Non-aqueous electrolyte and sodium ion battery

Abstract

The invention provides a non-aqueous electrolyte and a sodium ion battery. The non-aqueous electrolyte comprises an electrolyte salt, a non-aqueous organic solvent and an additive. The additive comprises a nitrile-containing compound and sodium nitrate, the nitrile-containing compound comprises a compound I and / or a compound A with a structural formula shown as a formula I, R1 and R2 are independently hydrogen groups, nitrile groups or R3CO, and R3 is C1-C10 alkyl groups or nitrogen heterocyclic rings. According to the non-aqueous electrolyte, through the synergistic effect of the nitrile-containing compound and the sodium nitrate, an SEI with relatively high stability and durability can be formed while the solvation environment of the electrolyte is optimized, so that high reversibility and long cycling stability of sodium are realized, and the high-rate characteristic and high and low temperature performance of a sodium ion battery can be improved. # imgabs 0 # imgabs 1 # compound formula I

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy batteries, and in particular relates to a non-aqueous electrolyte and a sodium ion battery. Background Art

[0002] Although sodium-ion batteries have made some progress and are partially commercialized at room temperature, their performance remains limited under high-rate charge and discharge conditions and extreme temperatures. Under low-temperature and high-rate conditions, battery performance degradation is primarily related to the sodium ion migration velocity and charge transfer rate in the electrolyte. Under high-temperature conditions, battery performance degradation is closely related to the stability of the electrode / electrolyte interface. As a key factor influencing the sodium ion transport kinetics and forming a stable electrode / electrolyte interface, the electrolyte's solvation structure plays a decisive role in the sodium ion desolvation process and interfacial stability.

[0003] To achieve the high rate characteristics of sodium ion batteries, the key is to improve the transmission efficiency of sodium ions, which is closely related to the performance of the electrolyte. + ) The migration process between hard carbon and layered oxides involves the following key steps: (1) Na + Entering the electrolyte through the cathode electrolyte interphase; (2) solvated Na + Diffusion into the electrolyte; (3) Solvated Na + Overcoming the energy barrier for desolvation; (4) Na + Diffusion through SEI; (5) Na + Solid-state diffusion in the anode. Among them, steps (3) and (4) mainly involve charge transfer at the interface, and the desolvation process has a higher kinetic barrier than other steps, so it becomes a key step to achieve high rate characteristics. It can be seen that Na + The migration process is closely related to the properties of the electrolyte, whether it is Na + The diffusion and desolvation of the electrolyte are affected by the sodium salt and the solvent. At the same time, the additives in the electrolyte can also adjust the composition of the SEI film. Therefore, the viscosity of the electrolyte, the composition of the SEI film, the energy required for desolvation, and the Na + The high adsorption energy has an important impact on the high-rate performance of the battery.

[0004] Therefore, there is an urgent need to develop a new type of electrolyte and a sodium-ion battery containing the electrolyte. By optimizing the solvation environment of the electrolyte and changing the reasonable regulation of the sodium-ion battery electrode / electrolyte interface structure, the battery can be given stable and excellent interface performance, thereby improving the high-rate characteristics and high and low-temperature performance of the sodium-ion battery. Summary of the Invention

[0005] Based on the above problems, the object of the present invention is to provide a non-aqueous electrolyte and a sodium ion battery. In the non-aqueous electrolyte, through the synergistic effect of a nitrile compound and sodium nitrate, a highly stable and durable SEI can be formed while optimizing the solvation environment of the electrolyte, thereby achieving high reversibility and long cycle stability of sodium, thereby improving the high rate characteristics and high and low temperature performance of the sodium ion battery.

[0006] To achieve the above-mentioned object, the first aspect of the present invention provides a non-aqueous electrolyte. The non-aqueous electrolyte comprises an electrolyte salt, a non-aqueous organic solvent, and an additive. The additive comprises a nitrile-containing compound and sodium nitrate, wherein the nitrile-containing compound comprises Compound 1 and / or Compound A as shown in Formula I, wherein R1 and R2 are each independently a hydrogen group, a nitrile group, or R3CO, and R3 is C1~C 10 a hydrocarbon group or a nitrogen-containing heterocyclic ring.

