Positive electrode sodium supplementing agent and preparation method and application thereof

Abstract

The invention discloses a positive electrode sodium supplementing agent and a preparation method and application thereof, and belongs to the technical field of battery materials. The structural formula of the anode sodium supplementing agent is NamTen, m is larger than 0, n is larger than 0, and the values of m and n meet the chemical formula charge balance. The positive electrode sodium supplementing agent has good compatibility with an electrolyte, does not release gas in a sodium removal process, and can effectively stabilize an interface between a sodium negative electrode and the electrolyte, so that the formation of sodium dendrites is reduced, the dendritic crystal effect of the sodium ion battery is relieved, and the service life of the sodium ion battery is prolonged. Therefore, the cycling stability and the capacity retention ratio of the sodium-ion battery can be improved. The preparation method of the positive sodium supplementing agent is simple, easy to operate, relatively low in preparation cost and relatively high in production efficiency, and the prepared product has good consistency and stability and can be further used for preparing a positive material, a positive pole piece and a sodium ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a positive electrode sodium supplement and a preparation method and application thereof. Background Art

[0002] During the initial cycles of sodium-ion batteries (SIBs), the anode consumes limited sodium ions from the cathode, resulting in a decrease in initial coulombic efficiency (ICE), which in turn reduces energy density. This situation is exacerbated by the sodium-deficient structure of P2 phase materials. Therefore, the development of pre-sodiumization technology is crucial.

[0003] Pre-sodiumization technology aims to compensate for the initial active sodium loss in sodium-ion batteries (SIBs) and achieve higher energy density. Typically, pre-sodiumization technology mainly introduces sacrificial sodium-rich materials on the positive electrode side to provide additional active sodium sources to compensate for the irreversible loss on the negative electrode side.

[0004] However, the sodium supplements currently used easily lead to the formation of sodium dendrites, which in turn affects the cycle life and safety of sodium-ion batteries.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a positive electrode sodium supplement and its preparation method and application, so as to solve or improve the above technical problems.

[0007] The present invention can be achieved like this:

[0008] In the first aspect, the present invention provides a positive electrode sodium supplement, the structural formula of the positive electrode sodium supplement is Na m Te n , where m>0, n>0, and the values ​​of m and n satisfy the chemical charge balance.

[0009] In an optional embodiment, the positive electrode sodium supplement includes at least one of NaTe3 and Na2Te.

[0010] In a second aspect, the present invention provides a method for preparing a positive electrode sodium supplement as described in the aforementioned embodiment, comprising the following steps: reacting a tellurium source with a reducing agent solution, and then removing the solvent to obtain a positive electrode sodium supplement.

[0011] In an optional embodiment, the reducing agent in the reducing agent solution includes at least one of NaH, NaBH4 and NaAlH4;

[0012] and / or, the solvent in the reducing agent solution comprises at least one of DME, DOL, DMF and Diglyme;

[0013] and / or, the concentration of the reducing agent in the reducing agent solution is 0.1 mol / L to 0.5 mol / L;

[0014] and / or, the mass ratio of the tellurium source to the reducing agent solution is 1:1 to 1:10;

[0015] And / or, the tellurium source and the reducing agent solution are reacted at 55° C. to 65° C. and 100 rpm to 300 rpm for 2 to 4 days.

[0016] In a third aspect, the present invention provides a positive electrode material, which includes a positive electrode active material and the positive electrode sodium supplement of the aforementioned embodiment.

[0017] In an optional embodiment, the mass ratio of the positive electrode active material to the positive electrode sodium supplement is 7:1 to 10:1.

[0018] In an alternative embodiment, the positive electrode active material includes at least one of sodium vanadium phosphate, a P2-type transition metal oxide, and an O3-type transition metal oxide.

[0019] In a fourth aspect, the present invention provides a positive electrode sheet, which is obtained by coating a positive electrode material slurry on the surface of a positive electrode current collector;

[0020] The raw materials for preparing the positive electrode material slurry include the positive electrode material of the aforementioned embodiment.

