Water-based zinc-sulfur primary battery based on organic / water mixed electrolyte and application of water-based zinc-sulfur primary battery

Abstract

The invention discloses an aqueous zinc-sulfur primary battery based on an organic / water mixed electrolyte. The organic / water mixed electrolyte capable of improving the voltage and discharging time of the zinc-sulfur primary battery is adopted. According to the additive, solid sulfur is promoted to be dissolved into liquid sulfur by enhancing the dissolving capacity of the electrolyte to a sulfur positive electrode, and the original solid-solid conversion process is changed into liquid-solid conversion, so that the reaction energy barrier of conversion from sulfur to zinc sulfide is reduced. According to the electrolyte, the electrochemical performance of the zinc-sulfur primary battery is remarkably improved, and the discharge voltage is improved, the discharge time is prolonged and the energy density is improved. Therefore, the zinc-sulfur primary battery disclosed by the invention has the characteristics of simple structure, low raw material cost, stable energy output and the like, and is suitable for portable electronic equipment, emergency power supplies and other energy storage fields.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing an aqueous zinc-sulfur primary battery based on an organic / water mixed electrolyte. Background Art

[0002] Zinc-sulfur primary batteries are a type of energy storage technology with high theoretical energy density. They are widely used in portable electronic devices, emergency power supplies, and large-scale energy storage due to their abundant raw materials, low cost, and environmentally friendly properties. Compared with traditional lithium-ion batteries, zinc-sulfur batteries have higher theoretical energy density and have development potential. However, although zinc-sulfur batteries have extremely high energy output in theory, in practical applications, the performance of the battery still faces some key technical challenges, mainly including excessively high reaction energy barriers and voltage limitations of aqueous electrolytes.

[0003] First, the sulfur, the positive electrode material in the zinc-sulfur battery, will undergo a reduction reaction during the battery discharge process to generate zinc sulfide. However, the solubility of solid sulfur in the electrolyte is poor, which prevents sulfur from fully participating in the electrochemical reaction, resulting in a high reaction energy barrier, which limits the discharge performance of the zinc-sulfur battery. Secondly, aqueous zinc-sulfur batteries use water as a solvent in the electrolyte, which makes the battery limited by the voltage window of water during operation. The voltage window of water is about 1.23 V, which results in a low maximum operating voltage of the aqueous electrolyte, which in turn affects the energy density and discharge voltage of the battery. This limitation limits the application scope of aqueous zinc-sulfur batteries to a certain extent, especially in application scenarios that require a higher discharge voltage, the battery performance cannot meet the requirements.

[0004] In order to overcome these problems, researchers have begun to explore improving the reactivity of sulfur through electrolyte design in recent years. Dinesh Patel et al. used dimethyl carbonate as a co-solvent and introduced iodine additives to achieve a 0.1 A g -1 At a current density of 1167 mAh g -1 The specific capacity of the zinc-sulfur primary battery is 2.5 V, but the working voltage is only 0.4 V. Therefore, how to select the type of solvent and use the appropriate solvent concentration to increase both the battery capacity and the voltage window of the electrolyte is still a technical problem that needs to be solved. In the prior art, the dissolution effect of many solvents is unstable, or it is difficult to balance the battery performance and the stability of the electrolyte, and the discharge voltage is low, making it difficult to achieve high energy density. Therefore, it is urgent to develop a new type of electrolyte additive that can increase the solubility of sulfur, reduce the reaction energy barrier, and expand the working voltage of the aqueous electrolyte, thereby improving the overall performance of the zinc-sulfur primary battery. Summary of the invention

[0005] The purpose of the present invention is to construct an aqueous zinc-sulfur primary battery with high discharge voltage and long discharge time based on the research of organic / water mixed solvents. The electrolyte significantly improves the electrochemical performance of the zinc-sulfur primary battery, including increasing the discharge voltage, extending the discharge time and improving the energy density. Therefore, the zinc-sulfur primary battery of the present invention has the characteristics of simple structure, low raw material cost, stable energy output, etc., and is suitable for portable electronic devices, emergency power supplies and other energy storage fields.

