Green hydrogen production and storage system and lithium battery cooling system and method using cascade heat pump

Abstract

The application discloses a green hydrogen preparation storage and lithium battery cooling system and method using a cascade heat pump, and belongs to the technical field of comprehensive energy systems. The lithium battery cabin in the system suppresses the power fluctuation of fluctuating power sources, outputs stable power, and simultaneously drives the cascade heat pump and the electrolytic cell. The cascade heat pump is configured to: absorb lithium battery cabin heat through its low-temperature stage circuit evaporator to cool the battery cabin; release heat to the electrolytic cell through its condensing evaporator to heat and maintain temperature; and release heat to the organic liquid hydrogen storage system through its high-temperature stage circuit condenser to provide a reaction heat source. The electrolytic cell produces hydrogen under stable power and suitable temperature, and the hydrogen is transported to the organic liquid hydrogen storage system for storage or release. The application uses the cascade heat pump as an energy hub, and utilizes the lithium battery waste heat in stages for electrolysis and hydrogen storage processes, realizes efficient collaboration of electricity-heat-hydrogen and energy self-consistency, and improves the energy efficiency, economy and accommodation capacity for fluctuating renewable energy of the system.

Description

Technical Field

[0001] This invention belongs to the field of integrated energy system technology, and specifically relates to a green hydrogen preparation, storage and lithium battery cooling system and method using a cascade heat pump. Background Technology

[0002] With the advancement of the "dual carbon" goals, the proportion of renewable energy power generation, represented by wind and solar power, continues to increase. However, their inherent intermittency and volatility pose challenges to the stable operation of the power system. Converting surplus renewable energy power into green hydrogen through water electrolysis is an important way to absorb fluctuating power sources, achieve long-term energy storage, and facilitate cross-seasonal energy regulation.

[0003] However, existing green hydrogen production and storage methods typically face the following technical challenges: (1) The problem of source-load mismatch is prominent: existing hydrogen production schemes mostly follow the idea of ​​large power grid hydrogen production, with insufficient energy storage configuration and insufficient consideration of the real-time fluctuation of hydrogen energy user demand, resulting in difficulty in effectively matching the fluctuating power source, hydrogen production load and hydrogen demand. (2) High system energy consumption and low energy efficiency: In the field of lithium battery energy storage, the battery compartment often relies on an independent air conditioning system for cooling. The waste heat generated by battery charging and discharging is not utilized, but instead consumes additional cooling energy. In the field of hydrogen production and storage, the start-up and efficient operation of electrolyzers (whether alkaline water electrolysis or proton exchange membrane water electrolysis) usually require an external heat source of 50-80℃ for heating and temperature maintenance; while organic liquid hydrogen storage technology usually requires a medium-high temperature heat source of 130-170℃ when carrying out hydrogenation or dehydrogenation reactions. These heat demands often require the configuration of an independent boiler or electric heating system, which increases the initial investment and operating energy consumption of the system, and reduces the overall energy efficiency and economy. (3) Low system integration and uncoupled energy utilization: In the existing technology, lithium battery cooling, electrolysis hydrogen production and organic liquid hydrogen storage are mostly independent subsystems. The energy flow (electricity and heat) is separated from each other, and waste heat recovery and cascade utilization have not been realized. The overall system integration and optimization level needs to be improved.

