Copper-manganese disordered high-voltage copper-based oxide material and application

Abstract

The invention discloses a copper-manganese disordered high-voltage copper-based oxide material and application thereof. The chemical general formula of the material is Na < 0.67 > Cu < 0.33 > Mn < 0.67-x > A < x > O < 2 >, wherein the valence state of Cu is + 2, the valence state of Mn is + 4, A is one or more of Ti, Zr, Si, Ge, Sn, Hf, Pb, Ce and Th, x is more than or equal to 0.02 and less than or equal to 0.34, and the valence state of A is + 4; in the transition metal layer, transition metal ions are arranged disorderly, elements of the transition metal layer are migrated to the sodium layer under the voltage of 4.5 V, a Na-O-A configuration is constructed, and the energy density of the material is improved by activating the oxidation-reduction reaction of oxygen. The material is used for a positive pole piece of a sodium ion secondary battery. The copper-manganese disordered high-voltage copper-based oxide material provided by the invention is simple to prepare, and the contained elements sodium, copper, manganese and titanium are non-toxic and safe elements. In the material, redox of copper has high voltage on the material. In the transition metal layer, transition metal ions are arranged in a disordered mode, so that the oxidation-reduction reaction of oxygen is activated under high voltage.

Description

Technical Field

[0001] The present invention relates to an oxide material and application, in particular to a copper-manganese disordered high-voltage copper-based oxide material and application, belonging to the field of material technology. Background Art

[0002] With the widespread use of lithium-ion batteries in new energy vehicles and various large-scale energy storage devices, the demand for lithium resources is also increasing. Due to the limited reserves and uneven distribution of lithium resources, the cost of lithium-ion batteries has increased, so there is a need to find a new resource to alleviate the current shortage of lithium resources. Sodium and lithium are in the same main group and have similar chemical properties. In addition, sodium resources are abundant, inexpensive, and non-toxic. Therefore, sodium-ion batteries can, to a certain extent, alleviate the problem of battery development being hindered by the lack of lithium resources and, to a certain extent, complement the market application of lithium-ion batteries, especially in large-scale energy storage grids. At the same time, sodium-ion batteries have high energy storage conversion efficiency and long cycle life, which provides an opportunity to gradually replace the use of lead-acid batteries.

[0003] In addition to the problem of lithium resources, the reserves of other elements commonly used in lithium-ion batteries, such as cobalt, nickel, and copper (negative electrode current collector), in the earth's crust are also relatively low. In contrast, the reserves of elements commonly used in sodium-ion batteries, such as iron, manganese, and aluminum (positive and negative electrode current collectors), in the earth's crust are relatively high. This has also promoted the development of sodium-ion battery related research to a certain extent. Especially the recent emergence of positive electrode materials that do not contain nickel and cobalt elements, such as Na x FeMnO2 and Na x CuFeMnO2 layered oxide electrode material. Because lithium and aluminum react to form a lithium-aluminum alloy, this limits the use of aluminum foil as a current collector on the negative electrode side of lithium-ion batteries. However, sodium and aluminum do not form an alloy, so aluminum foil can replace copper foil as the current collector for sodium-ion battery anode materials, further reducing the cost of sodium-ion batteries. Furthermore, sodium-ion batteries and lithium-ion batteries share similar operating principles and material systems, allowing the equipment, technology, and methods used to produce lithium-ion batteries to be directly utilized in large-scale production, accelerating the industrialization of sodium-ion batteries.

[0004] Due to the large mass and radius of sodium ions, their migration speed in sodium storage materials is slow, hindering improvements in the rate performance of sodium-ion batteries and resulting in lower mass / volume energy density than lithium-ion batteries. In traditional layered transition metal oxides, transition metals are considered the sole redox centers in electrochemical reactions, and the specific capacity of the cathode material is limited by the variable-valence transition metal content. However, recent research has shown that in some layered transition metal oxides, anionic oxygen can also participate in electrochemical reactions. Cooperative redox reactions based on transition metals and anionic oxygen offer the potential to increase the specific capacity of layered cathode materials. Anionic redox activity was first observed in lithium-rich cathode materials with a Li-O-Li structure, generating non-bonded O 2p states. In sodium-ion batteries, this concept has been extended to layered oxide cathodes with a Na-OA structure, where vacancies in the alkali, alkaline earth, or transition metal layers are present. Furthermore, the average operating voltage of most current sodium-ion battery cathode materials is only around 3V, far lower than the 3.7V of ternary lithium-ion battery cathodes, which significantly limits the operating scenarios of sodium-ion batteries. Therefore, it is necessary to develop more high-voltage sodium-ion battery positive electrode materials.

