An integrated photo-charged zinc tellurium secondary battery

Abstract

The present invention discloses an integrated photo-charging zinc tellurium secondary battery, belonging to the technical field of new energy batteries, which includes a photo-electrode, a tellurium cathode and a zinc anode. The photo-electrode includes an FTO glass, a TiO2 mesoporous film and a CH3NH3PbI3 thin film. There is a layer of hydrophobic carbon paper between the CH3NH3PbI3 thin film of the photo-electrode and the tellurium cathode, and a glass fiber separator between the tellurium cathode and the zinc anode. We use hydrophobic carbon paper to prevent the destruction of the CH3NH3PbI3 structure by water molecules, so as to improve the cycle stability of the battery. The Coulomb efficiency of long-cycle charge and discharge under light is 18% higher than that in the dark. The photo-cathode is composed of tellurium nanoparticles, CH3NH3PbI3 and TiO2. The energy level matching between the composites can effectively separate photo-generated electrons and holes, and convert light energy into electrical energy. The integrated photo-charging zinc tellurium battery has excellent photo-electrochemical performance, with a high specific capacity of 676 mAh g ‑1 and a super-flat discharge potential of 0.5 V. Moreover, the specific capacity under light is significantly higher than that in the dark, doubling at a current of 100 mAh g ‑1 and increasing by 83% at a current of 1000 mAh g ‑1 current.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy batteries, and particularly relates to an integrated photo-charging zinc-tellurium secondary battery. Background Art

[0002] Solar energy is a clean energy source, but the inherent drawback of its intermittency still hinders large-scale and efficient utilization, which is directly related to the availability of solar irradiation. Common solar cells have a photoelectric conversion function but no persistent energy storage function. To solve this problem, rechargeable batteries are an indispensable partner for solar cells. In order to improve the light conversion efficiency and reduce connection devices such as transformers and lines, the structure of perovskite solar cells different from that of silicon crystal solar cells is utilized to study a photo-charging battery that integrates photoelectric conversion and storage. The working principle is to transfer holes of photo-excited carriers of the photo-electrode of the perovskite solar cell through the cathode, and integrate the photo-electrode and the cathode into a bifunctional electrode, which transfers holes on the one hand and forms a battery with the counter electrode to store energy on the other hand.

[0003] The zinc-tellurium battery is a conversion-type battery, and the reaction occurring at the tellurium electrode is a solid-to-solid reaction without a shuttle effect. Therefore, it has a super-flat discharge platform. Also, due to factors such as the high conductivity and low density of tellurium, its specific capacity is very high. However, the zinc-tellurium battery also has a problem of volume expansion that needs to be solved. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an integrated photo-charging zinc-tellurium secondary battery.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] An integrated photo-charging zinc-tellurium secondary battery, comprising a photo-electrode, a tellurium cathode, and a zinc anode. The photo-electrode includes an FTO glass, a TiO2 mesoporous film, and a CH3NH3PbI3 thin film. There is a layer of hydrophobic carbon paper between the CH3NH3PbI3 thin film of the photo-electrode and the tellurium cathode, and a glass fiber separator between the tellurium cathode and the zinc anode.

[0007] A preparation method of an integrated photo-charging zinc-tellurium secondary battery, comprising the following steps:

[0008] Step 1: Drop the CH3NH3PbI3 precursor solution onto the FTO conductive glass coated with TiO2 slurry, and anneal to obtain a crystalline CH3NH3PbI3 thin film photo-electrode;

[0009] Step 2: Cut the carbon paper, wash it with acetone, immerse it in a polytetrafluoroethylene emulsion after drying, and perform heat treatment and annealing to obtain a hydrophobic carbon paper;

[0010] Step 3: Mix tellurium nanoparticles, multi-walled carbon nanotubes, and PVDF binder in NMP, ball mill to obtain a slurry, coat it on a titanium mesh, and dry to obtain a tellurium cathode;

[0011] Step 4: Cut the glass fiber separator and zinc sheet;

[0012] Step 5: Sequentially place the photo-electrode glass obtained in Step 1, the hydrophobic carbon paper obtained in Step 2, the tellurium cathode obtained in Step 3, the separator obtained in Step 4, and the zinc anode, and add the electrolyte dropwise into the open-window battery case to obtain an integrated photo-charging zinc-tellurium battery.

