Composite sodium supplementing material, sodium supplementing positive electrode and sodium ion battery

Abstract

The invention discloses a composite sodium-supplementing material, a sodium-supplementing positive electrode and a lithium ion battery. The composite sodium supplementing material at least comprises a sodium supplementing material and at least one of a lithium supplementing material, a magnesium supplementing material, a zinc supplementing material, a calcium supplementing material and a potassium supplementing material. According to the composite sodium supplementing scheme, the capacity can be increased, the cycle life can be prolonged and the service life of the battery cell can be prolonged due to the additional addition of the sodium source, and besides, the composition of SEI can be improved by supplementing lithium / magnesium / zinc / calcium / potassium materials, the stability of the SEI can be improved, the cycle attenuation rate can be reduced, and the service life of the battery cell can be further prolonged. Finally, the above mode of positive electrode sodium supplement and composite lithium supplement / magnesium supplement / zinc supplement / calcium supplement / potassium supplement can improve the capacity of the battery cell, improve the service life of the battery, and have extremely wide application prospects in the field of secondary batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary battery materials, and in particular to a composite sodium supplement material, a sodium supplement positive electrode and a sodium ion battery. Background Art

[0002] Lithium-ion batteries are widely used in 3C, electric vehicles, power tools and other products due to their many advantages such as high energy density, long cycle life and no memory effect. However, the limited reserves of lithium metal on the earth will restrict the long-term application of lithium batteries. Sodium and lithium are both alkali metal elements. They have similar chemical properties and applications in many aspects. Compared with lithium metal, sodium metal is abundant in the earth's crust, and its mining and utilization are relatively simple and low in cost. Therefore, sodium-ion batteries have the potential to become a substitute for lithium-ion batteries. However, during the first charge and discharge process of sodium-ion batteries, the electrolyte will be reduced and decomposed on the surface of the negative electrode to form a solid electrolyte interface film (SEI), which will permanently consume part of the sodium ions from the positive electrode, resulting in a low coulombic efficiency (ICE) of the first cycle, reducing the capacity and energy density of sodium-ion batteries. On the other hand, during the cycle storage of the battery, the consumption of active sodium will also cause the battery capacity to decay, further reducing the battery life.

[0003] In the related art, in order to solve the above problems, it can be solved by additionally supplementing active sodium. At present, there are mainly two ways of supplementing sodium at the positive electrode and supplementing sodium at the negative electrode. Among them, supplementing sodium at the negative electrode is less used due to low safety and other reasons, while supplementing sodium at the positive electrode is more commonly used. However, simply supplementing sodium at the positive electrode of sodium-ion batteries also has shortcomings: given that one of the reasons for the attenuation of cyclic capacity is the consumption of active sodium by SEI reforming and repair, simply supplementing sodium at the positive electrode cannot improve the stability of SEI and cannot reduce the consumption rate of active sodium.

[0004] Therefore, it is of great significance to solve the problem that the current positive electrode sodium supplement materials cannot improve the stability of SEI and provide a composite sodium supplement material that can improve the stability of SEI and reduce the cycle attenuation rate. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a composite sodium supplement material, a sodium supplement positive electrode and a sodium ion battery, aiming to solve the problem that the current positive electrode sodium supplement material cannot improve the stability of SEI.

[0006] In a first aspect of the present invention, a composite sodium supplement material is proposed, which comprises a sodium supplement material A and a composite supplement material B; the composite supplement material B comprises at least one of a lithium supplement material, a magnesium supplement material, a zinc supplement material, a calcium supplement material, and a potassium supplement material; the mass ratio of the sodium supplement material A to the composite supplement material B is (1 to 9): (0.1 to 5.5).

[0007] The composite sodium supplement material according to the embodiment of the present invention has at least the following beneficial effects: The present invention proposes a composite sodium supplement material, which at least includes a sodium supplement material and at least one of a lithium supplement / magnesium supplement / zinc supplement / calcium supplement / potassium supplement material. In addition to improving the capacity and cycle life, thereby improving the life of the battery cell, the above-mentioned composite sodium supplement scheme can also improve the composition of SEI through lithium supplement / magnesium supplement / zinc supplement / calcium supplement / potassium supplement materials, improve its stability, reduce the cycle attenuation rate, and further improve the life of the battery cell. Finally, the above-mentioned sodium supplement + composite lithium supplement / magnesium supplement / zinc supplement / calcium supplement / potassium supplement method can increase the capacity of the battery cell and improve the battery life, and has extremely broad application prospects in the field of secondary batteries.