[0004] Some technologies have attempted localized optimization, specifically utilizing battery waste heat and heat pumps to heat the automotive cabin. However, these methods target a single heating element and are not integrated with hydrogen production and storage processes. Other solutions involve utilizing waste heat from electrolyzers or designing cascade thermal management systems for batteries, but none have addressed the challenge of deeply coupling fluctuating renewable energy power, after energy storage, with a cascade heat pump system capable of simultaneously meeting the cooling needs of lithium batteries, maintaining electrolyzer temperatures, and providing heating for organic liquid hydrogen storage. To address some of these issues, existing technologies have proposed using trough-type solar thermal collectors to generate high-temperature heat transfer oil, providing a heat source for organic liquid hydrogen storage and methanol synthesis systems. This approach utilizes solar energy, but its heat source is entirely dependent on external light fields, making it ineffective in utilizing fluctuating power sources. The system's essence is a "solar thermal-hydrogen / methanol storage" path. Furthermore, in the field of thermal management, systems employing cascade heat pumps for multi-temperature zone cooling exist. However, such systems are typically used for single cooling or heating scenarios (such as automotive air conditioning and building HVAC), without integrating them into the process heat requirements of fluctuating power generation, hydrogen electrolysis, and organic liquid hydrogen storage. Therefore, existing technologies have not yet systematically solved the problem of efficient synergy between electricity, heat, and hydrogen in renewable energy hydrogen production scenarios. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a green hydrogen preparation, storage, and lithium battery cooling system utilizing a cascade heat pump, comprising: a fluctuating power supply, a lithium battery compartment, a cascade heat pump, an electrolyzer, and an organic liquid hydrogen storage system. The input terminal of the lithium battery compartment is electrically connected to the fluctuating power source to smooth out power fluctuations and output stable power. The stable power output from the lithium battery compartment is simultaneously supplied to the compressor of the cascade heat pump and the power input terminal of the electrolytic cell. Cascade heat pumps include a low-temperature stage circuit and a high-temperature stage circuit that are thermally coupled through a condenser-evaporator. The cascade heat pump is configured to: absorb heat from the lithium battery compartment through the evaporator of its low-temperature stage circuit to cool the lithium battery compartment; release heat to the electrolyzer through the condenser evaporator to heat and maintain the temperature of the electrolyzer; and release heat to the organic liquid hydrogen storage system through the condenser of its high-temperature stage circuit to provide a heat source for the reaction. The hydrogen output terminal of the electrolyzer is connected to an organic liquid hydrogen storage system to deliver the produced hydrogen to the organic liquid hydrogen storage system.

[0006] Furthermore, the evaporator of the low-temperature stage circuit is configured to maintain the operating temperature of the lithium battery compartment within the range of 18°C ​​to 25°C. The condenser-evaporator is configured to provide a heating source of 50°C to 80°C to the electrolytic cell; The condenser of the high-temperature stage circuit is configured to provide a heat source of 130°C to 170°C.

[0007] Furthermore, the organic liquid hydrogen storage system includes: an organic liquid storage tank, an organic hydrogen storage liquid storage tank, a hydrogenation reactor, a dehydrogenation reactor, and at least one heat exchanger; The heat exchangers are connected to the organic liquid storage tank, the organic hydrogen storage tank, the hydrogenation reactor, and the dehydrogenation reactor, respectively, and are used to exchange heat with the heat source provided by the high-temperature stage loop.

[0008] Furthermore, the condenser of the high-temperature stage circuit is connected to the heat exchanger via a heat transfer oil storage tank.

[0009] Furthermore, the hydrogen storage medium used in the organic liquid hydrogen storage system is ethylcarbazole, methylcyclohexane, dibenzyltoluene, or decahydronaphthalene.

[0010] Furthermore, the refrigerant used in the low-temperature stage circuit is R134a, and the refrigerant used in the high-temperature stage circuit is R744.

[0011] Furthermore, the heat source required for the organic liquid hydrogen storage system is entirely provided by the high-temperature stage loop of the cascade heat pump.

[0012] Furthermore, the low-temperature stage loop evaporator, condenser evaporator, and high-temperature stage loop condenser of the cascade heat pump are configured to serve the three thermal management objects—the lithium battery compartment, the electrolyzer, and the organic liquid hydrogen storage system—each and simultaneously.

