Lithium-rich manganese-based material with high ion channel and high-stability surface, preparation method of lithium-rich manganese-based material and lithium ion battery

Abstract

The invention provides a lithium-rich manganese-based material with a high ion channel and a high-stability surface, a preparation method of the lithium-rich manganese-based material and a lithium ion battery, and relates to the technical field of preparation of battery positive electrode materials. The surface of the lithium-rich manganese-based material is sequentially covered with a spinel Li4Mn5O12 layer and a composite layer of polydopamine and a fast ion conductor. A three-dimensional lithium transmission channel and stable surface composite combination improve the structural stability, in-situ introduction of the zero-strain material Li4Mn5O12 structure not only provides a lithium ion transmission channel, but also serves as a transition layer of a base material and polydopamine, stripping of a coating layer and the base material after long-period circulation is avoided, and the cycle life of the material is remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of battery positive electrode material preparation, and in particular to a lithium-rich manganese-based material with high ion channels and a highly stable surface, a preparation method thereof, and a lithium-ion battery. Background Art

[0002] Layered lithium-rich manganese has many advantages such as high specific capacity, low cost, and high safety, making it the focus of research on the next generation of positive electrode materials for lithium-ion batteries. Its high manganese, low nickel, and cobalt-free elemental composition can effectively circumvent the hidden dangers of nickel and cobalt resources, which is in line with my country's resource advantages of rich manganese and poor nickel. However, its commercialization process is restricted by its low first coulomb efficiency, poor rate performance, and cycle life.

[0003] The study found that after long-term charge and discharge cycles, the surface structure of lithium-rich manganese-based materials will change to spinel phase, accompanied by the valence of part of manganese changing from Mn 4+ Reduce to Mn 3+ , the latter has the Jahn-Taylor effect and is prone to disproportionation reaction to form Mn 2+ , dissolving in the electrolyte, causing the surface of the particles to pulverize, creating a new surface and continuing to dissolve, ultimately leading to severe decomposition of the material particles and degradation of the electrochemical performance. Building a stable surface layer is crucial to improving the structural stability of the material. On the one hand, it can effectively avoid structural phase changes and oxygen precipitation, and on the other hand, it can improve the interface stability of the electrode / electrolyte. The stability of the material surface structure can be effectively improved by surface coating: fast ion conductor coatings (such as lithium phosphate, lithium sulfate, etc.) can provide a stable transmission channel for lithium ions, improving the rate performance of the material; inert oxide coatings (such as Al 2 O 3 、ZrO 2 etc.) can isolate the direct contact between the electrolyte and the material, and avoid the corrosion of the material by harmful substances such as HF.

[0004] For example, Chinese patent CN115132998A discloses a lithium-rich manganese-based positive electrode material with a restructured surface structure, and its surface modification layer is 10 to 30 nm Li 4 Mn 5 O 12, the surface layer has three-dimensional fast lithium ion transmission channels and oxygen vacancies, which greatly improves the first coulombic efficiency and rate performance, but the cost of the hydrothermal process used is relatively high. Chinese patent CN118545770A discloses a layered lithium-rich manganese positive electrode material coated with polydopamine, which significantly improves the discharge capacity of the battery at high temperature, and inhibits the capacity decay at high temperature, and has excellent high temperature performance, but the polydopamine layer may hinder the transmission of lithium ions and thus affect the rate performance. It is generally difficult for a single type of coating layer to take into account various performances, and a multifunctional coating layer must be designed and constructed. For example, Chinese patent CN 109659538 A discloses a lithium-rich manganese-based oxide material coated with dopamine and lithium phosphate, which has a high discharge capacity and excellent rate performance, but the modified material obtained by the traditional coating method has a weak interface contact force between the coating layer and the base material, and may peel off after long-term circulation, thereby affecting the cycle life. Summary of the invention