[0008] In some embodiments of the present invention, the sodium supplement material A comprises Na x M y N z , wherein 0<x<10, 0≤y≤15, 0≤z≤30, and y+z>0; M is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, and Y, and N is selected from at least one of H, C, O, S, N, F, P, and Cl.

[0009] In some embodiments of the present invention, the sodium-supplementing material includes one or more of Na5FeO4, Na2O, Na2O2, Na3N, NaN3, Na2S, NaF, Na2C2O4, Na2C3O5, Na2C4O4, Na2C6O6, and Na2N4O2; preferably, the sodium-supplementing material may be Na5FeO4 or Na2O.

[0010] In some embodiments of the present invention, the composite supplementary material B comprises A a B b C c , wherein 0<a<10, 0≤b≤13, 0≤c≤30, and b+c>0; A is selected from at least one of Li, Mg, Zn, K, and Ca, B is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, Ti, Al, Ag, and Y, and C is selected from at least one of H, C, O, S, N, F, P, and Cl.

[0011] In some embodiments of the present invention, the composite supplementary material B includes at least one of a magnesium supplementary material, a zinc supplementary material, a calcium supplementary material, and a potassium supplementary material.

[0012] In some embodiments of the present invention, the composite supplementary material B comprises A a B b Cc , wherein 0<a<10, 0≤b≤13, 0≤c≤30, and b+c>0; A is selected from at least one of Mg, Zn, K, and Ca, B is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, Ti, Al, Ag, and Y, and C is selected from at least one of H, C, O, S, N, F, P, and Cl.

[0013] In some embodiments of the present invention, the composite supplementary material B includes a lithium supplementary material, and the lithium supplementary material includes one or more of Li5FeO4, Li2O, Li2O2, Li3N, LiN3, Li2S, LiF, Li2C4O4, Li2C2O4, Li2C3O5, Li2C6O6, and Li2N4O2. More preferably, the lithium supplementary material can be an inorganic lithium supplementary material Li5FeO4, Li2O, or an organic lithium supplementary material Li2C2O4.

[0014] In some embodiments of the present invention, the composite supplementary material B includes a magnesium supplement material, and the magnesium supplement material includes one or more of Mg2Mo6S8, MgS, MgMn2O4, MgMn2S4, MgCo2O4, MgNiO2, MgNi2S4, MgAl2O4, MgFe2O4, MgTiO3, and Mg3(PO4)2. Preferably, the magnesium supplement material may be Mg2Mo6S8 or MgS.

[0015] In some embodiments of the present invention, the composite supplementary material B includes a zinc supplement material, and the zinc supplement material includes one or more of ZnO, ZnCo2O4, ZnMn2O4, ZnFe2O4, ZnTiO3, ZnS, Zn3(PO4)2, ZnAl2O4, ZnNiO2, ZnV2O4, ZnMoO4, ZnCuO, and ZnAgVO4. Preferably, the zinc supplement material may be ZnS or ZnCo2O4.

[0016] In some embodiments of the present invention, the composite supplementary material B includes a calcium supplement material, and the calcium supplement material includes one or more of CaMnO3, CaNiO3, CaTiO3, CaCoO3, Ca3Co4O9, CaFeO3, Ca2Fe2O5, CaFePO4F, Ca3(PO4)2, Ca2P2O7, CaS, Ca2S, and CaCO3. Preferably, the calcium supplement material may be CaMnO3 or CaNiO3.

[0017] In some embodiments of the present invention, the composite supplementary material B comprises a potassium supplement material, and the potassium supplement material comprises KCoO2, KNiO2, KMnO2, K 1.5 V6O16 , K3V2(PO4)2, KFePO4, K2FeP2O7, K3PO4, KV3O8, K2S, KF, KNiF3, KN3. Preferably, the potassium supplement material may be K3PO4 or K2FeP2O7.

[0018] The second aspect of the present invention provides a pole piece, comprising the above-mentioned composite sodium supplement material.