[0007]

[0008] Compound Formula I The nitrile compound in the electrolyte additive of the present invention includes compound 1 and / or compound A as shown in formula I. Compound 1 and compound A respectively contain a Na-S-CN structure or a Na-C-CN structure. These two structures can react to release active sodium ions to compensate for the loss of sodium ions caused by irreversible reactions. In addition, the organic ligand (-CCN or -SCN) generated after decomposition will dimerize to form an electrolyte co-solvent (NCC-CCN or NCS-SCN), which can reduce Na + The coordination number of the nitrile compound is increased, thereby optimizing the electrolyte solvation environment and improving the battery's high-rate performance. At the same time, sodium nitrate forms inorganic components such as Na3N, which have lower solubility in non-aqueous organic solvents. This results in low interfacial impedance, which can reduce the battery's internal resistance and enhance the stability and durability of the SEI. Furthermore, the nitrile compound and sodium nitrate act synergistically to effectively inhibit the growth of sodium dendrites and reduce sodium side reactions during charge and discharge, thereby achieving high sodium reversibility and long-term cycling stability.

[0009] As a technical solution of the present invention, R3 is a C1-C6 alkyl group or a pyridyl group.

[0010] As a technical solution of the present invention, the compound A is selected from at least one of compounds 2 to 5.

[0011]

[0012] Compound 2 Compound 3

[0013] Compound Four and Compound Five As a technical solution of the present invention, the mass ratio of the nitrile-containing compound in the non-aqueous electrolyte is 0.5 to 5.0%, and the mass ratio of sodium nitrate in the non-aqueous electrolyte is 0.1 to 1.0%.

[0014] As a technical solution of the present invention, the mass ratio of the electrolyte salt in the non-aqueous electrolyte is 10 to 25%, and the electrolyte salt is selected from at least one of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate, sodium bis(trifluoromethylsulfonyl)imide, sodium bis(oxalato)borate, sodium difluorophosphate, sodium difluoro(oxalato)borate, sodium difluoro(dioxalato)phosphate, and sodium bis(fluorosulfonyl)imide.

[0015] As a technical solution of the present invention, the electrolyte salt is selected from sodium hexafluorophosphate and / or sodium bis(fluorosulfonyl)imide.

[0016] As a technical solution of the present invention, the non-aqueous organic solvent includes at least one of chain carbonates, cyclic carbonates, and carboxylic acid esters.

[0017] As a technical solution of the present invention, the non-aqueous organic solvent includes at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, butyl acetate, propyl propionate, ethyl propionate, and ethyl butyrate.

[0018] The second aspect of the present invention provides a sodium-ion battery, including a positive electrode material, a negative electrode material, and the aforementioned non-aqueous electrolyte. The non-aqueous electrolyte used in the sodium-ion battery of the present invention contains a nitrile-containing compound and sodium nitrate. Through the synergistic effect of the two, while optimizing the solvation environment of the electrolyte, an SEI with high stability and durability can be formed, thereby achieving high reversibility and long cycle stability of sodium, and thus improving the high-rate characteristics and high and low temperature performance of the sodium-ion battery.

[0019] As a technical solution of the present invention, the positive electrode material includes a layered oxide or a polyanionic phosphate positive electrode material. The chemical formula of the layered oxide is Na x M (1-y-z) Fe y Mn z O2, where M is selected from at least one of Co, Ni, Cu, Mg, Zn, Al, Sn, Ga, Cr, Sr, V, and Ti, 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z ≤ 1. The chemical formula of the polyanionic phosphate positive electrode material is Na4Fe3(PO4)2P2O7. The negative electrode material is selected from at least one of carbon-based materials, titanium-based materials, and alloy materials. Detailed Embodiments

[0020] The non-aqueous electrolyte of the present invention can improve the rate performance and high and low temperature performance of sodium ion batteries. The sodium ion battery of the present invention may include a positive electrode material, a negative electrode material, and a non-aqueous electrolyte.

