charge-discharge method.

[0113] The morphology of the cathode material on the surface of the cathode sheet prepared in this embodiment was characterized, and its high-resolution transmission electron microscope image is shown in Figure 1. It can be seen from the figure that there is a coating layer with a thickness of about 5 nm on the surface of the lithium-rich manganese oxide particles. The results of energy dispersive spectroscopy analysis of the composition of this layer (Figure 2) show that in addition to Ni, O and Mn elements, Mo and P elements are also uniformly distributed on the particle surface. This coating layer is mainly composed of Mo and P elements.

[0114] Figure 3 shows the infrared spectrum of the cathode material prepared in this embodiment before cycling, exhibiting additional infrared peak structural features, including PO (terminal phosphate oxygen) at 1064 cm⁻¹. -1 Asymmetric stretching vibrations at 869 cm⁻¹ and Mo-O-Mo (edge-sharing structure in MoO₆ octahedron) -1 and 796 cm -1 These spectral features confirm that the coating layer retains the Keggin-type anion [PMo]. 12 O 40 ] 3- structure.

[0115] The above test results confirm that lithium phosphomolybdate coats the surface of lithium-rich manganese oxide particles without disrupting the crystal structure of the lithium-rich manganese material. This indicates that phosphomolybdic acid is soluble in deionized water during slurry preparation, and the H+ ions it releases... + Li in layered lithium-rich manganese-based cathode materials + A substitution reaction occurs; H + By Li + After partial or complete replacement, lithium phosphomolybdate with high lithium-ion conductivity is generated in situ, which uniformly coats the surface of lithium-rich manganese oxide material particles. After drying, a lithium-rich manganese oxide cathode material with a lithium phosphomolybdate coating is finally formed. Since lithium phosphomolybdate is a fast lithium-ion conductor, it can significantly improve the lithium-ion diffusion coefficient. At the same time, the coating layer effectively suppresses the side reactions between the electrode and the electrolyte, thereby greatly improving the rate performance and cycle stability of the lithium-rich manganese cathode material.

[0116] Figure 4 shows the X-ray photoelectron spectrum of oxygen on the surface of the cathode material prepared in this embodiment. The peak at 531.5 eV corresponds to the binding energy of oxygen vacancies, and the oxygen vacancy content is 50.1%. Compared with the uncoated lithium phosphomolybdate lithium-rich manganese oxide (Comparative Example 1, Figure 21, oxygen vacancy content 31.0%), the binding energy peak intensity of oxygen vacancies in the cathode material prepared in this embodiment is relatively stronger than that in Comparative Example 1, indicating that phosphomolybdate treatment increases the number of oxygen vacancies on the surface of the lithium-rich manganese material. Based on this test conclusion, it can be shown that the acidity of the phosphomolybdate coating in this invention generates a large number of oxygen vacancies on the surface of the lithium-rich manganese material. These oxygen vacancies help suppress oxygen evolution during charge-discharge cycles, stabilize the electrode crystal structure, improve ionic and electronic conductivity, and thus enhance the electrochemical performance of the lithium-rich manganese cathode material.

[0117] Figure 5 shows the XPS spectrum of P element on the surface of the cathode material prepared in this embodiment before cycling. The characteristic peak centered at approximately 133.5 eV corresponds to PO4. 3- The binding energy.