[0019] The pole piece according to the embodiment of the present invention has at least the following beneficial effects: the pole piece provided by the present invention has additionally added a composite sodium supplement material, which at least includes a sodium supplement material and at least one of a lithium supplement / magnesium supplement / zinc supplement / calcium supplement / potassium supplement material. In addition to improving the capacity and cycle life and thus improving the life of the battery cell due to the additional addition of a sodium source, the above-mentioned composite sodium supplement scheme can also improve the composition of SEI through lithium supplement / magnesium supplement / zinc supplement / calcium supplement / potassium supplement materials, improve its stability, reduce the cycle attenuation rate, and further improve the life of the battery cell. Ultimately, the above-mentioned sodium supplement pole piece can increase the capacity of the battery cell, improve the battery life, and has extremely broad application prospects in the field of secondary batteries.

[0020] In a third aspect of the present invention, a sodium-supplementing positive electrode is proposed, comprising a positive electrode current collector and a positive electrode material arranged on at least one side of the positive electrode current collector, wherein the positive electrode material comprises a positive electrode active substance, a binder, a conductive agent and the above-mentioned composite sodium-supplementing material.

[0021] The sodium-supplemented positive electrode of the pole piece according to the embodiment of the present invention has at least the following beneficial effects: the sodium-supplemented positive electrode provided by the present invention has a composite sodium-supplemented material additionally added to the positive electrode material, and the material at least includes a sodium-supplemented material, and at least one of a lithium-supplemented / magnesium-supplemented / zinc-supplemented / calcium-supplemented / potassium-supplemented material. In addition to improving the capacity and cycle life and thus improving the life of the battery cell due to the additional addition of a sodium source, the above-mentioned positive electrode composite sodium-supplemented scheme can also improve the composition of SEI through lithium-supplemented / magnesium-supplemented / zinc-supplemented / calcium-supplemented / potassium-supplemented materials, improve its stability, reduce the cycle attenuation rate, and further improve the life of the battery cell. Ultimately, the above-mentioned sodium-supplemented positive electrode can increase the capacity of the battery cell, improve the battery life, and has extremely broad application prospects in the field of secondary batteries.

[0022] In some embodiments of the present invention, the composite sodium supplement material includes sodium supplement material A and composite supplement material B; the composite supplement material B includes at least one of lithium supplement material, magnesium supplement material, zinc supplement material, calcium supplement material, and potassium supplement material; the mass ratio of the sodium supplement material A to the composite supplement material B is (1 to 9): (0.1 to 5.5).

[0023] In some embodiments of the present invention, the sodium supplement material A comprises Na x M y Nz , wherein 0<x<10, 0≤y≤15, 0≤z≤30, and y+z>0; M is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, and Y, and N is selected from at least one of H, C, O, S, N, F, P, and Cl.

[0024] In some embodiments of the present invention, the sodium-supplementing material includes one or more of Na5FeO4, Na2O, Na2O2, Na3N, NaN3, Na2S, NaF, Na2C2O4, Na2C3O5, Na2C4O4, Na2C6O6, and Na2N4O2; preferably, the sodium-supplementing material may be Na5FeO4 or Na2O.

[0025] In some embodiments of the present invention, the composite supplementary material B comprises A a B b C c , wherein 0<a<10, 0≤b≤13, 0≤c≤30, and b+c>0; A is selected from at least one of Li, Mg, Zn, K, and Ca, B is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, Ti, Al, Ag, and Y, and C is selected from at least one of H, C, O, S, N, F, P, and Cl.

[0026] In some embodiments of the present invention, the composite supplementary material B includes at least one of a magnesium supplementary material, a zinc supplementary material, a calcium supplementary material, and a potassium supplementary material.

[0027] In some embodiments of the present invention, the composite supplementary material B comprises A a B b C c , wherein 0<a<10, 0≤b≤13, 0≤c≤30, and b+c>0; A is selected from at least one of Mg, Zn, K, and Ca, B is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, Ti, Al, Ag, and Y, and C is selected from at least one of H, C, O, S, N, F, P, and Cl.

[0028] In some embodiments of the present invention, the composite supplementary material B includes a lithium supplementary material, and the lithium supplementary material includes one or more of Li5FeO4, Li2O, Li2O2, Li3N, LiN3, Li2S, LiF, Li2C4O4, Li2C2O4, Li2C3O5, Li2C6O6, and Li2N4O2. More preferably, the lithium supplementary material can be an inorganic lithium supplementary material Li5FeO4, Li2O, or an organic lithium supplementary material Li2C2O4.

[0029] In some embodiments of the present invention, the composite supplementary material B includes a magnesium supplement material, and the magnesium supplement material includes one or more of Mg2Mo6S8, MgS, MgMn2O4, MgMn2S4, MgCo2O4, MgNiO2, MgNi2S4, MgAl2O4, MgFe2O4, MgTiO3, and Mg3(PO4)2. Preferably, the magnesium supplement material may be Mg2Mo6S8 or MgS.

