Energy storage system coupling electrochemistry and compressed carbon dioxide

Abstract

The invention relates to an energy storage system coupling electrochemistry and compressed carbon dioxide. The system comprises a compressed carbon dioxide energy storage subsystem and an electrochemical energy storage subsystem, the compressed carbon dioxide energy storage subsystem comprises a first liquid carbon dioxide storage tank and a second liquid carbon dioxide storage tank; the electrochemical energy storage subsystem comprises a cooling subsystem and an energy storage battery cabin consisting of a battery pack; and the cooling subsystem is respectively connected with the first liquid carbon dioxide storage tank and the second liquid carbon dioxide storage tank. By adopting the system, the safety of the electrochemical energy storage system can be improved.

Description

Technical Field

[0001] This application relates to the technical field of energy storage, and particularly to an energy storage system that couples electrochemistry and compressed carbon dioxide. Background Art

[0002] Currently, electrochemical energy storage technology has been widely used in the fields of new energy power generation and power regulation. Among them, lithium-ion batteries occupy the mainstream position due to their high energy density, fast response ability, and flexible deployment characteristics. However, due to the fact that lithium-ion batteries are easily affected by temperature changes during operation, their safety issues have become an important factor restricting their large-scale application. For example, overcharging, short-circuiting, or too high external environmental temperature may all lead to battery thermal runaway, which in turn may cause fires or explosions, posing serious safety hazards.

[0003] In order to reduce the risk of thermal runaway, existing technologies usually adopt water cooling or ethylene glycol cooling systems for battery thermal management. However, these traditional cooling methods have many limitations, such as low cooling efficiency, high system complexity, easy volatilization of the coolant, and corrosion of metal components. Therefore, there is still a large room for optimization in the safety of current electrochemical energy storage systems in terms of temperature control. Summary of the Invention

[0004] Based on this, it is necessary to provide an energy storage system that couples electrochemistry and compressed carbon dioxide to solve the above technical problems and improve the safety of the electrochemical energy storage system.

[0005] This application provides an energy storage system that couples electrochemistry and compressed carbon dioxide, including: a compressed carbon dioxide energy storage subsystem and an electrochemical energy storage subsystem; the compressed carbon dioxide energy storage subsystem includes a first liquid carbon dioxide storage tank and a second liquid carbon dioxide storage tank; the electrochemical energy storage subsystem includes a cooling subsystem and an energy storage battery compartment composed of battery packs;

[0006] The cooling subsystem is respectively connected to the first liquid carbon dioxide storage tank and the second liquid carbon dioxide storage tank.

[0007] In one embodiment, the compressed carbon dioxide energy storage subsystem further includes a compression unit, a cooling unit, a liquefaction unit, a first heat storage medium storage tank, a second heat storage medium storage tank, a gasification unit, a heating unit, and an expansion unit;

[0008] The first liquid carbon dioxide storage tank is also respectively connected to the compression unit and the expansion unit;

[0009] The cooling unit is respectively connected to the compression unit, the first heat storage medium storage tank, the second heat storage medium storage tank, and the liquefaction unit;

[0010] The second liquid carbon dioxide storage tank is also connected to the liquefaction unit and the gasification unit respectively;

[0011] The heating unit is connected to the gasification unit, the first heat storage medium storage tank, the second heat storage medium storage tank, and the expansion unit respectively.

[0012] In one embodiment, the compression unit includes a motor, a first compressor, and a second compressor; the cooling unit includes a first intercooler and a second intercooler;

[0013] The motor is used to drive the first compressor and the second compressor;

[0014] The carbon dioxide output port of the first compressor is connected to the carbon dioxide input port of the first intercooler;

[0015] The carbon dioxide output port of the first intercooler is connected to the carbon dioxide input port of the second compressor;

[0016] The carbon dioxide output port of the second compressor is connected to the carbon dioxide input port of the second intercooler;

[0017] The carbon dioxide output port of the second intercooler is connected to the carbon dioxide input port of the liquefaction unit.

[0018] In one embodiment, the medium output port of the first heat storage medium storage tank is connected to the medium input port of the first intercooler and the medium input port of the second intercooler respectively;

[0019] The medium input port of the second heat storage medium storage tank is connected to the medium output port of the first intercooler and the medium output port of the second intercooler respectively.