[0118] In Figure 6, (a) is the XPS spectrum of O on the surface of the positive electrode material prepared in this embodiment during the first charge and discharge process. It can be seen that the peak shape of the XPS is almost unchanged when charged to 4.8V (top figure) and discharged to 2.0V (bottom figure), and peroxide ions O2 are detected when charged to 4.8V. 2- The presence of O2 peroxide ions. When discharged to 2.0 V, O2 peroxide ions... 2- Characteristic peak due to peroxide ion O2 2- Reduced to lattice oxygen O 2- And disappear. Compared with lithium-rich manganese without lithium phosphomolybdate coating (Comparative Example 1, Figure 22), the lattice oxygen O in this embodiment disappears. 2- The content of oxygen in the material of Comparative Example 1 did not change much before and after charging and discharging, while the lattice oxygen content of the material after discharge was significantly different. 2- The content is significantly lower compared to the state of charge. This indicates that oxygen loss is negligible in this embodiment, which is beneficial for maintaining structural stability during cycling. Furthermore, the surface material of the positive electrode prepared according to this embodiment shows a decrease in Mo phosphomolybdate ions during the first charge-discharge cycle. 5+ (Figure (c)) and Mo 6+ (Figure (b)) The change in relative content revealed that within the voltage range of oxygen ion redox (4.4~4.8V), Mo 6+ Gradually reduced to Mo 5+ When charged to 4.8 V, Mo 5+ The atomic percentage reached its maximum. Further analysis of this test result can clarify the mechanism of action:

[0119] Mo in the lithium phosphomolybdate coating layer of this invention 6+During charging, it will release oxygen from the lithium-rich manganese lattice. 2- It accepts electrons and is reduced to Mo. 5+ In this process, the synchronous transfer of electrons from oxygen to molybdenum not only promotes the transfer of peroxide ions (O2) but also... 2- The selective generation of O2 can also suppress its irreversible decomposition into O2, and the generated O2 2- It can be bound at the interface through coordination with reduced phosphomolybdate ions. During discharge, Mo... 5+ It can be re-oxidized to Mo 6+ The reversible redox cycle is completed. This stable and reversible synergistic effect between molybdenum and the oxygen redox pair confirms the effective operation of the interfacial reduction coupling mechanism, which plays a key role in suppressing oxygen release and maintaining the structural integrity of the material during the cathode cycling process in this embodiment.

[0120] In Figure 7, (a) shows the initial charge-discharge curve of the battery assembled from the positive electrode prepared in this embodiment at a current density of 40 mA / g (0.2C), with an initial discharge capacity as high as 252 mAh / g and an initial coulombic efficiency of 82%. (b) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 40 mA / g. After 100 cycles, the capacity remains at 253 mAh / g, with virtually no capacity degradation. (c) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 200 mA / g (1C). Its initial discharge capacity reaches 195 mAh / g, and during cycling, the capacity shows a slow increasing trend. After 400 cycles, the capacity still remains at 199 mAh / g, exhibiting extremely high charge-discharge cycle stability.

[0121] Figure 8 shows the median discharge voltage curve of the battery assembled with the positive electrode prepared in this embodiment. The results show that the median potential of the positive electrode material prepared in this embodiment is 3.13 volts after 400 cycles at 1C, with a retention rate of 88%.

[0122] Figure 9 shows the rate performance curves of the battery assembled with the positive electrode prepared in this embodiment. It exhibits high electrochemical capacity at 5C, 10C, 20C, 30C, 40C, 50C, 60C, 70C, and 80C. It still has a capacity of 50 mAh / g at a high rate of 80C.

[0123] Example 2

[0124] The preparation process of the positive electrode is basically the same as that in Example 1, with the only difference being:

[0125] Lithium-rich manganese oxide, conductive agent Super P, CMC, and phosphomolybdic acid were mixed in a mass ratio of 84:10:5:1. The battery assembly and testing conditions were the same as in Example 1.

[0126] Figure 10 is a high-resolution transmission electron microscope (TEM) image of the cathode material on the surface of the cathode sheet prepared in this embodiment. The image shows a coating layer of approximately 3 nm on the surface of the lithium-rich manganese oxide particles. Compared to Example 1, the lithium phosphomolybdate coating layer on the surface becomes thinner as the amount of phosphomolybdic acid added decreases.

[0127] Further characterization was performed on the surface of the cathode material prepared in this embodiment, including the pre-cycle infrared spectrum, XPS spectrum of O, XPS spectrum of P, XPS spectrum of O during the first charge-discharge process, and XPS spectrum of Mo during the first cycle. 6+ and Mo 5+ The changes in relative content were characterized similarly to those in Example 1.

