A sodium-ion battery manganese-based layered oxide positive electrode material with high-pressure resistance and long cycle and a preparation method thereof

Abstract

This invention discloses a manganese-based crystalline oxide cathode material for sodium-ion batteries with high-voltage and long-cycle resistance, and its preparation method, belonging to the field of sodium battery material technology. The chemical formula of the manganese-based crystalline oxide cathode material for sodium-ion batteries with high-voltage and long-cycle resistance is Na. x A y B z Mn (1‑y‑z) O2, 0 < x ≤ 1, 0.1 ≤ y ≤ 0.3, 0 < z < 0.9, A is at least one of Li, Mg, Zn, Cu and vacancy (□), B is an element with strong covalent affinity to oxygen. The preparation method used in this invention is a solid-state reaction method, which is simple to operate, easy to control, has a short process flow, and is easy to industrialize. The cathode material provided by this invention can realize electron transfer from Mn to Zn based on the difference in electronegativity between elements. 3+ Transfer to B (MMCT) significantly reduces Mn after electrode cycling. 3+ The content of Mn. Cathode materials with the MMCT mechanism significantly inhibited Mn content. 3+ The Ginger-Taylor distortion exhibits higher crystal structure stability and superior high pressure resistance and cyclic stability.

Description

Technical Field

[0001] This invention belongs to the field of sodium battery materials technology, and particularly relates to a manganese-based basal oxide cathode material for sodium-ion batteries with high voltage resistance and long cycle life, and its preparation method. Background Technology

[0002] With the advent of the electrification era, the demand for rechargeable devices has increased dramatically. However, currently commercialized lithium-ion batteries face problems such as resource depletion and soaring costs, making it difficult to meet the growing demand for rechargeable devices and large-scale energy storage. Sodium-ion batteries, with their advantages of high abundance, wide distribution, and non-toxicity, have enormous potential in large-scale energy storage devices. Cathode materials, as a crucial component of sodium batteries, account for almost one-third of the battery cost and limit the battery's energy density. Among various cathode materials, manganese-based layered oxides have significant advantages as cathode materials for sodium-ion batteries.

[0003] Currently, sodium-ion batteries, which rely solely on the redox reactions of transition metal cations to provide capacity, have reached their energy density limit. Therefore, redox reactions of oxygen anions have been introduced to improve their energy density. However, anion redox reactions often involve excessive oxidation, leading to the release of oxygen and the production of trivalent manganese with Gain-Tale distortion at the end of discharge, severely compromising the battery's long-cycle performance. Furthermore, the low coulombic efficiency, slow kinetics, and voltage decay of anion redox reactions in the first cycle also significantly limit their practical application. Summary of the Invention

[0004] To address the aforementioned electrochemical problems of anion redox active cathode materials, such as poor high-voltage stability, poor cycle performance, slow kinetics, and severe Jan-Taylor distortion, this invention proposes a high-voltage, long-cycle-resistant manganese-based layered oxide cathode material for sodium-ion batteries and its preparation method. The preparation method of this material is simple, the materials are widely available, and the reaction conditions are easy to control. The manganese-based layered oxide cathode material for sodium-ion batteries prepared using the method of this invention exhibits improved Mn content after cycling. 3+ The content of [a specific component] was significantly reduced, which significantly suppressed the Ginger-Taylor distortion. Sodium-ion batteries assembled using this cathode material can fully utilize the capacity contributed by anion redox reactions, greatly improving the energy density of the battery, and have the ability to withstand high voltage, high-rate charge and discharge, and long-cycle stability.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a manganese-based layered oxide cathode material for sodium-ion batteries with high-voltage, long-cycle resistance, and its chemical formula is Na. x A y B z Mn (1-y-z)O2, where 0 < x ≤ 1, 0.1 ≤ y ≤ 0.3, 0 < z < 0.9, A is at least one of Li, Mg, Zn, Cu and vacancy (□), and B is an element with strong covalent affinity to oxygen, which can construct an asymmetric BO-Mn configuration; The high voltage range of the sodium-ion battery manganese-based layered oxide cathode material with high voltage resistance and long cycle life is ≥4.3 V.

[0006] The sodium-ion battery manganese-based layered oxide cathode material provided by this invention, which has high-voltage and long-cycle resistance, can realize electron transfer from Mn based on the difference in electronegativity between elements. 3+ Transfer to B (MMCT) significantly reduces Mn after electrode cycling. 3+ Therefore, the cathode material of this invention is a cathode material with a MMCT mechanism. This cathode material with a MMCT mechanism significantly inhibits the content of Mn. 3+ The Ginger-Taylor distortion exhibits higher crystal structure stability and superior high pressure resistance and cyclic stability.

