Manganese-based oxide materials, preparation methods, positive electrode sheets, batteries and electrical devices

Abstract

This disclosure provides a manganese-based oxide material, a preparation method, a positive electrode sheet, a battery, and an electrical device. The manganese-based oxide material exhibits a P2 phase crystal structure, and its chemical formula is Na. m Li a Ni b Zr c M 1‑a‑b‑c‑d Mn d O2, M includes one or more of Al, Ru, and Fe, and M does not contain Co; wherein 0 < a ≤ 0.2, 0 < b ≤ 0.2, 0.01 ≤ c ≤ 0.2, and d ≥ 0.5. This manganese-based oxide material exhibits significantly higher discharge specific capacity and longer cycle stability.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a manganese-based oxide material, a preparation method, a positive electrode sheet, a battery, and an electrical device. Background Technology

[0002] Lithium-ion batteries are a widely commercially available rechargeable battery system. Lithium-ion batteries require lithium-containing materials. The relatively limited reserves and high cost of lithium resources are significant factors restricting the further development of lithium-ion batteries. Compared to lithium resources, sodium resources are significantly more abundant and have lower acquisition costs, thus possessing broader application prospects.

[0003] The improvement in energy density of sodium-ion batteries largely depends on the enhancement of the reversible capacity and voltage of the cathode material. Compared to lithium-ion batteries, sodium-ion batteries are larger, placing more stringent requirements on material structural stability and kinetic performance, making the development of commercially viable sodium-ion battery cathode materials more challenging. Novel layered oxides with mixed cations and oxygen anions have attracted widespread attention due to their high operating voltage and specific capacity. However, the activity and reversibility of these oxide materials during redox reactions remain poor, and the discharge specific capacity and capacity retention during charge-discharge processes need further improvement. Summary of the Invention

[0004] Therefore, it is necessary to provide a manganese-based oxide material that can improve capacity retention while achieving a high discharge specific capacity, addressing the problems mentioned above.

[0005] In a first aspect, according to some embodiments of this disclosure, a manganese-based oxide material is provided, the manganese-based oxide material having a P2 phase crystal structure, and the chemical formula of the manganese-based oxide material is Na. m Li a Ni b Zr c M 1-a-b-c- d Mn d O2, M includes one or more of Al, Ru and Fe and does not contain Co; wherein, 0 < a ≤ 0.2, 0 < b ≤ 0.2, 0.01 ≤ c ≤ 0.2, d ≥ 0.5.

[0006] In some embodiments of this disclosure, in the manganese-based oxide material, 0.05 ≤ b ≤ 0.15; and / or,

[0007] In the manganese-based oxide material, 0.03 ≤ c ≤ 0.15; and / or,

[0008] In the manganese-based oxide material, d ≥ 0.6; and / or,

[0009] In the manganese-based oxide material, 0 ≤ 1 - abcd ≤ 0.1.

[0010] In some embodiments of this disclosure, in the manganese-based oxide material, b:c = 1:(0.4~2); and / or,

[0011] In the manganese-based oxide material, b:d = 1:(5~8).

[0012] In some embodiments of this disclosure, 0.6 ≤ m ≤ 0.9.

[0013] In some embodiments of this disclosure, in the manganese-based oxide material, a:b = (4~10):1.

[0014] In some embodiments of this disclosure, the chemical formula of the manganese-based oxide material is selected from Na. 0.82 Li 0.12 Ni 0.12 Ru 0.05 Zr 0.05 Mn 0.66 O2, Na 0.78 Li 0.10 Ni 0.10 Ru 0.05 Zr 0.05 Mn 0.70 O2, Na 0.75 Li 0.10 Ni 0.10 Al 0.04 Zr 0.06 Mn 0.70 O2, Na 0.80 Li 0.10 Ni 0.10 Fe 0.05 Zr 0.05 Mn 0.70 O2 or Na 0.80 Li 0.10 Ni 0.08 Zr 0.12 Mn 0.70 O2.

[0015] Secondly, according to some embodiments of this disclosure, a method for preparing a manganese-based oxide material is also provided, comprising the following steps:

[0016] Sodium source, lithium source, nickel source, zirconium source, manganese source and M source are mixed in the ratio of m:a:b:c:d:(1-abcd) and ball-milled to form a mixed precursor;

[0017] The mixed precursor is subjected to calcination treatment, and the calcination temperature is controlled at 700℃~950℃.