[0128] In Figure 11, (a) shows the initial charge-discharge curve of the battery assembled with the positive electrode sheet prepared in this embodiment at a current density of 40 mA / g (0.2C), with an initial discharge capacity of 251 mAh / g. (b) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 40 mA / g. After 100 cycles, the capacity remains at 239 mAh / g, with a capacity retention rate of 95%. (c) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 200 mA / g (1C). Its initial discharge capacity reaches 197 mAh / g, exhibiting extremely high charge-discharge cycle stability during cycling. After 400 cycles, the capacity still remains at 162 mAh / g, with a capacity retention rate as high as 82%.

[0129] Figure 12 shows the median discharge voltage curve of the battery assembled with the positive electrode prepared in this embodiment. The results show that the median potential of the positive electrode material prepared in this embodiment is 3.03 volts after 400 cycles, with a retention rate of 85%.

[0130] Example 3

[0131] The preparation process of the positive electrode is basically the same as that in Example 1, with the only difference being:

[0132] Lithium-rich manganese oxide, conductive agent Super P, CMC, and phosphomolybdic acid were mixed in a mass ratio of 80:10:5:5. The battery assembly and testing conditions were the same as in Example 1.

[0133] The morphology of the positive electrode material on the surface of the positive electrode sheet prepared in this embodiment was characterized by TEM. It was observed that there was a coating layer of about 10 nm on the surface of the lithium-rich manganese oxide particles.

[0134] Further characterization was performed on the surface of the cathode material prepared in this embodiment, including the pre-cycle infrared spectrum, XPS spectrum of O, XPS spectrum of P, XPS spectrum of O during the first charge-discharge process, and XPS spectrum of Mo during the first cycle. 6+ and Mo5+ The changes in relative content were characterized similarly to those in Example 1.

[0135] In Figure 13, (a) shows the initial charge-discharge curve of the battery assembled in this embodiment at a current density of 40 mAh / g, with an initial discharge capacity of 250 mAh / g. (b) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 40 mAh / g (0.2C). After 100 cycles, the capacity remains at 241 mAh / g, with a capacity retention rate of 96%. (c) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 200 mAh / g (1C). Its initial discharge capacity reaches 191 mAh / g, exhibiting extremely high charge-discharge cycle stability during cycling. After 400 cycles, the capacity still remains at 186 mAh / g, with a capacity retention rate of 97%, demonstrating extremely high charge-discharge cycle stability.

[0136] Example 4

[0137] The preparation process of the positive electrode is basically the same as that in Example 1, with the only difference being:

[0138] Replace phosphomolybdic acid with an equal mass of phosphotungstic acid. The battery assembly and testing conditions are the same as in Example 1.

[0139] The morphology of the positive electrode material on the surface of the positive electrode sheet prepared in this embodiment was characterized by TEM. It was observed that there was a coating layer of about 7 nm on the surface of the lithium-rich manganese oxide particles.

[0140] In Figure 14, (a) shows the initial charge-discharge curve of the battery assembled in this embodiment at a current density of 40 mAh / g (0.2C), with an initial discharge capacity of 245 mAh / g. (b) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 40 mAh / g. After 100 cycles, the capacity remains at 238 mAh / g, with a capacity retention rate as high as 97%. (c) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 200 mAh / g (1C). Its initial discharge capacity reaches 216 mAh / g, exhibiting a high initial discharge capacity. It also exhibits high charge-discharge cycle stability during cycling, maintaining a capacity of 170 mAh / g after 400 cycles.

[0141] Figure 15 shows the median discharge voltage curve of the battery assembled in this embodiment. The results show that after 400 cycles at 1C, the median potential of the material in this embodiment is 3.01 volts, with a retention rate of 84%.

[0142] Figure 16 shows the rate performance curves of the battery assembled in this embodiment, which exhibits high electrochemical capacity at 5C, 10C, 20C, 30C, 40C, 50C, 60C, 70C, and 80C. It still maintains a capacity of 30 mAh / g at a high rate of 80C.