[0007] The principle of this invention is as follows: First, the doping of A ions into the transition metal layer introduces a Na-OA configuration into the sodium-ion layered oxide, activating the redox activity of anions (oxygen anions). The participation of anions greatly increases the energy density of the battery, effectively alleviating range anxiety. However, anion redox is often uncontrollable, accompanied by the release of a large amount of oxygen. This released oxygen cannot be reduced in the subsequent discharge state, so tetravalent manganese will participate in charge compensation, leading to the formation of a large amount of trivalent manganese. Trivalent manganese has significant Jan-Taylor distortion, which leads to instability in the crystal structure, further resulting in capacity decay and long-cycle instability. Therefore, this invention further incorporates B ions to address the Jan-Taylor distortion problem. B has strong electronegativity and a stronger attraction for electrons than manganese, resulting in an uneven electron distribution in the BO-Mn configuration. This asymmetric configuration allows charge transfer between B and Mn, thereby triggering changes in the valence state of the transition metal. Especially at the end of the discharge, the trivalent manganese content is high and there are unstable isolated electrons, making it very easy for charge transfer to B ions, thus forming tetravalent manganese. This significantly suppresses Jamie-Taylor distortion and improves crystal structure stability. Thanks to this mechanism, the manganese-based layered oxide cathode material of this invention solves the long-standing problem of Jamie-Taylor distortion and greatly improves the cycle stability of the electrode. Furthermore, it was found that this cathode material exhibits high-voltage resistance; even when charged to 4.3 V, it can maintain structural stability, which is beneficial for capacity retention.

[0008] Furthermore, B is selected from at least one of Ru, Ni, Fe, Co, Ir, and Cu.

[0009] Furthermore, in the chemical formula Nax A y B z Mn (1-y-z) In O2, 0.5≤x≤1, 0.1≤y≤0.2, and 0.17≤z≤0.3.

[0010] Furthermore, the chemical formula of the sodium-ion battery manganese-based layered oxide cathode material with high-voltage and long-cycle resistance is Na. 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2, Na 0.65 Li 0.15 Fe 0.2 Mn 0.65 O2, Na 0.7 Cu 0.2 Fe 0.3 Mn 0.5 O2, Na 0.6 Mg 0.15 Zn 0.05 □ 0.05 Ru 0.2 Mn 0.55 O2 or Na 0.67 Mg 0.1 Ni 0.23 Mn 0.67 O2.

[0011] This invention also provides a method for preparing the above-mentioned sodium-ion battery manganese-based layered oxide cathode material with high voltage and long cycle resistance, comprising the following steps: Weigh the sodium source, element A source, element B source and manganese source according to the proportion of each element in the chemical formula, with the sodium source and lithium source each in excess by 3-5% (in this invention, the default is mass percentage for solids and volume percentage for liquids). Since sodium salt and lithium salt will volatilize and be lost at high temperatures, they should be in excess. The sodium source, element A source, element B source and manganese source were mixed evenly and ball-milled to obtain a mixture precursor. The mixture precursor is subjected to high-temperature solid-state sintering at 700-900℃, and finally naturally cooled to obtain the layered oxide cathode material.

[0012] This invention first mixes the raw materials, and then sintersects them into a phase through a one-step solid-state reaction method. The resulting sodium-ion battery manganese-based layered oxide cathode material has uniform particle distribution and obvious layered structure, which is resistant to high voltage and long cycle. The preparation method provided by this invention is simple to operate. The target product can be obtained through simple mixing, calcination and other processes, and it is easy to achieve large-scale production.

[0013] Furthermore, the sodium source, element A source, element B source, and manganese source are all oxides of the corresponding elements.

[0014] Furthermore, the high-temperature solid-state sintering time is 8-20 hours.

[0015] Furthermore, the heating rate of the high-temperature solid-state sintering is 3℃-10℃ / min.

[0016] The present invention also provides a positive electrode sheet, which is prepared from the above-mentioned sodium-ion battery manganese-based basal oxide positive electrode material with high voltage resistance and long cycle life.

[0017] The present invention also provides the above-mentioned sodium-ion battery manganese-based crystalline oxide cathode material with high voltage resistance and long cycle life, and the application of the above-mentioned cathode sheet in the preparation of sodium-ion batteries.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: The manganese-based layered oxide cathode material for sodium-ion batteries provided by this invention exhibits high-voltage resistance, primarily due to the stability of oxygen by highly covalent elements. Furthermore, it facilitates electron transfer from Mn during discharge. 3+ The transfer to the highly electronegative element B significantly reduced the amount of Mn transferred. 3+ The content of Mn inhibited the Ginger-Taylor distortion. Results showed that applying the layered oxide cathode material of this invention to sodium-ion batteries resulted in sodium-ion batteries with high discharge specific capacity in the voltage range of 2-4.3 V, as well as excellent long-cycle stability and fast-charging performance. Even when discharging to low voltage, Mn... 3+ The content remains at a low level, and the problem of transition metal dissolution has been greatly improved.

[0019] The preparation method used in this invention is a solid-state reaction method, which can obtain the target product through simple mixing, calcination and other processes. This method is simple to operate, easy to control, has a short process flow, and is easy to achieve large-scale production. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 These are the XRD patterns of the manganese-based basal oxide cathode materials for sodium-ion batteries prepared in Examples 1-5, which have high-voltage and long-cycle resistance.