[0021] In an optional embodiment, the positive electrode current collector includes at least one of aluminum foil, composite aluminum foil and copper foil.

[0022] In an optional embodiment, the raw materials for preparing the positive electrode material slurry further include a conductive agent, a binder and a solvent.

[0023] In an optional embodiment, the mass ratio of the positive electrode material to the conductive agent and the binder is 90:5:5 to 70:20:10.

[0024] In an optional embodiment, the conductive agent includes at least one of conductive carbon black, Ketjen black, acetylene black and carbon nanotubes; and / or the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene and sodium carboxymethyl cellulose; and / or the solvent used to prepare the positive electrode material slurry includes at least one of N-methylpyrrolidone, N,N-dimethylformamide and acetonitrile.

[0025] In a fifth aspect, the present invention provides a sodium ion battery, wherein the raw materials for preparing the sodium ion battery include the positive electrode sheet of the aforementioned embodiment.

[0026] In an optional embodiment, the raw materials for preparing the sodium ion battery further include an electrolyte, a negative electrode and a separator.

[0027] In an optional embodiment, the electrolyte comprises a sodium perchlorate solution containing fluoroethylene carbonate, the solvent in the sodium perchlorate solution comprises ethylene carbonate and diethyl carbonate; and / or the negative electrode comprises hard carbon; and / or the separator comprises a glass fiber separator.

[0028] The beneficial effects of the present invention include:

[0029] The structural formula provided by the present invention is Na m Te n The positive electrode sodium supplement (m>0, n>0, and the values ​​of m and n satisfy the chemical charge balance) has good compatibility with the electrolyte and does not release gas during the sodium extraction process. In addition, the positive electrode sodium supplement can effectively stabilize the interface between the sodium negative electrode and the electrolyte, thereby reducing the formation of sodium dendrites and alleviating the dendrite effect of sodium ion batteries, thereby improving the cycle stability and capacity retention of sodium ion batteries.

[0030] The preparation method of the positive electrode sodium supplement is simple, easy to operate, has low preparation cost and high production efficiency. The prepared product has good consistency and stability and can be further used to prepare positive electrode materials, positive electrode sheets and sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is the XRD data diagram of the positive electrode sodium supplement prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0034] The following describes in detail the positive electrode sodium supplement provided by the present invention, its preparation method and application.

[0035] The present invention provides a positive electrode sodium supplement, the structural formula of which is Na m Te n , where m>0, n>0, and the values ​​of m and n satisfy the chemical charge balance.

[0036] In some embodiments, the positive electrode sodium supplement may include only a sodium-deficient phase sodium supplement (such as NaTe3), or only a sodium-rich phase sodium supplement (such as Na2Te), or may include both the above sodium-deficient phase sodium supplement and the sodium-rich phase sodium supplement.

[0037] The present invention provides a positive electrode sodium supplement that exhibits excellent compatibility with the electrolyte and does not release gas during sodium removal. Furthermore, the positive electrode sodium supplement effectively stabilizes the interface between the sodium negative electrode and the electrolyte, thereby reducing the formation of sodium dendrites and alleviating the dendrite effect in sodium-ion batteries, thereby improving the cycle stability and capacity retention of sodium-ion batteries.

[0038] Correspondingly, the present invention also provides a method for preparing the above-mentioned positive electrode sodium supplement, comprising the following steps: reacting a tellurium source with a reducing agent solution, and then removing the solvent to obtain the positive electrode sodium supplement.

[0039] In some optional embodiments, the tellurium source may be tellurium powder, and the particle size thereof may be 200 mesh.

[0040] In some optional embodiments, the reducing agent in the reducing agent solution may include at least one of NaH, NaBH4, and NaAlH4. Among them, NaH can produce NaTe3, NaAlH4 can produce Na2Te, and the reducing agent NaBH4 can produce a Na2Te / NaTe3 composite phase.

