A sodium-ion battery with sodium supplementing positive electrode and preparation method thereof

Abstract

The application discloses a kind of positive pole sodium-supplementing sodium-ion battery and preparation method thereof, belong to sodium-ion battery technical field.The preparation method includes: S01, the addition amount of sodium-supplementing material is calculated: with the first charge capacity of positive electrode active material corresponding negative electrode active material as a, first discharge capacity is b;With the first charge capacity of the sodium-supplementing material corresponding the negative electrode active material as c, discharge capacity after cycle stabilization is d;According to the relationship between the amount of use e of the positive electrode active material and the addition amount f of the sodium-supplementing material: e*(a-b)=f*(c-d) the addition amount f of the sodium-supplementing material is calculated;S02, respectively, weigh positive electrode active material and sodium-supplementing material;S03, weigh negative electrode active material;S04, with the material prepared to obtain positive pole sodium-supplementing sodium-ion battery.The application compensates the loss of sodium element in the positive pole caused by the negative pole, which can effectively improve the overall volume energy density of the battery.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a sodium-ion battery with sodium replenishment at the positive electrode and its preparation method. Background Technology

[0002] Since the development of lithium-ion battery technology, lithium-ion batteries have become the most industrialized. However, lithium is scarce in the Earth's crust, while market demand is enormous. In recent years, with the large-scale application of lithium-ion batteries in electric vehicles, lithium resources have become increasingly scarce, leading to a significant increase in the price of lithium carbonate, the main raw material for lithium-ion batteries. This has also significantly increased production costs for companies in the industry chain. Sodium-ion batteries, due to their abundant raw material resources and stable, inexpensive prices, have once again attracted attention and research from the industry.

[0003] Sodium-ion batteries have similar electrochemical performance to lithium-ion batteries. However, the negative electrode of sodium-ion batteries cannot use graphite materials. Only hard carbon, soft carbon, or alloy materials can be used. The initial efficiency of these materials is generally not high, and the compaction density is also not high. They easily consume sodium elements from the positive electrode, resulting in a low overall volumetric energy density of sodium-ion batteries. This has greatly limited their application in digital battery applications, thus restricting their scope of use. Summary of the Invention

[0004] Based on this, the present invention provides a sodium-ion battery with sodium replenishment at the positive electrode and its preparation method, aiming to solve the problems of generally low initial efficiency of existing sodium-ion battery negative electrode materials, low subsequent compaction density, easy consumption of sodium elements from the positive electrode, and low overall volumetric energy density of sodium-ion batteries. This application, by compensating for the sodium element loss at the positive electrode caused by the negative electrode, can effectively improve the overall volumetric energy density of the battery, broaden the application range of sodium-ion batteries, and meet the usage requirements of sodium-ion batteries.

[0005] To achieve the above objectives, in one aspect, embodiments of the present invention provide a method for preparing a sodium-ion battery with sodium supplementation at the positive electrode, applicable to sodium-ion batteries, comprising the following steps:

[0006] S01. Calculate the amount of sodium-supplementing material to be added: Let a be the initial charge capacity of the positive electrode active material corresponding to the negative electrode active material, and b be the initial discharge capacity; let c be the initial charge capacity of the sodium-supplementing material corresponding to the negative electrode active material, and d be the discharge capacity after cycle stabilization; calculate the amount of sodium-supplementing material to be added f based on the relationship between the amount of positive electrode active material e and the amount of sodium-supplementing material f: e*(ab)=f*(cd);

[0007] S02, Weigh the positive electrode active material and the sodium supplement material respectively;

[0008] S03. Weigh the negative electrode active material;

[0009] S04. A sodium-ion battery with sodium-added positive electrode is prepared by weighing out the positive electrode active material, sodium-supplementing material and negative electrode active material.

[0010] In a preferred embodiment, the total capacity of the positive electrode active material is e*a+f*c.

[0011] In a preferred embodiment, the total reversible capacity of the positive electrode active material is e*a+f*d.

[0012] In a preferred embodiment, the amount j of the negative electrode active material is determined by the following method: the amount j of the negative electrode active material and the total capacity utilization of the positive electrode active material have the following relationship:

[0013] 1.3*(e*a+f*c)>j*g>1.03*(e*a+f*c);

[0014] Where g is the initial discharge capacity of sodium metal corresponding to the negative electrode active material; j is the amount of negative electrode active material used; 1.03 is the equipment tolerance coefficient; and 1.3 is a coefficient reflecting battery performance and economy.

[0015] In a preferred embodiment, the sodium-ion battery is a sodium-ion battery with sodium replenished at the positive electrode.

[0016] In a preferred embodiment, the positive electrode active material is one of sodium nickel iron manganese oxide, sodium copper iron manganese oxide, Prussian blue, or a polyanionic compound; the sodium supplementing material is one of sodium oxalate, sodium persilicate, layered sodium manganate, or sodium ferrite.