[0005] In view of the above problems, the present invention provides a lithium-rich manganese-based material with an efficient ion channel and a stable surface layer, wherein the outermost layer is a composite layer of polydopamine and a fast ion conductor, and the fast ion conductor is distributed in a dot-like manner in the middle of the dense dopamine coating layer. Dopamine can alleviate the volume expansion of the lithium-rich manganese-based material during the lithium ion deintercalation process and improve the structural stability. The dot-distributed fast ion conductor can provide a lithium ion transmission channel and improve the rate performance of the material; the second outer layer is an in-situ formed spinel Li 4 Mn 5 O 12 Layer, Li 4 Mn 5 O 12 It is a "zero strain" material with three-dimensional lithium ion channels, which can improve lithium transmission efficiency while alleviating volume expansion and contraction, and simultaneously improve cycle stability and rate performance. 4 Mn 5 O 12 The layer has a good lattice match with the base material. As a transition layer between the base and dopamine, it can avoid the peeling of the coating layer caused by long-term cycling. In addition, compared with the traditional low manganese (Mn 3+ ) valence state of spinel induced by the different Jan-Taylor effect, Li 4 Mn 5 O 12 The Mn in the material is +4, which can significantly slow down the Jiang-Taylor effect and disproportionation reaction, and reduce the Mn in the material cycle. 2+ formation and dissolution.

[0006] One of the objects of the present invention is to provide a lithium-rich manganese-based material with high ion channels and a highly stable surface.

[0007] The second object of the present invention is to provide a method for preparing the lithium-rich manganese-based material with high ion channels and high stable surface.

[0008] The third object of the present invention is to provide a lithium-ion battery, comprising the lithium-rich manganese-based material with high ion channels and high stability surface.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] In a first aspect, the present invention provides a lithium-rich manganese-based material having a high ion channel and a high stable surface, wherein the structure of the lithium-rich manganese-based material is as follows: Figure 1 As shown, from the inside to the outside, it includes the bulk phase, the subsurface layer and the surface layer. The bulk phase is a layered lithium-rich manganese-based material, and the subsurface layer is a spinel-structured Li 4 Mn 5 O 12 The surface layer is a composite layer of polydopamine and fast ion conductor.

[0011] In some embodiments, the lithium-rich manganese-based material has a general chemical formula of xLi 2 MnO 3 ·(1-x)LiMO 2 , wherein 0.1≤x≤0.9, and M is one or more of Ni, Co, Mn, Cr, Fe, Ti, Mo, Ru, V, Nb, Zr and Sn;

[0012] In some embodiments, the fast ion conductor is at least one of lithium sulfate, lithium phosphate, lithium pyrophosphate, lithium niobate, lithium vanadate, lithium silicate, and lithium aluminate;

[0013] In some embodiments, the thickness of the sub-surface layer is 1-5 nm, preferably 2-3 nm, and the thickness of the surface layer is 5-20 nm, preferably 5-6 nm.

[0014] In a second aspect, the present invention provides a method for preparing a lithium-rich manganese-based material having a high ion channel and a high stable surface, comprising the following steps:

[0015] (1) dissolving the lithium-rich manganese-based material, dopamine and coating raw materials in tris(hydroxymethylaminomethane) buffer, and adjusting the pH of the system to 8±1;

[0016] (2) stirring the mixed solution obtained in step (1), and then filtering, washing, and drying to obtain a solid;

[0017] (3) placing the solid obtained in step (2) in a furnace, introducing an oxygen-containing atmosphere for heat treatment, and obtaining a lithium-rich manganese-based material with a high ion channel and a highly stable surface after cooling.

[0018] Step (1):

[0019] The amount (mass) of dopamine added in step (1) is 0-10% of the mass of the lithium-rich manganese-based material, and is not 0.

[0020] The coating raw material in step (1) is at least one of ammonium sulfate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, potassium phosphate, sodium phosphate, potassium niobate, sodium niobate, potassium pyrophosphate, sodium pyrophosphate, potassium vanadate, sodium vanadate, potassium silicate, sodium silicate, potassium aluminate, and sodium aluminate;

[0021] The amount of the coating raw material added in step (1) (calculated as the molar amount of anions) is 0-200% of the molar amount of the lithium-rich manganese-based material, and is not 0;

[0022] Step (2):

[0023] The stirring time of step (2) is 1-5 hours.

[0024] Step (3):

[0025] The oxygen-containing atmosphere in step (3) is air or oxygen, the heat treatment temperature is 150-450° C., and the heat treatment time is 0.5-5 hours.