[0041] In some optional embodiments, the solvent in the reducing agent solution may include DME. In addition, it may also include DOL, DMF, Diglyme, etc.

[0042] In some optional embodiments, the concentration of the reducing agent in the reducing agent solution can be 0.1mol / L to 0.5mol / L, such as 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L or 0.5mol / L, etc., or other values ​​within the range of 0.1mol / L to 0.5mol / L.

[0043] In some optional embodiments, the mass ratio of the tellurium source to the reducing agent solution can be 1:1 to 1:10, such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10, or other values ​​within the range of 1:1 to 1:10.

[0044] In some optional embodiments, the tellurium source and the reducing agent solution can be reacted at 55°C to 65°C (such as 55°C, 58°C, 60°C, 62°C or 65°C, etc.) and 100rpm to 300rpm (such as 100rpm, 150rpm, 200rpm, 250rpm or 300rpm, etc.) for 2 days to 4 days (such as 2 days, 3 days or 4 days, etc.).

[0045] The entire preparation process can be carried out in a glove box filled with protective gas (such as argon).

[0046] As mentioned above, the preparation method of the above-mentioned positive electrode sodium supplement is simple, easy to operate, has low preparation cost, high production efficiency, and the prepared product has good consistency and stability.

[0047] In addition, the present invention also provides a positive electrode material, which includes a positive electrode active material and the positive electrode sodium supplement.

[0048] In some optional embodiments, the mass ratio of the positive electrode active material to the positive electrode sodium supplement can be 7:1 to 10:1, such as 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1 or 10:1, or other values ​​within the range of 7:1 to 10:1.

[0049] If the amount of the positive electrode sodium supplement is too low, such as the mass ratio of the positive electrode active material to the positive electrode sodium supplement is 6:1, it is not conducive to the full absorption of excess sodium ions in the positive electrode, which limits the further improvement of the battery capacity, which may lead to a shorter cycle life and lower energy density, reducing the overall performance of the battery. In addition, the loss of the positive electrode active material may also increase, further reducing the service life of the battery. If the amount of the positive electrode sodium supplement is too high, such as the mass ratio of the positive electrode active material to the positive electrode sodium supplement is 12:1, it will lead to a decrease in the energy density of the battery, because too much sodium supplement will occupy the effective space in the positive electrode, reducing the effective location for sodium ion storage, and reducing the capacity and cycle life of the battery. In addition, the positive electrode active material may not be able to fully contact the electrolyte, increasing the resistance and resulting in performance degradation. Therefore, optimizing the mass ratio of the positive electrode active material to the positive electrode sodium supplement is very important for achieving high-performance sodium-ion batteries.

[0050] In some optional embodiments, the positive electrode active material may include, for example, at least one of sodium vanadium phosphate, a P2-type transition metal oxide, and an O3-type transition metal oxide.

[0051] Among them, P2-type transition metal oxides may include P2-Na 0.67 Ni 0.33 Mn 0.67 O2, P2-Na 0.67 Cu 0.33 Mn0.67 O2, etc. O3 type transition metal oxides may include NaNi 1 / 3 Mn 1 / 3 Fe 1 / 3 O2, etc.

[0052] Furthermore, the present invention also provides a positive electrode plate, which is obtained by coating a positive electrode material slurry on the surface of a positive electrode current collector.

[0053] The raw materials for preparing the positive electrode material slurry include the above-mentioned positive electrode material, and further include a conductive agent, a binder and a solvent.

[0054] The positive electrode current collector may illustratively include at least one of aluminum foil, composite aluminum foil, and copper foil. The conductive agent may illustratively include at least one of conductive carbon black, Ketjen black, acetylene black, and carbon nanotubes. The binder may illustratively include at least one of polyvinylidene fluoride, polytetrafluoroethylene, and sodium carboxymethylcellulose. The solvent used to prepare the positive electrode material slurry may illustratively include at least one of N-methylpyrrolidone, N,N-dimethylformamide, and acetonitrile.