[0017] The polyanionic compound is sodium vanadium phosphate or sodium fluorophosphate.

[0018] In a preferred embodiment, step S04, which involves preparing a sodium-ion battery with a sodium-added positive electrode using the weighed positive electrode active material, sodium-supplementing material, and negative electrode active material, specifically includes the following steps:

[0019] 1) Prepare a positive electrode slurry by mixing (positive electrode active material + sodium supplement material): first conductive agent: first binder: first solvent in a mass ratio of 95:2.5:2.5:70, and then coat the positive electrode slurry onto an aluminum foil current collector;

[0020] 2) Prepare a negative electrode slurry by mixing negative electrode active material, thickener, second conductive agent, second binder, and second solvent in a mass ratio of 94.5:1.5:1.5:2.5:130, and then coat the negative electrode slurry onto an aluminum foil current collector.

[0021] 3) The positive electrode slurry is coated onto the aluminum foil current collector, and the negative electrode slurry is coated onto the aluminum foil current collector for further assembly into a sodium-ion battery with sodium supplementation at the positive electrode.

[0022] The first conductive agent is preferably carbon black.

[0023] The first adhesive is preferably PVDF.

[0024] The first solvent is preferably NMP.

[0025] The preferred negative electrode active material is hard carbon.

[0026] The second conductive agent is preferably carbon black.

[0027] The thickener is preferably CMC.

[0028] The second adhesive is preferably SBR.

[0029] The second solvent is preferably water.

[0030] On the other hand, embodiments of this application also provide a sodium-ion battery with sodium-supplemented positive electrode prepared by the preparation method described above.

[0031] In a preferred embodiment, the positive electrode active material of the sodium-ion battery with positive electrode sodium replenishment is one of sodium nickel iron manganese oxide, sodium copper iron manganese oxide, Prussian blue, or a polyanionic compound; the sodium replenishing material of the sodium-ion battery with positive electrode sodium replenishment is one of sodium oxalate, sodium persilicate, layered sodium manganate, or sodium ferrite.

[0032] In the embodiments of this application, compared with sodium-ion batteries without positive electrode sodium supplementation, the volumetric energy density of the sodium-ion battery with positive electrode sodium supplementation obtained in the embodiments of this application can be increased by about 5%.

[0033] This application compensates for the sodium loss at the positive electrode caused by the negative electrode, effectively improving the overall volumetric energy density of the battery. It addresses the problems of low initial efficiency and low compaction density in existing technologies, which easily consume sodium from the positive electrode, resulting in low overall volumetric energy density in sodium-ion batteries. The sodium-ion battery with positive electrode sodium replenishment prepared in this application can promptly replenish the sodium lost at the positive electrode, exhibiting high volumetric energy density and effectively broadening the application range of sodium-ion batteries, meeting their usage requirements. The preparation method of this application is simple, uses widely available raw materials, has low production costs, high production efficiency, and is easy to mass-produce or scale up.

[0034] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0037] Sodium-ion batteries possess similar electrochemical performance to lithium-ion batteries. However, the negative electrode of sodium-ion batteries cannot use graphite materials; only hard carbon, soft carbon, or alloy materials can be used. These materials generally have low initial efficiency, and their compaction density is also low, easily consuming sodium from the positive electrode. This results in a low overall volumetric energy density of sodium-ion batteries, significantly limiting their application in digital battery-based applications and restricting their scope of use. Therefore, it is necessary to provide a sodium-ion battery with sodium replenishment at the positive electrode and its preparation method to solve the aforementioned technical problems.

[0038] To achieve the above objectives, in one aspect, embodiments of the present invention provide a method for preparing a sodium-ion battery with sodium supplementation at the positive electrode, applicable to sodium-ion batteries, comprising the following steps:

[0039] S01. Calculate the amount of sodium-supplementing material to be added: Let a = 138 mAh / g and b = 123 mAh / g be the initial charging capacity of the positive electrode active material corresponding to the negative electrode active material; let c = 394 mAh / g be the initial charging capacity of the sodium-supplementing material corresponding to the negative electrode active material, and d = 7 mAh / g be the discharge capacity after cycle stabilization; based on the relationship between the amount e of the positive electrode active material and the amount f of the sodium-supplementing material: e*(ab) = f*(cd), calculate the amount f of the sodium-supplementing material. We can then calculate the ratio of the positive electrode active material to the sodium-supplementing material: e / f = 25.8 / 1.

[0040] S02, Weigh out the positive electrode active material and sodium supplement material according to the proportions;

[0041] S03. Weigh the negative electrode active material;

[0042] S04. A sodium-ion battery with sodium-added positive electrode is prepared by weighing out the positive electrode active material, sodium-supplementing material and negative electrode active material.