[0020] In one embodiment, the expansion unit includes a first expander, a second expander, and a generator; the heating unit includes a first reheater and a second reheater;

[0021] The first expander and the second expander are used to drive the generator to output electric energy;

[0022] The carbon dioxide output port of the gasification unit is connected to the carbon dioxide input port of the first reheater;

[0023] The carbon dioxide output port of the first reheater is connected to the carbon dioxide input port of the first expander;

[0024] The carbon dioxide output port of the first expander is connected to the carbon dioxide input port of the second reheater;

[0025] The carbon dioxide outlet of the second reheater is connected to the carbon dioxide inlet of the second expander.

[0026] In one embodiment, the medium outlet of the second heat storage medium storage tank is respectively connected to the medium inlet of the first reheater and the medium inlet of the second reheater;

[0027] The medium inlet of the first heat storage medium storage tank is respectively connected to the medium outlet of the first reheater and the medium outlet of the second reheater.

[0028] In one embodiment, the compressed carbon dioxide energy storage subsystem further includes a throttle valve and a cold accumulator;

[0029] The carbon dioxide outlet of the first liquid carbon dioxide storage tank is connected to the compression unit through the cold accumulator;

[0030] The carbon dioxide outlet of the first liquid carbon dioxide storage tank is connected to the cold accumulator through the throttle valve;

[0031] The carbon dioxide inlet of the first liquid carbon dioxide storage tank is connected to the expansion unit through the cold accumulator.

[0032] In one embodiment, the cooling subsystem includes a high-pressure pump, a heat accumulator, and a cooling pipeline;

[0033] The second liquid carbon dioxide storage tank is connected to the cooling pipeline through the high-pressure pump;

[0034] The first liquid carbon dioxide storage tank is connected to the cooling pipeline through the heat accumulator.

[0035] In one embodiment, the cooling pipeline includes an inlet pipeline, an outlet pipeline, a regulating valve provided on the inlet pipeline, and a check valve provided on the outlet pipeline.

[0036] In one embodiment, the cooling subsystem further includes a stop valve; the cooling pipeline also leads to the inside of the energy storage battery compartment through the stop valve.

[0037] The above-mentioned energy storage system coupling electrochemistry and compressed carbon dioxide includes a compressed carbon dioxide energy storage subsystem and an electrochemical energy storage subsystem. The compressed carbon dioxide energy storage subsystem includes a first liquid carbon dioxide storage tank and a second liquid carbon dioxide storage tank. The electrochemical energy storage subsystem includes a cooling subsystem and an energy storage battery compartment composed of battery packs. Among them, the cooling subsystem is respectively connected to the first liquid carbon dioxide storage tank and the second liquid carbon dioxide storage tank. By coupling the electrochemical energy storage and the compressed carbon dioxide energy storage system, the above system provides an efficient and safe battery temperature control solution, overcoming the defects of low cooling efficiency, high system complexity, easy volatilization of the coolant, and corrosion of metal components in traditional water cooling or ethylene glycol cooling systems. The system adopts the first liquid carbon dioxide storage tank and the second liquid carbon dioxide storage tank, and is connected to the battery pack through the cooling subsystem, so that low-temperature liquid carbon dioxide is directly used for battery cooling, and relies on its phase change endothermic characteristic to quickly reduce the battery temperature and improve the cooling efficiency. At the same time, as a non-corrosive coolant, carbon dioxide can reduce damage to equipment and avoid volatilization loss of the coolant. Compared with traditional independent cooling and fire extinguishing systems, the present invention reduces the system complexity through an integrated design, improves the reliability of operation and the convenience of maintenance, thereby significantly enhancing the safety of the electrochemical energy storage system in terms of temperature control. In addition, by coupling the compressed carbon dioxide energy storage subsystem, the energy storage capacity and energy storage duration of the electrochemical energy storage subsystem are improved, and its operating conditions are more flexible, which can meet the application requirements of the power grid for different energy storage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required to be used in the description of the embodiments of the present application or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic structural diagram of an energy storage system coupling electrochemistry and compressed carbon dioxide in an embodiment;

[0040] Figure 2 It is a schematic structural diagram of an energy storage system coupling electrochemistry and compressed carbon dioxide in another embodiment;

[0041] Figure 3 It is a schematic structural diagram of an electrochemical energy storage subsystem in another embodiment.