[0021] Among them, the positive electrode material may include a layered oxide or a polyanionic phosphate positive electrode material. The chemical formula of the layered oxide is Na x M (1-y-z) Fe y Mn z O2, where M is selected from at least one of Co, Ni, Cu, Mg, Zn, Al, Sn, Ga, Cr, Sr, V, and Ti, 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z ≤ 1. The chemical formula of the polyanionic phosphate positive electrode material is Na4Fe3(PO4)2P2O7. The electrolyte of the present invention contains a nitrile compound, and the nitrile group it contains has an excellent inhibitory effect on the dissolution of iron ions under high-temperature storage, thus improving the high-temperature performance of sodium ion batteries using Na x M (1-y-z) Fe y Mn z O2 or Na4Fe3(PO4)2P2O7 as the positive electrode material.

[0022] The negative electrode material is selected from at least one of carbon-based materials, titanium-based materials, and alloy materials. The carbon-based materials are selected from at least one of artificial graphite, natural graphite, soft carbon, and hard carbon. The titanium-based materials are selected from Na2Ti3O7, Na 0.6 [Cr 0.6 Ti 0.4 O2, Li4Ti5O 12 , NaTiOPO4, NASICON, NaTi2(PO4)3. The alloy material is an alloy formed by Sn, Sb, and In.

[0023] The non-aqueous electrolyte includes an electrolyte salt, a non-aqueous organic solvent, and an additive.

[0024] The mass proportion of the electrolyte salt in the non-aqueous electrolyte is 10-25%. Furthermore, the mass proportion of the electrolyte salt in the non-aqueous electrolyte is 8-14%. As an example, the mass proportion of the electrolyte salt can be, but is not limited to, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 24%, and 25%. The mass proportion of the electrolyte salt is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable. The electrolyte salt is selected from at least one of sodium hexafluorophosphate (NaPF6), sodium perchlorate (NaClO4), sodium tetrafluoroborate (NaBF4), sodium trifluoromethanesulfonate (NaCF3SO3), sodium bistrifluoromethanesulfonyl imide (NaTFSI), sodium bisoxalatoborate (NaBC4O8), sodium difluorophosphate (NaiPO2F2), sodium difluorooxalatoborate (NaBF2C2O4), sodium difluorobisoxalatophosphate (NaDFBP) and sodium bisfluorosulfonyl imide (NaFSI). Preferably, the electrolyte salt is selected from sodium hexafluorophosphate and / or sodium bisfluorosulfonyl imide. Further, the electrolyte salt is a mixture of sodium hexafluorophosphate and sodium bisfluorosulfonyl imide, and sodium hexafluorophosphate accounts for 10-60% of the mass of the electrolyte salt. Preferably, sodium hexafluorophosphate accounts for 40-60% of the mass of the electrolyte salt. As an example, sodium hexafluorophosphate accounts for 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, and 60% of the mass of the electrolyte salt. In the electrolyte additive of the present invention, compound 1 and compound A respectively contain a Na-S-CN structure or a Na-C-CN structure. On the one hand, these two structures are alkaline, which can effectively suppress the increase in the acid value of the high-content NaFSI electrolyte during long-term storage and stabilize the quality of the electrolyte.

[0025] The non-aqueous organic solvent includes at least one of a linear carbonate, a cyclic carbonate, and a carboxylate. Linear carbonates include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and propylene carbonate (PC). Cyclic carbonates may include, but are not limited to, ethylene carbonate (EC), propylene carbonate, butylene carbonate (BC), pentylene carbonate, vinylene carbonate (VC), or derivatives thereof. Carboxylate esters include, but are not limited to, cyclic carboxylate esters and linear carboxylate esters. Specifically, cyclic carboxylate esters may include, but are not limited to, at least one of γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Linear carboxylate esters include, but are not limited to, at least one of methyl acetate (MA), ethyl acetate (EA), propyl acetate (EP), butyl acetate, propyl propionate (PP), and butyl propionate.