[0018] Thirdly, according to some embodiments of this disclosure, a positive electrode sheet is also provided, which includes a current collector and an active material layer disposed on the current collector, the active material layer comprising a manganese-based oxide material as described in any of the above embodiments.

[0019] Thirdly, according to some embodiments of this disclosure, a battery is also provided, which includes a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode and the negative electrode are disposed opposite to each other, the electrolyte is located between the positive electrode and the negative electrode, and the positive electrode includes a manganese-based oxide material as described in any of the above embodiments, or the positive electrode includes a positive electrode sheet as described in any of the above embodiments.

[0020] Fourthly, according to some embodiments of this disclosure, an electrical device is also provided, which includes a functional body and a battery as described in any of the above embodiments, the battery being used to power the functional body.

[0021] The chemical formula of the manganese-based oxide material in at least one embodiment of this disclosure is Na. m Li a Ni b Zr c M 1-a-b-c- d Mn d O2, exhibiting P2 phase crystal structure characteristics, is a layered manganese-based oxide material. Lithium, nickel, and zirconium are used to replace a portion of the manganese. During their research, the inventors of this disclosure discovered that doping manganese-based oxide materials with the aforementioned proportions of lithium, nickel, and zirconium significantly improves the activity and reversibility of anionic redox reactions, enhances crystal structure stability, and suppresses irreversible phase transitions in a highly desodium-free state. Therefore, this manganese-based oxide material possesses significantly higher discharge specific capacity and long-cycle stability. Furthermore, the manganese-based oxide material in at least one embodiment of this disclosure does not contain elements such as cobalt, and also has the advantages of abundant raw materials, low cost, and non-toxicity.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described below. Detailed Implementation

[0023] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0025] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0026] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0028] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0029] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0030] In a first aspect, one embodiment of this disclosure provides a manganese-based oxide material having a P2 phase crystal structure, and the chemical formula of the manganese-based oxide material is Na. m Lia Ni b Zr c M 1-a-b-c-d Mn d O2, M includes one or more of Al, Ru and Fe and M does not contain Co; wherein, 0 < a ≤ 0.2, 0 < b ≤ 0.2, 0.01 ≤ c ≤ 0.2, d ≥ 0.5, 0 ≤ 1 - abcd ≤ 0.1.

[0031] The chemical formula of the manganese-based oxide material in this embodiment is Na. m Li a Ni b Zr c M 1-a-b-c-d Mn d O2, exhibiting P2 phase crystal structure characteristics, is a layered manganese-based oxide material. Lithium, nickel, and zirconium are used to replace a portion of the manganese. During their research, the inventors of this disclosure discovered that doping manganese-based oxide materials with the aforementioned proportions of lithium, nickel, and zirconium significantly improves the activity and reversibility of anionic redox reactions, enhances crystal structure stability, and suppresses irreversible phase transitions in a highly desodium-free state. Therefore, this manganese-based oxide material possesses significantly higher discharge specific capacity and long-cycle stability. Furthermore, the manganese-based oxide material in at least one embodiment of this disclosure does not contain elements such as cobalt, and also has the advantages of abundant raw materials, low cost, and non-toxicity.

[0032] It is understood that in this embodiment, Li, Ni, Zr, and M elements are used together as dopant elements to replace Mn elements in the crystal lattice, while simultaneously ensuring that the manganese-based oxide material retains the P2 phase crystal structure characteristics. The P2 phase crystal structure characteristics can be determined by the positions of diffraction peaks in the XRD diffraction image.

[0033] As an example of this embodiment, in the manganese-based oxide material, 0.05 ≤ b ≤ 0.15. In some examples, in the manganese-based oxide material, the value of b can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15, or the value of b can be between any two of the above values. A value of b within this range can effectively suppress the irreversible phase transition of the material in a highly desodium-free state, thereby achieving high cycle stability.

[0034] As an example of this embodiment, in the manganese-based oxide material, 0.03 ≤ c ≤ 0.15. In some examples, in the manganese-based oxide material, the value of c can be 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, or 0.15, or the value of c can be between any two of the above values. A value of c within this range can effectively suppress the irreversible phase transition of the material in a highly desodium-free state, thereby achieving high cycle stability.

[0035] As an example of this embodiment, in the manganese-based oxide material, b:c = 1:(0.4~2). In some examples, the ratio of b to c is 1:0.4, 1:0.5, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, or the ratio of b to c can be between any two of the above ratios. A ratio between these values ​​of Ni and Zr is beneficial for Ni and Zr to exert a better synergistic effect, thereby effectively improving the charge / discharge specific capacity and cycle stability of the material.