[0030] In some embodiments of the present invention, the composite supplementary material B includes a zinc supplement material, and the zinc supplement material includes one or more of ZnO, ZnCo2O4, ZnMn2O4, ZnFe2O4, ZnTiO3, ZnS, Zn3(PO4)2, ZnAl2O4, ZnNiO2, ZnV2O4, ZnMoO4, ZnCuO, and ZnAgVO4. Preferably, the zinc supplement material may be ZnS or ZnCo2O4.

[0031] In some embodiments of the present invention, the composite supplementary material B includes a calcium supplement material, and the calcium supplement material includes one or more of CaMnO3, CaNiO3, CaTiO3, CaCoO3, Ca3Co4O9, CaFeO3, Ca2Fe2O5, CaFePO4F, Ca3(PO4)2, Ca2P2O7, CaS, Ca2S, and CaCO3. Preferably, the calcium supplement material may be CaMnO3 or CaNiO3.

[0032] In some embodiments of the present invention, the composite supplementary material B comprises a potassium supplement material, and the potassium supplement material comprises KCoO2, KNiO2, KMnO2, K 1.5 V6O 16 , K3V2(PO4)2, KFePO4, K2FeP2O7, K3PO4, KV3O8, K2S, KF, KNiF3, KN3. Preferably, the potassium supplement material may be K3PO4 or K2FeP2O7.

[0033] In some embodiments of the present invention, the mass ratio of the positive electrode active material to the composite sodium supplement material is (70-98): (1-10).

[0034] In some embodiments of the present invention, the mass percentage W of the composite sodium supplement material to the positive electrode material satisfies 0<W≤10%, preferably 0.8%≤W≤8%.

[0035] In some embodiments of the present invention, the mass percentage of the sodium supplement material A in the positive electrode material is W A Satisfy 0<WA <10%, preferably 1%≤W A ≤9%.

[0036] In some embodiments of the present invention, the composite supplementary material B accounts for a mass percentage W of the positive electrode material. B Satisfy 0<W B <8%, preferably 0.1%≤W B ≤5.5%. The composite supplementary material B only participates in the formation of the first SEI (increasing capacity) and improves the stability of SEI. The amount used is small, and excessive materials cannot be used. In particular, when the composite supplementary material B is a magnesium supplementary material, a good effect can be achieved when the addition amount is low.

[0037] In some embodiments of the present invention, the preparation method of the composite sodium supplement material is not limited, as long as it can play the sodium supplement function in the positive electrode sheet. For example, the sodium supplement material A and the composite supplement material B can be added to the positive electrode slurry and directly coated and rolled into a positive electrode sheet. The sodium supplement material A and the composite supplement material B can also be sprayed onto the surface of the positive electrode sheet or coated on the isolation film.

[0038] In some embodiments of the present invention, taking the composite sodium-supplementing material, positive electrode active material, conductive agent and binder as a whole, the mass percentage of each component is: positive electrode active material 70% to 98%, conductive agent 0.5% to 10%, binder 0.5% to 10%, composite sodium-supplementing material 1% to 10%.

[0039] In some embodiments of the present invention, the positive electrode active material includes NaFePO4, NaCoO2, NaFe 0.5 Mn 0.5 O2、NaNi 0.3 Fe 0.4 Mn 0.3 O2、NaNi 0.33 Fe 0.34 Mn 0.33 O2、NaNi 0.25 Fe 0.5 Mn 0.25 O2、NaNi 0.2 Cu 0.1 Fe 0.4 Mn 0.3 O2、NaNi 0.25 Fe 0.4 Co 0.1 Mn 0.25 O2、NaN i0.5 Fe 0.4 Mn 0.4 O 2.4 、NaNi 0.4 Fe 0.2 Mn0.3 O 1.8 One or a combination of at least two of the following.

[0040] In some embodiments of the present invention, the conductive agent includes at least one of acetylene black, graphene, graphyne, carbon nanotubes, carbon fibers, and conductive carbon black. The present invention has no special requirements for the conductive agent, and any conventional conductive agent in the art can be used, such as conductive carbon black or carbon nanotubes.

[0041] In some embodiments of the present invention, the binder includes at least one of polyvinylidene fluoride PVDF, sodium carboxymethyl cellulose CMC, styrene butadiene rubber SBR, and PAA-based binders. The present invention has no special requirements for the binder, and any conventional binder in the art can be used.