[0055] In some optional embodiments, the mass ratio of the positive electrode material to the conductive agent and the binder may be 90:5:5 to 70:20:10, such as 90:5:5, 80:10:10 or 70:20:10.

[0056] Furthermore, the present invention provides a sodium ion battery, wherein the raw materials for preparing the sodium ion battery include the above-mentioned positive electrode sheet, and further include an electrolyte, a negative electrode, and a separator.

[0057] The electrolyte may illustratively include a sodium perchlorate solution containing fluoroethylene carbonate. The concentration of the sodium perchlorate solution may be 1 mol / L, and the content of fluoroethylene carbonate in the sodium perchlorate solution may be 5 wt %. The solvent in the sodium perchlorate solution may include ethylene carbonate and diethyl carbonate, and the volume ratio of ethylene carbonate to diethyl carbonate may illustratively be 1:1. The negative electrode may illustratively include hard carbon. The separator may illustratively include a glass fiber separator.

[0058] It should be noted that other details regarding the positive electrode plate and sodium ion battery that have not been elaborated in detail can be referred to the relevant existing technology, and no further elaboration or limitation will be made here.

[0059] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0060] Example 1

[0061] This embodiment provides a positive electrode sodium supplement NaTe3, the preparation method of which is as follows:

[0062] Tellurium powder was added to the reducing agent solution and reacted at 60°C and 200 rpm for 3 days. After the reaction, the solvent was removed to obtain a positive electrode sodium supplement.

[0063] The tellurium powder had a particle size of 200 mesh; the reducing agent solution was prepared by dissolving NaH in DMF at a concentration of 0.3 mol / L; and the mass ratio of tellurium powder to NaH was 1:5. The entire preparation process was performed in an argon-filled glove box.

[0064] The XRD pattern of the positive electrode sodium supplement is as follows Figure 1 As shown by Figure 1 It can be seen that the characteristic diffraction peak of the positive electrode sodium supplement prepared in this example corresponds to the peak position of the standard card (PDF#78-0460), indicating that the positive electrode sodium supplement NaTe3 was successfully prepared in this example.

[0065] Example 2

[0066] This embodiment provides a positive electrode sodium supplement NaTe3, the preparation method of which is as follows:

[0067] Tellurium powder was added to the reducing agent solution and reacted at 55°C and 100 rpm for 4 days. After the reaction, the solvent was removed to obtain a positive electrode sodium supplement.

[0068] The tellurium powder had a particle size of 200 mesh; the reducing agent solution was prepared by dissolving NaH in DMF at a NaH concentration of 0.1 mol / L; and the mass ratio of tellurium powder to NaH was 1:1. The entire preparation process was performed in an argon-filled glove box.

[0069] Example 3

[0070] This embodiment provides a positive electrode sodium supplement NaTe3, the preparation method of which is as follows:

[0071] Tellurium powder was added to the reducing agent solution and reacted at 65°C and 300 rpm for 2 days. After the reaction, the solvent was removed to obtain a positive electrode sodium supplement.

[0072] The tellurium powder had a particle size of 200 mesh; the reducing agent solution was prepared by dissolving NaH in DMF at a NaH concentration of 0.5 mol / L; and the mass ratio of tellurium powder to NaH was 1:10. The entire preparation process was performed in an argon-filled glove box.

[0073] Example 4

[0074] This embodiment provides a positive electrode sodium supplement Na2Te, the preparation method of which is as follows:

[0075] Tellurium powder was added to the reducing agent solution and reacted at 65°C and 300 rpm for 2 days. After the reaction, the solvent was removed to obtain a positive electrode sodium supplement.