[0043] In a preferred embodiment, the total capacity of the positive electrode active material is e*a+f*c.

[0044] In a preferred embodiment, the total reversible capacity of the positive electrode active material is e*a+f*d.

[0045] In a preferred embodiment, the amount j of the negative electrode active material is determined by the following method: the amount j of the negative electrode active material and the total capacity utilization of the positive electrode active material have the following relationship:

[0046] 1.3*(e*a+f*c)>j*g>1.03*(e*a+f*c);

[0047] Where g is the initial discharge capacity of sodium metal corresponding to the negative electrode active material; j is the amount of negative electrode active material used; 1.03 is the equipment tolerance coefficient; and 1.3 is a coefficient reflecting battery performance and economy.

[0048] In a preferred embodiment, the actual amount of sodium supplement material used is less than or equal to the theoretical amount f of sodium supplement material; preferably, the actual amount of sodium supplement material used is equal to the theoretical amount f of sodium supplement material used.

[0049] In a preferred embodiment, the positive electrode active material is one of sodium nickel iron manganese oxide, sodium copper iron manganese oxide, Prussian blue, or a polyanionic compound; the sodium supplementing material is one of sodium oxalate, sodium persilicate, layered sodium manganate, or sodium ferrite.

[0050] Specifically, in this embodiment, the positive electrode active material is sodium nickel iron manganese oxide; the sodium supplement material is sodium oxalate.

[0051] In a preferred embodiment, the sodium-ion battery is a sodium-ion battery with sodium replenished at the positive electrode.

[0052] In this embodiment of the sodium-ion battery with sodium supplementation at the positive electrode, the positive electrode slurry is prepared by mixing (positive electrode active material + sodium supplementation material), a first conductive agent (carbon black), a first binder (PVDF), and a first solvent (NMP) in a mass ratio of 95:2.5:2.5:70. PVDF is dissolved in NMP to prepare a gel solution, and then carbon black and active material are added to the gel solution in sequence and stirred until homogeneous to obtain the positive electrode slurry. Then, according to 150 g / m... 2 The areal density is used to coat the positive electrode paste onto the aluminum foil current collector.

[0053] The negative electrode slurry was prepared from negative electrode active material (hard carbon, initial discharge specific capacity of 320), thickener (CMC), second conductive agent (carbon black), second binder (SBR), and second solvent (water) in a mass ratio of 94.5:1.5:1.5:2.5:130. Then, it was prepared according to 83 g / m2 The areal density (with a negative electrode excess of 1.2) is used to coat the negative electrode slurry onto the aluminum foil current collector.

[0054] Specifically, in step S04, the preparation of a sodium-ion battery with sodium-added positive electrode using the weighed positive electrode active material, sodium-supplementing material, and negative electrode active material includes the following steps:

[0055] 1) Prepare a positive electrode slurry by mixing (positive electrode active material + sodium supplement material): first conductive agent: first binder: first solvent in a mass ratio of 95:2.5:2.5:70, and then coat the positive electrode slurry onto an aluminum foil current collector;

[0056] 2) Prepare a negative electrode slurry by mixing negative electrode active material, thickener, second conductive agent, second binder, and second solvent in a mass ratio of 94.5:1.5:1.5:2.5:130, and then coat the negative electrode slurry onto an aluminum foil current collector.

[0057] 3) The positive electrode slurry is coated onto the aluminum foil current collector, and the negative electrode slurry is coated onto the aluminum foil current collector for further assembly into a sodium-ion battery with sodium supplementation at the positive electrode.

[0058] The first conductive agent is carbon black. The first adhesive is PVDF. The first solvent is NMP.

[0059] The negative electrode active material is hard carbon. The second conductive agent is carbon black. The thickener is CMC. The second binder is SBR. The second solvent is water.

[0060] On the other hand, embodiments of this application also provide a sodium-ion battery with sodium-supplemented positive electrode prepared by the preparation method described above.

[0061] In a preferred embodiment, the sodium-ion battery is a sodium-ion battery with sodium replenished at the positive electrode.

[0062] In the embodiments of this application, the positive electrode active material of the sodium-ion battery with positive electrode sodium replenishment is one of sodium nickel iron manganese oxide, sodium copper iron manganese oxide, Prussian blue or polyanionic compound; the sodium replenishing material of the sodium-ion battery with positive electrode sodium replenishment is one of sodium oxalate, sodium persilicate, layered sodium manganate or sodium ferrite.

[0063] In the embodiments of this application, compared with sodium-ion batteries without positive electrode sodium supplementation, the volumetric energy density of the sodium-ion battery with positive electrode sodium supplementation obtained in the embodiments of this application can be increased by at least 5%.