[0042] In some embodiments of the present invention, the positive electrode current collector may be aluminum foil, composite aluminum foil or other common current collectors, which is not limited herein.

[0043] In some embodiments of the present invention, the positive electrode sheet or the battery cell as a whole should contain at least one sodium supplement material A and at least one of lithium supplement material / magnesium supplement material / zinc supplement material / calcium supplement material / potassium supplement material (composite supplement material B) in its initial state; during the actual use of the battery cell, the positive electrode sheet can still detect the above-mentioned substance residues (which cannot be completely decomposed) and residual products of the substance reaction.

[0044] In a fourth aspect of the present invention, a sodium ion battery is provided, comprising the above-mentioned sodium-supplementing positive electrode, a separator, an electrolyte and a negative electrode.

[0045] Since the sodium ion battery adopts all the technical solutions of the sodium supplementing positive electrode of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, that is, it has good gram capacity and cycle life, improves the stability of SEI, reduces the cycle attenuation rate, increases the cell capacity, improves the battery life, and reduces the cost, and has extremely broad application prospects.

[0046] In some embodiments of the present invention, the negative electrode is selected from at least one of hard carbon, soft carbon, or a composite of hard and soft carbon.

[0047] In some embodiments of the present invention, the separator is disposed between the sodium-supplementing positive electrode and the negative electrode, and the electrolyte infiltrates the sodium-supplementing positive electrode, the negative electrode and the separator.

[0048] In some embodiments of the present invention, the material of the diaphragm includes at least one of polyethylene, polypropylene and polyvinylidene fluoride. In actual production, the material and structure of the diaphragm are not strictly limited, for example, it can be a multi-layer structure formed by stacking the above materials, or a single-layer structure formed by mixing the above materials, or a single-layer structure formed by a single material; as long as it can play the basic role of the diaphragm.

[0049] In some embodiments of the present invention, the electrolyte includes an electrolyte salt and an organic solvent. The electrolyte salt includes lithium hexafluorophosphate. The organic solvent includes at least one of a carbonate solvent and a carboxylate solvent.

[0050] In some embodiments of the present invention, the carbonate solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC).

[0051] In some embodiments of the present invention, the carboxylate solvent includes propyl propionate (PP).

[0052] In some embodiments of the present invention, in the electrolyte solution, the concentration of the electrolyte salt is 0.8 to 1.5 mol / L.

[0053] In some embodiments of the present invention, in the lithium-ion battery, the electrolyte has a retention capacity of 6.05 to 9.65 g / 5 Ah, for example, 7.2 to 7.95 g / 5 Ah.

[0054] In some embodiments of the present invention, the conductive agent, binder, current collector, etc. used to prepare the negative electrode are all conventional materials in the art and will not be described in detail here.

[0055] In a fifth aspect of the present invention, an application of the above-mentioned sodium ion battery in an energy storage device, an electrical device or an electronic device is proposed. DETAILED DESCRIPTION

[0056] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0057] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0058] In the description of the present invention, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, wherein a and b are real numbers. Unless otherwise specified, each reaction or operation step may be performed in sequence or not. Preferably, the reaction method of the present invention is performed in sequence.

[0059] If no specific techniques or conditions are specified in the following examples, the techniques or conditions described in the literature in the art or the product instructions are used. All reagents or instruments without manufacturer specified are conventional products that can be purchased commercially.

[0060] Example 1

[0061] (1) Preparation of positive electrode sheet

[0062] The positive electrode active material sodium iron phosphate NaFePO4, the sodium supplement material Na2C2O4, the magnesium supplement material MgS, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an N-methylpyrrolidone solvent system in a mass ratio of 88:3:2:4:3, and then coated on the positive electrode current collector Al foil, and dried, cold pressed, and slit to obtain the positive electrode sheet.

[0063] (2) Preparation of negative electrode sheet

[0064] The negative electrode active material hard carbon, the conductive agent acetylene black, the binder styrene butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are fully stirred and mixed in a deionized water solvent system at a mass ratio of 90:2:4.5:3.5, and then coated on the negative electrode current collector Al foil, and dried, cold pressed, and slit to obtain a negative electrode sheet.

[0065] (3) Preparation of isolation membrane

[0066] A polyethylene (PE) porous polymer film is used as the isolation membrane.