[0076] The tellurium powder had a particle size of 200 mesh; the reducing agent solution was prepared by dissolving NaAlH₄ in DMF at a concentration of 0.5 mol / L; and the mass ratio of tellurium powder to NaAlH₄ was 1:10. The entire preparation process was performed in an argon-filled glove box.

[0077] Example 5

[0078] This embodiment provides a positive electrode plate, the preparation of which includes:

[0079] S1: The positive electrode sodium supplement NaTe3 prepared in Example 1 is mixed with the positive electrode active material (NaNi 1 / 3 Mn 1 / 3 Fe 1 / 3 O2) were mixed at a mass ratio of 1:9 to obtain the positive electrode material (denoted as NaTe3@NaNi 1 / 3 Mn 1 / 3 Fe 1 / 3 O2).

[0080] S2: The above-mentioned positive electrode material is mixed with acetylene black and polyvinylidene fluoride in a mass ratio of 80:10:10, and the mixture is added to N-methylpyrrolidone and mixed evenly to obtain a positive electrode active slurry. The positive electrode active slurry is coated on the surface of the current collector (aluminum foil) and dried to obtain a positive electrode sheet.

[0081] Example 6

[0082] The difference between this embodiment and embodiment 5 is that the positive electrode sodium supplement NaTe3 and the positive electrode active material (NaNi 1 / 3 Mn 1 / 3Fe 1 / 3 The mass ratio of O2 is 1:7.

[0083] Example 7

[0084] The difference between this embodiment and embodiment 5 is that the positive electrode sodium supplement NaTe3 and the positive electrode active material (NaNi 1 / 3 Mn 1 / 3Fe 1 / 3 The mass ratio of O2 is 1:8.

[0085] Example 8

[0086] The difference between this embodiment and embodiment 5 is that the positive electrode sodium supplement NaTe3 and the positive electrode active material (NaNi 1 / 3 Mn 1 / 3Fe 1 / 3 The mass ratio of O2 is 1:10.

[0087] Example 9

[0088] The difference between this embodiment and embodiment 5 is that the mass ratio of the positive electrode material to acetylene black and polyvinylidene fluoride is 70:20:10.

[0089] Example 10

[0090] The difference between this embodiment and embodiment 5 is that the positive electrode sodium supplement NaTe3 and the positive electrode active material (NaNi 1 / 3 Mn 1 / 3Fe 1 / 3 The mass ratio of the positive electrode material to acetylene black and polyvinylidene fluoride is 90:5:5.

[0091] Example 11

[0092] This embodiment provides a positive electrode plate, the preparation of which includes:

[0093] S1: The positive electrode sodium supplement NaTe3 prepared in Example 1 is mixed with the positive electrode active material (Na3V2(PO4)3) in a mass ratio of 1:9 to obtain a positive electrode material (denoted as NaTe3@Na3V2(PO4)3).

[0094] S2: The above-mentioned positive electrode material is mixed with acetylene black and polyvinylidene fluoride in a mass ratio of 80:10:10, and the mixture is added to N-methylpyrrolidone and mixed evenly to obtain a positive electrode active slurry. The positive electrode active slurry is coated on the surface of the current collector (aluminum foil) and dried to obtain a positive electrode sheet.

[0095] Example 12

[0096] This embodiment provides a positive electrode plate, the preparation of which includes:

[0097] S1: The positive electrode sodium supplement NaTe3 prepared in Example 1 is mixed with the positive electrode active material (P2-Na 0.67 Ni 0.33 Mn 0.67 O2) were mixed in a mass ratio of 1:9 to obtain the positive electrode material (denoted as NaTe3@P2-Na 0.67 Ni 0.33 Mn 0.67 O2).

[0098] S2: The above-mentioned positive electrode material is mixed with acetylene black and polyvinylidene fluoride in a mass ratio of 80:10:10, and the mixture is added to N-methylpyrrolidone and mixed evenly to obtain a positive electrode active slurry. The positive electrode active slurry is coated on the surface of the current collector (aluminum foil) and dried to obtain a positive electrode sheet.