[0143] Example 5

[0144] The preparation process of the positive electrode is basically the same as that in Example 4, with the only difference being:

[0145] Lithium-rich manganese oxide, conductive agent Super P, CMC, and phosphotungstic acid were mixed in a mass ratio of 80:10:5:5. The battery assembly and testing conditions were the same as in Example 1.

[0146] The morphology of the positive electrode material on the surface of the positive electrode sheet prepared in this embodiment was characterized by TEM. It was observed that there was a 10 nm thick layer of lithium phosphotungsten oxide coating on the surface of the lithium-rich manganese oxide particles.

[0147] In Figure 17, (a) shows the initial charge-discharge curve of the battery assembled in this embodiment at a current density of 40 mAh / g (0.2C), with an initial discharge capacity of 239 mAh / g. (b) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 20 mAh / g. After more than ten cycles of activation, the capacity of the material is very stable, maintaining 237 mAh / g after 100 cycles, with a capacity retention rate of 99%. (c) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 200 mAh / g (1C). Its initial discharge capacity is 176 mAh / g, and after 400 cycles, the capacity still maintains 172 mAh / g, with a capacity retention rate of 98%, demonstrating extremely high charge-discharge cycle stability.

[0148] Figure 18 shows the median discharge voltage curve of the battery assembled in this embodiment. The results show that after 400 cycles at 1C, the median potential of the material in this embodiment is 3.08 volts, with a retention rate of 87%.

[0149] Example 6

[0150] The preparation process of the positive electrode is basically the same as that in Example 3, with the only difference being:

[0151] Replace phosphomolybdic acid with an equal mass of ammonium phosphomolybdate. The battery assembly and testing conditions are the same as in Example 1.

[0152] In Figure 19, (a) shows the cycle performance curve of the battery assembled in this embodiment at a current density of 200 mA / g (1C). Its initial discharge capacity is 207 mAh / g, and after 400 cycles, the capacity remains at 172 mAh / g, with a capacity retention rate of 83%. (b) shows the median discharge voltage curve of the battery assembled in this embodiment. The results show that after 400 cycles at 1C, the median potential of the material in this embodiment is 3.10 volts, with a retention rate of 88%.

[0153] Example 7

[0154] The preparation process of the positive electrode is basically the same as that in Example 1, with the only difference being:

[0155] Partially replacing phosphomolybdic acid with phosphotungstic acid, the lithium-rich manganese oxide, conductive agent Super P, CMC, phosphomolybdic acid, and phosphotungstic acid were mixed in a mass ratio of 82:10:5:1.5:1.5. The battery assembly and testing conditions were the same as in Example 1.

[0156] Figure 20 shows the cycle performance curve of the battery assembled in this embodiment at a current density of 200 mA / g (1C). Its initial discharge capacity is 200 mAh / g, and after 300 cycles, the capacity remains at 195 mAh / g, with a capacity retention rate of 98%, demonstrating extremely high charge-discharge cycle stability. Figure (b) shows the median discharge voltage curve of the battery assembled in this embodiment. The results show that after 300 cycles, the median potential of the material in this embodiment is 3.17 volts, with a retention rate of 89%.

[0157] Comparative Example 1

[0158] The preparation process of the positive electrode sheet is basically the same as that in Example 1, except that phosphomolybdic acid is not added, and lithium-rich manganese oxide, conductive agent Super P, and CMC are mixed in a mass ratio of 85:10:5. The battery assembly and testing conditions are the same as in Example 1.

[0159] Figure 21 shows the XPS spectrum of O in the uncoated cathode material prepared in this comparative example. The peak at 531.5 eV corresponds to the binding energy of oxygen vacancies. The oxygen vacancy content is 31.0%, indicating that its oxygen vacancy concentration is low.

[0160] Figure 22 shows the XPS spectrum of O in the cathode material prepared in this comparative example during the first charge-discharge process. The peak at 530.5 eV corresponds to the peroxide ion O2. 2- The binding energy shows that the material in this comparative example, when first charged to 4.8 V (see the figure above), has O2. 2- The peak appears and its content is relatively low. When the discharge reaches 2.0 V (see figure below), the peak shape changes dramatically, the peak of oxygen vacancies becomes significantly stronger, and the lattice oxygen O 2-The peak weakens significantly, indicating that a large amount of oxygen is released during the first charge and discharge process.

