Preparation method and application of tin-based sulfide sodium ion battery negative electrode sheet

Abstract

The invention discloses a preparation method and application of a tin-based sulfide sodium ion battery negative electrode sheet, comprising heating an alloy foil with an oxidizing gas to react, obtaining a nanoporous metal foil, wherein the alloy foil is a copper-tin alloy or an aluminum-tin alloy, the oxidizing gas is chlorine or a mixture of chlorine and an inert gas, the metal foil is placed in an organic solvent, tin tetrachloride and an organic sulfide are added to the organic solvent, and the reaction is heated under an inert atmosphere to obtain a tin-based sulfide sodium ion battery negative electrode sheet. The invention reacts the prepared alloy foil with chlorine, the aluminum in the alloy foil is oxidized to form a dense oxide film, the copper does not react with the chlorine, the dealloying of tin is achieved, and a nanoporous metal foil is obtained, tin disulfide is obtained by a solvent thermal method, and the tin disulfide is embedded using the nanopores of the metal foil as a template, thereby avoiding the subsequent coating process of the negative electrode material, and the embedded structure is tight, and the phenomenon of powder removal will not occur, thereby improving the cycle performance when it is used as a negative electrode material.

Description

Technical Field

[0001] The invention belongs to the technical field of negative electrode materials for sodium ion batteries, and specifically relates to a preparation method and application of a tin-based sulfide sodium ion battery negative electrode sheet. Background Art

[0002] In the 1970s and 1980s, the research on sodium-ion batteries and lithium-ion batteries was at almost the same level. However, the successful application of graphite anodes in lithium-ion batteries directly promoted its commercialization process, but sodium-ion batteries have not yet achieved industrial breakthroughs. One of the bottlenecks is the lack of suitable practical anode materials. In recent years, the research on sodium-ion batteries has made important progress, among which the research on anode materials mainly focuses on carbon materials and some non-carbon materials (metals and oxide materials, alloy materials and phosphorus, etc.). Non-carbon materials show high storage capacity for both lithium and sodium, but due to problems such as low conductivity, large volume change and easy pulverization, they have not been widely used even in lithium-ion batteries with a high degree of commercialization. The above problems also exist in sodium-ion batteries.

[0003] Based on the characteristics of sodium-ion batteries, aluminum foil can be used as the current collector for both the positive and negative electrodes, unlike lithium-ion batteries where the positive electrode is aluminum foil and the negative electrode is copper foil. Therefore, the cost of sodium-ion batteries is lower than that of lithium-ion batteries.

[0004] The production of positive and negative electrodes of sodium-ion batteries is the same as that of lithium-ion batteries. Both need to be coated in organic solvents, which may cause powder shedding during use.

[0005] Related technology discloses a three-dimensional sea urchin / porous composite structure lithium ion battery copper / copper oxide / tin dioxide / carbon negative electrode, which is composed of three-dimensional nanoporous copper, copper oxide film, tin dioxide and carbon. The copper oxide film is a continuous film formed by partial oxidation of the surface of the three-dimensional nanoporous copper. The copper oxide film wraps the three-dimensional nanoporous copper, and the tin dioxide is wrapped by carbon. The carbon-wrapped tin dioxide forms a carbon-wrapped tin dioxide layer with a sea urchin structure on the outer surface of the three-dimensional nanoporous copper wrapped by the copper oxide film. It simplifies the production process of the negative electrode of the lithium ion battery, avoids the active components from falling off during the charge and discharge process of the lithium ion battery, and effectively improves the cycle performance and rate performance of the negative electrode of the lithium ion battery. However, this method can only be applied to copper foil of lithium ion batteries, and is not applicable to aluminum foil. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a preparation method and application of a tin-based sulfide sodium ion battery negative electrode sheet, wherein the negative electrode sheet current collector can be copper or aluminum, and does not require coating, thereby avoiding material powdering.

[0007] According to one aspect of the present invention, a method for preparing a tin-based sulfide sodium ion battery negative electrode sheet is provided, comprising the following steps:

[0008] S1: heating the alloy foil and the oxidizing gas to react, washing, and obtaining a nanoporous metal foil, wherein the alloy foil is a copper-tin alloy or an aluminum-tin alloy, and the oxidizing gas is chlorine or a mixture of chlorine and an inert gas; during the reaction, tin and chlorine generate tin tetrachloride, aluminum is oxidized to form a dense oxide film, and copper does not react with chlorine, thereby achieving dealloying of tin.

[0009] S2: placing the metal foil in an organic solvent, adding tin tetrachloride and an organic sulfide to the organic solvent, and heating the mixture under an inert atmosphere to react, thereby obtaining the tin-based sulfide sodium ion battery negative electrode sheet.

[0010] In some embodiments of the present invention, in step S1, the content of tin atoms in the alloy foil is 15-50%.