[0067] (4) Preparation of electrolyte

[0068] A solution prepared by mixing sodium salt NaPF6 and non-aqueous organic solvent (ethylene carbonate (EC): diethyl carbonate (DEC): propylene carbonate (PC): propyl propionate (PP): vinylene carbonate (VC)) = 20:30:20:23:5, mass ratio) in a mass ratio of 10:90 is used as the electrolyte of sodium ion secondary battery.

[0069] (5) Preparation of sodium ion secondary batteries

[0070] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, the separator is placed between the positive electrode sheet and the negative electrode sheet to play a role of safety isolation, and then wound to obtain an electrode assembly. The electrode assembly is placed in a packaging shell, the electrolyte is injected and packaged to obtain a sodium ion secondary battery.

[0071] Example 2

[0072] The difference from Example 1 is that the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, the sodium supplement material Na2C2O4, the magnesium supplement material MgS, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) is 86:3:4:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0073] Example 3

[0074] The difference from Example 1 is that the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, the sodium supplement material Na2C2O4, the magnesium supplement material MgS, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) is 87.8:2.8:2.4:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0075] Example 4

[0076] The difference from Example 1 is that the sodium supplement material Na2C2O4 is replaced by Na2NiO2. The rest is the same as Example 1 and will not be described again.

[0077] Example 5

[0078] The difference from Example 1 is that the magnesium supplement material MgS is replaced by Mg2Mo6S8. The rest is the same as Example 1 and will not be described again.

[0079] Example 6

[0080] The difference from Example 1 is that it does not contain magnesium supplement material, but contains zinc supplement material ZnNiO2 of equal mass, and the rest is the same as Example 1 and will not be described again.

[0081] Example 7

[0082] The difference from Example 1 is that it does not contain magnesium supplement material, but contains calcium supplement material CaMnO3 of the same mass, and the rest is the same as Example 1 and will not be described again.

[0083] Example 8

[0084] The difference from Example 1 is that it does not contain magnesium supplement material, but contains potassium supplement material KCoO2 of the same mass, and the rest is the same as Example 1 and will not be repeated here.

[0085] Example 9

[0086] The difference from Example 1 is that it also contains zinc supplement material ZnNiO2, and the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, the sodium supplement material Na2C2O4, the magnesium supplement material MgS, the zinc supplement material ZnNiO2, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) is 87.9:3:1.6:0.5:4:3. The rest is the same as Example 1 and will not be repeated here.

[0087] Example 10

[0088] The difference from Example 1 is that it also contains potassium supplement material KCoO2, and the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, sodium supplement material Na2C2O4, magnesium supplement material MgS, potassium supplement material KCoO2, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) is 87.8:3:1.4:0.8:4:3, and the rest is the same as Example 1 and will not be repeated.

[0089] Embodiment 11

[0090] The difference from Example 1 is that it does not contain magnesium supplement material, but contains lithium supplement material Li5FeO4 and calcium supplement material CaMnO3, and the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, sodium supplement material Na2C2O4, lithium supplement material Li5FeO4, calcium supplement material CaMnO3, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) is 88.3:3:0.9:0.8:4:3. The rest is the same as Example 1 and will not be repeated here.

[0091] Example 12

[0092] The difference from Example 1 is that it contains zinc supplement material ZnNiO2 and calcium supplement material CaMnO3, and the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, sodium supplement material Na2C2O4, magnesium supplement material MgS, zinc supplement material ZnNiO2, calcium supplement material CaMnO3, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) is 88:3:1:0.5:0.5:4:3. The rest is the same as Example 1 and will not be repeated here.

[0093] Embodiment 13

[0094] The difference from Example 1 is that it does not contain magnesium supplement material, but contains lithium supplement material Li5FeO4, zinc supplement material ZnNiO2 and potassium supplement material KCoO2, and the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, sodium supplement material Na2C2O4, zinc supplement material ZnNiO2, lithium supplement material Li5FeO4, potassium supplement material KCoO2, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) is 87.2:3:1.5:0.9:0.4:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0095] Comparative Example 1

[0096] The difference from Example 1 is that no magnesium supplement material is contained, the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, the sodium supplement material Na2C2O4, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) is 89:4:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0097] Comparative Example 2

[0098] The difference from Example 1 is that the content of sodium supplement material is 11%, the mass ratio of positive electrode active material sodium iron phosphate NaFePO4, sodium supplement material Na2C2O4, magnesium supplement material MgS, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) is 81.5:11:0.5:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0099] Comparative Example 3