[0006] In order to solve the technical problem of the present invention, the technical solution proposed is: an aqueous zinc-sulfur primary battery based on an organic / water mixed electrolyte, characterized in that: the aqueous zinc-sulfur primary battery comprises: a positive electrode is a sulfur and porous carbon composite positive electrode, and the mass fraction of sulfur is 30 to 60 parts, the mass fraction of the conductive agent is 40-60 parts, and the mass fraction of the binder is 10-15 parts;

[0007] The electrolyte is zinc salt, the solvent is a mixed solution of dimethyl sulfoxide (an organic solvent capable of dissolving sulfur) and ultrapure water, wherein the volume fraction of dimethyl sulfoxide is 40%, and zinc iodide is an electrolyte additive;

[0008] The negative electrode is zinc; the diaphragm is a glass fiber diaphragm.

[0009] Preferably, the sulfur positive electrode is an active material sulfur supported on a porous carbon substrate, wherein the porous carbon substrate is selected from one of conductive carbon black, activated carbon, coconut shell carbon or carbon nanotubes.

[0010] Preferably, the zinc salt is zinc sulfate, zinc acetate or zinc trifluoromethanesulfonate.

[0011] Preferably, the zinc salt concentration is 1-3 mol / L.

[0012] Preferably, the concentration of the zinc iodide additive is 50 mM.

[0013] Preferably, the pH value of the electrolyte is 3 to 6.

[0014] Preferably, the zinc negative electrode is composed of pure zinc foil or a mixture of zinc powder and other materials, and has good conductivity and low expansion coefficient.

[0015] Preferably, the glass fiber membrane has good ionic conductivity and a particle retention rate of 0.7-1.6 microns.

[0016] Preferably, the positive electrode: sublimated sulfur is used as the main active material, sulfur powder is loaded on conductive carbon black using a high-pressure reactor at 155°C, kept warm for 12 hours, and then the sulfur positive electrode, conductive carbon black and binder PTFE are mixed in a mass ratio of 8:1:1, rolled into a thin sheet with uniform thickness, pressed onto the surface of a stainless steel mesh, and dried in a vacuum to obtain a positive electrode;

[0017] Negative electrode: 0.2 mm thick zinc foil;

[0018] Electrolyte: 2 mol / L zinc sulfate solution, the solvent is a mixed solution of dimethyl sulfoxide and water, where the volume fraction of dimethyl sulfoxide is 40%, and the pH value is 5.2;

[0019] Electrolyte additives: zinc iodide concentration of 50 mM;

[0020] Diaphragm: GF / F type glass fiber diaphragm, thickness 0.42 mm, particle retention 0.7 micron;

[0021] A CR2025 battery case was used to assemble the positive and negative electrode sheets and separators into button cells for discharge testing.

[0022] The aqueous zinc-sulfur primary battery of the organic / water mixed electrolyte is applied, and the zinc-sulfur primary battery is suitable for portable electronic devices, emergency power supplies and other energy storage fields.

[0023] Beneficial effects:

[0024] By introducing organic solvents such as alcohols, carbon disulfide and dimethyl sulfoxide into the electrolyte, the solubility of sulfur can be effectively improved, the conversion of solid sulfur into liquid sulfur can be promoted, and the reaction energy barrier of sulfur conversion into zinc sulfide can be reduced, thereby increasing the discharge voltage and discharge time of the battery. By optimizing the electrolyte composition, the operating voltage of the aqueous electrolyte is increased, overcoming the limitation of the low voltage of the traditional aqueous electrolyte, and further increasing the energy density of the battery. The use of additives improves the discharge stability and energy output of the battery, especially at high discharge currents, the battery can also discharge stably and quickly. The zinc-sulfur primary battery of the present invention is suitable for portable electronic devices, emergency power supplies, consumer electronics and other fields.