[0011] In some embodiments of the present invention, in step S1, the volume fraction of chlorine in the oxidizing gas is 10-100%. Further, the inert gas is nitrogen or argon.

[0012] In some embodiments of the present invention, in step S1, the reaction temperature is 70-80°C.

[0013] In some embodiments of the present invention, in step S1, the alloy foil is obtained by co-melting.

[0014] In some embodiments of the present invention, in step S2, the organic sulfide is at least one of n-dodecyl mercaptan, tert-dodecyl mercaptan, thiourea, phenylthiourea, diphenyl disulfide or cysteine.

[0015] In some embodiments of the present invention, in step S2, the organic solvent is at least one of a hexadecane, octadecane, eicosane or docosane unsaturated fatty acid or an unsaturated fatty amine.

[0016] In some embodiments of the present invention, in step S2, the molar ratio of the organic sulfide to tin tetrachloride is (2-4):1.

[0017] In some embodiments of the present invention, in step S2, the reaction temperature is 220-290° C. Further, the reaction time is 10-30 minutes. The inert gas is nitrogen or argon.

[0018] In some embodiments of the present invention, in step S2, after the reaction is completed, the step of washing the tin-based sulfide sodium ion battery negative electrode sheet is further included, wherein the washing is first washed with water and then washed with at least one of n-hexane, cyclohexane, methylcyclohexane, toluene, tetrahydrofuran, cycloheptane, isopropanol, n-propanol or ethanol.

[0019] In some embodiments of the present invention, in step S2, the tin tetrachloride is the tin tetrachloride generated by the reaction in step S1.

[0020] The present invention also provides application of the preparation method in sodium ion batteries.

[0021] According to a preferred embodiment of the present invention, at least the following beneficial effects are achieved:

[0022] 1. The present invention utilizes the high reactivity of tin and chlorine and the characteristics that the generated tin tetrachloride is liquid, and reacts the manufactured alloy foil with chlorine. The aluminum in the alloy foil is oxidized to form a dense oxide film, and the copper does not react with chlorine, thereby achieving dealloying of tin and obtaining a nanoporous metal foil.

[0023] 2. Since aluminum reacts in hot water, the metal foil is placed in an organic solvent and tin disulfide is obtained by a solvothermal method. The tin disulfide is embedded using the nanopores of the metal foil as a template, avoiding the subsequent coating process of the negative electrode material. The embedded structure is tight and will not cause powder shedding. The entire reaction does not produce water, which further improves the crystallinity of tin disulfide and improves its cycle performance when used as a negative electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 This is a SEM image of the surface of the aluminum foil after tin is removed in Example 1 of the present invention;

[0026] Figure 2 This is a SEM image of the surface of the tin-based sulfide sodium ion battery negative electrode sheet prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] 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.

[0028] Example 1

[0029] This embodiment prepares a tin-based sulfide sodium ion battery negative electrode sheet, including a nanoporous aluminum foil and tin disulfide embedded in the aluminum foil. The specific preparation process is:

[0030] (1) The aluminum-tin alloy is made into the required specifications of the metal foil of the negative electrode current collector of the sodium ion battery, and the content of tin atoms in the alloy foil accounts for 15%;

[0031] (2) placing 1.2 g of alloy foil in a sealed glass tower, and introducing dry oxidizing gas into the glass tower, wherein the oxidizing gas is a mixture of chlorine and nitrogen, and the volume fraction of chlorine is 90%. The reaction temperature in the tower is controlled to be 70-80° C. During the reaction, tin and chlorine generate tin tetrachloride, and aluminum is oxidized to form a dense oxide film, thereby achieving dealloying of tin and obtaining a nanoporous aluminum foil;

[0032] (3) After the reaction in step (2) is completed, the aluminum foil is taken out, washed with deionized water, and dried to a mass of 0.61 g, which is placed in 20 mL of oleylamine;

[0033] (4) adding 0.8 g of tin tetrachloride produced in step (2) to oleylamine, and adding 1.58 g of n-dodecyl mercaptan;

[0034] (5) heating under a nitrogen atmosphere, and controlling the reaction temperature to 290° C. and the reaction time to 20 minutes;

[0035] (6) After the reaction in step (5) is completed, the aluminum foil is removed, washed with deionized water, and then washed with n-hexane. After drying, a tin-based sulfide sodium ion battery negative electrode sheet is obtained, with a mass of 1.13 g.