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 5 is that the positive electrode material does not contain a positive electrode sodium supplement.

[0101] Comparative Example 2

[0102] The difference between this comparative example and Example 5 is that the positive electrode sodium supplement is replaced by sodium oxalate.

[0103] Comparative Example 3

[0104] The difference between this comparative example and Example 5 is that the positive electrode sodium supplement is replaced by Na2NiO2.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 5 is that the mass ratio of the positive electrode active material to the positive electrode sodium supplement is 6:1.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 5 is that the mass ratio of the positive electrode active material to the positive electrode sodium supplement is 12:1.

[0109] Test example

[0110] The positive electrode sheets prepared in the above Examples 5 to 12 and Comparative Examples 1 to 5 were used as positive electrodes and prepared into sodium ion full batteries according to the following method: hard carbon was used as the negative electrode, a commercial ceramic diaphragm was used as the diaphragm, and the electrolyte used was a 1 mol / L sodium perchlorate solution containing 5 wt% fluoroethylene carbonate (FEC). The solvent of the electrolyte was ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1:1. The battery was then assembled in the following order: starting from the positive electrode shell, the positive electrode shell, positive electrode sheet, 50 μL electrolyte, diaphragm, hard carbon, gasket, spring sheet and negative electrode shell were assembled in this order to obtain a CR2032 button cell. The entire process was assembled in an argon-filled glove box, where the moisture and oxygen content were kept below 0.1 ppm for a long time.

[0111] The sodium-ion full battery was subjected to cycling performance testing using the LAND Blue Electric Battery Testing System. The tests were conducted at a charge / discharge current of 1C / 1C and a charge / discharge voltage ranging from 2.0V to 4.0V. The test results are shown in Table 1, which includes discharge capacity data for the first cycle and after 50 cycles, as well as the corresponding capacity retention.

[0112] Table 1 Cycling performance test results of sodium ion full battery

[0113]

[0114]

[0115] As can be seen from Table 1, the first discharge specific capacity and capacity retention of the battery in Example 1 at 1C are significantly better than those in Comparative Example 1, indicating that the addition of the sodium supplement not only significantly improves the battery's cycle stability but also increases the battery's capacity. This means that the introduction of the sodium supplement has played a positive role in improving battery performance and provides a new direction for the development of sodium-ion battery technology. These results indicate that sodium supplements have potential application prospects in sodium-ion full batteries and are expected to provide an effective solution for improving battery performance and stability.

[0116] It can be seen from Example 5 and Comparative Examples 2-3 that the sodium supplement provided by the present invention has a better effect than conventional sodium supplements.

[0117] It can be seen from Example 5 and Comparative Examples 4-5 that the sodium supplement provided by the present invention can achieve better effects only when the mass ratio of the sodium supplement provided by the present invention to the positive electrode active material is appropriate.

[0118] The reason why the positive electrode sodium supplement provided by the present invention can make the sodium ion full battery have excellent electrochemical performance may be attributed to the following points: the positive electrode sodium supplement provided by the present invention has a high ionic conductivity, which is conducive to the transmission of sodium ions in the material, improves the reaction rate of the electrode and the charge and discharge performance of the battery; and the positive electrode sodium supplement provided by the present invention has good structural stability, which can reduce the structural damage of the material during the cycle, thereby improving the cycle life of the battery. In addition, the positive electrode sodium supplement provided by the present invention is well compatible with the electrolyte, reduces interfacial reactions, reduces the formation of sodium dendrites, thereby reducing the dendrite effect of the sodium ion battery and improving its cycle performance and safety.

[0119] Therefore, when the positive electrode sodium supplement provided by the present invention is applied to the positive electrode material of a sodium ion battery, the resulting sodium ion full battery exhibits excellent cycle performance.