[0025] Example 1 Ultrapure water was used as the electrolyte solvent for zinc-sulfur primary batteries. The batteries were subjected to a constant current discharge test with a current density of 0.1 A g -1 ,The battery discharge voltage is about 0.1V, the polarization is large, and the discharge time is only 1 minute.

[0026] Example 2: An isopropanol / water mixed solution was used as the electrolyte solvent for a zinc-sulfur primary battery. The battery was subjected to a constant current discharge test with a current density of 0.1 A g -1 ,The battery discharge voltage is about 0.42 V and the discharge time is about 3.4 hours.

[0027] Example 3: A carbon disulfide / water mixed solution was used as the electrolyte solvent for a zinc-sulfur primary battery. The battery was subjected to a constant current discharge test at 0.1 A g -1,The battery discharge voltage is about 0.6 V and the discharge time is about 8 hours.

[0028] Best embodiment 4 uses a dimethyl sulfoxide / water mixed solution as an electrolyte solvent for a zinc-sulfur primary battery, wherein the volume fraction of dimethyl sulfoxide is 40%. The aqueous zinc-sulfur primary battery is -1 The current density is , the discharge voltage is as high as 0.76 V, and the discharge time is about 16 hours. At the same time, under different current densities, the battery can provide corresponding capacity. In addition, the battery system has a simple preparation process, a safe use process, and a low production cost, and has great development potential.

[0029] Figure 6 The discharge time and voltage curves of zinc-sulfur primary batteries using mixed solutions of dimethyl sulfoxide / water with different ratios as electrolyte solvents. As the volume percentage of dimethyl sulfoxide increases, the discharge voltage increases. -1 Under the current density, the discharge voltage of the battery corresponding to the volume ratio of 10%, 20%, 40%, and 60% of the dimethyl sulfoxide aqueous solution is 0.61 V, 0.65 V, 0.76 V, and 0.8 V, and the corresponding discharge time is 14.3 hours, 14.6 hours, 16.1 hours, and 13.4 hours. Therefore, when the volume of dimethyl sulfoxide is 40%, it has both a higher discharge platform and a longer discharge time.

[0030] Figure 7 The discharge time and voltage curves of 40% by volume dimethyl sulfoxide aqueous solution as the electrolyte solvent at different currents. The current density is 0.5 A g -1 , 1 A g -1 , 2 A g -1 , 3 A g -1 The corresponding discharge voltages are 0.59 V, 0.51 V, 0.45 V, and 0.41 V, and the corresponding discharge times are 163 minutes, 70 minutes, 30 minutes, and 18 minutes, respectively.

[0031] Figure 8 This is the impedance diagram of a 40% by volume dimethyl sulfoxide solution as the electrolyte solvent. The impedance of this battery is smaller, indicating that the redox reaction is easier to carry out.

[0032] Fig. 9 The battery assembled with 40% by volume dimethyl sulfoxide solution as the electrolyte solvent was -1 The discharge capacity and voltage curve under current density. The discharge capacity of the battery is 1594 mAh g -1 , which is very close to the theoretical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of improving the discharge platform of aqueous zinc-sulfur batteries for organic / water mixed solvents;

[0034] Figure 2 The discharge time and voltage curve of zinc-sulfur primary battery using ultrapure water as electrolyte solvent;

[0035] Figure 3 XRD pattern of the positive electrode material S@KB;

[0036] Figure 4 This is the SEM image of the cathode material S@KB;

[0037] Figure 5 EDS image of the cathode material S@KB;

[0038] Figure 6 The discharge time and voltage curves of the battery assembled with different ratios of dimethyl sulfoxide / water mixed solution as the electrolyte solvent;

[0039] Figure 7 The discharge time and voltage curves of the battery assembled with 40% by volume dimethyl sulfoxide aqueous solution as the electrolyte solvent at different currents;

[0040] Figure 8 The impedance diagram of the battery assembled with 40% by volume dimethyl sulfoxide solution as the electrolyte solvent;

[0041] Fig. 9 The discharge capacity and voltage curve of the battery assembled with 40% by volume dimethyl sulfoxide aqueous solution as the electrolyte solvent. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the performance of the present invention, and are not limited to the following examples.