[0026] After the sintering temperature (or inert atmosphere) is increased, the reducing environment caused by the carbonization of dopamine will reduce the metal elements on the surface of the lithium-rich manganese-based material, resulting in a decrease in the manganese valence state in the formed spinel, thereby forming LiMn 2 O 4 (Mn chemical valence is +3.5), and the present invention adopts low temperature air calcination to form Li 4 Mn 5 O 12 (Mn valence is +4) is a necessary condition for spinel. From the perspective of crystal structure and JT effect, the latter has stronger structural stability.

[0027] The present invention is based on the in-situ polymerization reaction of dopamine to obtain Li 4 Mn 5 O 12 Surface composite coating of spinel and fast ion.

[0028] In a third aspect, the present invention provides a lithium-ion battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode comprises the above-mentioned lithium-rich manganese-based material with high ion channels and high stability surface.

[0029] Beneficial effects:

[0030] (1) The lithium-rich manganese-based material with efficient ion channels and stable surface layer disclosed in the present invention has excellent electrochemical properties, can achieve a high rate discharge of 15C, and the capacity retention rate can reach 90% after 500 cycles, which is mainly due to the three-dimensional lithium transmission channel and the stable surface composite combination to improve the structural stability. The "zero strain" material Li 4 Mn 5 O 12 The in-situ introduction of the structure not only provides a lithium ion transmission channel, but also acts as a transition layer between the matrix material and polydopamine, avoiding the peeling of the coating layer and the matrix material after long-term cycling, and significantly improving the cycle life of the material.

[0031] (2) The method adopted by the present invention has simple process and mild conditions, and can be treated at a low temperature of 150-450° C. in an air atmosphere. The process cost is low and can be used for industrial mass production.

[0032] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention;

[0034] Figure 2 This is a high-resolution transmission electron microscope photograph of Example 1;

[0035] Figure 3 This is a high-resolution transmission electron microscope photograph of Comparative Example 1;

[0036] Figure 4 The XRD patterns of Example 1 and Comparative Example 1 are shown in FIG.

[0037] Figure 5 The Raman spectra of Example 1 and Comparative Example 1;

[0038] Figure 6 It is the XRD pattern of comparative example 4;

[0039] Figure 7 The XPS spectra (Mn 2p) of Example 1 and Comparative Example 1;

[0040] Figure 8 The XPS spectrum (Mn 2p) of Comparative Example 3;

[0041] Fig. 9 The XPS spectra (S2p) of Example 1 and Comparative Example 1;

[0042] Fig.10The discharge specific capacities at different rates of Example 1 and Comparative Example 1;

[0043] Fig.11 The cycle performance of Example 1 and Comparative Example 1;

[0044] Fig.12 This is the cycle performance of Example 2. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0046] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0047] Preparation Example

[0048] The preparation process of GL-R1, a lithium-rich manganese-based positive electrode raw material independently developed by our company:

[0049] (1) weighing manganese sulfate, nickel sulfate and cobalt sulfate according to the lithium-rich manganese stoichiometric ratio and dissolving them in deionized water to obtain a metal salt solution, dissolving sodium hydroxide in deionized water to obtain a precipitant solution; mixing the metal salt solution and the sodium hydroxide solution, reacting at 50° C. to obtain a suspension, washing, filtering and drying, and obtaining a manganese-cobalt-nickel coprecipitation precursor;

[0050] (2) The manganese, cobalt, and nickel coprecipitation precursor and lithium carbonate (in terms of lithium) were weighed at a molar ratio of 1:1.18, and the mixture was uniformly mixed and heated to 550°C at a heating rate of 3°C / min. After being kept at this temperature for 5 hours, the mixture was further heated to 900°C at the same heating rate and kept at this temperature for 12 hours. The sintering process was carried out in an air atmosphere, and after being cooled to room temperature, a polycrystalline lithium-rich manganese-based material Li 1.18 Mn 0.52 Co 0.15 Ni 0.15 O 2 .

[0051] Example 1

[0052] 2g of lithium-rich manganese-based positive electrode material GL-R1, 0.03g of dopamine, and 5g of ammonium sulfate were dissolved in 20mL of tris(hydroxymethyl)aminomethane buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5, and stirred at room temperature for 1 hour, washed with deionized water, filtered three times, and vacuum dried. The dried sample was placed in a muffle furnace and air was introduced, and the temperature was raised to 375℃ at a rate of 3℃ / min and kept for 2 hours, and naturally cooled to room temperature to obtain a surface layer of lithium sulfate and polydopamine complex, and a subsurface layer of Li 4 Mn 5 O12 Lithium-rich manganese-based materials with spinel layers.