[0036] Example 2

[0037] This embodiment prepares a tin-based sulfide sodium ion battery negative electrode sheet, including a nanoporous aluminum foil and tin disulfide embedded in the aluminum foil. The specific preparation process is:

[0038] (1) The aluminum-tin alloy is made into the required specifications of the metal foil of the negative electrode current collector of the sodium ion battery, and the content of tin atoms in the alloy foil accounts for 20%;

[0039] (2) placing 1.36 g of alloy foil in a sealed glass tower, and introducing dry oxidizing gas into the glass tower, wherein the oxidizing gas is a mixture of chlorine and argon, and the volume fraction of chlorine is 80%. The reaction temperature in the tower is controlled to be 70-80° C. During the reaction, tin and chlorine generate tin tetrachloride, and aluminum is oxidized to form a dense oxide film, thereby achieving dealloying of tin to obtain a nanoporous aluminum foil;

[0040] (3) After the reaction in step (2) is completed, the aluminum foil is taken out, washed with deionized water, and dried to a mass of 0.606 g, which is placed in 30 mL of oleylamine;

[0041] (4) adding 1.2 g of tin tetrachloride produced in step (2) to oleylamine, and adding 12.5 g of thiourea;

[0042] (5) heating under a nitrogen atmosphere, and controlling the reaction temperature to 260° C. and the reaction time to 30 minutes;

[0043] (6) After the reaction in step (5) is completed, the aluminum foil is removed, washed with deionized water, and then washed with ethanol. After drying, a tin-based sulfide sodium ion battery negative electrode sheet is obtained, with a mass of 1.38 g.

[0044] Example 3

[0045] This embodiment prepares a tin-based sulfide sodium ion battery negative electrode sheet, including a nanoporous copper foil and tin disulfide embedded in the copper foil. The specific preparation process is:

[0046] (1) The copper-tin alloy is made into the required specifications of the metal foil of the negative electrode current collector of the sodium ion battery, and the content of tin atoms in the alloy foil accounts for 30%;

[0047] (2) placing 2.8 g of alloy foil in a sealed glass tower, and introducing dry oxidizing gas into the glass tower, wherein the oxidizing gas is chlorine gas, and controlling the reaction temperature in the tower to be 70-80° C., to obtain a nanoporous copper foil;

[0048] (3) After the reaction in step (2) is completed, the copper foil is taken out, washed with deionized water, and dried to a mass of 1.57 g, which is placed in 40 mL of oleylamine;

[0049] (4) adding 1.8 g of tin tetrachloride produced in step (2) to oleylamine, and adding 1.8 g of thiourea;

[0050] (5) heating under an argon atmosphere, and controlling the reaction temperature to 220° C. and the reaction time to 30 minutes;

[0051] (6) After the reaction in step (5) is completed, the copper foil is taken out, washed with deionized water, and then washed with n-propanol. After drying, a tin-based sulfide sodium ion battery negative electrode sheet is obtained, with a mass of 2.77 g.

[0052] Test example

[0053] The tin-based sulfide sodium ion battery negative electrode sheets prepared in Examples 1-3 were assembled into sodium ion half-cells, and their cycle performance was tested at a high current density of 200 mA / g. The results are shown in Table 1.

[0054] First discharge capacity mAh / g Gram capacity after 100 cycles mAh / g Example 1 721.6 683.5 Example 2 742.8 699.7 Example 3 694.2 657.3

[0055] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for preparing a tin-based sulfide sodium ion battery negative electrode sheet, characterized in that: The following steps are involved: S1: heating and reacting the alloy foil with an oxidizing gas, and washing to obtain a nanoporous metal foil, wherein the alloy foil is a copper-tin alloy or an aluminum-tin alloy, and the oxidizing gas is chlorine or a mixture of chlorine and an inert gas; S2: placing the metal foil in an organic solvent, adding tin tetrachloride and an organic sulfide to the organic solvent, and heating the mixture under an inert atmosphere to react, thereby obtaining the tin-based sulfide sodium ion battery negative electrode sheet; In step S1, the reaction temperature is 70-80°C.

2. The preparation method according to claim 1, characterized in that: In step S1, the content of tin atoms in the alloy foil is 15-50%.

3. The preparation method according to claim 1, characterized in that: In step S1, the volume fraction of chlorine in the oxidizing gas is 10-100%.

4. The preparation method according to claim 1, characterized in that: In step S2, the organic sulfide is at least one of n-dodecyl mercaptan, tert-dodecyl mercaptan, thiourea, phenylthiourea, diphenyl disulfide or cysteine.

5. The preparation method according to claim 1, characterized in that: In step S2, the organic solvent is at least one of unsaturated fatty acids or unsaturated fatty amines containing 16, 18, 20 or 22 carbon atoms.

6. The preparation method according to claim 1, characterized in that: In step S2, the molar ratio of the organic sulfide to tin tetrachloride is (2-4):

1.

7. The preparation method according to claim 1, characterized in that: In step S2, the reaction temperature is 220-290°C.

8. The preparation method according to claim 1, characterized in that: In step S2, after the reaction is completed, the step of washing the tin-based sulfide sodium ion battery negative electrode sheet is also included, wherein the washing is first washed with water and then washed with at least one of n-hexane, cyclohexane, methylcyclohexane, toluene, tetrahydrofuran, cycloheptane, isopropanol, n-propanol or ethanol.

9. Application of the preparation method according to any one of claims 1 to 8 in sodium ion batteries.

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