Integrated self-charging system of perovskite flexible solar cell and lithium-sulfur battery and preparation thereof

Abstract

The application discloses a perovskite flexible solar cell and lithium-sulfur battery integrated self-charging system and a preparation method thereof. The system comprises a perovskite flexible solar cell and a lithium-sulfur battery. The perovskite flexible solar cell comprises a flexible substrate, a transparent conductive layer and a plurality of perovskite cell units arranged in sequence. The perovskite cell unit comprises an electron transport layer, a perovskite layer and a hole transport layer arranged in sequence. Each perovskite cell unit is in a series connection relationship. The positive electrode of the last perovskite cell unit serves as the positive electrode of the perovskite flexible solar cell. The negative electrode of the first perovskite cell unit serves as the negative electrode of the perovskite flexible solar cell. The lithium-sulfur battery comprises a positive electrode, a negative electrode and a solid electrolyte. The positive electrode is electrically connected with the positive electrode, and the negative electrode is electrically connected with the negative electrode, so as to form a loop. The application can improve the integration, overall efficiency and stability of the self-charging system.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology and relates to the integration of solar cells and lithium-sulfur batteries, particularly to an integrated self-charging system for perovskite flexible solar cells and lithium-sulfur batteries. Background Technology

[0002] Solar energy is the most promising clean energy source. If fully utilized, it can largely replace traditional thermal power generation, mitigate the greenhouse effect, and achieve sustainable development. However, a stable energy supply is essential. Using only solar cells makes it difficult to achieve a stable energy supply, thus combining solar cells with storage devices has a broad application market. This invention integrates a perovskite solar cell with a lithium-sulfur battery. When the perovskite layer is exposed to sunlight, it absorbs photons, generating photogenerated electrons and holes. Electrons accumulate at the ITO negative electrode and are transferred to the lithium-sulfur battery via external wires. Holes are transferred through the top electrode of the perovskite solar cell to the lithium-sulfur battery, driving the conversion of Li₂S into S₈ and Li, achieving the storage of electrical energy as chemical energy. This is the specific photocharging process. During discharge, S₈ and Li are converted back to Li₂S, converting chemical energy into electrical energy, thereby achieving a stable energy supply. Because a flexible substrate is used, the self-charging system can also be made into a flexible wearable device, providing a stable energy supply in complex working environments, thus broadening the application market for self-charging systems. With the development of perovskite solar cells, various self-charging systems for perovskite solar cells and energy storage batteries have been researched, such as: 1. Connecting multiple single-junction perovskite solar cells in series to form a charging module in a self-charging system. Under illumination, photogenerated electrons and holes generated in the perovskite layer are transferred to the positive and negative electrodes of the lithium battery through wires connected to the electrodes, completing photocharging; 2. A self-charging system integrating perovskite and a lithium battery (using a liquid electrolyte), where the perovskite acts as a photoelectrode. When the photoelectrode is under illumination, the perovskite substrate generates photoelectrodes... The photogenerated electrons are collected by the ITO transparent electrode substrate and moved to the negative electrode through an external circuit. The photogenerated holes repel lithium ions and expel them from the perovskite matrix. The lithium ions eventually move to the negative electrode, gain electrons, and become lithium atoms, thus completing the photocharging process. 3. A self-charging system using a single perovskite solar cell connected in series with a lithium-sulfur battery. The photogenerated electrons and holes generated by the perovskite layer are collected by the transparent conductive oxide substrate and the back electrode, and boosted by a DC boost converter through wires. Finally, the electrons and holes are transported to the lithium-sulfur battery through wires to complete the photocharging process.

[0003] First, charging modules constructed using perovskite solar cells connected in series with wires result in an excessive number of wires in the overall system, leading to significant waste during energy transfer. Furthermore, this series connection method drastically reduces the output current of the perovskite solar cells, increasing the scale of the self-charging system and hindering portable applications. Second, self-charging systems integrating perovskite with lithium-ion batteries (using liquid electrolytes) are prone to perovskite degradation due to the perovskite acting as the photoelectrode adjacent to the separator. This significantly limits the system's stability and lifespan. Third, self-charging systems using a single perovskite solar cell connected in series with a lithium-sulfur battery, similar to series-connected perovskite modules, still exhibit significant energy waste during transfer. The DC-DC boost module used further increases the complexity of the overall self-charging system, thus raising production costs. Finally, all of the above technologies involve self-charging systems manufactured on rigid substrates, limiting their flexibility and restricting their application scenarios, thus hindering market adoption. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide an integrated self-charging system of perovskite flexible solar cells and lithium-sulfur batteries, thereby improving the integration, overall efficiency, and stability of the self-charging system. It primarily addresses one or more of the following four technical problems: 1. Traditional self-charging systems have low integration, which is not conducive to portable applications; 2. The output voltage of a single-junction perovskite solar cell needs to be matched with the voltage of the energy storage device; 3. When integrating perovskite and energy storage devices, substances in the electrolyte within the energy storage device diffuse into the perovskite, causing decomposition of the perovskite portion and affecting the overall stability of the self-charging system; 4. The storage efficiency of self-charging systems based on perovskite solar cells is low.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An integrated self-charging system for a perovskite flexible solar cell and a lithium-sulfur battery, comprising a perovskite flexible solar cell and a lithium-sulfur battery.