[0053] Example 2

[0054] 2g of lithium-rich manganese-based cathode material raw material GL-R1, 0.03g of dopamine, and 5g of ammonium sulfate were dissolved in 20mL of tris(hydroxymethyl)aminomethane buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5, and stirred at room temperature for 1 hour, washed with deionized water, filtered three times, and vacuum dried. The dried sample was placed in a muffle furnace and air was introduced, and the temperature was raised to 450℃ at a rate of 3℃ / min for 2 hours, and naturally cooled to room temperature to obtain a surface layer of lithium sulfate and polydopamine complex, and a subsurface layer of Li 4 Mn 5 O 12 Lithium-rich manganese-based materials with spinel layers.

[0055] Example 3

[0056] 2g of lithium-rich manganese-based cathode material raw material GL-R1, 0.03g of dopamine, and 5g of potassium niobate were dissolved in 20mL of tris(hydroxymethyl)aminomethane buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5. The mixture was stirred at room temperature for 1 hour, washed with deionized water, filtered three times, and vacuum dried. The dried sample was placed in a muffle furnace and air was introduced. The temperature was raised to 375℃ at a rate of 3℃ / min and kept for 2 hours. The mixture was naturally cooled to room temperature to obtain a surface layer of lithium sulfate and polydopamine complex, and a subsurface layer of Li 4 Mn 5 O 12 Lithium-rich manganese-based materials with spinel layers.

[0057] Example 4

[0058] 2g of lithium-rich manganese-based positive electrode material GL-R1, 0.03g of dopamine, and 5g of potassium orthovanadate were dissolved in 20mL of tris(hydroxymethyl)aminomethane buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5. The mixture was stirred at room temperature for 1 hour, washed with deionized water, filtered three times, and vacuum dried. The dried sample was placed in a muffle furnace and air was introduced. The temperature was raised to 375°C at a rate of 3°C / min and kept for 2 hours. The sample was naturally cooled to room temperature to obtain a surface layer of lithium sulfate and polydopamine complex, and a subsurface layer of Li 4 Mn 5 O 12 Lithium-rich manganese-based materials with spinel layers.

[0059] Example 5

[0060] 2g of lithium-rich manganese-based positive electrode material GL-R1, 0.03g of dopamine, and 4.6g of potassium aluminate were dissolved in 20mL of tris(hydroxymethyl)aminomethane buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5. The mixture was stirred at room temperature for 1 hour, washed with deionized water, filtered three times, and vacuum dried. The dried sample was placed in a muffle furnace and air was introduced. The temperature was raised to 375°C at a rate of 3°C / min and kept for 2 hours. The mixture was naturally cooled to room temperature to obtain a surface layer of lithium sulfate and polydopamine complex, and a subsurface layer of Li 4 Mn 5 O 12 Lithium-rich manganese-based materials with spinel layers.

[0061] Comparative Example 1

[0062] Lithium-rich manganese-based positive electrode material GL-R1 without any modification.

[0063] Comparative Example 2

[0064] 2 g of lithium-rich manganese-based positive electrode material raw material GL-R1, 0.03 g of dopamine, and 5 g of ammonium sulfate were dissolved in 20 mL of tris(hydroxymethyl)aminomethane buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5. The mixture was stirred at room temperature for 1 hour, washed with deionized water, filtered three times, and vacuum dried. The dried sample was placed in a muffle furnace and air was introduced. The temperature was increased to 500°C at a rate of 3°C / min and kept for 2 hours. The modified lithium-rich manganese-based material was obtained by naturally cooling to room temperature.

[0065] Comparative Example 3

[0066] 2 g of lithium-rich manganese-based positive electrode material raw material GL-R1, 0.03 g of dopamine, and 5 g of ammonium sulfate were dissolved in 20 mL of tris(hydroxymethylaminomethane) buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5. The mixture was stirred at room temperature for 1 hour, washed with deionized water, filtered three times and vacuum dried. The dried sample was placed in a muffle furnace and nitrogen was introduced. The temperature was increased to 375°C at a rate of 3°C / min and kept for 2 hours. The modified lithium-rich manganese-based material was obtained by naturally cooling to room temperature.