[0042] Reference Numerals in the Drawings:

[0043] Compressed carbon dioxide energy storage subsystem - 10, electrochemical energy storage subsystem - 20, first liquid carbon dioxide storage tank - 100, second liquid carbon dioxide storage tank - 101, compression unit - 102, cooling unit - 103, liquefaction unit - 104, first heat storage medium storage tank - 105, second heat storage medium storage tank - 106, gasification unit - 107, heating unit - 108, expansion unit - 109, throttle valve - 110, cold accumulator - 111, cooling subsystem - 200, energy storage battery compartment - 201, motor - 1020, first compressor - 1021, second compressor - 1022, first intercooler - 1030, second intercooler - 1031, first reheater - 1080, second reheater - 1081, first expander - 1090, second expander - 1091, generator - 1092, high - pressure pump - 2001, heat accumulator - 2002, inlet pipeline - 2003, outlet pipeline - 2004, regulating valve - 2005, check valve - 2006, stop valve - 2007. Detailed implementation manners

[0044] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0046] It can be understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of this application, the first compressor may be referred to as the second compressor, and similarly, the second compressor may be referred to as the first compressor. Both the first compressor and the second compressor are compressors, but they are not the same compressor.

[0047] It can be understood that in the following embodiments, "connection", if there is an electrical signal or data transfer between the connected circuits, modules, units, etc., should be understood as "electrical connection", "communication connection", etc.

[0048] It can be understood that "at least one" means one or more, and "a plurality" means two or more. "At least part of an element" means part or all of the element.

[0049] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprises / comprising" or "has / have" etc. specify the presence of the stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0050] Electrochemical energy storage is a technology that converts electrical energy into chemical energy for storage based on the principle of electrochemical reactions. It has the advantages of high energy density, fast response speed, short construction period, and flexible layout, and is widely used in the new power system with new energy as the main body. Among them, lithium-ion batteries are relatively mature and are currently the electrochemical energy storage technology with the highest installed capacity and the fastest development speed. However, due to reasons such as overcharging, overheating, and short circuits, lithium-ion batteries are prone to thermal runaway, releasing a large amount of heat and combustible substances in a short time, which may lead to fires or explosions. In recent years, a series of fire safety accidents in battery energy storage systems or energy storage power stations caused by battery thermal runaway have brought severe challenges to the healthy and sustainable development of the energy storage industry.

[0051] Compressed carbon dioxide energy storage uses carbon dioxide (CO2) as the working medium of the energy storage system, and realizes the storage and release of energy through the compression and expansion processes of carbon dioxide gas. Compared with air, carbon dioxide has a larger molecular weight and can store more energy under the same volume. Moreover, the critical point of CO2 (31.3°C and 7.38 MPa) is relatively easy to reach, and it can condense into a liquid under conditions close to room temperature at high pressure, further increasing its energy storage density. In addition, carbon dioxide is odorless, non-toxic and non-flammable, and absorbs a large amount of heat during the vaporization process, rapidly cooling the surrounding environment and achieving an asphyxiating effect by diluting the oxygen concentration. Therefore, it is also widely used as a refrigerant and fire extinguishing agent in the industrial and fire protection fields.

[0052] Currently, electrochemical energy storage and compressed carbon dioxide energy storage technologies each have certain application scenarios, but there is no coupled energy storage system that deeply connects the two. In fact, carbon dioxide can not only be used as an energy storage medium to increase the energy storage capacity of the system, but also be used as a cooling and flame-retardant medium to control the battery temperature, thus effectively preventing thermal runaway and fire incidents. In this way, the two subsystems cooperate with each other, improving the overall efficiency of the system while also significantly enhancing its safety. Therefore, the energy storage system combining electrochemical energy storage and compressed carbon dioxide has good development potential.

[0053] The main energy carrier of existing electrochemical energy storage power stations is lithium-ion batteries, whose safety, service life, charge and discharge efficiency, etc. are closely related to their operating temperature. The commonly used coolant in existing battery thermal management systems is ethylene glycol and water. However, ethylene glycol has a low boiling point, large volatilization loss, high viscosity, low heat transfer efficiency, high energy consumption during the circulation process, and may produce acidic substances at high temperatures, which has a certain corrosiveness to metals. At the same time, the commonly used fire extinguishing agents (heptafluoropropane, perfluoromethylcyclohexanone) currently achieve fire extinguishing by inhibiting the combustion chain chemical reaction, and can quickly extinguish open flames. However, due to their small heat of vaporization and poor cooling ability, they cannot effectively inhibit re-ignition. Moreover, the coolant and fire extinguishing agent in the existing technology work through two sets of independent pipelines, resulting in a high system complexity, reduced reliability, and high operation and maintenance costs. In addition, lithium-ion batteries will experience self-discharge phenomena during storage, resulting in energy loss and energy storage time limitations, and cannot meet the grid's demand for long-term energy storage.