[0013] This invention also provides a method for preparing, storing, and cooling green hydrogen in lithium batteries using a cascade heat pump, comprising the following steps: Power supply steps: The lithium battery compartment is used to smooth out power fluctuations in the fluctuating power supply to output stable power, and this stable power is used to drive the cascade heat pump and electrolytic cell simultaneously. Thermal management steps: Thermal management operations are performed by a cascade heat pump, which include: absorbing heat from the lithium battery compartment through the evaporator in its low-temperature stage loop to cool the lithium battery compartment, releasing heat to the electrolyzer through its condenser-evaporator to heat and maintain the temperature of the electrolyzer, and releasing heat to the organic liquid hydrogen storage system through the condenser in its high-temperature stage loop to provide a heat source for the reaction. Hydrogen production and storage steps: Based on stable power and heating temperature maintenance, the electrolyzer is controlled to electrolyze water to produce hydrogen, and the generated hydrogen is transported to an organic liquid hydrogen storage system for storage or release.

[0014] Furthermore, in the thermal management step, the cascade heat pump is controlled so that the temperature of the evaporator side of the low-temperature stage loop is maintained at 18°C ​​to 25°C, the temperature of the evaporator side of the condenser is maintained at 50°C to 80°C, and the temperature of the condenser side of the high-temperature stage loop is maintained at 130°C to 170°C.

[0015] Furthermore, in the thermal management step, the heat released by the high-temperature stage loop condenser is stored in a thermal oil storage tank, and heat is supplied from the thermal oil storage tank according to the needs of the organic liquid hydrogen storage system.

[0016] Furthermore, in the hydrogen production and storage steps, When the organic liquid hydrogen storage system is used for hydrogen storage, the organic liquid is heated to 130°C to 170°C and then reacted with hydrogen gas for hydrogenation. When the organic liquid hydrogen storage system releases hydrogen, the organic hydrogen storage liquid is heated to 130°C to 170°C to carry out a dehydrogenation reaction to release hydrogen gas.

[0017] Compared with the prior art, the present invention has the following advantages: To address the issues of existing technologies relying on stable power grids or failing to effectively absorb wind and solar power, this invention utilizes a "fluctuating power source - lithium battery compartment" configuration to convert unstable power sources into stable electricity, providing a reliable power foundation for subsequent electrolytic hydrogen production and heat pump operation. This effectively solves the power fluctuation problem in renewable energy hydrogen production, achieving stable connection (matching) between the power source and load side (hydrogen production and storage), and improving the system's ability to directly absorb intermittent renewable energy and its operational stability.

[0018] Addressing the issue of high energy consumption and the need for multiple independent thermal systems for lithium battery cooling, electrolyzer temperature maintenance, and hydrogen storage heating in existing technologies, this invention innovatively configures a "cascade heat pump" as the core energy hub. This heat pump simultaneously performs three functions: absorbing waste heat from lithium batteries at its low-temperature end for cooling (eliminating the need for a separate air conditioner); providing a precise temperature-maintaining heat source for the electrolyzer at its medium-temperature end (eliminating the need for electric heating or a boiler); and heating the organic liquid hydrogen storage reaction at its high-temperature end (eliminating the need for a separate high-temperature heat source). This "one machine, three uses" design recovers and upgrades the previously discarded low-grade waste heat from batteries into medium- and high-grade process heat, achieving maximum self-circulation and closed-loop utilization of energy within the system, thereby systematically and significantly reducing overall energy consumption.

[0019] Addressing the issues of fragmented and low-integration subsystems (energy storage, cooling, hydrogen production, and hydrogen storage) in existing technologies, this invention unifies power supply through a lithium battery compartment and provides all process heat requirements through a single cascade heat pump, deeply coupling multiple independent systems into a compact and collaborative organic whole. This highly integrated design reduces the number of devices, floor space, and initial investment, while avoiding the control complexity and maintenance costs associated with operating multiple systems independently, significantly improving the project's economics and feasibility.

[0020] Addressing the issue of existing solar thermal fields relying on specific geographical conditions and weather, the core heat source of this invention comes from a self-electrically driven cascade heat pump, with the heat ultimately derived from a fluctuating power source. Therefore, this system does not require large-scale solar thermal fields or other specific external facilities, and can operate stably in various regions and weather conditions with wind and solar resources, achieving true "all-weather" hydrogen production and energy storage, greatly expanding the applicable scenarios and geographical scope of the technology.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of a green hydrogen preparation, storage, and lithium battery cooling system utilizing a cascade heat pump according to an embodiment of the present invention is shown.