[0007] The flexible perovskite solar cell includes a flexible substrate, a transparent conductive layer, and a plurality of perovskite cell units arranged sequentially. Each perovskite cell unit includes an electron transport layer, a perovskite layer, and a hole transport layer arranged sequentially. The perovskite cell units are connected in series. The positive electrode of the last perovskite cell unit serves as the positive electrode of the flexible perovskite solar cell. The negative electrode of the first perovskite cell unit serves as the negative electrode of the flexible perovskite solar cell.

[0008] The lithium-sulfur battery includes a positive electrode, a negative electrode, and a solid electrolyte. The positive electrode is electrically connected to the positive electrode, and the negative electrode is electrically connected to the negative electrode, forming a circuit.

[0009] In one embodiment, the negative electrode of the perovskite flexible solar cell is the electrode of the negative electrode region of the first perovskite cell, which conducts electrons to the lithium negative electrode of the lithium-sulfur battery through a wire; the positive electrode of the last perovskite cell is disposed on top of the hole transport layer, and transmits holes to the lithium-sulfur battery through the positive electrode attached thereto; each intermediate perovskite cell is connected in series with the previous perovskite cell through the electron transport layer and the top positive electrode, and except for the positive electrode of the last perovskite cell, the other positive electrodes are attached to the insulating material.

[0010] In one embodiment, the positive electrode of the lithium-sulfur battery is a first metal foil, and a phosphorus-doped graphene coating and a boron-doped graphene coating are sequentially disposed between the first metal foil and the solid electrolyte; the side of the first metal foil away from the solid electrolyte is electrically connected to the positive electrode of the perovskite flexible solar cell.

[0011] In one embodiment, the positive electrode is a second metal foil, and the side of the first metal foil away from the solid electrolyte is bonded to the second metal foil.

[0012] This invention also provides a method for fabricating an integrated self-charging system of the perovskite flexible solar cell and the lithium-sulfur battery, comprising the following steps:

[0013] Step 1: Fabrication of perovskite flexible solar cells;

[0014] The flexible perovskite solar cell includes a flexible substrate, a transparent conductive layer, and a plurality of perovskite cell units arranged sequentially. Each perovskite cell unit includes an electron transport layer, a perovskite layer, and a hole transport layer arranged sequentially. The perovskite cell units are connected in series. The positive electrode of the last perovskite cell unit serves as the positive electrode of the flexible perovskite solar cell. The negative electrode of the first perovskite cell unit serves as the negative electrode of the flexible perovskite solar cell.

[0015] Step 2, Preparation of lithium-sulfur batteries

[0016] The lithium-sulfur battery includes a positive electrode, a negative electrode, and a solid electrolyte.

[0017] Step 3: Integrate the perovskite solar cell and the lithium-sulfur battery.

[0018] The positive electrode is electrically connected to the positive electrode, and the negative electrode is electrically connected to the negative electrode to form a circuit.

[0019] In one embodiment, step 1 involves fabricating a transparent conductive layer on a flexible substrate and then fabricating perovskite battery cells on the transparent conductive layer. The perovskite battery cells are connected in series via an electron transport layer and electrodes to achieve the operating voltage of a lithium-sulfur battery. Only the negative electrode of the first perovskite battery cell and the positive electrode of the last perovskite battery cell are exposed, while the remaining electrodes are attached to an insulating material to prevent short circuits.

[0020] In one embodiment, the fabrication of the perovskite flexible solar cell includes:

[0021] Step 1a: Mix PbI2, CsI, DMF and DMSO thoroughly.

[0022] Step 1b: Mix FAI, MAI, MACl and IPA thoroughly.

[0023] Step 1c: Mix spiro, chlorobenzene, lithium salt, cobalt salt and TBP until homogeneous;

[0024] Step 1d: Place the etched ITO substrate into a spin coater, spin coat the ITO surface with tin oxide solution, then wipe off the tin oxide film in the negative electrode area and perform annealing to complete the preparation of the tin oxide electron transport layer.

[0025] Step 1e: The ITO substrate treated in step 1d is transferred to a glove box, and a perovskite thin film is prepared in a two-step method under an inert gas atmosphere. First, the solution obtained in step 1a is spin-coated onto the ITO substrate and annealed. Then, the solution obtained in step 1b is spin-coated onto the ITO substrate and annealed to complete the preparation of the perovskite layer. The solution obtained in step 1c is spin-coated onto the perovskite layer using a dynamic spin-coating method to complete the preparation of the hole transport layer. The perovskite thin film in the negative electrode region is scraped off to expose the ITO layer in the negative electrode region, and the series region is scribed out using a laser scribing machine. Finally, the positive and negative electrodes are deposited by vacuum thermal evaporation to complete the preparation of the perovskite flexible solar cell.