[0021] Figure 2 The images show the XRD patterns of manganese-based basal oxide cathode materials for sodium-ion batteries prepared in Comparative Examples 1-3 that do not involve MMCT.

[0022] Figure 3 This is a charge-discharge specific capacity curve of the sodium-ion battery in Example 1 for the first three cycles.

[0023] Figure 4 This is a charge-discharge specific capacity curve of the sodium-ion battery in Example 2 for the first three cycles.

[0024] Figure 5 This is a charge-discharge specific capacity curve of the sodium-ion battery in Example 3 for the first three cycles.

[0025] Figure 6 This is a charge-discharge specific capacity curve of the sodium-ion battery in Example 4 for the first three cycles.

[0026] Figure 7 This is a charge-discharge specific capacity curve of the sodium-ion battery in Example 5 during the first three cycles.

[0027] Figure 8 This is a charge-discharge specific capacity curve of the sodium-ion battery in Comparative Example 1 during the first three cycles.

[0028] Figure 9 This is a charge-discharge specific capacity curve of the sodium-ion battery in Comparative Example 2 during the first three cycles.

[0029] Figure 10 This is a charge-discharge specific capacity curve of the sodium-ion battery in Comparative Example 3 during the first three cycles.

[0030] Figure 11 This is a comparison chart of the long-cycle performance of sodium-ion batteries in Example 1 and Comparative Example 1.

[0031] Figure 12 This is a SEM image of the manganese-based basal oxide cathode material for sodium-ion batteries prepared in Example 1, which has high-voltage and long-cycle resistance. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] An embodiment of the present invention provides a manganese-based layered oxide cathode material for sodium-ion batteries with high-voltage and long-cycle resistance, the chemical formula of which is Na. x A y B z Mn (1-y-z) O2, where 0 < x ≤ 1, 0.1 ≤ y ≤ 0.3, 0 < z < 0.9, A is at least one of Li, Mg, Zn, Cu and vacancy (□), and B is an element with strong covalent affinity to oxygen; The high voltage range of the manganese-based layered oxide cathode material for sodium-ion batteries with high voltage resistance and long cycle life is ≥4.3V.

[0038] Strong covalent interactions exist between highly electronegative transition metal elements and oxygen atoms, leading to differences in electron cloud density. In this invention, element A in the chemical formula can activate oxygen activation, and element B, being an element with strong covalent interaction with oxygen, can construct an asymmetric BO-Mn configuration. This asymmetric BO-Mn configuration allows charge transfer between the transition metals (TM and Mn), thereby inducing a change in the valence state of the transition metal. The discharge process involves charge transfer from Mn to element B. This cathode material exhibits a superlattice-ordered arrangement, and its structural stability is more pronounced when the transition metal layers are arranged in a serrated pattern. This invention is highly suitable for preparing manganese-based oxygen-activated cathode materials with Gain-Taylor distortion, significantly improving their high-voltage and cycle stability.

[0039] In a preferred embodiment of the present invention, B is selected from at least one of Ru, Ni, Fe, Co, Ir, and Cu.

[0040] In a preferred embodiment of the present invention, in the chemical formula Na x A y B z Mn (1-y-z) In O2, 0.5≤x≤1, 0.1≤y≤0.2, and 0.17≤z≤0.3.

[0041] In a preferred embodiment of the present invention, the chemical formula of the sodium-ion battery manganese-based layered oxide cathode material with high voltage and long cycle resistance is Na. 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2, Na 0.65 Li 0.15 Fe 0.2 Mn 0.65 O2, Na 0.7 Cu 0.2 Fe 0.3 Mn 0.5 O2, Na 0.6 Mg 0.15 Zn 0.05 □ 0.05 Ru 0.2 Mn 0.55 O2 or Na 0.67 Mg 0.1 Ni 0.23 Mn 0.67 O2.

[0042] Embodiments of the present invention also provide a method for preparing the above-mentioned sodium-ion battery manganese-based layered oxide cathode material with high voltage and long cycle resistance, comprising the following steps: Weigh the sodium source, element A source, element B source, and manganese source according to the proportions of each element in the chemical formula, with the sodium source and element A source each in excess by 3-5% when they are lithium salts. The sodium source, element A source, element B source and manganese source were mixed evenly and ball-milled to obtain a mixture precursor. The mixed precursor is subjected to high-temperature solid-state sintering at 700-900℃, and finally naturally cooled to obtain the layered oxide cathode material.

[0043] In a preferred embodiment of the present invention, the sodium source, element A source, element B source and manganese source are all oxides of the corresponding elements.

[0044] In a preferred embodiment of the present invention, the sodium source is Na2CO3; the manganese source is MnO2; when A is Li, the element A source is Li2CO3; when A is Cu, the element A source is CuO; when A is Mg, the element A source is MgO; when A is Zn, the element A source is ZnO; when B is Ru, the element B source is RuO2; when B is Fe, the element B source is Fe2O3; and when B is Ni, the element B source is NiO.