[0026] The additives include nitrile compounds and sodium nitrate. The nitrile compounds include compound 1 and / or compound A as shown in formula I, wherein R1 and R2 are each independently a hydrogen group, a nitrile group or R3CO, and R3 is C1~C 10 wherein R1 is a hydrocarbon group or a nitrogen-containing heterocyclic ring, and further, R3 is a C1-C6 alkyl group or a pyridyl group. As an example, R1 can be, but is not limited to, a hydrogen group, a nitrile group, an acetaldehyde group, a propionaldehyde group, an isopropionaldehyde group, a butyraldehyde group, a sec-butyraldehyde group, a tert-butyraldehyde group, a valeraldehyde group, or a p-pyridinecarboxaldehyde group.

[0027]

[0028] Formula I Furthermore, compound A is selected from at least one of compounds 2 to 5. That is, the nitrile-containing compound is selected from at least one of compounds 1 to 5.

[0029]

[0030] Compound 1 Compound 2 Compound 3 CAS:540-72-7CAS:1449007-47-9CAS:36603-80-2

[0031] Compound 4 Compound 5 CAS:70807-22-6CAS:1040724-98-8 The mass proportion of the nitrile compound in the non-aqueous electrolyte is 0.5-5.0%. Further, the mass proportion of the nitrile compound in the non-aqueous electrolyte is 0.5-3.0%. Further, the mass proportion is 0.5-1.5%. As an example, the mass proportion of the nitrile compound can be, but is not limited to, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, and 5.0%, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0032] The mass proportion of sodium nitrate in the non-aqueous electrolyte is 0.1-1.0%. Furthermore, the mass proportion of sodium nitrate in the non-aqueous electrolyte is 0.5-1.0%. As an example, the mass proportion of sodium nitrate can be, but is not limited to, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, and 1.0%, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0033] In order to further illustrate the purpose, technical solutions and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific examples. It should be noted that, in the examples and comparative examples, if the specific conditions of other raw materials are not specified, they can be carried out according to conventional conditions or the conditions recommended by the manufacturer, and if the manufacturer of the reagents or instruments is not specified, they are all conventional products available on the market.

[0034] Example 1 1.1 Preparation of electrolyte Under an argon atmosphere and with a moisture content of less than 1 ppm, the electrolyte was prepared in a vacuum glove box. Propylene carbonate (PC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a weight ratio of 1:1:1 PC:EMC:DEC to form a mixed solvent. Compound 1 and sodium nitrate were then added to form a mixed solution. The mixed solution was sealed and packaged, placed in a quick freezer (-4°C) for 2 hours, then removed. Sodium hexafluorophosphate was slowly added to the mixed solution and mixed thoroughly to form the electrolyte.

[0035] 1.2 Preparation of positive electrode NaNi 0.3 Mn 0.3 Fe 0.3 O2 material, adhesive PVDF and conductive agent SuperP are evenly mixed in a mass ratio of 95:1:4 to form a sodium ion battery positive electrode slurry with a certain viscosity. The mixed slurry is coated on both sides of the aluminum foil, dried and rolled to obtain the positive electrode sheet.

[0036] 1.3 Preparation of negative electrode Artificial graphite, conductive agent SuperP, thickener CMC, and adhesive SBR (styrene-butadiene rubber emulsion) are prepared into a slurry in a mass ratio of 95:1.5:1.0:2.5, mixed evenly, and the mixed slurry is coated on both sides of the copper foil, dried, and rolled to obtain the negative electrode sheet.

[0037] 1.4 Preparation of sodium ion batteries: The positive electrode sheet, the separator and the negative electrode sheet are stacked to form a square battery cell, which is then packaged with a polymer and filled with the above-prepared electrolyte. After the formation and capacity separation processes, a sodium ion battery with a capacity of 1500mAh is produced.

[0038] The components and contents of the electrolytes of Examples 1 to 12 and Comparative Examples 1 to 3 are shown in Table 1. The preparation processes of the sodium ion battery electrolytes, positive electrode sheets, negative electrode sheets, and sodium ion batteries of Examples 2 to 12 and Comparative Examples 1 to 3 are the same as those of Example 1.