[0024] In the picture: 100. Fluctuating power supply; 200. Lithium battery compartment; 300. Cascade heat pump; 301. Low-temperature stage circuit; 302. High-temperature stage circuit; 303. Condenser / evaporator; 304. Heat transfer oil storage tank; 400. Electrolytic cell; 501. Organic liquid storage tank; 502. Organic hydrogen storage tank; 503. Hydrogenation reactor; 504. Dehydrogenation reactor; 505. Heat exchanger. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] refer to Figure 1A preferred embodiment of the present invention provides a green hydrogen preparation, storage, and lithium battery cooling system utilizing a cascade heat pump. The system mainly includes a fluctuating power supply 100, a lithium battery compartment 200, a cascade heat pump 300, an electrolyzer 400, and an organic liquid hydrogen storage system.

[0027] The fluctuating power source 100 is, for example, a wind turbine generator, a photovoltaic power generation array, or a combination thereof, whose output power is intermittent and randomly fluctuates.

[0028] The input terminal of the lithium battery compartment 200 is electrically connected to the fluctuating power supply 100. The lithium battery compartment 200 contains a battery management system (BMS) and a power conversion system (PCS), whose core function is to smooth out power fluctuations in the fluctuating power supply 100. When the power supply is excessive, the lithium battery charges and stores energy; when the power supply is insufficient, the lithium battery discharges to supplement it. Through this "peak shaving and valley filling" effect, the lithium battery compartment 200 can output relatively smooth and stable DC or AC power to the back end of the system.

[0029] The approximately 150°C heat source provided to the organic liquid hydrogen storage system in this invention originates entirely from the condensation heat released by the high-temperature stage circuit 302 during the operation of the cascade heat pump 300. The initial sources of this heat are the waste heat from the lithium battery compartment 200 and the power consumption of the compressor. This invention results in a more compact device and achieves closed-loop utilization of energy within the system.

[0030] The stable power output from the lithium battery compartment 200 is simultaneously distributed to two power supply branches: one connects to the compressor of the cascade heat pump 300, providing it with operating power; the other connects to the power input terminal of the electrolyzer 400, providing power for its electrolytic reaction. This means that both the cascade heat pump 300 and the electrolyzer 400 are driven by stable green electricity "filtered" by the lithium battery compartment 200, and their operation is unaffected by fluctuations in upstream wind and solar power, thus improving the direct absorption rate of green electricity.

[0031] The cascade heat pump 300 is the core of energy coupling and conversion in this system. It includes a low-temperature stage loop 301 and a high-temperature stage loop 302, which are thermally coupled through a condenser-evaporator 303. In a specific embodiment, the low-temperature stage loop 301 uses R134a as the refrigerant, and the high-temperature stage loop 302 uses R744 (carbon dioxide) as the refrigerant. R744 can output high-temperature hot water or hot oil in a transcritical cycle, making it very suitable for generating heat at around 150°C.

[0032] The specific operating configuration and functions of the cascade heat pump 300 are as follows: Cooling the lithium battery compartment: The evaporator of the low-temperature stage circuit 301 is located in the cooling channel of the lithium battery compartment 200. The low-temperature, low-pressure R134a working fluid in the evaporator absorbs heat from the coolant in the channel (or directly contacts the battery) and evaporates, thereby dissipating the waste heat generated by the operation of the lithium battery compartment 200 and maintaining the internal battery cell temperature within the optimal range of 18°C ​​to 25°C. This process replaces the traditional independent air conditioning refrigeration system.

[0033] Heating and maintaining the temperature of the electrolyzer: The heat absorbed by the low-temperature stage circuit 301, along with the heat generated by the compressor, is released at the condenser-evaporator 303. The condenser-evaporator 303 serves as the condenser end of the low-temperature stage circuit and the evaporator end of the high-temperature stage circuit, and its temperature is designed and controlled at approximately 70°C (range 50-80°C). This medium-temperature heat source is connected to the electrolyte circulation system or shell insulation system of the electrolyzer 400 via a heat exchanger 505 (such as a coil), providing the heat required for startup and maintaining efficient operation of the alkaline electrolyzer (ALK) or proton exchange membrane electrolyzer (PEM), thus optimizing the electrolyzer's power consumption.