[0013] Further, the preparation method of the CH3NH3PbI3 precursor solution is to mix PbI2 and CH3NH3I in N,N-dimethylformamide.

[0014] Further, the mass ratio of tellurium nanoparticles, multi-walled carbon nanotubes, and PVDF in Step 3 is 7:2:1.

[0015] Further, the electrode placement and addition order in Step 5 are fixed.

[0016] Further, the TiO2 slurry in Step 1 is composed of terpineol, ethyl cellulose, TiO2, and lauric acid.

[0017] Further, the proportion of TiO2 in the TiO2 slurry is 20%.

[0018] Advantages of the present invention:

[0019] 1. The purpose of integrating photoelectric conversion and storage is achieved. Compared with the combination of a solar cell and a rechargeable battery, a transformer and connection lines can be removed, achieving the effects of improving the photoelectric conversion efficiency and reducing costs.

[0020] 2. The advantages of the aqueous battery are retained, and at the same time, the specific capacity of the battery and the stable output potential are improved under illumination. The specific capacity is as high as 676 mAhg -1 , and the output potential is super flat, maintaining around 0.5V.

[0021] 3. Utilize the characteristics that both ZnTe2 and ZnTe are wide-bandgap semiconductors and can also undergo photocatalytic reactions, and cooperate with photo-charging. Under illumination, with a constant current discharge of 100 mAg -1 , the specific capacity is increased by about 100%, and with a current discharge of 1000 mAg -1 , it is increased by about 83%.

[0022] 4. Use the hydrophobic carbon paper to protect the CH3NH3PbI3 structure, and the cycle stability of the battery is well guaranteed. The Coulomb efficiency of long-cycle charge and discharge under illumination is increased by 18%. Brief Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 is a schematic structural diagram of a photo-charged zinc telluride battery in an embodiment of the present invention;

[0025] Figure 2 is an SEM image of CH3NH3PbI3 when the photo-charged zinc telluride battery in an experimental example of the present invention is photo-charged to 0.7V;

[0026] Figure 3 is a comparison chart of constant current charge and discharge curves of the photo-charged zinc telluride battery in an experimental example of the present invention under light and dark conditions at 100mAg -1 constant current charge and discharge curves;

[0027] Figure 4 is a performance curve of the photo-charged zinc telluride battery in an experimental example of the present invention when cycling at a current density of 1000mAg -1 under light and dark conditions. Detailed Embodiments

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0029] An integrated photo-charged zinc telluride secondary battery, as Figure 1 shown, the main part of the battery is: a photo-electrode composed of an FTO glass, a TiO2 mesoporous film, and a CH3NH3PbI3 thin film, a tellurium cathode, and a zinc anode. There is a layer of hydrophobic carbon paper between the photo-electrode and the tellurium cathode, which can effectively prevent the CH3NH3PbI3 thin film from failing. There is a glass fiber separator between the cathode and the anode, and 3M ZnSO4 aqueous solution is dropped on both sides. Finally, it is all encapsulated into a self-made open-window battery case, and the electrode placement and operation steps involved are fixed.

[0030] The principle of the present invention is that light excites a semiconductor to generate high-energy electron-hole pairs with a tendency to recombine. By screening materials with matching energy levels, electrons and holes can react separately, enabling their effective separation. Then, combined with a tellurium cathode, the energy stored by light excitation is converted into electrical energy. This requires the charging potential of the battery's positive electrode material to be higher than that of the holes, and the charging potential of the negative electrode to be lower than that of the electrons, while CH3NH3PbI3 and the zinc tellurium battery can meet the combination requirements. Electrons pass through the external circuit to 2+ reduce Zn Figure 1 to Zn atoms, and the holes oxidize ZnTe in two steps, successively to ZnTe2 and Te. As

[0031] shown, due to direct energy conversion and a small gap in energy level matching, more light energy can be converted into electrical energy. And it can be directly stored without the need for an external charging circuit, reducing the use of transformers and wires.

[0032] Preparation method of an integrated photo-charging zinc tellurium secondary battery

[0033] Step 1: Cut the purchased FTO conductive glass to a size determined by the battery case size. Then, ultrasonically clean it successively with a cleaner, deionized water, ethanol, and acetone, and dry it.