[0039] Table 1 Compositions of the electrolytes of Examples and Comparative Examples

[0040] The sodium ion batteries prepared in Examples 1 to 12 and Comparative Examples 1 to 3 were subjected to performance tests under the following conditions. The results are shown in Table 2.

[0041] (1) First Coulomb efficiency test The sodium-ion battery was placed in a high-temperature, high-pressure formation cabinet and subjected to a three-step formation process at 25°C and a pressure of 0.28 MPa (4 PCS batteries). The first step was a 0.05C constant current for 60 minutes, and the charge capacity C1 was recorded. The second step was a 0.1C constant current for 120 minutes, and the charge capacity C2 was recorded. The third step was a 0.2C constant current for 240 minutes, and the charge capacity C3 was recorded. The upper limit voltage was 3.9V. The battery was then sealed twice using a rotary sealer. The battery was then charged at room temperature using a 0.5C constant current to a voltage of 4.1V, then charged at a 4.1V constant voltage to a current of 0.05C, and then discharged at a 1C constant current to a voltage of 2.5V. The first discharge capacity C0 was recorded.

[0042] First coulombic efficiency = C0 / (C1+C2+C3)×100% (2) High-temperature cycle test of sodium ion batteries Place the sodium-ion battery in a 45°C thermostat and let it rest for 30 minutes to allow the battery to reach a constant temperature. Charge the battery at a constant current of 2C to a voltage of 4.1V, then charge it at a constant voltage of 4.1V to a current of 0.05C. Then, discharge it at a constant current of 2C to a voltage of 2.0V. Record the discharge capacity of the battery during the first cycle. This constitutes one charge-discharge cycle. Repeat this cycle for 400 cycles, recording the discharge capacity of the first cycle and the discharge capacity of the last cycle. Calculate the capacity retention rate using the following formula.

[0043] Capacity retention rate = discharge capacity of the last cycle / discharge capacity of the first cycle × 100% (3) Sodium ion battery high temperature storage test At room temperature (25°C), the lithium-ion battery was charged and discharged at 0.5C / 0.5C (the battery discharge capacity was recorded as C0), with an upper limit voltage of 4.1V. The battery was then charged to 4.1V under 0.5C constant current and constant voltage conditions, and the battery thickness was measured (the thickness was recorded as D0). The battery was placed in a 60°C oven for 30 days, taken out and the battery thickness was measured (the thickness was recorded as D1), and the thickness expansion rate was calculated.

[0044] Thickness expansion rate = (D1 / D0) × 100% (4) Low temperature discharge test At room temperature (25°C), the sodium-ion battery was charged and discharged at 0.5C / 0.5C (the battery discharge capacity was recorded as C0), with an upper limit voltage of 4.1V; the battery was then placed in a low-temperature box at -10°C, and then discharged at a constant current of 0.1C to a voltage of 2.0V, and the first discharge capacity C1 of the battery was recorded. This was a charge and discharge cycle. The lithium-ion battery was then charged and discharged at room temperature (25°C) at 0.5C / 0.5C (the battery discharge capacity was recorded as C2). The capacity recovery rate was calculated after 10 cycles.

[0045] Capacity recovery rate = (C2 / C0) × 100% (4) Rate discharge test At room temperature (25°C), the sodium ion battery was charged and discharged at 0.5C / 0.5C (the battery discharge capacity was recorded as C0), with an upper limit voltage of 4.1V; then it was discharged at a constant current of 10C to a voltage of 2.0V, and the first cycle discharge capacity C1 of the battery was recorded to calculate the discharge capacity ratio.