[0161] In Figure 23, (a) shows the initial charge-discharge curve of the battery assembled in this comparative example at a current density of 40 mAh / g (0.2C), with an initial discharge capacity of 249 mAh / g and an initial coulombic efficiency of 78%. (b) shows the cycle performance curve of the battery at a current density of 40 mAh / g, with a discharge specific capacity of only 228 mAh / g after 100 cycles and a capacity retention of only 91%. (c) shows the cycle performance curve of the battery at a current density of 200 mAh / g (1C). Its initial discharge specific capacity is 205 mAh / g, and the discharge specific capacity after 300 cycles is 160 mAh / g with a retention of only 78%; after 400 cycles, the discharge specific capacity is only 134 mAh / g with a retention of only 65%. The cycle stability of this comparative example is poor and significantly inferior to that of the embodiments of the present invention.

[0162] Figure 24 shows the median discharge voltage curve of the battery assembled in this comparative example. After 300 cycles, the median voltage was 3.02 volts, with a retention rate of 84%; after 400 cycles, the median voltage was 2.85 volts, with a retention rate of 79%. It can be seen that the voltage decay of the material in this comparative example is relatively fast, and is not as good as the material in the embodiment of the present invention.

[0163] Figure 25 shows the rate performance curves of the battery assembled in this comparative example. Its electrochemical capacity at 5C, 10C, 20C, 30C, 40C, 50C, 60C, 70C and 80C is lower than that of the embodiment of the present invention. The discharge specific capacity at 80C is only 13 mAh / g, which is significantly lower than that of the embodiment of the present invention.

[0164] Comparative Example 2

[0165] The preparation process of the positive electrode is basically the same as that in Example 1, with the only difference being:

[0166] Lithium-rich manganese oxide, conductive agent Super P, CMC, and phosphomolybdic acid were mixed in a mass ratio of 70:10:5:15. The battery assembly and testing conditions were the same as in Example 1.

[0167] Figure 26 shows the cycle performance curves of the battery assembled in this comparative example at a current density of 200 mAh / g (1C). Its initial discharge capacity was 154 mAh / g, but after 300 cycles, the capacity remained at only 134 mAh / g; after 400 cycles, the discharge specific capacity was only 123 mAh / g, with a retention rate of only 80%. This indicates that excessive addition of phosphomolybdic acid has a significant negative impact on both the capacity and cycle stability of lithium-rich manganese batteries.

[0168] The above description is only a few specific embodiments of the present invention. It should be noted that many variations and improvements can be made by those skilled in the art. All variations or improvements that do not exceed the scope of the claims should be considered as the protection scope of the present invention.

Claims

1. A lithium-rich manganese-based lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises a current collector and a positive electrode material uniformly deposited on the surface of the current collector, characterized in that: The positive electrode material includes a uniformly mixed positive electrode active material, a conductive agent and a binder. The positive electrode active material includes a layered lithium-rich manganese positive electrode material and a heteropolyacid lithium coating layer in situ coated on the surface of the layered lithium-rich manganese positive electrode material. The heteropolyacid lithium coating layer has one or more of the following general formulas (1) to (3). （1）； （2）； (3); where n is an integer from 3 to 5, specifically determined by the valence of the central atom X; m is an integer from 6 to 8, specifically determined by the valence of the central atom Y; p is an integer from 6 to 8, specifically determined by the valence of the central atom Z; X, Y, and Z are central atoms, independently selected from one or more of P, Si, Ge, and B; M, N, and P are coordinating atoms, independently selected from one or more of Mo, W, and V.

2. The lithium-rich manganese-based lithium-ion battery according to claim 1, characterized in that: The lithium heteropolyacid coating layer is selected from... and / or The thickness of the lithium heteropolyacid coating layer is 1~50 nm.