[0026] In one embodiment, step 2 includes:

[0027] Step 2a: Mix and grind the reduced graphene oxide powder with red phosphorus until no red phosphorus powder is visible. Then transfer it to a ceramic boat and put it into a tube furnace and introduce inert gas to complete the high-temperature doping in the inert gas atmosphere. Mix the doped phosphorus-doped graphene with sulfur elemental powder and put it into a reaction vessel, fill it with inert gas, and heat it to complete the sulfur loading operation.

[0028] Step 2b: Mix and grind the reduced graphene oxide powder with boric acid until no white boric acid powder is visible. Then transfer it to a ceramic boat and put it into a tube furnace and introduce inert gas to complete the high-temperature doping in an inert gas atmosphere. Mix the doped boron-doped graphene with sulfur elemental powder and put it into a reaction vessel, fill it with inert gas, and heat it to complete the sulfur loading operation.

[0029] Step 2c: The sulfur-loaded phosphorus-doped graphene is mixed and ground with Super P, then PVDF is added and stirred. After stirring, a coating is applied to the positive electrode using a coating tool, and finally transferred to a drying oven to dry.

[0030] In step 2d, the sulfur-loaded boron-doped graphene is mixed and ground with Super P, then PVDF is added and stirred. After stirring, a coating is applied to the phosphorus-doped graphene coating on the positive electrode using a coating tool, and finally transferred to a drying oven to dry.

[0031] In one embodiment, in step 1a, the amounts of PbI2, CsI, DMF, and DMSO are 693.5 mg, 17.5 mg, 0.85 mL, and 0.15 mL, respectively; magnetic stirring is performed at 50-70°C.

[0032] In step 1b, the amounts of FAI, MAI, MACl, and IPA used are 185 mg, 13.8 mg, 17 mg, and 2 mL, respectively; the mixture is magnetically stirred at room temperature.

[0033] In step 1c, the amounts of spiro, chlorobenzene, lithium salt, cobalt salt, and TBP used are 72.5 mg, 1 mL, 0.018 mL, 0.029 mL, and 0.029 mL, respectively; the mixture is magnetically stirred at room temperature.

[0034] In step 2a, the amounts of reduced graphene oxide powder and red phosphorus are 0.05 g and 0.25 g, respectively. The high-temperature doping conditions are 900℃~1000℃ in an inert gas atmosphere. The mass ratio of phosphorus-doped graphene to sulfur powder is 3:7. The sulfur loading operation conditions are 155℃ for 20 h.

[0035] In step 2b, the amounts of reduced graphene oxide powder and boric acid are 0.05 g and 0.25 g, respectively. The high-temperature doping conditions are 900℃~1000℃ in an inert gas atmosphere. The mass ratio of boron-doped graphene to sulfur powder is 3:7. The sulfur loading operation conditions are 155℃ for 20 h.

[0036] In step 2c, the mass ratio of sulfur-loaded phosphorus-doped graphene, Super P, and PVDF is 7:2:1; the coating thickness of the phosphorus-doped graphene is 50 nm.

[0037] In step 2d, the mass ratio of sulfur-loaded boron-doped graphene, Super P, and PVDF is 7:2:1; the coating thickness of boron-doped graphene is 50 nm.

[0038] In one embodiment, step 3 includes:

[0039] First, the negative electrode of the first perovskite cell and the positive electrode of the last perovskite cell are exposed, and the remaining electrodes are attached to the insulating material.

[0040] Then, the negative electrode, solid electrolyte, and positive electrode coated with sulfur-containing material are sent into the glove box to complete the assembly of the lithium-sulfur battery.

[0041] Next, attach the side of the positive electrode without the insulating coating to the top of the only exposed positive electrode, while the rest of the positive electrode is attached to the insulating material;

[0042] Finally, the self-charging system was sealed in the glove box and encapsulated with UV-curable adhesive.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] The integrated system of this invention avoids the energy losses in wires and boost converters found in most traditional wire-connected perovskite self-charging systems, reducing system complexity and cost because the system only contains perovskite solar cells and lithium-sulfur batteries, without other components. Since this invention uses a solid electrolyte, it avoids the problem of electrolyte substances diffusing into the perovskite solar cells and causing perovskite decomposition, resulting in a significantly higher overall efficiency and longer lifespan compared to traditional integrated systems using liquid electrolytes.

[0045] In terms of photoelectric conversion equipment, this invention selects perovskite solar cells as the photoelectric conversion device for the following considerations: 1. Currently, the theoretical conversion efficiency of commercially available crystalline silicon solar cells is far lower than that of perovskite solar cells; the open-circuit voltage of crystalline silicon cells is lower than that of perovskite solar cells, requiring a higher number of cells in series to meet the charging voltage of lithium batteries; 2. The manufacturing process of perovskite solar cells is simpler than that of crystalline silicon solar cells, enabling large-area fabrication through printing processes and low-temperature fabrication; 3. The production cost of perovskite solar cells is lower than that of crystalline silicon solar cells; 4. In low-light environments, perovskite solar cells can maintain a high photoelectric conversion efficiency (above 40%), allowing the integrated system to continue operating normally in low-light conditions; 5. Perovskite solar cells can also be applied to flexible devices, enabling flexible wearable applications.