[0045] In a preferred embodiment of the present invention, the ball milling time is 12-15 hours.

[0046] In a preferred embodiment of the present invention, the ball-milled material is first compressed into tablets, and then subjected to high-temperature solid-state sintering.

[0047] In a preferred embodiment of the present invention, the tableting pressure is 10 MPa.

[0048] In a preferred embodiment of the present invention, the temperature of high-temperature solid-state sintering is 800-900℃, preferably 800℃.

[0049] In a preferred embodiment of the present invention, the high-temperature solid-state sintering time is 8-20 hours, preferably 12-15 hours.

[0050] In a preferred embodiment of the present invention, the atmosphere during high-temperature solid-state sintering is at least one of air and oxygen; the heating rate is 3-10°C / min, preferably 5°C / min.

[0051] An embodiment of the present invention also provides a positive electrode sheet, which is prepared from the above-mentioned sodium-ion battery manganese-based basal oxide positive electrode material with high voltage resistance and long cycle life.

[0052] In a preferred embodiment of the present invention, the raw materials for preparing the above-mentioned positive electrode sheet include conductive additives, binders, organic solvents, and the above-mentioned sodium-ion battery manganese-based basal oxide positive electrode material with high voltage resistance and long cycle life.

[0053] In a preferred embodiment of the present invention, the mass ratio of the above-mentioned sodium-ion battery manganese-based basal oxide cathode material with high voltage resistance and long cycle life, conductive additives and binders is 8:1:1.

[0054] In a preferred embodiment of the present invention, the ratio of the sodium-ion battery manganese-based basal oxide cathode material with high voltage resistance and long cycle life to the organic solvent is 1g:1mL.

[0055] For example, the conductive additive is Super P, the binder is polyvinylidene fluoride (PVDF), and the organic solvent is N-methylpyrrolidone (NMP).

[0056] Embodiments of the present invention also provide the application of the above-mentioned sodium-ion battery manganese-based crystalline oxide cathode material with high voltage resistance and long cycle life, and the above-mentioned cathode sheet in the preparation of sodium-ion batteries.

[0057] An embodiment of the present invention also provides a sodium-ion battery, which includes the above-described positive electrode, separator, negative electrode and electrolyte.

[0058] In a preferred embodiment of the present invention, the separator in the sodium-ion battery is made of glass fiber, the negative electrode is made of metallic sodium sheet, and the electrolyte is a carbonate electrolyte.

[0059] For example, the electrolyte in a sodium-ion battery contains ethylene carbonate (EC), propylene carbonate (PC), lithium salt, and fluoroethylene carbonate (FEC), wherein the volume ratio of EC to PC is 1:1, the lithium salt is 1 M NaClO4, and the amount of FEC added is 5% of the total mass of EC, PC, and 1 M NaClO4.

[0060] CN117457888A discloses a layered oxide single-crystal cathode material for sodium-ion batteries, with the chemical formula Na. a Ni x Fe y Mn z M 1‑x‑y‑z O2, this cathode material has a single-crystal particle morphology, which is significantly different from the polycrystalline morphology of the cathode material of this invention. Compared with single-crystal particles, polycrystalline particles have a larger specific surface area and a shorter Na+ ionization. + Migration paths, which greatly improve Na + Diffusion kinetics.

[0061] CN116425212A discloses a high-entropy doped sodium-ion battery layered oxide with the chemical formula Na. x A y M z O 2 The cathode in this patent is a high-entropy cathode, which is significantly different from the conventional low-entropy cathode in this invention. This invention uses fewer element types, resulting in higher preparation efficiency and better showcasing the positive effects of element doping.

[0062] CN115939336A discloses a sodium-ion battery cathode material Na n Mn 1‑x‑y M x A y O 2M is at least one of Li, Mg, Cu, Ni, Ca, Zn, Fe, Cr, and Al, and A is at least one of Ta, Mo, W, Nb, Si, Sn, and V. Li in M ​​is used to increase the valence state of Mn, while the high-valence inactive element in A is used to stabilize the crystal lattice. The aim is to increase the valence state of Mn and improve the stability of the crystal structure. However, the selection of elements A and B in this invention is fundamentally different. This invention activates the capacity contribution of oxygen by doping with element A, thereby increasing the energy density of the electrode. Secondly, the doping with the highly electronegative element B is used to construct an asymmetric BO-Mn configuration, allowing Mn to transfer its electrons to element B, thereby suppressing the Jan-Taylor distortion. In summary, this invention not only efficiently improves the energy density of the battery but also greatly maintains the stability of the system.

[0063] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0064] All raw materials used in the embodiments of the present invention were obtained through commercial purchase.

[0065] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0066] The technical solution of the present invention will be further illustrated by the following embodiments.