[0100] The difference from Example 1 is that the content of magnesium supplement is 8.5%, the mass ratio of positive electrode active material sodium iron phosphate NaFePO4, sodium supplement material Na2C2O4, magnesium supplement material MgS, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) is 80.5:4:8.5:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0101] Comparative Example 4

[0102] The difference from Example 1 is that the content of sodium supplement is 7%, the content of magnesium supplement is 4%, the mass ratio of positive electrode active material sodium iron phosphate NaFePO4, sodium supplement material Na2C2O4, magnesium supplement material MgS, conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) is 82:7:4:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0103] Comparative Example 5

[0104] The difference from Example 1 is that no sodium supplement material is contained, the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, the magnesium supplement material MgS, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) is 90:3:4:3, and the rest is the same as Example 1 and will not be repeated here.

[0105] Comparative Example 6

[0106] The difference from Example 1 is that no sodium supplement material and magnesium supplement material are contained, the mass ratio of the positive electrode active material sodium iron phosphate NaFePO4, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) is 93:4:3, and the rest is the same as Example 1 and will not be repeated.

[0107] The materials and proportions of Examples 1-13 and Comparative Examples 1-6 are shown in Table 1:

[0108] Table 1

[0109]

[0110]

[0111] Performance Testing

[0112] Gram Capacity Test

[0113] Ten sodium ion secondary batteries in the comparative example and the example were taken, and charged at room temperature at a constant current of 0.1C until the voltage reached 3.7V, and further charged at a constant voltage of 3.7V until the current was lower than 0.05C. Then, they were discharged at a constant current of 0.1C until the voltage reached 2.5V.

[0114] Cyclic performance test

[0115] Take 10 sodium ion secondary batteries prepared in the comparative example and the example, and repeatedly charge and discharge the lithium sodium ion secondary batteries through the following steps, and calculate the cycle capacity retention rate of the sodium ion secondary batteries: in an environment of 45°C, perform the first charge and discharge, perform constant current and constant voltage charging at a charging current of 0.1C (i.e., the current value of completely discharging the theoretical capacity within 10h) until the upper limit voltage is 3.7V, and then perform constant current discharge at a discharge current of 1C until the final voltage is 2.5V, and record the discharge capacity of the first cycle; then perform 200 charge and discharge cycles, and record the discharge capacity of the 200th cycle.

[0116] Cycle capacity retention rate C200=(discharge capacity at the 200th cycle / discharge capacity at the first cycle)×100%.

[0117] The test data is shown in Table 2:

[0118] Table 2

[0119] Gram capacity mAh / g C200 Comparative Example 1 132.3 72.1 Comparative Example 2 128.5 65.3 Comparative Example 3 126.4 63.5 Comparative Example 4 127.6 66.6 Comparative Example 5 131.7 71.5 Comparative Example 6 130.9 70.9 Example 1 134.6 76.5 Example 2 134.7 76.6 Example 3 134.9 76.2 Example 4 134.4 77.1 Example 5 135.1 77.2 Example 6 135.2 76.8 Example 7 134.9 76.5 Example 8 135.3 76.9 Example 9 135.1 76.8 Example 10 135.2 76.7 Embodiment 11 134.7 76.6 Example 12 134.8 76.8 Embodiment 13 134.6 76.7

[0120] From Table 1 and Examples 1-3, it can be seen that different ratios of sodium-supplementing and magnesium-supplementing materials within the scope of the present invention can also achieve similar effects; at the same time, Example 2 illustrates that further increasing the sodium-supplementing material cannot further increase the capacity and improve the lifespan.

[0121] It can be seen from Table 1, Example 1 and Examples 4-8 that one of the different sodium supplementation + lithium supplementation / magnesium supplementation / zinc supplementation / calcium supplementation / potassium supplementation materials can achieve similar effects.

[0122] It can be seen from Table 1, Example 1 and Examples 9-13 that the combined supplementation of sodium supplementation + lithium supplementation / magnesium supplementation / zinc supplementation / calcium supplementation / potassium supplementation can achieve better results.

[0123] It can be seen from Table 1, Example 1 and Comparative Examples 2-4 that when the content of sodium supplement and magnesium supplement is too high, the active material of the battery cell decreases, and the gram capacity of the battery cell will deteriorate.