[0046] In terms of energy storage devices, this invention selects lithium-sulfur batteries as the energy storage device not only because lithium-sulfur batteries have a high theoretical energy density, but also because they have advantages such as low production cost, environmental friendliness, and ease of recycling.

[0047] This invention utilizes graphene as the positive electrode carrier in lithium-sulfur batteries because graphene possesses many excellent properties: 1. Graphene has an extremely large specific surface area, providing more space to accommodate the expansion of sulfur; 2. Graphene has excellent electrical conductivity, enabling efficient current conduction; 3. Graphene is a porous carbon-based material, which is considered an excellent carrier material for sulfur. Research has shown that boron doping of carbon materials can alter the electron distribution on the carbon material surface, enhancing surface polarity, while phosphorus doping can improve the stability after doping. Therefore, by using high-temperature doping to incorporate boron and phosphorus into graphene, the electrochemical performance of lithium-sulfur batteries and the stability of the carbon material are optimized. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0049] Figure 2 This is a schematic diagram of the perovskite flexible solar cell structure of the present invention.

[0050] Figure 3 This is a schematic diagram of the lithium-sulfur battery technology route of the present invention. Detailed Implementation

[0051] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0052] like Figure 1 and Figure 2 As shown, the present invention provides an integrated self-charging system for a perovskite flexible solar cell and a lithium-sulfur battery, which includes a perovskite flexible solar cell and a lithium-sulfur battery.

[0053] The flexible perovskite solar cell comprises a flexible substrate 1, a transparent conductive layer 2, and a plurality of perovskite cell units. The transparent conductive layer 2 is disposed on the flexible substrate 1, and each perovskite cell unit is disposed on the transparent conductive layer 2. Each perovskite cell unit comprises an electron transport layer 3, a perovskite layer 4, and a hole transport layer 5. The electron transport layer 3 is disposed on the transparent conductive layer 2, the perovskite layer 4 is disposed on the electron transport layer 3, and the hole transport layer 5 is disposed on the perovskite layer 4. The perovskite cell units are connected in series. In this invention, the negative electrode 7 of the negative electrode region of the first perovskite cell unit is defined as the negative electrode of the flexible perovskite solar cell; the positive electrode 8 of the last perovskite cell unit is defined as the negative electrode of the flexible perovskite solar cell.

[0054] The lithium-sulfur battery includes a positive electrode, a negative electrode, and a solid electrolyte.

[0055] The positive electrode of the lithium-sulfur battery is electrically connected to the positive electrode of the perovskite flexible solar cell, and the negative electrode of the lithium-sulfur battery is electrically connected to the negative electrode of the perovskite flexible solar cell, forming a circuit, which constitutes a self-charging system.

[0056] This invention utilizes a flexible substrate 1 to connect perovskite solar cell units in series using a transparent conductive layer 2 and electrodes during the manufacturing process. This achieves an output voltage comparable to that of a lithium-sulfur battery, while also avoiding energy losses associated with wires, thus reducing system complexity and cost. In lithium-sulfur batteries, this invention uses a solid electrolyte, preventing the diffusion of electrolyte substances from the integrated system into the perovskite solar cell and causing perovskite decomposition. This solves the problem of substances diffusing from liquid electrolytes into the perovskite. Furthermore, the solid electrolyte also functions as a separator, preventing short circuits between the positive and negative electrodes and simplifying the manufacturing process. Therefore, the integrated system of this invention offers significant advantages in overall efficiency and lifespan compared to traditional integrated systems using liquid electrolytes. Additionally, the use of a flexible substrate allows for the application of the self-charging system in wearable devices, broadening its application scenarios.

[0057] Its self-charging principle:

[0058] Sunlight shines from the flexible substrate 1 onto the perovskite layer 4. The perovskite layer 4 absorbs photons, generating photogenerated electrons and holes. Electrons are transported through the electron transport layer 3 to the transparent conductive layer 2, where they accumulate on the negative electrode of the first perovskite cell. Electrons are then transferred to the lithium foil of the lithium-sulfur battery via wires connected to the negative electrode. Holes are transported through the hole transport layer 5 and the positive electrode (the positive electrode at the top of the last perovskite cell) to the positive electrode of the lithium-sulfur battery, thus forming a circuit that charges the lithium battery. Lithium ions gain electrons at the negative electrode to become lithium, and sulfur ions gain holes at the positive electrode to become sulfur, completing the charging process. In this way, the electrical energy of the perovskite is converted into the chemical energy of the lithium-sulfur battery for storage.

[0059] In embodiments of the present invention, the PEN flexible substrate, ITO transparent conductive layer, SnO2 electron transport layer, lead halide perovskite layer, Spiro hole transport layer, and copper electrode may be selected.

[0060] In an embodiment of the present invention,

[0061] The negative electrode of the flexible perovskite solar cell is the copper electrode in the negative electrode region of the first perovskite cell (other perovskite cells have no negative electrode, only the positive electrode at the top of the hole transport layer). Electrons are conducted to the negative electrode (e.g., lithium foil) of the lithium-sulfur battery section through wires. The positive electrode of the last perovskite cell is located at the top of the hole transport layer, and holes are transported to the lithium-sulfur battery section through the positive electrode (e.g., copper foil) of the lithium-sulfur battery that is attached to it. The intermediate perovskite cells are connected in series with the previous perovskite cell through the electron transport layer and the top positive electrode. Except for the positive electrode of the last perovskite cell, the other positive electrodes are attached to the insulating material.