[0067] Comparative Example 4

[0068] 2g of lithium-rich manganese-based positive electrode material GL-R1, 0.03g of dopamine, and 15g of ammonium sulfate were dissolved in 20mL of tris(hydroxymethyl)aminomethane buffer, and a trace amount of hydrochloric acid was added to adjust the pH of the system to 8.5, and stirred at room temperature for 1 hour, washed with deionized water, filtered three times, and vacuum dried. The dried sample was placed in a muffle furnace and air was introduced, and the temperature was raised to 375℃ at a rate of 3℃ / min for 2 hours, and naturally cooled to room temperature to obtain a surface layer of lithium sulfate and polydopamine complex, and a subsurface layer of Li 4 Mn 5 O 12Lithium-rich manganese-based materials with spinel layers.

[0069] Figure 2 and Figure 3 These are high-resolution transmission electron microscopy images of Example 1 and Comparative Example 1. It can be seen that both the surface and the interior of the bulk of Comparative Example 1 are layered structures, while obvious polydopamine layers and spinel layers can be seen in Example 1.

[0070] Figure 4 and Figure 5 The XRD and Raman spectra of Example 1 and Comparative Example 1 are given. From the XRD graph, it can be seen that Comparative Example 1 is a typical layered structure, while Example 1 has a spinel peak at a diffraction angle of 43.5°. Figure 5 Raman spectroscopy can also prove the existence of spinel phase.

[0071] Figure 6 The XRD spectrum of the sample in Comparative Example 4 is given. It can be seen that when the amount of ammonium sulfate added is increased to 15 g, the peak near 22.5° in the XRD spectrum corresponds to Li 2 SO 4 However, adding too much ammonium sulfate will affect its performance.

[0072] Figure 7 The XPS-Mn-2p spectra of Example 1 and Comparative Example 1 are given. It can be seen that after the modification treatment, the binding energy is around 642 eV corresponding to Mn 4+ The peak ratio of Mn increased, indicating that Mn reduction did not occur after treatment, and further confirmed that the formed spinel phase was high-valent Li 4 Mn 5 O 12 Spinel instead of LiMn 2 O 4 Spinel, the latter is more susceptible to the Jahn-Taylor effect and deteriorates material properties.

[0073] Fig. 9 The XPS-S-2p spectra of Example 1 and Comparative Example 1 are given. It can be seen that after treatment, a 2p peak of S appears at around 168.5 eV, corresponding to SO 4 , combined with XRD, it can be proved that Li 2 SO 4 formation.

[0074] Comparative Example 2: High-temperature sintering in air will cause oxidation and decomposition of the polydopamine layer on the surface, and cannot form the highly stable surface structure described in the present invention, thus affecting the cycle life of the material.

[0075] Figure 8The XPS-Mn-2p spectrum of Comparative Example 3 is given. It can be seen that after sintering under inert atmosphere, the binding energy is around 642 eV, corresponding to Mn 4+ The proportion dropped to 38.46%, which is lower than the original material without any treatment (43.91%), indicating that Mn was reduced under inert atmosphere and the average valence decreased. Comparative Example 3 Under inert atmosphere sintering, dopamine will be carbonized as a carbon source, resulting in a reducing atmosphere on the surface of the material, reducing the valence of manganese in the structure, and the surface layer has a higher proportion of Mn 3+ , thus affecting Li 4 Mn 5 O 12 (All Mn 4+ ) formation, affecting the rate and cycle performance of the material.

[0076] Electrochemical performance test:

[0077] The positive electrode active material, acetylene black, polyvinylidene fluoride and N-methylpyrrolidone are mixed to form a slurry, which is evenly coated on the surface of an aluminum foil to obtain a positive electrode plate; then, a lithium plate is used as a negative electrode plate, and a 1 mol / L lithium hexafluorophosphate ethylene carbonate (EC) and dimethyl carbonate (DMC) solution (the volume ratio of EC to DMC is 1:1) is used as an electrolyte, and assembled in a glove box to obtain a lithium-ion battery.