[0043] Example 1: Ultrapure water as electrolyte solvent for zinc-sulfur primary batteries

[0044] Positive electrode: sublimated sulfur is used as the main active material. The sulfur powder is placed in a high-pressure reactor at 155°C for 12 hours and loaded onto the conductive carbon black Ketjen Black (KB). Then the sulfur positive electrode, conductive carbon black and binder PTFE are mixed in a mass ratio of 8:1:1, rolled into a sheet of uniform thickness, pressed onto the surface of a stainless steel mesh, and dried in a vacuum to obtain the positive electrode.

[0045] Negative electrode: Use zinc foil with a thickness of 0.2 mm.

[0046] Electrolyte: 2 mol / L zinc sulfate solution, the solvent is 100% ultrapure water.

[0047] Electrolyte additive: zinc iodide, concentration 50 mM.

[0048] Diaphragm: GF / F type glass fiber diaphragm.

[0049] Assemble the positive and negative electrode sheets and separator into button cells and conduct discharge tests. Figure 1 Discharge time and voltage curve of zinc-sulfur primary battery assembled with ultrapure water as electrolyte solvent.

[0050] The above battery was subjected to a constant current discharge test with a current density of 0.1 A g -1 ,The battery discharge voltage is about 0.1V, the polarization is large, and the discharge time is only 1 minute.

[0051] Example 2: Isopropyl alcohol / water mixed solution as electrolyte solvent for zinc-sulfur primary battery

[0052] Positive electrode: sublimated sulfur is used as the main active material. The sulfur powder is placed in a high-pressure reactor at 155°C for 12 hours and loaded onto the conductive carbon black Ketjen Black (KB). Then the sulfur positive electrode, conductive carbon black and binder PTFE are mixed in a mass ratio of 8:1:1, rolled into a sheet of uniform thickness, pressed onto the surface of a stainless steel mesh, and dried in a vacuum to obtain the positive electrode.

[0053] Negative electrode: Use zinc foil with a thickness of 0.2 mm.

[0054] Electrolyte: 2 mol / L zinc sulfate solution was used, the solvent was a mixed solution of isopropanol and water, and the amount of isopropanol added accounted for 10% of the total volume.

[0055] Electrolyte additive: zinc iodide, concentration 50 mM.

[0056] Diaphragm: GF / F type glass fiber diaphragm.

[0057] Assemble the positive and negative electrode sheets and separator into button cells and conduct discharge tests.

[0058] The above battery was subjected to a constant current discharge test with a current density of 0.1 A g -1 ,The battery discharge voltage is about 0.42V and the discharge time is about 3.4 hours.

[0059] Example 3: Carbon disulfide / water mixed solution as electrolyte solvent for zinc-sulfur primary battery

[0060] Positive electrode: sublimated sulfur is used as the main active material. The sulfur powder is placed in a high-pressure reactor at 155°C for 12 hours and loaded onto the conductive carbon black Ketjen Black (KB). Then the sulfur positive electrode, conductive carbon black and binder PTFE are mixed in a mass ratio of 8:1:1, rolled into a sheet of uniform thickness, pressed onto the surface of a stainless steel mesh, and dried in a vacuum to obtain the positive electrode.

[0061] Negative electrode: Use zinc foil with a thickness of 0.2 mm.

[0062] Electrolyte: 2 mol / L zinc sulfate solution, the solvent is a mixed solution of carbon disulfide and water, and the amount of carbon disulfide added accounts for 3% of the total volume.