[0062] In this embodiment, energy loss in the overall system through wire transmission can be minimized. The entire system uses only one wire and has a high degree of integration, which facilitates subsequent wearable design, etc.

[0063] In an embodiment of the present invention, the positive electrode of the lithium-sulfur battery is a first metal foil, and a phosphorus-doped graphene coating and a boron-doped graphene coating are sequentially disposed between the first metal foil and the solid electrolyte; the side of the first metal foil away from the solid electrolyte is electrically connected to the positive electrode.

[0064] In this embodiment, boron-doped graphene coating and phosphorus-doped graphene coating are used to improve the stability and surface polarity of carbon materials, thereby suppressing the shuttle effect of lithium-sulfur batteries and improving the electrochemical performance of the batteries.

[0065] In an embodiment of the present invention, the positive electrode is a second metal foil, and the side of the first metal foil away from the solid electrolyte is bonded to the second metal foil. For example, the first and second metals can be the same metal; in this invention, copper foil is used for both.

[0066] In this embodiment, metal foil bonding facilitates assembly during manufacturing and maintains battery specifications and dimensions.

[0067] In one embodiment, the present invention also provides a method for fabricating an integrated self-charging system of the perovskite flexible solar cell and the lithium-sulfur battery, comprising the following steps:

[0068] Perovskite flexible solar cells and lithium-sulfur batteries were prepared sequentially and assembled to obtain an integrated self-charging system.

[0069] The preparation method of this invention is as follows: First, lead iodide and cesium iodide are mixed with MAI, FAI, and MACl in a certain proportion, and a transparent conductive layer 2 is etched on a flexible substrate 1 according to a fixed process step. Perovskite battery cells are then fabricated on the transparent conductive layer 2. The perovskite battery cells are connected in series with electrodes through an electron transport layer 3 to achieve the working voltage of the lithium-sulfur battery. It is important to note that only the positive electrode (i.e., the copper electrode at the top) of the last perovskite battery cell in the series module is exposed, while the remaining positive electrodes are in contact with an insulating material such as PMMA to prevent short circuits. Second, reduced graphene oxide powder is mixed with boric acid and red phosphorus respectively, and high-temperature doping is carried out in an inert gas atmosphere in a tube furnace. After the process, boron-doped graphene and phosphorus-doped graphene are obtained respectively, which serve as sulfur-carrying materials for the positive electrode of the lithium-sulfur battery, thus completing the sulfur loading operation. Then, SuperP, binder (PVDF), boron-doped graphene, and phosphorus-doped graphene are mixed evenly in a certain proportion. A layer of phosphorus-doped graphene coating is first applied to the positive electrode, and after drying, a layer of boron-doped graphene coating is applied, followed by drying again. Next, the negative electrode, the positive electrode coated with the positive electrode materials (phosphorus-doped graphene and boron-doped graphene), and the solid electrolyte are placed into a glove box to complete the battery assembly. The uncoated side of the positive electrode is attached to the top of the positive electrode of the only exposed last perovskite battery cell, while the rest of the positive electrode is attached to the insulating material PMMA. Finally, the self-charging system is sealed in the glove box and encapsulated with UV-cured adhesive.

[0070] Based on the above ideas, the specific implementation of the present invention includes the following:

[0071] (1) Fabrication of perovskite solar cells:

[0072] (1a) Weigh and thoroughly mix lead iodide, cesium iodide, DMF, and DMSO in equal amounts of 693.5 mg, 17.5 mg, 0.85 mL, and 0.15 mL, respectively, preferably in the order of weighing. After mixing, transfer the mixture to a magnetic stirrer and stir at a specific temperature and time until the mixture is homogeneous. For example, the stirring temperature is 50-70°C, and the time is 10-18 hours, preferably 12 hours.

[0073] (1b) Weigh and mix FAI, MAI, MACl and IPA in equal amounts of 185 mg, 13.8 mg, 17 mg and 2 mL respectively, preferably in the order of weighing. After mixing, transfer to a magnetic stirrer and stir at room temperature until the drugs are evenly mixed.

[0074] (1c) Weigh and thoroughly mix spiro, chlorobenzene, lithium salt, cobalt salt, and TBP in the following quantities: 72.5 mg, 1 mL, 0.018 mL, 0.029 mL, and 0.029 mL, respectively, preferably in the order of weighing. After mixing, transfer to a magnetic stirrer and stir at room temperature until the mixture is homogeneous.

[0075] (1d) The etched ITO substrate is placed in a spin coater, and a tin oxide solution of a certain concentration is spin-coated onto the ITO surface at a certain rotation speed and time. The tin oxide film in the negative electrode region of the device is then wiped off, and an annealing treatment is performed at a certain temperature and time to complete the fabrication of the tin oxide electron transport layer. For example, the mass concentration of the tin oxide solution is 5%. The spin coater rotation speed is 3500 r / s, and the time is 30 s. The annealing temperature is 150 °C, and the time is 30 min.