[0034] Step 2: Uniformly apply the purchased TiO2 slurry on the conductive surface of the cleaned FTO glass in a central 1×1 cm square area. Then, sinter it in a muffle furnace at 450 °C for 2 hours. After sintering, the TiO2 slurry becomes a TiO2 mesoporous film.

[0035] Step 3: Uniformly mix 461 mg of PbI2 and 159 mg of CH3NH3I in 10 mL of N,N-dimethylformamide (DMF) to prepare a CH3NH3PbI3 precursor solution. Drop it on the TiO2 mesoporous film and anneal it at 100 °C for 10 minutes to obtain a crystalline CH3NH3PbI3 thin film. The FTO / TiO2 / CH3NH3PbI3 photoanode is ready.

[0036] Step 4: Mix tellurium nanoparticles, multi-walled carbon nanotubes (MCNTs), and PVDF binder in a mass ratio of 7:2:1 in NMP, ball-mill them evenly to obtain a tellurium cathode, coat it on a titanium mesh, and dry it thoroughly.

[0037] Step 5: Cut the carbon paper into 2×2 cm squares, wash with acetone, fully dry and then immerse in polytetrafluoroethylene emulsion, perform heat treatment, and then anneal to obtain hydrophobic carbon paper;

[0038] Step 6: Prepare 3M ZnSO4 aqueous solution as the electrolyte;

[0039] Step 7: Cut the glass fiber separator and zinc sheet, wash and fully dry them, and use them as the separator and anode respectively;

[0040] Step 8: Sequentially install the FTO / TiO2 / CH3NH3PbI3 photoanode obtained in the third step, the hydrophobic carbon paper obtained in the fourth step, the tellurium mixed cathode obtained in the fifth step, the separator obtained in the seventh step, and the zinc sheet anode into a self-made windowed battery case. Drop the electrolyte on both sides of the separator, and the photo-charging zinc tellurium battery is assembled.

[0041] As one of the improvements of the technical solution of the present invention, in the second step, the TiO2 slurry is composed of terpineol, ethyl cellulose, TiO2 and lauric acid. Among them, the proportion of TiO2 is 20%. The sintering temperature of the muffle furnace is 450 °C, and the sintering time is 2 hours.

[0042] As one of the improvements of the technical solution of the present invention, in the third step, the preparation method of the CH3NH3PbI3 precursor solution is to mix 461 mg of PbI2 and 159 mg of CH3NH3I in 10 mL of N,N-dimethylformamide (DMF), and the annealing scheme is to maintain at 100 °C for 10 minutes;

[0043] As one of the improvements of the technical solution of the present invention, in the fourth step, the heat treatment scheme is to maintain at 100 °C for 30 minutes, and the annealing scheme is to maintain at 340 °C for 2 hours.

[0044] As one of the improvements of the technical solution of the present invention, in the fifth step, the mass ratio of Te, MCNTs, and PVDF is 7:2:1;

[0045] Performance detection

[0046] In the performance detection stage of the present invention, the waterproof effect of the hydrophobic carbon paper was verified. As Figure 2 , is the SEM image when the battery is photo-charged to 0.7 V, showing that the structure of CH3NH3PbI3 is not damaged, fully indicating that the hydrophobic carbon paper has achieved the expected waterproof effect and the function of protecting the CH3NH3PbI3 structure; and, the waterproof function improves the cycle stability of the battery, and the Coulomb efficiency of the long-term charge and discharge cycle under light is 18% higher than that in the dark;

[0047] In the performance detection stage of the present invention, the photo-charging zinc tellurium battery was discharged at a constant current under light and in the dark respectively. As Figure 3As shown, it is found that at 100 mAg -1 current, the specific capacity increases by 362 mAhg -1 , which is about twice the original specific capacity.

[0048] During the performance detection stage of the present invention, the long-cycle performance under light and dark conditions was compared. The results are as Figure 4 shown. At a current density of 1000 mA·g -1 , the discharge specific capacity under light increases from 302 mAhg -1 to 590 mAhg -1 , and after 28 cycles, the discharge specific capacity can still remain at 601 mAhg -1 .