[0067] Example 1 The chemical formula of the manganese-based substrate oxide cathode material for sodium-ion batteries prepared in this embodiment, which exhibits high-voltage and long-cycle resistance, is Na. 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2 is a manganese-based oxide cathode material for sodium-ion batteries, which is doped with Ru, an element with a significant difference in electronegativity from Mn, and is involved in MMCT. The preparation method of the above-mentioned sodium-ion battery manganese-based layered oxide cathode material with high voltage resistance and long cycle life is as follows: (1) Weigh out the corresponding amounts of Na2CO3 (3% excess), Li2CO3 (3% excess), RuO2 and MnO2 according to the proportion of each element in the chemical formula, mix them, ball mill for 12 hours, and press them into round discs with a diameter of 12 mm under a pressure of 10 MPa. (2) The pressed discs were placed in a corundum ceramic boat and calcined directly in an air atmosphere in a muffle furnace at a heating rate of 5 °C / min. After reaching 800 °C, the temperature was maintained for 12 hours, and then naturally cooled to room temperature to synthesize a sodium-ion battery manganese-based layered oxide cathode material (Na) with high-voltage and long-cycle resistance. 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2).

[0068] Preparation of Na 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2 positive electrode plate Prepare 1 g of Na 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2 cathode material, conductive additive Super P, and binder polyvinylidene fluoride (PVDF) were uniformly mixed at a mass ratio of 8:1:1, and 1 mL of solvent N-methylpyrrolidone (NMP) was added. After stirring for 4 hours, a uniform slurry was obtained. The slurry was then uniformly coated onto carbon-coated aluminum foil using a 150 μm scraper. After drying in a vacuum drying oven at 100℃ for 12 hours, the foil was removed and cut into Na particles with a diameter of 12 mm. 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2 positive electrode plate.

[0069] Assemble sodium-ion batteries The Na prepared above 0.69 Li 0.23 Ru 0.17 Mn 0.6 The O2 positive electrode and the sodium metal negative electrode are assembled into a CR 2032 sodium battery. The separator is made of glass fiber, and the electrolyte is a commercial carbonate electrolyte of 1 M NaClO4 in EC (ethylene carbonate): PC (propylene carbonate) = 1:1 (volume ratio), with 5% FEC (fluoroethylene carbonate).

[0070] Sodium-ion battery testing The electrochemical performance of the aforementioned sodium-ion batteries was tested using the Wuhan Landian Battery Testing System.

[0071] Example 2 The chemical formula of the manganese-based substrate oxide cathode material for sodium-ion batteries prepared in this embodiment, which exhibits high-voltage and long-cycle resistance, is Na. 0.65 Li 0.15 Fe 0.2 Mn 0.65 O2 is a manganese-based oxide cathode material for sodium-ion batteries, which is doped with Fe, an element with a significant difference in electronegativity from Mn, and is involved in MMCT. The preparation method of the above-mentioned sodium-ion battery manganese-based layered oxide cathode material with high voltage resistance and long cycle life is as follows: (1) Weigh out the corresponding amounts of Na2CO3 (5% excess), Li2CO3 (5% excess), Fe2O3 and MnO2 according to the proportion of each element in the chemical formula, mix them, ball mill for 12 hours, and press them into round discs with a diameter of 12 mm under a pressure of 10 MPa. (2) The pressed discs were placed in a corundum ceramic boat and calcined directly in an air atmosphere in a muffle furnace at a heating rate of 5 °C / min. After reaching 900 °C, the temperature was maintained for 15 hours, and then naturally cooled to room temperature to synthesize a sodium-ion battery manganese-based layered oxide cathode material (Na) with high-voltage and long-cycle resistance. 0.65 Li 0.15 Fe 0.2 Mn 0.65 O2).

[0072] Using the above-mentioned sodium-ion battery manganese-based basal oxide cathode material with high voltage resistance and long cycle life, a cathode sheet and a sodium-ion battery were prepared. The preparation of the cathode sheet, the assembly of the sodium-ion battery, and the testing steps of the sodium-ion battery were the same as in Example 1.

[0073] Example 3 The chemical formula of the manganese-based substrate oxide cathode material for sodium-ion batteries prepared in this embodiment, which exhibits high-voltage and long-cycle resistance, is Na. 0.7 Cu 0.2 Fe 0.3 Mn 0.5 O2 is a manganese-based oxide cathode material for sodium-ion batteries, which is doped with Fe, an element with a significant difference in electronegativity from Mn, and is involved in MMCT. The preparation method of the above-mentioned sodium-ion battery manganese-based layered oxide cathode material with high voltage resistance and long cycle life is as follows: (1) Weigh out the corresponding amounts of Na2CO3 (5% excess), CuO, Fe2O3 and MnO2 according to the proportion of each element in the chemical formula, mix them, ball mill for 12 hours, and press them into round discs with a diameter of 12 mm under a pressure of 10 MPa. (2) The pressed discs were placed in a corundum ceramic boat and calcined directly in an air atmosphere in a muffle furnace at a heating rate of 5 °C / min. After heating to 900 °C, the temperature was maintained for 15 hours and then naturally cooled to room temperature to synthesize a sodium-ion battery manganese-based morphological oxide cathode material with high pressure resistance and long cycle life.