[0076] (1e) The substrate from step 1d is transferred to a glove box, and a perovskite thin film is prepared using a two-step method under an inert gas atmosphere. First, the solution from step 1a is spin-coated onto the substrate at a certain rotation speed and time, followed by annealing at a certain temperature and time. For example, the spin coater speed is 1500 rpm for 30 s, and the annealing temperature is 70°C for 1 min. Then, the solution prepared in step 1b is spin-coated onto the substrate at a certain rotation speed and time, followed by annealing at a certain temperature and time, thus completing the preparation of the perovskite layer. For example, the spin coater speed is 3500 rpm for 30 s, and the annealing temperature is 150°C for 15 min. The solution from step 1c is then spin-coated onto the perovskite layer using a dynamic spin-coating method, thus completing the preparation of the Spiro hole transport layer. For example, the dynamic spin-coating is performed at a spin coater speed of 1000 rpm for 5 s and 4000 rpm for 30 s. The perovskite film in the negative electrode region of the device is scraped off with a doctor blade to expose the ITO layer in the negative electrode region. A laser scribing machine is then used to mark the series connection area, which can be up to 1000 μm wide, to allow copper electrodes to be evaporated between the perovskite cell units, achieving series connection. Finally, a Cu electrode of a certain thickness is deposited using vacuum thermal evaporation to complete the fabrication of the perovskite solar cell. For example, the thickness of the deposited Cu electrode is 100 nm, which is the thickness of the top electrode of the perovskite cell unit.

[0077] In this embodiment, the tin oxide electron transport layer penetrates into the ITO gap between adjacent perovskite solar cells during spin coating. After annealing, the tin oxide electron transport layer connects the ITO transparent conductive layer. After the perovskite solar cell is coated with Spiro, a gap is etched between each perovskite solar cell using a laser. This allows the electrodes to be deposited between adjacent perovskite solar cells during electrode evaporation, thereby achieving series connection of the perovskite solar cells.

[0078] The specific structure of the perovskite solar cell is shown in the attached diagram. Figure 2 As shown.

[0079] (2) Fabrication of boron-doped graphene and phosphorus-doped graphene for use as sulfur-supporting materials in the positive electrode of lithium-sulfur batteries:

[0080] (2a) Mix reduced graphene oxide powder with red phosphorus in amounts of 0.05 g and 0.25 g respectively. After weighing, transfer the mixture to an agate mortar and grind until no red phosphorus powder is visible. Transfer the well-mixed mixture to a porcelain boat, spread it evenly, and place it in a tube furnace with an inert gas atmosphere to complete high-temperature doping at a certain temperature and time. For example, the doping temperature is 900°C to 1000°C. Weigh and mix the doped phosphorus-doped graphene and elemental sulfur powder in a certain ratio, and grind them evenly in an agate mortar. For example, the mass ratio of the two is 3:7. Then, transfer the well-mixed material to a high-temperature resistant glass vessel, place it in the liner of a reaction vessel, fill it with inert gas, and finally place it in a drying oven at 155°C for 20 hours to complete the sulfur loading operation.

[0081] (2b) Mix reduced graphene oxide powder with boric acid, using amounts of 0.05 g and 0.25 g respectively. After weighing, transfer the mixture to an agate mortar and grind until no white boric acid powder is visible. Transfer the well-mixed mixture to a porcelain boat, spread it evenly, and place it in a tube furnace with inert gas introduced. The mixture is then subjected to high-temperature doping at a specific temperature and time in an inert gas atmosphere. For example, the doping temperature is 900°C to 1000°C. Weigh and mix the doped boron-doped graphene and elemental sulfur powder in a specific ratio, and grind them evenly in an agate mortar. For example, the mass ratio is 3:7. Then, transfer the well-mixed material to a high-temperature resistant glass container, place it in a reactor liner, fill it with inert gas, and finally place it in a drying oven at 155°C for 20 hours to complete the sulfur loading operation.

[0082] (2c) The sulfur-loaded phosphorus-doped graphene, Super P, and PVDF are weighed in a certain ratio, for example, the mass ratio of the three is 7:2:1. The weighed graphene and Super P are transferred to an agate mortar and ground for 45 minutes. After grinding, they are transferred to a glass bottle and the weighed PVDF is added and stirred for 5 hours. After stirring, a coating is applied to the positive electrode using a coating applicator with a certain scale, and finally transferred to a drying oven to dry. For example, the scale of the coating applicator is 50 nm, that is, the coating thickness of the phosphorus-doped graphene is 50 nm.

[0083] (2d) The sulfur-loaded boron-doped graphene, Super P, and PVDF were weighed in a certain ratio, for example, 7:2:1. The weighed graphene and Super P were transferred to an agate mortar and ground for 45 minutes. After grinding, the graphene was transferred to a glass bottle, and the weighed PVDF was added and stirred for 5 hours. After stirring, a coating was applied to the phosphorus-doped graphene coating on the positive electrode using a graduated coating applicator. Finally, the coating was dried in a drying oven. For example, the coating applicator was graduated to 50 nm, meaning the thickness of the boron-doped graphene coating was 50 nm.