[0054] In an exemplary embodiment, as Figure 1 shown, an energy storage system coupling electrochemistry and compressed carbon dioxide includes:

[0055] A compressed carbon dioxide energy storage subsystem 10 and an electrochemical energy storage subsystem 20; the compressed carbon dioxide energy storage subsystem 10 includes a first liquid carbon dioxide storage tank 100 and a second liquid carbon dioxide storage tank 101; the electrochemical energy storage subsystem 20 includes a cooling subsystem 200 and an energy storage battery compartment 201 composed of battery packs;

[0056] The cooling subsystem 200 is respectively connected to the first liquid carbon dioxide storage tank 100 and the second liquid carbon dioxide storage tank 101.

[0057] Among them, the compressed carbon dioxide energy storage subsystem 10 is a subsystem for storing and releasing carbon dioxide energy, including a first liquid carbon dioxide storage tank 100 and a second liquid carbon dioxide storage tank 101, which are respectively used to store liquid carbon dioxide in different states to support the coordinated operation of the cooling and energy storage functions.

[0058] Among them, the electrochemical energy storage subsystem 20 is a system that realizes energy storage and release based on electrochemical reactions, mainly composed of a cooling subsystem 200 and an energy storage battery compartment 201. The cooling subsystem 200 is responsible for temperature management of the battery packs in the energy storage battery compartment 201 to ensure the stability and safety of system operation.

[0059] Exemplarily, the entire system connects the first liquid carbon dioxide storage tank 100 and the second liquid carbon dioxide storage tank 101 through the cooling subsystem 200, enabling the liquid carbon dioxide to circulate in the system to achieve cooling. When the battery temperature in the energy storage battery compartment 201 rises, the cooling subsystem 200 controls the flow rate of the liquid carbon dioxide, causing it to evaporate and absorb heat in the battery compartment, taking away the heat generated during the battery operation, thereby reducing the battery temperature and improving the thermal management efficiency.

[0060] In the energy storage mode, the electrochemical energy storage subsystem 200 stores electrical energy through battery pack charging, while the compressed carbon dioxide energy storage subsystem 10 maintains the liquid carbon dioxide stored at an appropriate pressure. When the battery discharges, the cooling subsystem 200 monitors the temperature change of the battery pack and adjusts the return flow rate of the first liquid carbon dioxide storage tank 100 and the supply amount of the second liquid carbon dioxide storage tank 101 according to the temperature requirement to maintain the battery pack within a stable temperature range.

[0061] The above-mentioned energy storage system coupling electrochemistry and compressed carbon dioxide includes a compressed carbon dioxide energy storage subsystem and an electrochemical energy storage subsystem. The compressed carbon dioxide energy storage subsystem includes a first liquid carbon dioxide storage tank and a second liquid carbon dioxide storage tank. The electrochemical energy storage subsystem includes a cooling subsystem and an energy storage battery compartment composed of battery packs. Among them, the cooling subsystem is respectively connected to the first liquid carbon dioxide storage tank and the second liquid carbon dioxide storage tank. The above system provides an efficient and safe battery temperature control solution by coupling the electrochemical energy storage and the compressed carbon dioxide energy storage system, overcoming the defects of low cooling efficiency, high system complexity, and easy volatilization or corrosion of metal components of traditional water cooling or ethylene glycol cooling systems. The system uses the first liquid carbon dioxide storage tank and the second liquid carbon dioxide storage tank and is connected to the battery pack through the cooling subsystem, enabling the low-temperature liquid carbon dioxide to be directly used for battery cooling. Relying on its phase change heat absorption characteristics, it quickly reduces the battery temperature and improves the cooling efficiency. At the same time, carbon dioxide, as a non-corrosive coolant, can reduce damage to equipment and avoid volatilization loss of the coolant. Compared with traditional independent cooling and fire extinguishing systems, the present invention reduces the system complexity through an integrated design, improves the reliability of operation and the convenience of maintenance, thereby significantly enhancing the safety of the electrochemical energy storage system in terms of temperature control. In addition, by coupling the compressed carbon dioxide energy storage subsystem, the energy storage capacity and energy storage duration of the electrochemical energy storage subsystem are improved, making its operating conditions more flexible and meeting the application requirements of the power grid for different energy storage scenarios.