[0005] Among the cathode materials for high-voltage sodium-ion batteries, Na 0.67 Cu 0.33 Mn 0.67 O2 is a copper-manganese ordered high-voltage copper-based oxide material that can reach over 3.5V for sodium metal and has a high energy density, making it suitable for large-scale applications. However, in its transition metal layer, manganese ions surround copper ions in an orderly honeycomb pattern. This periodic arrangement creates a very rigid crystal structure, resulting in minimal structural changes during charge and discharge. This prevents the activation of oxygen redox reactions at high voltages, further increasing energy density. Summary of the Invention

[0006] In order to solve the shortcomings of the above-mentioned technology, the present invention provides a copper-manganese disordered high-voltage copper-based oxide material and its application, so as to solve the problems of the existing copper-manganese ordered high-voltage copper-based oxide Na 0.67 Cu 0.33 Mn 0.67 The problem that O2 materials cannot activate the redox reaction of oxygen under high voltage.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a copper-manganese disordered high-voltage copper-based oxide material, the chemical formula of which is: Na 0.67 Cu 0.33 Mn 0.67-x A xO2; wherein the valence state of Cu is +2, the valence state of Mn is +4, A is one or more elements selected from Ti, Zr, Si, Ge, Sn, Hf, Pb, Ce, and Th, 0.02≤x≤0.34, and the valence state of A is +4;

[0008] In the transition metal layer, the transition metal ions are arranged in a disordered manner. At a voltage of 4.5V, the elements of the transition metal layer migrate to the sodium layer, constructing a Na-OA configuration and increasing the energy density of the material by activating the redox reaction of oxygen.

[0009] Preferably, the average operating voltage of the copper-manganese disordered high-voltage copper-based oxide material relative to metallic sodium is above 4.25V.

[0010] A positive electrode plate for a sodium ion secondary battery comprises a current collector, a conductive additive and a binder coated on the current collector, and a copper-manganese disordered high-voltage copper-based oxide material.

[0011] A sodium ion secondary battery comprising the above-mentioned positive electrode plate.

[0012] Preferably, the sodium ion secondary battery is used in any of large-scale energy storage devices for solar energy and wind power generation, or energy storage devices for smart grid peak regulation, distributed power stations, backup power supplies, communication base stations, and electric vehicles.

[0013] The present invention is mainly based on the redox reaction of copper and oxygen and the disordered copper-manganese positive electrode material structure, so that the material can activate the redox reaction of oxygen when working above 4.25V, thereby improving the reversible capacity and energy density.

[0014] In the transition metal layer, the transition metal ions are arranged in a disordered arrangement, which reduces the hardness of the crystal structure when arranged in an ordered manner. This makes interlayer sliding between the transition metal layers easy to occur under high voltage. Interlayer sliding generates octahedral sites in the sodium layer, allowing the transition metal ions to migrate from the transition metal layer to the Na layer through the octahedron-tetrahedron-octahedron pathway, and forming vacancies in the transition metal layer. This process produces a new Na-OA configuration, activates the reversible oxygen redox reaction, and improves the reversible capacity and energy density.

[0015] The copper-manganese disordered high-voltage copper-based oxide material provided by the present invention is simple to prepare, and the elements sodium, copper, manganese, and titanium it contains are all non-toxic and safe. In this material, the copper redox pair itself has a high voltage. In the transition metal layer, the transition metal ions are arranged in a disordered arrangement, resulting in the activation of oxygen redox reactions under high voltage. The charge capacity is its theoretical capacity, the cycle is stable, the rate performance is excellent, and the safety is high. The required elements are abundant in the earth's crust, the raw materials used are low-cost, and the material is green, energy-saving, and environmentally friendly.