[0084] The specific technical approach is shown in the attached diagram. Figure 3 As shown.

[0085] (3) Integration of perovskite solar cells and lithium-sulfur batteries:

[0086] Both positive and negative electrodes were chosen to be copper electrodes. First, the copper electrode at the top of the series module was attached to the insulating PMMA material, leaving only the copper electrode at the top of the last perovskite cell exposed. Then, lithium foil was used as the negative electrode, and together with copper foil coated with positive electrode materials (phosphorus-doped graphene and boron-doped graphene) and solid electrolyte, it was placed in a glove box to complete the assembly of the lithium-sulfur battery. Next, the uncoated side of the copper foil was attached to the top of the copper electrode of the only exposed last perovskite cell, while the rest of the copper foil was attached to the insulating PMMA material. Finally, the self-charging system was sealed in the glove box and encapsulated with UV-cured adhesive.

[0087] The detailed integrated system architecture diagram is shown in the attached figure. Figure 1 As shown.

Claims

1. An integrated self-charging system for a perovskite flexible solar cell and a lithium-sulfur battery, characterized in that, Including perovskite flexible solar cells and lithium-sulfur batteries; The flexible perovskite solar cell includes a flexible substrate, a transparent conductive layer, and a plurality of perovskite cell units arranged sequentially. Each perovskite cell unit is disposed on the transparent conductive layer and includes an electron transport layer, a perovskite layer, and a hole transport layer arranged sequentially. The perovskite cell units are connected in series. The positive electrode of the last perovskite cell unit serves as the positive electrode of the flexible perovskite solar cell, and the negative electrode of the first perovskite cell unit serves as the negative electrode of the flexible perovskite solar cell. The lithium-sulfur battery includes a positive electrode, a negative electrode, and a solid electrolyte. The positive electrode is electrically connected to the positive electrode, and the negative electrode is electrically connected to the negative electrode to form a circuit. The negative electrode of the perovskite flexible solar cell is the electrode of the negative electrode region of the first perovskite cell unit, which conducts electrons to the lithium negative electrode of the lithium-sulfur battery through wires; the positive electrode of the last perovskite cell unit is located on top of the hole transport layer, and holes are transported to the lithium-sulfur battery through the positive electrode attached to it; each intermediate perovskite cell unit is connected in series with the previous perovskite cell unit through the electron transport layer and the top positive electrode, and except for the positive electrode of the last perovskite cell unit, the other positive electrodes are attached to the insulating material; The positive electrode of the lithium-sulfur battery is a first metal foil, and a phosphorus-doped graphene coating and a boron-doped graphene coating are sequentially disposed between the first metal foil and the solid electrolyte; the side of the first metal foil away from the solid electrolyte is electrically connected to the positive electrode of the perovskite flexible solar cell.

2. The integrated self-charging system of perovskite flexible solar cell and lithium-sulfur battery according to claim 1, characterized in that, The positive electrode is made of a second metal foil, and the side of the first metal foil away from the solid electrolyte is bonded to the second metal foil.

3. The method for fabricating an integrated self-charging system of a perovskite flexible solar cell and a lithium-sulfur battery as described in claim 1, characterized in that, Includes the following steps: Step 1: Fabrication of perovskite flexible solar cells; The flexible perovskite solar cell includes a flexible substrate, a transparent conductive layer, and a plurality of perovskite cell units arranged sequentially. Each perovskite cell unit includes an electron transport layer, a perovskite layer, and a hole transport layer arranged sequentially. The perovskite cell units are connected in series. The positive electrode of the last perovskite cell unit serves as the positive electrode of the flexible perovskite solar cell. The negative electrode of the first perovskite cell unit serves as the negative electrode of the flexible perovskite solar cell. Step 2, Preparation of lithium-sulfur batteries The lithium-sulfur battery includes a positive electrode, a negative electrode, and a solid electrolyte. Step 3: Integrate the perovskite flexible solar cell with the lithium-sulfur battery. The positive electrode is electrically connected to the positive electrode, and the negative electrode is electrically connected to the negative electrode to form a circuit.

4. The method for fabricating the integrated self-charging system of perovskite flexible solar cell and lithium-sulfur battery according to claim 3, characterized in that, In step 1, a transparent conductive layer is fabricated on a flexible substrate, and perovskite battery cells are fabricated on the transparent conductive layer. The perovskite battery cells are connected in series through an electron transport layer and electrodes to achieve the working voltage of a lithium-sulfur battery. Only the negative electrode of the first perovskite battery cell and the positive electrode of the last perovskite battery cell are exposed, while the remaining electrodes are attached to an insulating material to prevent short circuits.