[0034] Provide reaction heat for organic liquid hydrogen storage: The compressor of the high-temperature stage circuit 302 does work on the R744 gas from the condenser evaporator 303. The resulting high-temperature and high-pressure R744 working fluid condenses and releases heat in the high-temperature stage condenser, releasing high-grade heat at a temperature of about 150°C (range 130-170°C).

[0035] Preferably, the heat released by the condenser in the high-temperature stage circuit is not directly supplied to the organic liquid hydrogen storage system, but is first transferred to a heat transfer oil storage tank 304. The heat transfer oil storage tank 304 is filled with high-temperature heat transfer oil (such as a biphenyl-diphenyl ether mixture, hydrogenated terphenyl, etc.) as a buffer and storage device for high-temperature heat. This decouples the continuous operation of the cascade heat pump 300 from the intermittent heat demand of the organic liquid hydrogen storage system (the hydrogenation or dehydrogenation reaction is not continuous), improving the flexibility and independence of the operation of each component of the system.

[0036] The organic liquid hydrogen storage system includes an organic liquid storage tank 501, an organic hydrogen storage tank 502, a hydrogenation reactor 503, a dehydrogenation reactor 504, and a heat exchanger 505. One end of the heat exchanger 505 is connected to both the organic liquid storage tank 501 and the organic hydrogen storage tank 502 via pipes and valves, while the other end is connected to a heat transfer oil storage tank 304 for heat exchange. The preferred hydrogen storage medium used in this system is ethylcarbazole (NEC), as its hydrogenation and dehydrogenation reactions can be carried out efficiently at a relatively mild temperature of around 150°C, perfectly matching the heat source temperature provided by the cascade heat pump 300. Of course, other organic hydrogen storage media such as methylcyclohexane (MCH), dibenzyltoluene (DBT), or decahydronaphthalene can also be used.

[0037] Under conditions of a stable power supply and a suitable temperature (approximately 70°C) provided by the cascade heat pump 300, the electrolyzer 400 efficiently performs the water electrolysis reaction to produce high-purity hydrogen and oxygen. The oxygen can be further processed or utilized, while the hydrogen is transported through pipelines to an organic liquid hydrogen storage system.

[0038] The workflow of the organic liquid hydrogen storage system is as follows: Hydrogen storage (hydrogenation) process: When hydrogen storage is required, the valve between the organic liquid storage tank 501 and the heat exchanger 505 is opened. The organic liquid (such as ethylcarbazole) is pumped to the heat exchanger 505, where it exchanges heat with high-temperature heat transfer oil from the heat transfer oil storage tank 304, and is heated to a reaction temperature of approximately 150°C. The heated organic liquid enters the hydrogenation reactor 503, where it undergoes a hydrogenation reaction with hydrogen from the electrolyzer 400 in the presence of a catalyst, generating an organic hydrogen storage liquid (such as fully hydrogenated ethylcarbazole). The reacted organic hydrogen storage liquid is then transferred to the organic hydrogen storage liquid storage tank 502 for storage.

[0039] Hydrogen release (dehydrogenation) process: When the user needs hydrogen, the valve between the organic hydrogen storage liquid tank 502 and the heat exchanger 505 is opened. The organic hydrogen storage liquid is pumped to the heat exchanger 505, where it is heated to approximately 150°C, the dehydrogenation reaction temperature. The heated organic hydrogen storage liquid enters the dehydrogenation reactor 504, where a dehydrogenation reaction occurs under the action of a catalyst, releasing hydrogen and reverting to an organic liquid. The released hydrogen is supplied to the user, while the dehydrogenated organic liquid returns to the organic liquid storage tank 501 (i.e., the dehydrogenation reactor 504 is connected to the organic liquid storage tank 501), completing one cycle. It should be noted that two heat exchangers 505 connected in series can be set up. One end of one heat exchanger 505 is connected to the heat transfer oil storage tank 304, and the other ends are connected to the organic liquid storage tank 501, the hydrogenation reactor 503 and the other heat exchanger 505 respectively. The other heat exchanger 505 described is connected to the organic hydrogen storage liquid storage tank 502, the dehydrogenation reactor 504 and the heat transfer oil storage tank 304 respectively (to return untreated or unprocessable substances to the tank for reprocessing).