[0016] The present invention provides an application of a sodium ion secondary battery. The sodium ion secondary battery is used in large-scale energy storage equipment for solar and wind power generation, or in energy storage equipment for smart grid peak regulation, distributed power stations, backup power supplies, communication base stations, and electric vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the material of the present invention;

[0018] Figure 2 X-ray diffraction (XRD) patterns of the cathode materials of Examples 1 to 5 of the present invention;

[0019] Figure 3 This is a selected area electron diffraction image of a transmission electron microscope according to Example 1 of the present invention;

[0020] Figure 4 This is a distribution function fitting curve diagram of Example 1 of the present invention;

[0021] Figure 5 This is a charge and discharge curve diagram of the sodium ion battery provided in Example 1 of the present invention at 2-4.5V;

[0022] Figure 6 The copper-manganese disordered material Na provided in Example 1 of the present invention 2 / 3 Cu 1 / 3 Mn 1 / 2 Ti 1 / 6 O2 and Na 0.67 Cu 0.33 Mn 0.67 Comparison of O2 charge and discharge curves at 2-4.5V;

[0023] Figure 7 The copper-manganese disordered material Na provided in Example 1 of the present invention 2 / 3 Cu 1 / 3 Mn 1 / 2 Ti 1 / 6 O2 and Na 0.67 Cu 0.33 Mn 0.67 Spherical aberration corrected transmission electron microscopy image of O2 at 4.5V charge state;

[0024] Figure 8 The X-ray absorption spectrum of O K-edge (K edge of oxygen element) of the sodium ion battery provided in Example 1 of the present invention during the charge and discharge process of 2-4.5V;

[0025] Figure 9 This is a charge and discharge curve diagram of the sodium ion battery provided in Example 2 of the present invention at 2-4.5V;

[0026] Figure 10This is a charge and discharge curve diagram of the sodium ion battery provided in Example 3 of the present invention at 2-4.5V;

[0027] Figure 11 This is a charge and discharge curve diagram of the sodium ion battery provided in Example 6 of the present invention at 2-4.5V. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The present invention proposes a copper-manganese disordered high-voltage copper-based oxide material, the chemical formula of which is: Na 0.67 Cu 0.33 Mn 0.67-x A x O2; wherein the valence state of Cu is +2, the valence state of Mn is +4, A is one or more elements with a valence state of +4 such as Ti, Zr, Si, Ge, Sn, Hf, Pb, Ce, Th, 0.02≤x≤0.34; in the transition metal layer, the transition metal ions are arranged in a disordered manner, and the specific structure is as follows Figure 1 As shown, the TM layer is a disordered arrangement of any of copper, manganese, and aluminum. This disordered arrangement can reduce the hardness of the crystal structure when the order is arranged, allowing the transition metal layer elements to migrate to the sodium layer, forming a Na-OA configuration, activating the redox reaction of oxygen, and improving the energy density.

[0030] During the first week of charging, copper ions lose electrons and their valence state completely changes from +2 to +3, and oxygen ions lose electrons and their valence state is oxidized from -2; during the first week of discharging, copper ions and oxygen ions regain electrons and change back to +2 and -2.

[0031] Example 1

[0032] In this embodiment, a solid phase method is used to prepare disordered copper-manganese high-voltage copper-based oxide material:

[0033] NaNO3 (analytical grade), CuO (analytical grade), MnO2 (analytical grade), and TiO2 (analytical grade) were mixed in the required stoichiometric ratio; the mixture was ground in an agate mortar for 20 minutes to obtain a precursor; the precursor was pressed into a pellet and transferred to an alumina crucible, and treated in a muffle furnace at 950°C for 15 hours (heating rate of 5°C / min) to obtain a black powder of layered oxide material Na 2 / 3Cu 1 / 3 Mn 1 / 2 Ti 1 / 6 O2, its X-ray diffraction pattern is shown in Figure 2 , from the X-ray diffraction pattern, Na 2 / 3 Cu 1 / 3 Mn 1 / 2 Ti1 / The crystal structure of 6O2 is a P2 phase layered oxide with no superlattice peaks, proving that it is a disordered transition metal structure. Figure 3 The selected area electron diffraction image of the transmission electron microscope shown shows that there are no diffraction spots caused by the superlattice structure in the (100) crystal direction, further proving that it is a disordered structure of the transition metal.