3. The lithium-rich manganese-based lithium-ion battery according to claim 1, characterized in that: The lithium heteropolyacid coating layer is selected from... The thickness of the lithium heteropolyacid coating layer is 3~10 nm.

4. The lithium-rich manganese-based lithium-ion battery according to claim 1, characterized in that, The thickness of the lithium heteropolyacid coating layer is 5~7 nm.

5. A method for preparing a lithium-rich manganese-based lithium-ion battery according to any one of claims 1 to 4, characterized in that, include: (1) A slurry is obtained by mixing layered lithium-rich manganese cathode material, heteropoly acid and its salt, conductive agent, binder and solvent; (2) The slurry is coated on the current collector, and the cathode is prepared by drying and pressing; (3) The cathode, anode and electrolyte are assembled to obtain a lithium-rich manganese-based lithium-ion battery.

6. The method for preparing a lithium-rich manganese-based lithium-ion battery according to claim 5, characterized in that, In step (1): the heteropolyacid and its salts include heteropolyacids and / or ammonium salts of heteropolyacids; the type of the heteropolyacid and its salts is selected from one or more of Keggin type, Dawson type, and Anderson type; the general formula of Keggin type heteropolyacids is The general formula for Keggin-type heteropolyacid ammonium salts is: In the formula, n is an integer from 3 to 5, specifically determined by the valence of the central atom X; X is the central atom, selected from one or more of P, Si, Ge, and B; M is the coordinating atom, selected from one or more of Mo, W, and V; the general formula for Dawson-type heteropolyacids is... The general formula for Dawson-type heteropolyacid ammonium salts is In the formula, m is selected from integers from 6 to 8, specifically determined by the valence of the central atom Y; Y is the central atom, selected from one or more of P, Si, Ge, and B; N is the coordinating atom, selected from one or more of Mo, W, and V; the general formula of Anderson-type heteropolyacids is... The general formula for Anderson-type heteropolyacid ammonium salts is: In the formula, p is selected from integers from 6 to 8, specifically determined by the valence of the central atom Z; Z is the central atom, selected from one or more of P, Si, Ge, and B; P is the coordinating atom, selected from one or more of Mo, W, and V; the general structural formula of the layered lithium-rich manganese cathode material is... In the formula, TM is selected from one or more of Ni, Co, Mn, Cr, Fe, Al, Nb, Mo, and Ru, and 0 ≤ x ≤ 1; the conductive agent is selected from one or more of graphite, acetylene black, Super P, carbon nanotubes, graphene, and Ketjen black; the binder is selected from one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, styrene-butadiene rubber, sodium carboxymethyl cellulose, and sodium alginate; and the solvent is selected from water or a mixture of water and an organic solvent.

7. The method for preparing a lithium-rich manganese-based lithium-ion battery according to claim 5, characterized in that, In step (1): based on 100% of all raw materials excluding water, the composition includes: 70-95% layered lithium-rich manganese cathode material; 0.5-10% heteropoly acid and its salts; 1-20% conductive agent; 1-15% binder; and the mass ratio of all raw materials except water to water is 1:(2-10).

8. The method for preparing a lithium-rich manganese-based lithium-ion battery according to claim 5, characterized in that: In step (2), the current collector is selected from one or more of aluminum foil, carbon-coated aluminum foil, and nickel foil; in step (3), the negative electrode is selected from one or more of carbon negative electrode, silicon-based negative electrode, metal oxide negative electrode, and lithium metal negative electrode.

9. The method for preparing a lithium-rich manganese-based lithium-ion battery according to any one of claims 5 to 8, characterized in that: The heteropolyacids and their salts are selected from 、 、 、 One or more of the following; based on all raw materials excluding water as 100%, the mass percentage of heteropoly acids and their salts is 1-5%.

10. The method for preparing a lithium-rich manganese-based lithium-ion battery according to claim 9, characterized in that: The heteropolyacids and their salts are selected from and / or The mass percentage of heteropoly acids and their salts is 3%, based on 100% of all raw materials excluding water.

Images