[0036] As an example of this embodiment, in the manganese-based oxide material, d ≥ 0.6. As a further example of this embodiment, d ≤ 0.8. In some examples, the value of d can be 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, or 0.8, or the value of d can be between any two of the above values.

[0037] As an example of this embodiment, in the manganese-based oxide material, b:d = 1:(5~8). In some examples, the ratio of b to d is 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, or the ratio of b to d can be between any two of the above ratios. The presence of Ni and Mn elements within this ratio is beneficial for achieving higher charge / discharge specific capacity and capacity retention while ensuring a relatively stable overall crystal structure.

[0038] As an example of this embodiment, 0.6 ≤ m ≤ 0.9. In some examples, m can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or the value of m can be between any two of the above values.

[0039] As an example of this embodiment, in the manganese-based oxide material, a:b = (4~10):1. In some examples, the ratio of a to b can be 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or the ratio of a to b can be between any two of the above ratios.

[0040] As an example of this embodiment, the chemical formula of the manganese-based oxide material is selected from Na. 0.82 Li 0.12 Ni 0.12 Ru 0.05 Zr 0.05 Mn 0.66 O2, Na 0.78 Li 0.10 Ni 0.10 Ru 0.05 Zr 0.05 Mn 0.70 O2, Na 0.75 Li 0.10 Ni 0.10 Al 0.04 Zr 0.06 Mn 0.70 O2, Na 0.80 Li 0.10 Ni 0.10 Fe 0.05 Zr 0.05 Mn 0.70 O2 or Na 0.80 Li 0.10 Ni 0.08 Zr 0.12 Mn 0.70 O2. Manganese-based oxide materials with this chemical formula exhibit significantly higher initial discharge specific capacity and more stable cycling performance.

[0041] Secondly, this disclosure also provides a method for preparing a manganese-based oxide material as described in any of the above embodiments, comprising the following steps S1 to S2.

[0042] Step S1: Sodium source, lithium source, nickel source, zirconium source, manganese source and M source are mixed and ball-milled to form a mixed precursor.

[0043] It is understood that the amounts of sodium, lithium, nickel, zirconium, manganese, and M sources correspond to the stoichiometric ratios of the elements in the final manganese-based oxide material. Therefore, in this embodiment, the sodium, lithium, nickel, zirconium, manganese, and M sources should be mixed in a ratio of m:a:b:c:d:(1-abcd) to obtain a material with the chemical formula Na. m Li a Ni b Zr c M 1-a-b-c-d Mn d O2-based manganese oxide materials.

[0044] It is understandable that a sodium source contains Na, and a sodium source can be a compound containing Na. A lithium source contains Li, and a lithium source can be a compound containing Li. A nickel source contains Ni, and a nickel source can be a compound containing Ni. A zirconium source contains nickel, and a zirconium source can be a compound containing Zr. A manganese source contains manganese, and a manganese source can be a compound containing Mn.

[0045] As an example of this embodiment, the sodium source is selected from one or more of sodium hydroxide, sodium carbonate, and sodium oxide. Using sodium hydroxide, sodium carbonate, and sodium oxide as sodium sources ensures that virtually no impurity elements are introduced during calcination, which is beneficial for forming pure-phase manganese-based oxide materials.

[0046] As an example of this embodiment, the lithium source is selected from one or more of lithium hydroxide, lithium carbonate, and lithium oxide. Using lithium hydroxide, lithium carbonate, and lithium oxide as lithium sources ensures that virtually no impurity elements are introduced during calcination, which is beneficial for forming pure-phase manganese-based oxide materials.

[0047] As an example of this embodiment, the nickel source is selected from one or more of nickel oxide and high-nickel oxide. Using nickel oxide and high-nickel oxide as the nickel source ensures that virtually no impurity elements are introduced during calcination, which is beneficial for forming pure-phase manganese-based oxide materials.

[0048] As an example of this embodiment, the zirconium source is selected from zirconium oxide. Using zirconium oxide as the zirconium source ensures that virtually no impurity elements are introduced during calcination, which is beneficial for forming pure-phase manganese-based oxide materials.

[0049] It is understood that the M source can be selected based on the desired M element. As an example of this embodiment, the M source can be selected from one or more of alumina, ruthenium oxide, and iron oxide. Using alumina, ruthenium oxide, and iron oxide as the M source ensures that virtually no impurity elements are introduced during calcination, which is beneficial for forming pure-phase manganese-based oxide materials.