[0034] Using Ag target X-ray to collect Na 2 / 3 Cu 1 / 3 Mn 1 / 2 Ti 1 / 6 The distribution function data of O2 was fitted and analyzed using PDFgui software, such as Figure 4 As shown in the figure, the black line is the pair distribution function data obtained from the test, the red line is the fitting curve obtained using PDFgui software, and the blue line is the error value between the experiment and the fitting. Figure a shows the transition metal layer ordered space group P63, and Figure b shows the transition metal layer disordered space group P63 / mmc. Within the short-range structure, the structure fitting using the transition metal layer ordered space group P63 results in an error R factor of 37.5%, while the fitting using the transition metal layer disordered space group P63 / mmc results in an error R factor of only 15.2%, proving that the short-range structure is disordered, further proving that it is a transition metal disordered structure.

[0035] The above active material copper-manganese disordered high voltage copper-based oxide is used as the positive electrode material to prepare a sodium ion battery. 2 / 3 Cu 1 / 3 Mn 1 / 2 Ti 1 / 6 O2 powder is mixed with conductive carbon black and binder polyvinylidene fluoride (PVDF) in a mass ratio of 80:10:10. An appropriate amount of N-methylpyrrolidone (NMP) solution is added and stirred into a uniform slurry using a degassing machine in a dry environment at room temperature. The slurry is then evenly coated on the current collector aluminum foil and dried in a forced air drying oven at 70°C. The electrodes are then cut into circular pieces with a diameter of 10 mm. The electrodes are dried at 120°C under vacuum for 6 hours and then transferred to a glove box for later use.

[0036] The simulated battery was assembled in an Ar atmosphere glove box, using metallic sodium as the counter electrode and a solution of 1 mol NaClO4 dissolved in ethylene carbonate (EC) + diethyl carbonate (DEC) (volume ratio of 1:1) as the electrolyte. A CR2032 button cell was assembled. The constant current charge and discharge mode was used for charge and discharge tests. The first week of charge and discharge tests were conducted at a current density of 0.1C in the voltage range of 2-4.5V. The results are shown below. Figure 5 As shown, the charge capacity reaches more than 130mAh / g, the discharge capacity reaches more than 150mAh / g, and the curve is smooth.

[0037] Figure 6 For the copper-manganese disordered material Na 2 / 3 Cu 1 / 3 Mn 1 / 2 Ti 1 / 6 O2 and ordered copper-based materials

[0038] Na 0.67 Cu 0.33 Mn 0.67 Comparison of electrochemical properties of O2. Ordered copper-based materials Na 0.67 Cu 0.33 Mn 0.67 O2 can only obtain a specific capacity of 93mAh / g during the charging process. Since the valence state of Mn ions is +4, only Cu ions can be Cu 2+ / Cu 3+ The redox reaction of copper manganese is consistent with the theoretical capacity of copper redox reaction. And it has almost no contribution to the specific capacity at high voltages above 4V, proving that it cannot activate the redox reaction of oxygen. 2 / 3 Cu 1 / 3 Mn 1 / 2Ti 1 / 6 During the charging process, it can be seen that when O2 is used at a voltage of ≥4.25V, an additional smooth curve will be produced compared to the sequenced copper-based material, and the resulting specific capacity far exceeds the theoretical specific capacity that can be obtained by copper and manganese in the material.

[0039] like Figure 7 As shown, the ordered copper-based material Na in Figure a can be seen through spherical aberration corrected scanning electron microscopy. 0.67 Cu 0.33 Mn 0.67 When O2 is charged to 4.5V, the transition metal layer atoms cannot migrate to the sodium layer due to the high hardness of the ordered crystal structure. 2 / 3 Cu 1 / 3 Mn 1 / 2 Ti 1 / 6 When O2 is charged to 4.5V, transition metal atoms can migrate, leaving vacancies in the transition metal layer to construct the Na-OA configuration and activate the oxygen redox reaction to increase the energy density of the material.

[0040] like Figure 8As shown in the figure, the O K-edge in different charged states is tested by X-ray absorption spectroscopy. The oxygen redox reaction is hidden in the front edge of the O K-edge spectrum. Since the density of the bound state above the molecular energy level is related to the hybridization of the metal 3d-O-2p orbital, the change in the intensity of the edge peak with electrochemical deintercalation can provide information on the distribution of oxygen atom vacancy states and the effective charge. As can be seen from the figure, the intensity of the O K-edge decreases when it is charged from the uncharged state to the 4.25V state, proving that the voltage between this period is the redox reaction of copper ions, from Cu 2+ Oxidized to Cu 3+ The covalent strength between copper ions and oxygen ions increases. However, during the process of charging from 4.25V to 4.5V, the intensity of O K-edge increases instead, proving that this voltage is the redox reaction of oxygen. 2- Oxidized to O n- The number of oxygen vacancies increases, and the strength of the O K-edge increases. This proves that it can activate the oxygen redox reaction. The oxygen redox reaction shows a smooth curve above 4.2V during the charging process, with an average voltage of 3.72V, which exceeds that of most layered oxide positive electrodes and further improves the energy density of the material.