[0120] In summary, the sodium supplement provided by the present invention helps to compensate for the irreversible loss of negative electrode sodium during the sodium ion battery cycle, and improves the cycle life and cycle stability of the battery. Secondly, the sodium supplement can promote the performance improvement of battery materials, improve the energy density and charge and discharge efficiency of the battery, thereby promoting the development of sodium ion battery technology. In addition, NaTe3 sodium supplement helps to solve problems existing in sodium ion batteries, such as sodium dendrites, thereby improving the safety and reliability of the battery. The preparation process of the positive electrode sodium supplement is simple, the production cost is low, the operation is convenient, and it can be mass-produced. It is very beneficial for applying the sodium supplement to real-life scenarios such as sodium ion batteries, and is expected to accelerate its commercialization process and promote the development and application of sodium ion battery technology.

[0121] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A positive electrode sodium supplement, characterized in that: The structural formula of the positive electrode sodium supplement is Na m Te n , where m>0, n>0, and the values ​​of m and n satisfy the chemical charge balance.

2. The positive electrode sodium supplement according to claim 1, characterized in that The positive electrode sodium supplement includes at least one of NaTe3 and Na2Te.

3. A method for preparing a positive electrode sodium supplement as claimed in claim 1 or 2, characterized in that: The following steps are involved: The tellurium source is reacted with a reducing agent solution, and the solvent is subsequently removed to obtain a positive electrode sodium supplement.

4. The preparation method according to claim 3, characterized in that: The reducing agent in the reducing agent solution includes at least one of NaH, NaBH4 and NaAlH4; and / or, the solvent in the reducing agent solution comprises at least one of DME, DOL, DMF and Diglyme; and / or, the concentration of the reducing agent in the reducing agent solution is 0.1 mol / L to 0.5 mol / L; and / or, the mass ratio of the tellurium source to the reducing agent solution is 1:1 to 1:10; And / or, the tellurium source and the reducing agent solution are reacted at 55° C. to 65° C. and 100 rpm to 300 rpm for 2 to 4 days.

5. A positive electrode material, characterized in that The positive electrode material comprises a positive electrode active material and the positive electrode sodium supplement agent according to claim 1 or 2; Preferably, the mass ratio of the positive electrode active material to the positive electrode sodium supplement is 7:1 to 10:

1.

6. The positive electrode material according to claim 5, characterized in that The positive electrode active material includes at least one of sodium vanadium phosphate, a P2-type transition metal oxide and an O3-type transition metal oxide.

7. A positive electrode sheet, characterized in that: The positive electrode sheet is obtained by coating the positive electrode material slurry on the surface of the positive electrode current collector; Wherein, the raw material for preparing the positive electrode material slurry includes the positive electrode material according to claim 5 or 6; Preferably, the positive electrode current collector comprises at least one of aluminum foil, composite aluminum foil and copper foil.

8. The positive electrode sheet according to claim 7, characterized in that: The raw materials for preparing the positive electrode material slurry also include a conductive agent, a binder and a solvent; Preferably, the mass ratio of the positive electrode material to the conductive agent and the binder is 90:5:5 to 70:20:10; Preferably, the conductive agent includes at least one of conductive carbon black, Ketjen black, acetylene black and carbon nanotubes; and / or the binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene and sodium carboxymethyl cellulose; and / or the solvent used to prepare the positive electrode material slurry includes at least one of N-methylpyrrolidone, N,N-dimethylformamide and acetonitrile.

9. A sodium ion battery, characterized in that: The raw materials for preparing the sodium ion battery include the positive electrode sheet according to claim 7 or 8.

10. The sodium ion battery according to claim 9, characterized in that: The raw materials for preparing the sodium ion battery also include an electrolyte, a negative electrode and a separator; Preferably, the electrolyte comprises a sodium perchlorate solution containing fluoroethylene carbonate, the solvent in the sodium perchlorate solution comprises ethylene carbonate and diethyl carbonate; and / or, the negative electrode comprises hard carbon; and / or, the separator comprises a glass fiber separator.

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