[0050] As an example of this embodiment, during the ball milling process, liquid ball milling media can be added to the ball milling jar to perform wet ball milling of the raw materials. The ball milling media may include ethanol.

[0051] As an example of this embodiment, the rotational speed of the ball mill during the ball milling process can be from 200 r / min to 600 r / min. For example, the rotational speed of the ball mill can be 200 r / min, 300 r / min, 400 r / min, 500 r / min, or 600 r / min, or the rotational speed of the ball mill can be between any two of the above rotational speeds.

[0052] As an example of this embodiment, the ball milling time can be 2h to 12h. For example, the ball milling time can be 2h, 4h, 6h, 8h, 10h, or 12h, or the ball milling time can be between any two of the above-mentioned times.

[0053] Step S2: Calcine the mixed precursor.

[0054] As an example of this embodiment, before calcination, a step of compressing the mixed raw materials into tablets may be included. During tableting, the pressure applied to the mixed raw materials can be between 2 MPa and 10 MPa. For example, the pressure applied to the mixed raw materials can be 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa, or the pressure applied to the mixed raw materials can be between any two of the above pressures.

[0055] As an example of this embodiment, the calcination temperature can be controlled between 700°C and 950°C during the calcination process. For example, the calcination temperature can be controlled at 750°C, 780°C, 800°C, 820°C, 850°C, 880°C, 900°C, 920°C, or 950°C, or the calcination temperature can be controlled between any two of the above temperatures.

[0056] As some examples of this embodiment, the calcination time is controlled to be 10h to 20h during the calcination process. For example, the calcination time can be controlled to be 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, or 20h, or the calcination time can be controlled to be between any two of the above times.

[0057] By using the above-mentioned calcination temperature and time, it is possible to ensure that the raw materials are fully combined and transformed into the desired manganese-based oxide materials.

[0058] It is understood that manganese-based oxide materials as described in the embodiments of this disclosure can be prepared through the above steps S1 to S2.

[0059] Thirdly, this disclosure also provides a positive electrode sheet, which includes a current collector and an active material layer disposed on the current collector, the active material layer including a manganese-based oxide material as described in the above embodiments.

[0060] It is understood that this manganese-based oxide material can serve as the active material in the positive electrode active layer. This positive electrode active layer may also include other auxiliary materials.

[0061] As a further example of this embodiment, the positive electrode active layer may further include at least one of a conductive agent and a binder. Further, the conductive agent may include one or more of conductive carbon black, acetylene black, carbon fiber, carbon nanotubes, and graphene. The binder may include polyvinylidene fluoride (PVDF).

[0062] The positive electrode active layer of this embodiment can be used as the positive electrode material of a sodium-ion battery.

[0063] Fourthly, this disclosure also provides a battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive and negative electrodes are disposed opposite to and spaced apart, the electrolyte is disposed between the positive and negative electrodes, and the positive electrode comprises a manganese-based oxide material as described in any of the above embodiments, or the positive electrode comprises a positive electrode sheet as described in any of the above embodiments.

[0064] It is understood that this battery can be a sodium-ion battery. In this battery, the electrolyte can be a solid electrolyte or a liquid electrolyte. When the electrolyte is a liquid electrolyte, the battery may also include a separator.

[0065] Fifthly, this disclosure also provides an electrical device that includes a functional body and a battery as described in the above embodiments, the battery being used to power the functional body.

[0066] As an example of this embodiment, the electrical equipment may be selected from, but is not limited to, portable communication devices and electric vehicles.

[0067] The present application will be described in further detail below with reference to several specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0068] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0069] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0070] Example 1

[0071] According to the molar ratio of Na:Li:Ni:Ru:Zr:Mn=0.82:0.12:0.12:0.05:0.05:0.66, Na2CO3, Li2CO3, NiO, RuO2, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0072] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.82 Li 0.12 Ni 0.12 Ru 0.05 Zr 0.05 Mn 0.66 O2.

[0073] Example 2

[0074] According to the molar ratio of Na:Li:Ni:Ru:Zr:Mn=0.78:0.1:0.1:0.05:0.05:0.7, Na2CO3, Li2CO3, NiO, RuO2, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0075] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.78 Li 0.10 Ni 0.10 Ru 0.05 Zr 0.05 Mn 0.70 O2.