[0063] Electrolyte additive: zinc iodide, concentration 50 mM.

[0064] Diaphragm: GF / F type glass fiber diaphragm.

[0065] Assemble the positive and negative electrode sheets and separator into button cells and conduct discharge tests.

[0066] The above batteries were subjected to constant current discharge test, 0.1 A g -1 ,The battery discharge voltage is about 0.6 V and the discharge time is about 8 hours.

[0067] Example 4: Dimethyl sulfoxide / water mixed solution as electrolyte solvent for zinc-sulfur primary battery

[0068] Positive electrode: sublimated sulfur is used as the main active material. The sulfur powder is loaded onto the conductive carbon black Ketjen black (KB) in a high-pressure reactor at 155°C for 12 hours. Then the sulfur positive electrode, conductive carbon black and binder PTFE are mixed in a mass ratio of 8:1:1, rolled into a thin sheet of uniform thickness, pressed onto the surface of a stainless steel mesh, and dried in a vacuum to obtain the positive electrode. The stainless steel mesh is 250 mesh, and the loading amount of active sulfur is about 0.7~0.9 mg cm -2 .

[0069] Figure 3 This is the XRD diagram of the positive electrode material S@KB. The S@KB material does not have the characteristic peak of sulfur, indicating that sulfur is successfully mixed with the KB material through melt diffusion. Figure 4 This is the SEM image of the positive electrode material S@KB, and the shape of the material is round particles. Figure 5 This is the EDS image of the positive electrode material S@KB. S@KB is mainly composed of sulfur and carbon elements, and the two elements are evenly distributed.

[0070] Negative electrode: Use 0.2 mm thick zinc foil, cut into a disc with a diameter of 14 mm.

[0071] Electrolyte: 2 mol / L zinc sulfate solution was used, the solvent was a mixed solution of dimethyl sulfoxide and water, and different volumes of dimethyl sulfoxide aqueous solution were prepared, namely 10%, 20%, 40%, and 60%. The pH value was 5.2.

[0072] Electrolyte additive: zinc iodide, concentration 50 mM.

[0073] Diaphragm: GF / F type glass fiber diaphragm, thickness 0.42 mm, particle retention 0.7 micron.

[0074] A CR2025 battery case was used to assemble the positive and negative electrode sheets and separators into button cells for discharge testing.

[0075] Figure 6 The discharge time and voltage curves of zinc-sulfur primary batteries using mixed solutions of dimethyl sulfoxide / water with different ratios as electrolyte solvents. As the volume percentage of dimethyl sulfoxide increases, the discharge voltage increases. -1 Under the current density, the discharge voltage of the battery corresponding to the volume ratio of 10%, 20%, 40%, and 60% of the dimethyl sulfoxide aqueous solution is 0.61 V, 0.65 V, 0.76 V, and 0.8 V, and the corresponding discharge time is 14.3 hours, 14.6 hours, 16.1 hours, and 13.4 hours. Therefore, when the volume of dimethyl sulfoxide is 40%, it has both a higher discharge platform and a longer discharge time.

[0076] Figure 7 The discharge time and voltage curves of 40% by volume dimethyl sulfoxide aqueous solution as the electrolyte solvent at different currents. The current density is 0.5 A g -1 , 1 A g -1 , 2 A g -1 , 3 A g -1 The corresponding discharge voltages are 0.59 V, 0.51 V, 0.45 V, and 0.41 V, and the corresponding discharge times are 163 minutes, 70 minutes, 30 minutes, and 18 minutes, respectively.

[0077] Figure 8 This is the impedance diagram of a 40% by volume dimethyl sulfoxide solution as the electrolyte solvent. The impedance of this battery is smaller, indicating that the redox reaction is easier to carry out.