[0041] Example 2

[0042] In this embodiment, a solid phase method is used to prepare disordered copper-manganese high-voltage copper-based oxide material:

[0043] The stoichiometric ratios of NaNO3 (analytical pure), CuO (analytical pure), MnO2 (analytical pure), and TiO2 (analytical pure) were different from those in Example 1, and the heat treatment conditions were 950°C for 15 hours. The layered oxide material obtained as black powder was Na 0.67 Cu 0.33 Mn 0.65 Ti 0.08 O2, its X-ray diffraction pattern is shown in Figure 2 , from the X-ray diffraction pattern, Na 0.67 Cu 0.33 Mn 0.65 Ti 0.08 The crystal structure of O2 is a transition metal disordered oxide with a P2 phase layered structure.

[0044] The above active material copper-manganese disordered high voltage copper-based oxide was used as the positive electrode material for the preparation of sodium ion batteries, and electrochemical charge and discharge tests were carried out. The preparation process and test method were the same as in Example 1. The test voltage range was 2V-4.5V, and the test results were shown in FIG. Figure 8As can be seen, when used at voltages ≥4.25V, an additional smooth curve is generated. The resulting specific capacity far exceeds the theoretical specific capacity of the copper and manganese in the material, activating the oxygen redox reaction. The first-cycle charge capacity can reach 118mAh / g, with an average operating voltage of 3.82V.

[0045] Example 3

[0046] In this embodiment, a solid phase method is used to prepare disordered copper-manganese high-voltage copper-based oxide material:

[0047] The stoichiometric ratios of NaNO3 (analytical pure), CuO (analytical pure), MnO2 (analytical pure), and TiO2 (analytical pure) were different from those in Example 1, and the heat treatment conditions were 950°C for 15 hours. The layered oxide material obtained as black powder was Na 0.67 Cu 0.33 Mn 0.59 Ti 0.25 O2, its X-ray diffraction pattern is shown in Figure 2 , from the X-ray diffraction pattern, Na 0.67 Cu 0.33 Mn 0.59 Ti 0.25 The crystal structure of O2 is a transition metal disordered oxide with a P2 phase layered structure.

[0048] The above active material copper-manganese disordered high voltage copper-based oxide was used as the positive electrode material for the preparation of sodium ion batteries and electrochemical charge and discharge tests were carried out. The preparation process and test method were the same as in Example 1. The test voltage range was 2V-4.5V, and the test results were shown in Figure 2. Figure 9 As can be seen, when used at voltages ≥4.25V, an additional smooth curve is generated. The resulting specific capacity far exceeds the theoretical specific capacity of the copper and manganese contained in the material. The redox reaction that activates oxygen can achieve a first-cycle charge capacity of 121mAh / g, with an average operating voltage of 3.82V.

[0049] Example 4

[0050] In this embodiment, a solid phase method is used to prepare disordered copper-manganese high-voltage copper-based oxide material:

[0051] The stoichiometric ratios of NaNO3 (analytical pure), CuO (analytical pure), MnO2 (analytical pure), and TiO2 (analytical pure) were different from those in Example 1, and the heat treatment conditions were 950°C for 15 hours. The layered oxide material obtained as black powder was Na 0.67 Cu 0.33 Mn 0.42 Ti 0.02 O2, its X-ray diffraction pattern is shown in Figure 2 , from the X-ray diffraction pattern, Na0.67 Cu 0.33 Mn 0.42 Ti 0.02 The crystal structure of O2 is a transition metal disordered oxide with a P2 phase layered structure.

[0052] Example 5

[0053] In this embodiment, a solid phase method is used to prepare disordered copper-manganese high-voltage copper-based oxide material:

[0054] The stoichiometric ratios of NaNO3 (analytical pure), CuO (analytical pure), MnO2 (analytical pure), and TiO2 (analytical pure) were different from those in Example 1, and the heat treatment conditions were 950°C for 15 hours. The layered oxide material obtained as black powder was Na 0.67 Cu 0.33 Mn 0.33 Ti 0.33 O2, its X-ray diffraction pattern is shown in Figure 2 , from the X-ray diffraction pattern, Na 0.67 Cu 0.33 Mn 0.33 Ti 0.33 The crystal structure of O2 is a transition metal disordered oxide with a P2 phase layered structure.