[0076] Example 3

[0077] According to the molar ratio of Na:Li:Ni:Al:Zr:Mn=0.75:0.1:0.1:0.04:0.06:0.7, Na2CO3, Li2CO3, NiO, Al2O3, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0078] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.75 Li 0.10 Ni 0.10 Al 0.04 Zr 0.06 Mn 0.70 O2.

[0079] Example 4

[0080] According to the molar ratio of Na:Li:Ni:Fe:Zr:Mn=0.8:0.1:0.1:0.05:0.05:0.7, Na2CO3, Li2CO3, NiO, Fe2O3, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0081] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.80 Li 0.10 Ni 0.10 Fe 0.05 Zr 0.05 Mn 0.70 O2.

[0082] Example 5

[0083] According to the molar ratio of Na:Li:Ni:Zr:Mn=0.8:0.1:0.08:0.12:0.7, Na2CO3, Li2CO3, NiO, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0084] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.80 Li 0.10 Ni 0.08 Zr 0.12 Mn 0.70 O2.

[0085] Comparative Example 1

[0086] According to the molar ratio of Na:Li:Ru:Zr:Mn=0.82:0.12:0.05:0.05:0.78, Na2CO3, Li2CO3, RuO2, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0087] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.82 Li 0.12 Ru 0.05 Zr 0.05 Mn 0.78 O2.

[0088] Comparative Example 2

[0089] According to the molar ratio of Na:Li:Ni:Ru:Mn=0.82:0.12:0.12:0.05:0.71, Na2CO3, Li2CO3, NiO, RuO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0090] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.82 Li 0.12 Ni 0.12 Ru 0.05 Mn 0.71 O2.

[0091] Comparative Example 3

[0092] According to the molar ratio of Na:Ni:Ru:Zr:Mn=0.82:0.12:0.05:0.05:0.78, Na2CO3, NiO, RuO2, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0093] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.82 Ni 0.12 Ru 0.05 Zr 0.05 Mn 0.66 O2.

[0094] Comparative Example 4

[0095] According to the molar ratio of Na:Li:Ni:Ru:Zr:Mn=0.82:0.12:0.3:0.05:0.05:0.48, Na2CO3, Li2CO3, NiO, RuO2, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0096] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.82 Li 0.12 Ni 0.3 Ru 0.05 Zr 0.05 Mn 0.48 O2.

[0097] Comparative Example 5

[0098] According to the molar ratio of Na:Li:Ni:Ru:Zr:Mn=0.82:0.12:0.12:0.05:0.25:0.46, Na2CO3, Li2CO3, NiO, RuO2, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. The mixture was then removed to obtain the mixed precursor.

[0099] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.82 Li 0.12 Ni 0.12 Ru 0.05 Zr 0.25 Mn 0.46 O2.

[0100] Comparative Example 6

[0101] According to the molar ratio of Na:Li:Ni:Ru:Zr:Mn=0.82:0.12:0.12:0.05:0.005:0.705, Na2CO3, Li2CO3, NiO, RuO2, ZrO2 and MnO2 were weighed and mixed evenly. Using ethanol as the ball milling medium, the mixture was placed in a ball mill and ball milled at a speed of 400 r / min for 6 h. After that, the mixture was taken out to obtain the mixed precursor.

[0102] The mixed precursors were pressed into discs with a diameter of 10 mm under a pressure of 8 MPa, heated to 850 °C in a muffle furnace, and calcined for 15 h. After natural cooling to room temperature, the material was removed and ground into powder to obtain a manganese-based oxide material with the chemical formula Na. 0.82 Li 0.12 Ni 0.12 Ru 0.05 Zr 0.005 Mn 0.705 O2.

[0103] Preparation of the positive electrode: The manganese-based oxide material, conductive agent SuperP, and binder PVDF prepared in the above embodiments and comparative examples were mixed and ground evenly in a mass ratio of 80:10:10. The mixture was then added to N-methylpyrrolidone (NMP) and ground again to form a slurry. The slurry was uniformly coated onto an aluminum foil current collector and then dried in a vacuum oven at 120°C for 12 hours to form the positive electrode.

[0104] Assembly and testing of sodium-ion batteries: Metallic sodium was used as the negative electrode, and a glass fiber membrane as the separator. The negative electrode, separator, and the aforementioned positive electrode were stacked within a CR2032 battery casing, and electrolyte was added. The electrolyte solvent was a mixture of propylene carbonate and ethylene carbonate, and the solute was 1 mol / L NaClO4. After assembly, charge-discharge tests were conducted within a voltage range of 1.5V to 4.5V. First, a first charge-discharge cycle was performed at a current density of 20 mA / g, and the initial discharge specific capacity was recorded. Then, 50 charge-discharge cycles were performed at a current density of 100 mA / g, and the capacity retention rate was recorded. The results are shown in Table 1.