[0040] Based on the above system, the working method of the present invention can be summarized as the following coordinated steps: Power supply steps: The lithium battery compartment 200 smooths out the power fluctuations of the fluctuating power supply 100 in real time, outputs stable power, and simultaneously distributes the power to the compressor of the cascade heat pump 300 and the electrolytic cell 400.

[0041] Thermal management steps: The cascade heat pump 300 starts up and operates, performing integrated thermal management. Its low-temperature end absorbs heat from the lithium battery compartment 200 to achieve cooling (maintaining 18-25℃); its medium-temperature end releases heat to the electrolytic cell 400 to maintain the temperature (maintaining 50-80℃); its high-temperature end stores and distributes heat through the heat transfer oil storage tank 304 to prepare heat for subsequent reactions (providing a heat source of 130-170℃).

[0042] Hydrogen production and storage steps: Electrolyzer 400 starts up and efficiently produces hydrogen under stable power and suitable temperature. The produced hydrogen is transported to the organic liquid hydrogen storage system according to system instructions. Within the hydrogen storage system, a stable high-temperature heat source provided by cascade heat pump 300 is used to drive a hydrogenation reaction to store hydrogen, or to drive a dehydrogenation reaction to release hydrogen, thereby flexibly meeting end-user hydrogen energy needs.

[0043] In summary, this invention, through ingenious system integration design, uses a cascade heat pump as an energy hub connecting "electrical storage" and "hydrogen storage," achieving the recovery and utilization of lithium battery waste heat, self-supply of electrolysis process heat, and green supply of hydrogen storage reaction heat. Simultaneously, it utilizes lithium batteries to solve the problem of power fluctuations. The entire system forms a highly efficient, synergistic, and multi-energy complementary organic whole of "electricity-heat-hydrogen," significantly improving the energy efficiency, economy, and operational reliability of the entire renewable energy hydrogen production, storage, and utilization chain.

[0044] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A green hydrogen preparation, storage, and lithium battery cooling system utilizing a cascade heat pump, characterized in that, include: Fluctuating power supply (100), lithium battery compartment (200), cascade heat pump (300), electrolyzer (400) and organic liquid hydrogen storage system; The input terminal of the lithium battery compartment (200) is electrically connected to the fluctuating power supply (100) to smooth out the power fluctuations of the fluctuating power supply (100) and output stable power. The stable power output from the lithium battery compartment (200) is simultaneously supplied to the compressor of the cascade heat pump (300) and the power input terminal of the electrolytic cell (400); The cascade heat pump (300) includes a low-temperature stage circuit (301) and a high-temperature stage circuit (302) thermally coupled through a condenser-evaporator (303); The cascade heat pump (300) is configured to: absorb heat from the lithium battery compartment (200) through the evaporator of its low-temperature stage circuit (301) to cool the lithium battery compartment (200); release heat to the electrolyzer (400) through the condenser evaporator (303) to heat and maintain the temperature of the electrolyzer (400); and release heat to the organic liquid hydrogen storage system through the condenser of its high-temperature stage circuit (302) to provide a heat source for the reaction. The hydrogen output terminal of the electrolyzer (400) is connected to the organic liquid hydrogen storage system for transporting the prepared hydrogen to the organic liquid hydrogen storage system.

2. The system according to claim 1, characterized in that, The evaporator of the low-temperature stage circuit (301) is configured to maintain the operating temperature of the lithium battery compartment (200) within the range of 18°C ​​to 25°C. The condenser-evaporator (303) is configured to provide a heating source of 50°C to 80°C to the electrolytic cell (400); The condenser of the high-temperature stage circuit (302) is configured to provide a heat source of 130°C to 170°C.