[0046] Discharge capacity ratio = (C1 / C0) × 100% Table 2 Test results of sodium ion battery performance

[0047] From the results in Table 2, it can be seen that compared with Comparative Examples 1 to 3, Examples 1 to 12 use nitrile-containing compounds and sodium nitrate in synergy, which can greatly improve the initial coulombic performance, high and low temperature performance and rate performance. This is because Compounds 1 to 5 contain Na-S-CN structures or Na-C-CN structures that can react to release active sodium ions to compensate for the loss of sodium ions caused by irreversible reactions. In addition, the organic ligands (-CCN or -SCN) generated after decomposition will dimerize to form electrolyte co-solvents (NCC-CCN or NCS-SCN), which can reduce Na + The coordination number of sodium nitrate increases, thereby optimizing the electrolyte solvation environment and improving the battery's high-rate performance. At the same time, sodium nitrate forms inorganic components such as Na3N, which have lower solubility in non-aqueous organic solvents. This results in low interfacial impedance, which can reduce the battery's internal resistance and improve the stability and durability of the SEI.

[0048] By comparing Example 1 with Examples 10-11, it can be seen that when the electrolyte salt is combined with NaFSI on the basis of NaPF6, the electrochemical performance of the battery is more significantly improved. This may be because the nitrile-containing compound can effectively inhibit the increase in the acid value of NaFSI and enable the performance of NaFSI to be stabilized. In addition, the higher the content of NaFSI, the more obvious the performance difference.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A non-aqueous electrolyte comprising an electrolyte salt, a non-aqueous organic solvent, and an additive, wherein the additive comprises a nitrile-containing compound and sodium nitrate, wherein the nitrile-containing compound comprises Compound 1 and / or Compound A having a structural formula as shown in Formula I, wherein: R1 and R2 are each independently a hydrogen group, a nitrile group or R3CO, and R3 is C1~C 10 a hydrocarbon group or a nitrogen-containing heterocyclic ring, Compound of formula I.

2. The non-aqueous electrolyte according to claim 1, wherein R3 is a C1~C6 alkyl group or a pyridyl group.

3. The non-aqueous electrolyte according to claim 1, wherein The compound A is selected from at least one of compound 2 to compound 5, Compound 2 Compound 3 Compound 4 Compound 5 4. The non-aqueous electrolyte according to claim 1, wherein The mass proportion of the nitrile-containing compound in the non-aqueous electrolyte is 0.5-5.0%, and the mass proportion of the sodium nitrate in the non-aqueous electrolyte is 0.1-1.0%.

5. The non-aqueous electrolyte according to claim 1, characterized in that The electrolyte salt accounts for 10-25% by mass in the non-aqueous electrolyte, and the electrolyte salt is selected from at least one of sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium trifluoromethanesulfonate, sodium bistrifluoromethanesulfonyl imide, sodium bisoxalatoborate, sodium difluorophosphate, sodium difluorooxalatoborate, sodium difluorodioxalatophosphate, and sodium bisfluorosulfonyl imide.

6. The non-aqueous electrolyte according to claim 5, characterized in that The electrolyte salt is selected from sodium hexafluorophosphate and / or sodium bis(fluorosulfonyl)imide.

7. The non-aqueous electrolyte according to claim 1, wherein The non-aqueous organic solvent includes at least one of a chain carbonate, a cyclic carbonate, and a carboxylate.

8. The non-aqueous electrolyte according to claim 7, characterized in that The non-aqueous organic solvent includes at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, butyl acetate, propyl propionate, ethyl propionate and ethyl butyrate.

9. A sodium ion battery comprising a positive electrode material, a negative electrode material and the non-aqueous electrolyte according to any one of claims 1 to 8.

10. The sodium ion battery according to claim 9, characterized in that The positive electrode material includes a layered oxide or a polyanionic phosphate positive electrode material. The chemical formula of the layered oxide is Na x M (1-y-z) Fe y Mn z O2, where M is selected from at least one of Co, Ni, Cu, Mg, Zn, Al, Sn, Ga, Cr, Sr, V, and Ti, 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z ≤ 1. The chemical formula of the polyanionic phosphate positive electrode material is Na4Fe3(PO4)2P2O7. The negative electrode material is selected from at least one of carbon-based materials, titanium-based materials, and alloy materials.

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