[0074] Using the above-mentioned sodium-ion battery manganese-based basal oxide cathode material with high voltage resistance and long cycle life, a cathode sheet and a sodium-ion battery were prepared. The preparation of the cathode sheet, the assembly of the sodium-ion battery, and the testing steps of the sodium-ion battery were the same as in Example 1.

[0075] Example 4 The chemical formula of the manganese-based substrate oxide cathode material for sodium-ion batteries prepared in this embodiment, which exhibits high-voltage and long-cycle resistance, is Na. 0.6 Mg 0.15 Zn 0.05 □ 0.05 Ru 0.2 Mn 0.55 O2 is a manganese-based oxide cathode material for sodium-ion batteries, which is doped with Ru, an element with a significant difference in electronegativity from Mn, and is involved in MMCT. The preparation method of the above-mentioned sodium-ion battery manganese-based layered oxide cathode material with high voltage resistance and long cycle life is as follows: (1) Weigh out the corresponding amounts of Na2CO3 (5% excess), MgO, ZnO, RuO2 and MnO2 according to the proportion of each element in the chemical formula, mix them, ball mill for 15 hours, and press them into round discs with a diameter of 12 mm under a pressure of 10 MPa. (2) The pressed discs were placed in a corundum ceramic boat and calcined directly in an oxygen atmosphere in a muffle furnace at a heating rate of 10 °C / min. After heating to 850 °C, the temperature was maintained for 15 hours and then naturally cooled to room temperature to synthesize a sodium-ion battery manganese-based morphological oxide cathode material with high pressure resistance and long cycle life.

[0076] Using the above-mentioned sodium-ion battery manganese-based basal oxide cathode material with high voltage resistance and long cycle life, a cathode sheet and a sodium-ion battery were prepared. The preparation of the cathode sheet, the assembly of the sodium-ion battery, and the testing steps of the sodium-ion battery were the same as in Example 1.

[0077] Example 5 The chemical formula of the manganese-based substrate oxide cathode material for sodium-ion batteries prepared in this embodiment, which exhibits high-voltage and long-cycle resistance, is Na. 0.67 Mg 0.1 Ni 0.23 Mn 0.67 O2 is a manganese-based oxide cathode material for sodium-ion batteries that is doped with Ni, an element with a significant difference in electronegativity from Mn, and is involved in MMCT. The preparation method of the above-mentioned sodium-ion battery manganese-based layered oxide cathode material with high voltage resistance and long cycle life is as follows: (1) Weigh out the corresponding amounts of Na2CO3 (3% excess), MgO, NiO and MnO2 according to the proportion of each element in the chemical formula, mix them, ball mill for 12 hours, and press them into round discs with a diameter of 12 mm under a pressure of 10 MPa. (2) The pressed discs were placed in a corundum ceramic boat and calcined directly in an air atmosphere in a muffle furnace at a heating rate of 3 ℃ / min. After heating to 800 ℃, the temperature was maintained for 15 hours and then naturally cooled to room temperature to synthesize a sodium-ion battery manganese-based morphological oxide cathode material with high pressure resistance and long cycle life.

[0078] Using the above-mentioned sodium-ion battery manganese-based basal oxide cathode material with high voltage resistance and long cycle life, a cathode sheet and a sodium-ion battery were prepared. The preparation of the cathode sheet, the assembly of the sodium-ion battery, and the testing steps of the sodium-ion battery were the same as in Example 1.

[0079] Comparative Example 1 Preparation of Na 0.69 Li 0.23 Mn 0.77 O2 is a manganese-based oxide cathode material for sodium-ion batteries that does not involve MMCT. In step (1), the raw materials are changed to Na2CO3, Li2CO3 and MnO2, and the remaining steps and sodium-ion battery testing methods are the same as in Example 1.

[0080] Comparative Example 2 Preparation of Na 0.69 Li 0.23 Ti 0.17 Mn 0.6 O2 is a manganese-based oxide cathode material for sodium-ion batteries that does not involve MMCT. In step (1), the raw materials are changed to Na2CO3, Li2CO3, TiO2 and MnO2, and the remaining steps and sodium-ion battery testing methods are the same as in Example 1.

[0081] Comparative Example 3 Preparation of Na 0.75 Mg 0.1 Li 0.15 Al 0.1 Mn 0.65 O2 is a manganese-based oxide cathode material for sodium-ion batteries that does not involve MMCT; the specific steps are as follows: (1) Weigh out the corresponding amounts of Na2CO3 (5% excess), Li2CO3 (5% excess), MgO, Al2O3 and MnO2 according to the proportion of each element in the chemical formula, mix them, ball mill for 12 hours, and press them into round discs with a diameter of 12 mm under a pressure of 10 MPa. (2) The pressed discs were placed in a corundum ceramic boat and calcined directly in an air atmosphere in a muffle furnace at a heating rate of 5 °C / min. After heating to 850 °C, the temperature was held for 15 hours and then naturally cooled to room temperature to synthesize the target sodium-ion battery manganese-based morphological oxide cathode material.