[0078] The lithium-ion battery was tested for cycle performance using an electrochemical tester at a temperature of 25°C and a current density of 0.1C (1C = 200 mAg -1 ), the charge and discharge voltage range is 4.8-2.0V, the initial charge and discharge performance of the battery is tested, the subsequent charge current is 0.2C, and the discharge current is 1C, 3C, 5C, 10C and 15C to test the discharge capacity at different rates. The cycle performance is tested at 2.0-4.8V, 1C / 1C.

[0079] Negative electrode Mn content test:

[0080] The button cell after the cycle was disassembled in a glove box, and the powder on the positive electrode sheet was scraped off after drying. The manganese content in the powder was tested using the ICP method in accordance with the national standard GB / T 23942-2009.

[0081] The results are shown in Table 1.

[0082] Table 1 Comparison of electrochemical performance of examples and comparative examples

[0083]

[0084] Fig.10 and Fig.11 The rate and cycle performance of Example 1 and Comparative Example 1 are given respectively. Fig.12 The cycle performance of Example 2 is given, and it can be seen that the electrochemical performance of the lithium-rich manganese-based material with efficient ion channels and a stable surface layer proposed in the present invention is significantly improved.

[0085] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A lithium-rich manganese-based material with high ion channels and high surface stability, characterized in that: The structure of the lithium-rich manganese-based material includes a bulk phase, a subsurface layer and a surface layer from the inside to the outside, wherein the bulk phase is a lithium-rich manganese-based material with a layered structure, and the subsurface layer is a spinel-structured Li4Mn5O 12 The surface layer is a composite layer of polydopamine and fast ion conductor.

2. The lithium-rich manganese-based material with high ion channels and high surface stability according to claim 1, characterized in that: The general chemical formula of the lithium-rich manganese-based material is xLi2MnO3·(1-x)LiMO2, wherein 0.1≤x≤0.9, and M is one or more of Ni, Co, Mn, Cr, Fe, Ti, Mo, Ru, V, Nb, Zr and Sn.

3. The lithium-rich manganese-based material with high ion channels and high surface stability according to claim 1, characterized in that: The fast ion conductor is at least one of lithium sulfate, lithium phosphate, lithium pyrophosphate, lithium niobate, lithium vanadate, lithium silicate, and lithium aluminate.

4. The lithium-rich manganese-based material with high ion channels and high surface stability according to claim 1, characterized in that: The thickness of the subsurface layer is 1-5nm, and the thickness of the surface layer is 5-20nm.

5. A method for preparing the lithium-rich manganese-based material with high ion channels and high surface stability according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) dissolving the lithium-rich manganese-based material, dopamine and coating raw materials in tris(hydroxymethylaminomethane) buffer, and adjusting the pH of the system to 8±1; (2) stirring the mixed solution obtained in step (1), and then filtering, washing, and drying to obtain a solid; (3) placing the solid obtained in step (2) in a furnace, introducing an oxygen-containing atmosphere for heat treatment, and obtaining a lithium-rich manganese-based material with a high ion channel and a highly stable surface after cooling.

6. The preparation method according to claim 5, characterized in that: The amount of dopamine added in step (1) is 0%-10% of the mass of the lithium-rich manganese-based material, and is not 0.

7. The preparation method according to claim 5, characterized in that: The coating raw material in step (1) is at least one of ammonium sulfate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, potassium phosphate, sodium phosphate, potassium niobate, sodium niobate, potassium pyrophosphate, sodium pyrophosphate, potassium vanadate, sodium vanadate, potassium silicate, sodium silicate, potassium aluminate, and sodium aluminate; The amount of the coating raw material added in step (1) is 0-200% of the molar amount of the lithium-rich manganese-based material calculated as the molar amount of anions, and is not 0.

8. The preparation method according to claim 5, characterized in that: The stirring time of step (2) is 1-5 hours.

9. The preparation method according to claim 5, characterized in that: The oxygen-containing atmosphere in step (3) is air or oxygen, the heat treatment temperature is 150-450° C., and the heat treatment time is 0.5-5 hours.

10. A lithium-ion battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode comprises the lithium-rich manganese-based material with high ion channels and high stable surface as described in any one of claims 1 to 4 or the lithium-rich manganese-based material with high ion channels and high stable surface prepared by the preparation method according to any one of claims 5 to 9.

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