[0055] Example 6

[0056] In this embodiment, a solid phase method is used to prepare disordered copper-manganese high-voltage copper-based oxide material:

[0057] The stoichiometric ratios of NaNO3 (analytical pure), CuO (analytical pure), MnO2 (analytical pure), and ZrO2 (analytical pure) were different from those in Example 1, and the heat treatment conditions were 950°C for 15 hours. The layered oxide material of the black powder was Na 0.67 Cu 0.33 Mn 0.59 Zr 0.08 O2.

[0058] The above active material copper-manganese disordered high voltage copper-based oxide was used as the positive electrode material for the preparation of sodium ion batteries, and electrochemical charge and discharge tests were carried out. The preparation process and test method were the same as in Example 1. The test voltage range was 2V-4.5V, and the test results were shown in FIG. Figure 10 As can be seen, when used at voltages ≥4.25V, an additional smooth curve is generated. The resulting specific capacity far exceeds the theoretical specific capacity of the copper and manganese in the material. It can activate the redox reaction of oxygen, achieving a first-cycle charge capacity of 133mAh / g and an average operating voltage of 3.56V.

[0059] The present invention provides a copper-manganese disordered high-voltage copper-based oxide material that is not only simple to prepare, but also contains non-toxic and safe elements such as sodium, copper, manganese, and titanium. In the material, the copper redox couple itself has a relatively high voltage. The metal ions in the transition metal layer are disordered, which reduces the lattice strength of the ordered arrangement. Under high voltage, the transition metal layer elements can migrate to the sodium layer, forming a Na-OA configuration. When used at a voltage of 4.25V or higher, the oxygen redox reaction can be activated to increase the energy density of the material. These two aspects can effectively increase the overall operating voltage of the material, thereby increasing the specific energy of the material. In sodium metal half-cell tests, it was found that the operating potential of the copper redox reaction can reach above 3.65V, which is comparable to that of lithium-ion batteries. It also has excellent cycle stability and great practical value. Sodium-ion secondary batteries using the copper-manganese disordered high-voltage copper-based oxide material of the present invention can be used in large-scale energy storage equipment for solar and wind power generation, or in energy storage equipment for smart grid peak regulation, distributed power stations, backup power supplies, communication base stations, and electric vehicles.

[0060] The above embodiments are not limitations of the present invention, and the present invention is not limited to the above examples. Any changes, modifications, additions or substitutions made by technicians in this technical field within the scope of the technical solution of the present invention also fall within the scope of protection of the present invention.

Claims

1. A copper-manganese disordered high-voltage copper-based oxide material, characterized in that: The general chemical formula of this material is: Na 0.67 Cu 0.33 Mn 0.67-x A x O2; wherein the valence state of Cu is +2, the valence state of Mn is +4, A is one or more elements selected from Ti, Zr, Si, Ge, Sn, Hf, Pb, Ce, and Th, 0.02≤x≤0.34, and the valence state of A is +4; In the transition metal layer, the transition metal ions are arranged in a disordered manner. At a voltage of 4.25V, the transition metal layer elements migrate to the sodium layer, constructing a Na-OA configuration and increasing the energy density of the material by activating the oxygen redox reaction.

2. The copper-manganese disordered high-voltage copper-based oxide material according to claim 1, characterized in that: The average working voltage of the copper-manganese disordered high-voltage copper-based oxide material relative to metallic sodium is above 4.25V.

3. A positive electrode sheet for a sodium ion secondary battery, characterized in that: The positive electrode plate comprises: a current collector, a conductive additive and a binder coated on the current collector, and the copper-manganese disordered high-voltage copper-based oxide material as described in any one of claims 1 to 2 above.

4. A sodium ion secondary battery comprising the positive electrode sheet according to claim 3.

5. The sodium ion secondary battery according to claim 4, characterized in that: The sodium ion secondary battery is used in any of large-scale energy storage devices for solar energy and wind power generation, or energy storage devices for smart grid peak regulation, distributed power stations, backup power supplies, communication base stations, and electric vehicles.

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