[0105] Table 1

[0106]

[0107] Referring to Table 1, compared to Comparative Examples 1 to 6, the sodium-ion battery prepared in Example 1 achieved significantly higher initial discharge specific capacity and capacity retention. Specifically, compared to Example 1, the manganese-based oxide material in Comparative Example 1 did not contain Ni, the manganese-based oxide material in Comparative Example 2 did not contain Zr, and the manganese-based oxide material in Comparative Example 3 did not contain Li. Comparative Examples 1 to 3 demonstrate that doping with Ni, Zr, and Li all play important roles in improving the initial discharge specific capacity and capacity retention. The manganese-based oxide material in Comparative Example 4 contained 0.3% Ni, the manganese-based oxide material in Comparative Example 5 contained 0.25% Zr, and the manganese-based oxide material in Comparative Example 6 contained only 0.005% Zr. Comparative Examples 4 to 6 demonstrate that excessive Ni doping, excessive or insufficient Zr doping, all lead to a decrease in initial discharge specific capacity and capacity retention.

[0108] Furthermore, compared to Example 1, the initial discharge specific capacity and / or capacity retention rate of Examples 2 to 5 are slightly different, mainly due to differences in doping elements or doping content. However, overall, Examples 1 to 5 all achieved an initial discharge specific capacity of 190 mAh / g while maintaining a capacity retention rate of over 91%. This is primarily because appropriate doping with Li, Ni, and Zr significantly improves the activity and reversibility of the anionic redox reaction, enhances crystal structure stability, and suppresses irreversible phase transitions in the highly desodium-free state. In general, controlling the Ni doping amount below 0.2 and the Zr doping amount between 0.01 and 0.2 effectively improves capacity retention while achieving a high initial discharge specific capacity.

[0109] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A manganese-based oxide material, characterized in that, The manganese-based oxide material has a P2 phase crystal structure and the chemical formula of the manganese-based oxide material is Na. m Li a Ni b Zr c M 1-a-b-c-d Mn d O2, M includes one or more of Al, Ru and Fe and M does not contain Co; wherein, 0.6≤m≤0.9, 0<a≤0.2, 0.05≤b≤0.15, 0.01≤c≤0.2, d≥0.5, 0<1-abcd≤0.1, b:c=1:(0.4~2), b:d=1:(5~8).

2. The manganese-based oxide material according to claim 1, characterized in that, In the manganese-based oxide material, 0.03 ≤ c ≤ 0.

15.

3. The manganese-based oxide material according to claim 1, characterized in that, In the manganese-based oxide material, d ≥ 0.

6.

4. The manganese-based oxide material according to any one of claims 1 to 3, characterized in that, The chemical formula of the manganese-based oxide material is selected from Na. 0.82 Li 0.12 Ni 0.12 Ru 0.05 Zr 0.05 Mn 0.66 O2, Na 0.78 Li 0.10 Ni 0.10 Ru 0.05 Zr 0.05 Mn 0.70 O2, Na 0.75 Li 0.10 Ni 0.10 Al 0.04 Zr 0.06 Mn 0.70 O2, Na 0.80 Li 0.10 Ni 0.10 Fe 0.05 Zr 0.05 Mn 0.70 O2 or Na 0.80 Li 0.10 Ni 0.08 Zr 0.12 Mn 0.70 O2.

5. A method for preparing a manganese-based oxide material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Sodium source, lithium source, nickel source, zirconium source, manganese source and M source are mixed in the ratio of m:a:b:c:d:(1-abcd) and ball-milled to form a mixed precursor; The mixed precursor is subjected to calcination treatment, and the calcination temperature is controlled at 700℃~950℃.

6. A positive electrode sheet, characterized in that, It includes a current collector and an active material layer disposed on the current collector, wherein the active material layer includes a manganese-based oxide material as described in any one of claims 1 to 4.

7. A battery, characterized in that, It includes a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode and the negative electrode are disposed opposite to each other, and the electrolyte is located between the positive electrode and the negative electrode. The positive electrode includes a manganese-based oxide material as described in any one of claims 1 to 4, or the positive electrode includes a positive electrode sheet as described in claim 6.

8. An electrical appliance, characterized in that, It includes a functional body and a battery as described in claim 7, the battery being used to power the functional body.

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