[0082] The above-mentioned sodium-ion battery manganese-based basal oxide cathode material was used to prepare a cathode sheet and a sodium-ion battery. The preparation of the cathode sheet, the assembly of the sodium-ion battery, and the testing steps of the sodium-ion battery were the same as in Example 1.

[0083] The layered oxide cathode materials prepared in the above embodiments and comparative examples of the present invention were tested. For the electrochemical performance tests, the voltage range for coin cell charge / discharge was 2.0-4.3 V, and all electrochemical performance tests were performed at room temperature.

[0084] XRD tests were performed on the layered oxide cathode materials prepared in the above embodiments and comparative examples of the present invention. XRD patterns of layered oxide cathode material samples were obtained using an X-ray diffractometer by taking advantage of the diffraction effect of X-rays in crystals. The diffraction patterns of the materials were then effectively analyzed according to standard PDF cards.

[0085] Figure 1 The XRD patterns of the sodium-ion battery manganese-based layered oxide cathode materials with high-voltage and long-cycle resistance prepared in Examples 1-5 are shown. All samples exhibit relatively sharp peaks, indicating good crystallinity and a hexagonal P2 phase layered structure with almost no impurity peaks. The sodium-ion battery manganese-based layered oxide cathode material prepared in Example 1 has the best morphology. Comparison with the standard PDF card confirms that the sodium-ion battery manganese-based layered oxide cathode material prepared in Example 1 is a typical P2-type layered oxide, space group [missing information]. P6 3 The superlattice diffraction peaks observed between 20° and 28° indicate that the transition metal layer in Example 1 has a honeycomb-shaped ordered superlattice structure and is arranged in a serrated order between the transition metal layers, which is beneficial to improving cycle stability.

[0086] Figure 2 The XRD patterns of the sodium-ion battery manganese-based layered oxide cathode materials prepared in Comparative Examples 1-3 without involving MMCT are shown. It can be seen that the samples obtained in Comparative Examples 1-3 are all P2 layered structures without impurity phases.

[0087] Figure 3 The graph shows the charge-discharge specific capacity curves of the sodium-ion battery in Example 1 for the first three cycles. It can be seen that at 20 mA·g... -1 At a current density of 2.0–4.3 V, the sodium-ion battery achieved a first-cycle efficiency of 177.4 mAh·g. -1 The specific charging capacity is 154.3 mAh·g. -1 The discharge specific capacity still remains at 147.9 mAh·g after three cycles. -1 The preferred cathode material fully utilizes the additional capacity provided by anion redox and exhibits good capacity retention.

[0088] Figure 4 The graph shows the charge-discharge specific capacity curves of the sodium-ion battery in Example 2 for the first three cycles. It can be seen that at 20 mA·g...-1 At the specified current density, within a voltage range of 2.0-4.3 V, the first charge-discharge specific capacity of the sodium-ion battery was 138.7 / 139.9 mAh·g, respectively. -1 The reversible capacity after three cycles is 136.0 mAh·g. -1 .

[0089] Figure 5 The graph shows the charge-discharge specific capacity curves of the sodium-ion battery in Example 3 for the first three cycles. It can be seen that at 20 mA·g... -1 At the specified current density, within a voltage range of 2.0–4.3 V, the first charge-discharge specific capacities of the sodium-ion battery were 119.9 / 127.2 mAh·g, respectively. -1 The reversible capacity after three cycles is 117.1 mAh·g. -1 .

[0090] Figure 6 The graph shows the charge-discharge specific capacity curves of the sodium-ion battery in Example 4 for the first three cycles. It can be seen that at 20 mA·g... -1 At the specified current density, within a voltage range of 2.0-4.3 V, the first charge-discharge specific capacity of the sodium-ion battery was 105.1 / 115.1 mAh·g, respectively. -1 The reversible capacity after three cycles is 101 mAh·g. -1 .

[0091] Figure 7 The graph shows the charge-discharge specific capacity curves of the sodium-ion battery in Example 5 for the first three cycles. It can be seen that at 20 mA·g... -1 At the specified current density, within a voltage range of 2.0–4.3 V, the first charge-discharge specific capacities of the sodium-ion battery were 142.1 / 131.1 mAh·g, respectively. -1 The reversible capacity after three cycles is 132.8 mAh·g. -1 .

[0092] Figure 8 The graph shows the charge-discharge specific capacity curves of the sodium-ion battery in Comparative Example 1 for the first three cycles. It can be seen that at 20 mA·g... -1 At the specified current density, within a voltage range of 2.0-4.3 V, the first charge-discharge specific capacity of the sodium-ion battery was 100.8 / 87.1 mAh·g, respectively. -1 The reversible capacity after three cycles is 86 mAh·g. -1 .