[0124] From Table 1, Example 1 and Comparative Example 1, Comparative Examples 5-6, it can be seen that simple magnesium supplementation can also replenish SEI to consume active Li and improve SEI, thereby improving lifespan; however, the method of combined sodium supplementation + magnesium supplementation is better than simple sodium supplementation or simple magnesium supplementation, and is better than no supplementation.

[0125] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A composite sodium supplement material, characterized in that: The composite sodium supplement material includes a sodium supplement material A and a composite supplement material B; the composite supplement material B includes at least one of a lithium supplement material, a magnesium supplement material, a zinc supplement material, a calcium supplement material, and a potassium supplement material; The mass ratio of the sodium supplement material A to the composite supplement material B is (1-9): (0.1-5.5).

2. The composite sodium supplement material according to claim 1, characterized in that The composite supplement material B includes at least one of a magnesium supplement material, a zinc supplement material, a calcium supplement material, and a potassium supplement material.

3. The composite sodium supplement material according to claim 1, characterized in that The sodium supplement material A includes Na x M y N z , wherein 0<x<10, 0≤y≤15, 0≤z≤30, and y+z>0; M is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, and Y, and N is selected from at least one of H, C, O, S, N, F, P, and Cl; and / or, the composite supplementary material B includes A a B b C c , wherein 0<a<10, 0≤b≤13, 0≤c≤30, and b+c>0; A is selected from at least one of Li, Mg, Zn, K, and Ca, B is selected from at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, Sn, Cr, V, Mo, Ti, Al, Ag, and Y, and C is selected from at least one of H, C, O, S, N, F, P, and Cl.

4. The composite sodium supplement material according to claim 1, characterized in that The sodium supplement material includes one or more of Na5FeO4, Na2O, Na2O2, Na3N, NaN3, Na2S, NaF, Na2C2O4, Na2C3O5, Na2C4O4, Na2C6O6, and Na2N4O2; And / or, the lithium supplement material A includes one or more of Li5FeO4, Li2O, Li2O2, Li3N, LiN3, Li2S, LiF, Li2C4O4, Li2C2O4, Li2C3O5, Li2C6O6, and Li2N4O2; And / or, the magnesium supplement material includes one or more of Mg2Mo6S8, MgS, MgMn2O4, MgMn2S4, MgCo2O4, MgNiO2, MgNi2S4, MgAl2O4, MgFe2O4, MgTiO3, and Mg3(PO4)2; And / or, the zinc supplement material includes one or more of ZnO, ZnCo2O4, ZnMn2O4, ZnFe2O4, ZnTiO3, ZnS, Zn3(PO4)2, ZnAl2O4, ZnNiO2, ZnV2O4, ZnMoO4, ZnCuO, and ZnAgVO4; And / or, the calcium supplement material includes one or more of CaMnO3, CaNiO3, CaTiO3, CaCoO3, Ca3Co4O9, CaFeO3, Ca2Fe2O5, CaFePO4F, Ca3(PO4)2, Ca2P2O7, CaS, Ca2S, and CaCO3; And / or, the potassium supplement material includes KCoO2, KNiO2, KMnO2, K 1.5 V6O 16 , one or more of K3V2(PO4)2, KFePO4, K2FeP2O7, K3PO4, KV3O8, K2S, KF, KNiF3, and KN3.

5. A pole piece, characterized in that: It comprises the composite sodium supplement material as described in any one of claims 1 to 4.

6. A sodium supplementing positive electrode, comprising a positive electrode current collector and a positive electrode material disposed on at least one side of the positive electrode current collector, characterized in that: The positive electrode material comprises a positive electrode active material, a binder, a conductive agent and the composite sodium supplement material according to any one of claims 1 to 4.

7. The sodium supplementing positive electrode according to claim 6, characterized in that The mass percentage W of the composite sodium supplement material to the positive electrode material satisfies 0<W≤10%.

8. The sodium supplementing positive electrode according to claim 7, characterized in that: The mass percentage of the sodium supplement material A in the positive electrode material is W A Satisfy 0<W A <10%, preferably 1%≤W A ≤9%; And / or, the mass percentage of the composite supplementary material B in the positive electrode material is W B Satisfy 0<W B <8%, preferably 0.1%≤W B ≤5.5%.

9. A sodium ion battery, characterized in that: The method comprises a sodium-supplementing positive electrode, a separator, an electrolyte and a negative electrode as described in any one of claims 5 to 8.

10. Use of the sodium ion battery according to claim 9 in an energy storage device, an electrical device or an electronic device.

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