[0064] This application compensates for the sodium loss at the positive electrode caused by the negative electrode, effectively improving the overall volumetric energy density of the battery. It addresses the problems of low initial efficiency and low compaction density in existing technologies, which easily consume sodium from the positive electrode, resulting in low overall volumetric energy density in sodium-ion batteries. The sodium-ion battery with positive electrode sodium replenishment prepared in this application can promptly replenish the sodium lost at the positive electrode, exhibiting high volumetric energy density and effectively broadening the application range of sodium-ion batteries, meeting their usage requirements. The preparation method of this application is simple, uses widely available raw materials, has low production costs, high production efficiency, and is easy to mass-produce or scale up.

[0065] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for the preparation of a sodium-ion battery with sodium-supplying cathode, suitable for sodium-ion batteries, characterized in that: Comprising the following steps: S01, calculating the addition amount of sodium supplement material: taking the first charge capacity of the positive active material corresponding to the negative active material as a, the first discharge capacity as b; taking the first charge capacity of the sodium supplement material corresponding to the negative active material as c, the discharge capacity after cycle stabilization as d; according to the relationship between the amount e of the positive active material and the addition amount f of the sodium supplement material: e*(a-b)=f*(c-d), the addition amount f of the sodium supplement material is calculated; S02, respectively weighing the positive active material and the sodium supplement material; S03, weighing the negative active material; S04, preparing the sodium ion battery with sodium-supplemented positive electrode by using the weighed positive active material, sodium supplement material and negative active material.

2. The method of claim 1, wherein the sodium-ion battery is a sodium-ion battery with sodium deficient cathode. The total capacity of the positive active material is e*a+f*c.

3. The method for preparing a sodium-ion battery with sodium supplementation at the positive electrode according to claim 1, characterized in that: The total reversible capacity of the positive active material is e*a+f*d.

4. The method for preparing a sodium-ion battery with sodium supplementation at the positive electrode according to claim 1, characterized in that: The amount j of the negative active material is determined by the following method: there is a relationship between the amount j of the negative active material and the total capacity of the positive active material: 1.3*(e*a+f*c)>j*g>1.03*(e*a+f*c); Wherein, g is the first discharge capacity of the negative active material corresponding to metallic sodium; j is the amount of the negative active material; 1.03 is the equipment tolerance coefficient; 1.3 is the coefficient reflecting the performance and economy of the battery.

5. The method for preparing a sodium-ion battery with sodium supplementation at the positive electrode according to claim 1, characterized in that: The positive active material is one of sodium nickel iron manganese oxide, sodium copper iron manganese oxide, prussian blue or polyanion type compound; the sodium supplement material is one of sodium oxalate, high-silicon sodium, layered sodium manganate or sodium ferrite.

6. The method for preparing a sodium-ion battery with sodium supplementation at the positive electrode according to claim 1, characterized in that: In step S04, the sodium ion battery with sodium-supplemented positive electrode is prepared by using the weighed positive active material, sodium supplement material and negative active material, which specifically includes the following steps: 1) The positive active material + sodium supplement material: first conductive agent: first adhesive: first solvent are prepared into positive electrode slurry in a mass ratio of 95:2.5:2.5:70, and the positive electrode slurry is coated on the aluminum foil current collector; 2) The negative active material: thickening agent: second conductive agent: second adhesive: second solvent are prepared into negative electrode slurry in a mass ratio of 94.5:1.5:1.5:2.5:130, and the negative electrode slurry is coated on the aluminum foil current collector; 3) The positive electrode slurry is coated on the aluminum foil current collector, and the negative electrode slurry is coated on the aluminum foil current collector to further assemble into the sodium ion battery with sodium-supplemented positive electrode.

7. The method for preparing a sodium-ion battery with sodium supplementation at the positive electrode according to claim 6, characterized in that: The first conductive agent is carbon black; the first adhesive is PVDF; and the first solvent is NMP.

8. The method for preparing a sodium-ion battery with sodium supplementation at the positive electrode according to claim 6, characterized in that: The negative active material is hard carbon; the thickening agent is CMC; the second conductive agent is carbon black; the second adhesive is SBR; and the second solvent is water.

9. A sodium-ion battery with sodium supplementing cathode, characterized in that: Prepared by the preparation method of any one of claims 1-8.

10. The sodium-ion battery with sodium supplementing cathode according to claim 9, characterized in that: The positive active material of the sodium ion battery with sodium-supplemented positive electrode is one of sodium nickel iron manganese oxide, sodium copper iron manganese oxide, prussian blue or polyanion type compound; and the sodium supplement material of the sodium ion battery with sodium-supplemented positive electrode is one of sodium oxalate, high-silicon sodium, layered sodium manganate or sodium ferrite.