[0093] Figure 9 The chart shows the charge-discharge specific capacity curves of the sodium-ion battery in Comparative Example 2 for the first three cycles. It can be seen that at 20 mA·g... -1At the specified current density, within a voltage range of 2.0-4.3 V, the first charge-discharge specific capacity of the sodium-ion battery was 144.5 / 145.8 mAh·g, respectively. -1 The reversible capacity after three cycles is 128.7 mAh·g. -1 The capacity decay is significant. Different doping elements have different effects on battery performance. The sodium-ion battery in Comparative Example 2 only appears to have a high capacity in the first three cycles, but its cycle performance is poor in subsequent cycles. Moreover, the sodium-ion battery in Comparative Example 2 experiences a significant capacity decay in each of the first three cycles.

[0094] Figure 10 The chart shows the charge-discharge specific capacity curves of the sodium-ion battery in Comparative Example 3 for the first three cycles. It can be seen that at 20 mA·g... -1 At the specified current density, within a voltage range of 2.0-4.3 V, the first charge / discharge specific capacities of the sodium-ion battery were 153.2 / 132.8 mAh·g, respectively. -1 The reversible capacity after three cycles is 101.4 mAh·g. -1 The capacity decay is significant. Different doping elements cause changes in capacity, so performance differences cannot be judged solely by capacity levels. However, from the perspective of capacity retention, Comparative Example 3's performance is still inferior to the other examples.

[0095] Figure 11 This is a comparison graph showing the long-cycle performance of the sodium-ion battery in Example 1 and the sodium-ion battery in Comparative Example 1. (At 2000 mA·g) -1 At the specified current density and within a voltage range of 2.0-4.3 V, Example 1 achieved a capacity retention of over 80% after 900 cycles. In contrast, Comparative Example 1's capacity retention dropped to 80% after only 400 cycles.

[0096] Figure 12 The image shows the SEM image of the sodium-ion battery manganese-based crystalline oxide cathode material prepared in Example 1, which has high voltage resistance and long cycle life. It can be seen that the sample has a polycrystalline structure, which improves the kinetic performance of the sample.

[0097] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A manganese-based layered oxide cathode material for sodium-ion batteries with high-voltage, long-cycle resistance, characterized in that, The chemical formula is Na x A y B z Mn (1-y-z) O2, where 0 < x ≤ 1, 0.1 ≤ y ≤ 0.3, 0 < z < 0.9, A is at least one of Li, Mg, Zn, Cu and vacancy, and B is an element with strong covalent affinity to oxygen; The high voltage range of the sodium-ion battery manganese-based basal oxide cathode material with high voltage resistance and long cycle life is ≥4.3V.

2. The sodium-ion battery manganese-based layered oxide cathode material with high-voltage and long-cycle resistance according to claim 1, characterized in that, B is selected from at least one of Ru, Ni, Fe, Co, Ir, and Cu.

3. The sodium-ion battery manganese-based layered oxide cathode material with high-voltage and long-cycle resistance according to claim 1, characterized in that, 0.5≤x≤1, 0.1≤y≤0.2, 0.17≤z≤0.

3.

4. The sodium-ion battery manganese-based layered oxide cathode material with high-voltage and long-cycle resistance according to claim 1, characterized in that, The chemical formula is Na 0.69 Li 0.23 Ru 0.17 Mn 0.6 O2, Na 0.65 Li 0.15 Fe 0.2 Mn 0.65 O2, Na 0.7 Cu 0.2 Fe 0.3 Mn 0.5 O2, Na 0.6 Mg 0.15 Zn 0.05 □ 0.05 Ru 0.2 Mn 0.55 O2 or Na 0.67 Mg 0.1 Ni 0.23 Mn 0.67 O2.

5. A method for preparing a sodium-ion battery manganese-based layered oxide cathode material with high-voltage and long-cycle resistance as described in any one of claims 1-4, characterized in that, Includes the following steps: Weigh the sodium source, element A source, element B source, and manganese source according to the proportions of each element in the chemical formula, with the sodium source and lithium source each in excess by 3-5%; The sodium source, element A source, element B source and manganese source were mixed evenly and ball-milled to obtain a mixture precursor. The mixture precursor is subjected to high-temperature solid-state sintering at 700-900℃, and finally naturally cooled to obtain the layered oxide cathode material.

6. The method for preparing a manganese-based layered oxide cathode material for sodium-ion batteries with high-voltage and long-cycle resistance according to claim 5, characterized in that, The sodium source, element A source, element B source, and manganese source are all oxides of the corresponding elements.

7. The method for preparing a sodium-ion battery manganese-based layered oxide cathode material with high-voltage and long-cycle resistance according to claim 5, characterized in that, The heating rate for the high-temperature solid-state sintering is 3℃-10℃ / min.

8. The method for preparing a sodium-ion battery manganese-based layered oxide cathode material with high-voltage and long-cycle resistance according to claim 5, characterized in that, The high-temperature solid-state sintering time is 8-20 hours.

9. A positive electrode plate, characterized in that, It is prepared from the sodium-ion battery manganese-based crystalline oxide cathode material with high voltage resistance and long cycle life as described in any one of claims 1-4.

10. The application of a sodium-ion battery manganese-based crystalline oxide cathode material with high voltage resistance and long cycle life as described in any one of claims 1-4 and the cathode sheet as described in claim 9 in the preparation of sodium-ion batteries.

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