[0078] Fig. 9 The battery assembled with 40% by volume dimethyl sulfoxide solution as the electrolyte solvent was -1 The discharge capacity and voltage curve under current density. The discharge capacity of the battery is 1594 mAh g -1 , which is very close to the theoretical value.

[0079] The above description is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the creative concept of the present invention, and these should also be regarded as within the scope of protection of the present invention.

Claims

1. An aqueous zinc-sulfur primary battery based on an organic / water mixed electrolyte, characterized in that: The aqueous zinc-sulfur primary battery comprises: a positive electrode which is a composite positive electrode of sulfur and porous carbon, wherein the mass fraction of sulfur is 30-60 parts, the mass fraction of a conductive agent is 40-60 parts, and the mass fraction of a binder is 10-15 parts; The electrolyte is zinc salt, the solvent is a mixed solution of dimethyl sulfoxide (an organic solvent capable of dissolving sulfur) and ultrapure water, wherein the volume fraction of dimethyl sulfoxide is 40%, and zinc iodide is an electrolyte additive; The negative electrode is zinc; the diaphragm is a glass fiber diaphragm.

2. The aqueous zinc-sulfur primary battery of organic / water mixed electrolyte according to claim 1, characterized in that: The sulfur positive electrode is an active material sulfur supported on a porous carbon substrate, wherein the porous carbon substrate is selected from one of conductive carbon black, activated carbon, coconut shell carbon or carbon nanotubes.

3. The aqueous zinc-sulfur primary battery of the organic / water mixed electrolyte according to claim 1, characterized in that: The zinc salt is zinc sulfate, zinc acetate or zinc trifluoromethanesulfonate.

4. The aqueous zinc-sulfur primary battery of the organic / water mixed electrolyte according to claim 1, characterized in that: The zinc salt concentration is 1-3 mol / L.

5. The aqueous zinc-sulfur primary battery of organic / water mixed electrolyte according to claim 1, characterized in that: The concentration of the zinc iodide additive is 50 mM.

6. The aqueous zinc-sulfur primary battery of organic / water mixed electrolyte according to claim 1, characterized in that: The pH value of the electrolyte is 3 to 6.

7. The aqueous zinc-sulfur primary battery of organic / water mixed electrolyte according to claim 1, characterized in that: The zinc negative electrode is composed of pure zinc foil or a mixture of zinc powder and other materials, and has good conductivity and low expansion coefficient.

8. The aqueous zinc-sulfur primary battery with organic / water mixed electrolyte according to claim 1, characterized in that: The glass fiber diaphragm has good ion conductivity and a particle retention rate of 0.7-1.6 microns.

9. The aqueous zinc-sulfur primary battery with organic / water mixed electrolyte according to claim 1, characterized in that: Positive electrode: sublimated sulfur is used as the main active material. The sulfur powder is placed in a high-pressure reactor at 155°C for 12 hours and loaded onto conductive carbon black. The sulfur positive electrode, conductive carbon black and binder PTFE are then mixed in a mass ratio of 8:1:1, rolled into a sheet with uniform thickness, pressed onto the surface of a stainless steel mesh, and dried in a vacuum to obtain the positive electrode. Negative electrode: 0.2 mm thick zinc foil; Electrolyte: 2 mol / L zinc sulfate solution, the solvent is a mixed solution of dimethyl sulfoxide and water, where the volume fraction of dimethyl sulfoxide is 40%, and the pH value is 5.2; Electrolyte additive: zinc iodide concentration of 50 mM; diaphragm: GF / F type glass fiber diaphragm, thickness of 0.42 mm, particle retention of 0.7 microns; A CR2025 battery case was used to assemble the positive and negative electrode sheets and separators into button batteries for discharge testing.

10. Application of an aqueous zinc-sulfur primary battery using the organic / water mixed electrolyte according to any one of claims 1 to 9, characterized in that: The zinc-sulfur primary battery is suitable for portable electronic devices, emergency power supplies and other energy storage fields.

Images