3. The system according to claim 1, characterized in that, The organic liquid hydrogen storage system includes: an organic liquid storage tank (501), an organic hydrogen storage liquid storage tank (502), a hydrogenation reactor (503), a dehydrogenation reactor (504), and at least one heat exchanger (505); The heat exchanger (505) is connected to the organic liquid storage tank (501), the organic hydrogen storage liquid storage tank (502), the hydrogenation reactor (503), and the dehydrogenation reactor (504) respectively, and is used to exchange heat with the heat source provided by the high-temperature stage circuit (302).

4. The system according to claim 4, characterized in that, The condenser of the high-temperature stage circuit (302) is connected to the heat exchanger (505) through a heat transfer oil storage tank (304).

5. The system according to claim 4, characterized in that, The hydrogen storage medium used in the organic liquid hydrogen storage system is ethylcarbazole, methylcyclohexane, dibenzyltoluene, or decahydronaphthalene.

6. The system according to claim 1, characterized in that, The refrigerant used in the low-temperature stage circuit (301) is R134a, and the refrigerant used in the high-temperature stage circuit (302) is R744.

7. The system according to claim 1, characterized in that, The heat source required by the organic liquid hydrogen storage system is entirely provided by the high-temperature stage loop (302) of the cascade heat pump (300).

8. The system according to any one of claims 1-7, characterized in that, The low-temperature stage circuit (301) evaporator, the condenser-evaporator (303), and the high-temperature stage circuit (302) condenser of the cascade heat pump (300) are configured to serve the three thermal management objects—the lithium battery compartment (200), the electrolyzer (400), and the organic liquid hydrogen storage system—respectively and simultaneously.

9. A method for preparing, storing, and cooling green hydrogen in lithium batteries, characterized in that, Includes the following steps: Power supply steps: The lithium battery compartment (200) is used to smooth the power fluctuations of the fluctuating power supply (100) to output stable power, and the stable power is used to drive the cascade heat pump (300) and the electrolytic cell (400) to operate simultaneously. Thermal management steps: Thermal management operations are performed by the cascade heat pump (300), the thermal management operations including: absorbing heat from the lithium battery compartment (200) through the evaporator of its low-temperature stage circuit (301) to cool the lithium battery compartment (200), releasing heat to the electrolyzer (400) through its condenser evaporator (303) to heat and maintain the temperature of the electrolyzer (400), and releasing heat to the organic liquid hydrogen storage system through the condenser of its high-temperature stage circuit (302) to provide a reaction heat source; Hydrogen production and storage steps: Based on the stable power and the heating and temperature maintenance, the electrolyzer (400) is controlled to electrolyze water to produce hydrogen, and the generated hydrogen is transported to the organic liquid hydrogen storage system for storage or release.

10. The method according to claim 9, characterized in that, In the thermal management step, the cascade heat pump (300) is controlled such that the evaporator side temperature of its low-temperature stage circuit (301) is maintained at 18°C ​​to 25°C, the evaporator side temperature of its condenser (303) is maintained at 50°C to 80°C, and the condenser side temperature of its high-temperature stage circuit (302) is maintained at 130°C to 170°C.

11. The method according to claim 9, characterized in that, In the thermal management step, the heat released by the condenser of the high-temperature stage circuit (302) is stored in a thermal oil storage tank (304), and heat is supplied from the thermal oil storage tank (304) according to the needs of the organic liquid hydrogen storage system.

12. The method according to claim 9, characterized in that, In the hydrogen production and storage steps, When the organic liquid hydrogen storage system is used for hydrogen storage, the organic liquid is heated to 130°C to 170°C and then reacted with hydrogen gas for hydrogenation. When the organic liquid hydrogen storage system releases hydrogen, the organic hydrogen storage liquid is heated to 130°C to 170°C to carry out a dehydrogenation reaction to release hydrogen.

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