5. The method for fabricating the integrated self-charging system of perovskite flexible solar cell and lithium-sulfur battery according to claim 4, characterized in that, The fabrication of the perovskite flexible solar cell includes: Step 1a, CsI, DMF and DMSO are mixed and stirred until homogeneous; Step 1b: Mix FAI, MAI, MACl and IPA thoroughly. Step 1c: Mix spiro, chlorobenzene, lithium salt, cobalt salt and TBP until homogeneous; Step 1d: Place the etched ITO substrate into a spin coater, spin coat the ITO surface with tin oxide solution, then wipe off the tin oxide film in the negative electrode area and perform annealing to complete the preparation of the tin oxide electron transport layer. Step 1e: The ITO substrate treated in step 1d is transferred to a glove box, and a perovskite thin film is prepared in a two-step method under an inert gas atmosphere. First, the solution obtained in step 1a is spin-coated onto the ITO substrate and annealed. Then, the solution obtained in step 1b is spin-coated onto the ITO substrate and annealed to complete the preparation of the perovskite layer. The solution obtained in step 1c is spin-coated onto the perovskite layer using a dynamic spin-coating method to complete the preparation of the hole transport layer. The perovskite thin film in the negative electrode region is scraped off to expose the ITO layer in the negative electrode region, and the series region is scribed out using a laser scribing machine. Finally, the positive and negative electrodes are deposited by vacuum thermal evaporation to complete the preparation of the perovskite flexible solar cell.

6. The method for fabricating an integrated self-charging system of perovskite flexible solar cells and lithium-sulfur batteries according to claim 4 or 5, characterized in that, Step 2 includes: Step 2a: Mix and grind the reduced graphene oxide powder with red phosphorus until no red phosphorus powder is visible. Then transfer it to a ceramic boat and put it into a tube furnace and introduce inert gas to complete the high-temperature doping in the inert gas atmosphere. Mix the doped phosphorus-doped graphene with sulfur elemental powder and put it into a reaction vessel, fill it with inert gas, and heat it to complete the sulfur loading operation. Step 2b: Mix and grind the reduced graphene oxide powder with boric acid until no white boric acid powder is visible. Then transfer it to a ceramic boat and put it into a tube furnace and introduce inert gas to complete the high-temperature doping in an inert gas atmosphere. Mix the doped boron-doped graphene with sulfur elemental powder and put it into a reaction vessel, fill it with inert gas, and heat it to complete the sulfur loading operation. Step 2c: The sulfur-loaded phosphorus-doped graphene is mixed and ground with Super P, then PVDF is added and stirred. After stirring, a coating is applied to the positive electrode using a coating tool, and finally transferred to a drying oven to dry. In step 2d, the sulfur-loaded boron-doped graphene is mixed and ground with Super P, then PVDF is added and stirred. After stirring, a coating is applied to the phosphorus-doped graphene coating on the positive electrode using a coating tool, and finally transferred to a drying oven to dry.

7. The method for fabricating the integrated self-charging system of perovskite flexible solar cell and lithium-sulfur battery according to claim 6, characterized in that, Step 1a, The dosages of CsI, DMF, and DMSO were 693.5 mg, 17.5 mg, 0.85 mL, and 0.15 mL, respectively; the mixture was magnetically stirred at 50-70 °C. In step 1b, the amounts of FAI, MAI, MACl, and IPA are 185 mg, 13.8 mg, 17 mg, and 2 mL, respectively; the mixture is stirred magnetically at room temperature. In step 1c, the amounts of spiro, chlorobenzene, lithium salt, cobalt salt, and TBP used are 72.5 mg, 1 mL, 0.018 mL, 0.029 mL, and 0.029 mL, respectively; the mixture is magnetically stirred at room temperature. In step 2a, the amounts of reduced graphene oxide powder and red phosphorus are 0.05 g and 0.25 g, respectively. The high-temperature doping conditions are 900℃~1000℃ in an inert gas atmosphere. The mass ratio of phosphorus-doped graphene to sulfur powder is 3:

7. The sulfur loading operation conditions are 155℃ for 20 h. In step 2b, the amounts of reduced graphene oxide powder and boric acid are 0.05 g and 0.25 g, respectively. The high-temperature doping conditions are 900℃~1000℃ in an inert gas atmosphere. The mass ratio of boron-doped graphene to sulfur powder is 3:

7. The sulfur loading operation conditions are 155℃ for 20 h. In step 2c, the mass ratio of sulfur-loaded phosphorus-doped graphene, Super P, and PVDF is 7:2:1; the coating thickness of the phosphorus-doped graphene is 50 nm. In step 2d, the mass ratio of sulfur-loaded boron-doped graphene, Super P, and PVDF is 7:2:1; the coating thickness of boron-doped graphene is 50 nm.

8. The method for fabricating the integrated self-charging system of perovskite flexible solar cell and lithium-sulfur battery according to claim 7, characterized in that, Step 3 includes: First, the negative electrode of the first perovskite cell and the positive electrode of the last perovskite cell are exposed, and the remaining electrodes are attached to the insulating material. Then, the negative electrode, solid electrolyte, and positive electrode coated with sulfur-containing material are sent into the glove box to complete the assembly of the lithium-sulfur battery. Next, attach the side of the positive electrode without the insulating coating to the top of the only exposed positive electrode, while the rest of the positive electrode is attached to the insulating material; Finally, the self-charging system was sealed in the glove box and encapsulated with UV-curable adhesive.

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