[0049] Based on the combination of an aqueous zinc telluride battery and a halide perovskite solar cell, the present invention invents an integrated photo-charging zinc telluride secondary battery. The aqueous zinc telluride battery has the advantages of high specific capacity and stable output potential, but there is a problem of volume expansion. This is improved by incorporating multi-walled carbon nanotubes and further utilized. ZnTe2, ZnTe, and Te all belong to wide-bandgap semiconductor materials and have photocatalytic effects. Therefore, by combining the aqueous zinc telluride battery with photo-charging, the photocatalytic effects of ZnTe2 and ZnTe can be fully utilized to further improve the photoelectric conversion efficiency. After screening, it is found that the energy levels of the halide perovskite (CH3NH3PbI3) are highly matched with the conversion reactions of Te, ZnTe2, and ZnTe, so it is used as a photosensitive material. The holes generated by it can convert ZnTe into Te through two-step reactions, and the intermediate product is ZnTe2. However, CH3NH3PbI3 is unstable in water. To this end, we use hydrophobic carbon paper to prevent water molecules from damaging the structure of CH3NH3PbI3 to improve the cycle stability of the battery. The Coulomb efficiency of the long-cycle charge and discharge under light is 18% higher than that under dark. The photo-cathode is composed of tellurium nanoparticles, CH3NH3PbI3, and TiO2. The energy level matching between the composite materials can effectively separate photo-generated electrons and holes and convert light energy into electrical energy. The integrated photo-charging zinc telluride battery has excellent photoelectrochemical performance, with a high specific capacity of 676 mAhg -1 and a super-flat discharge potential of 0.5 V. Moreover, the specific capacity under light is significantly higher than that under dark. It doubles at a current of 100 mAhg -1 and increases by 83% at a current of 1000 mAhg -1 .

[0050] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do 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.

[0051] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification are only used to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and all these changes and improvements fall within the scope of the present invention claimed.

Claims

1. An integrated photo-charged zinc tellurium secondary battery, comprising a photo-electrode, a tellurium cathode and a zinc anode, characterized in that, The photoanode includes FTO glass, on which a TiO2 mesoporous film is provided, and on which a CH3NH3PbI3 thin film is provided. There is a layer of hydrophobic carbon paper between the CH3NH3PbI3 thin film of the photoanode and the tellurium cathode, and a glass fiber separator is provided between the tellurium cathode and the zinc anode.

2. The preparation method of an integrated optical charging zinc tellurium secondary battery according to claim 1, characterized in that, It includes the following steps: Step 1: Drop the CH3NH3PbI3 precursor solution onto the FTO conductive glass coated with TiO2 paste, and anneal to obtain a crystalline CH3NH3PbI3 thin film photoanode; Step 2: Cut the carbon paper, clean it with acetone, immerse it in polytetrafluoroethylene emulsion after drying, perform heat treatment and annealing to obtain a hydrophobic carbon paper; Step 3: Mix tellurium nanoparticles, multi-walled carbon nanotubes and PVDF binder in NMP, ball mill to obtain a paste, coat it on a titanium mesh, and dry to obtain a tellurium cathode; Step 4: Cut the glass fiber separator and zinc sheet; Step 5: Combine the photoanode glass obtained in Step 1, the hydrophobic carbon paper obtained in Step 2, the tellurium cathode obtained in Step 3, the separator obtained in Step 4 and the zinc anode with the dropwise addition of an electrolyte, and sequentially install them into an open-window battery case to obtain an integrated photo-charging zinc-tellurium battery.

3. The preparation method of an integrated optical charging zinc tellurium secondary battery according to claim 2, characterized in that, The preparation method of the CH3NH3PbI3 precursor solution is to mix PbI2 and CH3NH3I in N,N-dimethylformamide.

4. The preparation method of an integrated optical charging zinc tellurium secondary battery according to claim 2, wherein, The mass ratio of tellurium nanoparticles, multi-walled carbon nanotubes, and PVDF in Step 3 is 7:2:

1.

5. An integrated photo-charging zinc tellurium secondary battery according to claim 2, characterized in that, The electrode placement and addition order in Step 5 are fixed.

6. The preparation method of an integrated photo-charged zinc tellurium secondary battery according to claim 2, characterized in that, The electrolyte in Step 5 is a 3M aqueous ZnSO4 electrolyte.

7. The preparation method of an integrated optical charging zinc tellurium secondary battery according to claim 2, wherein, The TiO2 paste in Step 1 is composed of terpineol, ethyl cellulose, TiO2 and lauric acid.

8. The preparation method of an integrated optical charging zinc tellurium secondary battery according to claim 2, characterized in that The proportion of TiO2 in the TiO2 paste is 20%.

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