[0062] In an exemplary embodiment, as Figure 2As shown, the above-mentioned compressed carbon dioxide energy storage subsystem 10 further includes a compression unit 102, a cooling unit 103, a liquefaction unit 104, a first heat storage medium storage tank 105, a second heat storage medium storage tank 106, a gasification unit 107, a heating unit 108, and an expansion unit 109;

[0063] The first liquid carbon dioxide storage tank 100 is also respectively connected to the compression unit 102 and the expansion unit 109;

[0064] The cooling unit 103 is respectively connected to the compression unit 102, the first heat storage medium storage tank 105, the second heat storage medium storage tank 106, and the liquefaction unit 104;

[0065] The second liquid carbon dioxide storage tank 101 is also respectively connected to the liquefaction unit 104 and the gasification unit 107;

[0066] The heating unit 108 is respectively connected to the gasification unit 107, the first heat storage medium storage tank 105, the second heat storage medium storage tank 106, and the expansion unit 109.

[0067] Exemplarily, the first liquid carbon dioxide storage tank 100 is respectively connected to the compression unit 102 and the expansion unit 109, and is used to store the liquid carbon dioxide in the system and provide a gas source to the compression unit 102 when needed to complete the cycle process. The cooling unit 103 is respectively connected to the compression unit 102, the first heat storage medium storage tank 105, the second heat storage medium storage tank 106, and the liquefaction unit 104 to form a complete thermal management system, and improves the overall energy efficiency by reasonably recovering and utilizing the waste heat of the system.

[0068] The second liquid carbon dioxide storage tank 101 is also respectively connected to the liquefaction unit 104 and the gasification unit 107 to ensure that the liquid carbon dioxide can be effectively managed under the energy storage demand and is converted into gaseous carbon dioxide during the energy release stage and enters the gasification unit 107 for gasification. Subsequently, the heating unit 108 is connected to the gasification unit 107, the first heat storage medium storage tank 105, the second heat storage medium storage tank 106, and the expansion unit 109 to provide additional heat for the gasified carbon dioxide and improve the efficiency of subsequent expansion work.

[0069] The carbon dioxide in the first liquid carbon dioxide storage tank 100 has a lower pressure than the carbon dioxide in the second liquid carbon dioxide storage tank 101. The heat storage medium in the first heat storage medium storage tank 105 has a lower temperature than the heat storage medium in the second heat storage medium storage tank 106.

[0070] During the energy storage stage, the carbon dioxide in the first liquid carbon dioxide storage tank 100 is output to the compression unit 102 for compression, then cooled by the cooling unit 103, and then the supercritical carbon dioxide is liquefied by the liquefaction unit 104 (condenser) and stored in the second liquid carbon dioxide storage tank 101. Among them, the heat generated during the compression process is absorbed by the low-temperature heat storage medium in the first heat storage medium storage tank 105, and the low-temperature heat storage medium becomes a high-temperature heat storage medium and is stored in the second heat storage medium storage tank 106.

[0071] During the energy release stage, the carbon dioxide in the second liquid carbon dioxide storage tank 101 is output to the gasification unit 107 (evaporator), converted into gaseous carbon dioxide, heated by the heating unit 108, and expanded by the expansion unit 109 to output electric energy externally. Among them, the cold generated during the expansion process is absorbed by the high-temperature heat storage medium in the second heat storage medium storage tank 106, and the high-temperature heat storage medium becomes a low-temperature heat storage medium and is stored in the first heat storage medium storage tank 105. Finally, the low-pressure carbon dioxide gas after doing work is liquefied and stored back in the first liquid carbon dioxide storage tank 100 to complete a thermodynamic cycle.

[0072] In this embodiment, through staged compression, cooling, and liquefaction, carbon dioxide can be efficiently converted under different pressure and temperature conditions, reducing energy loss and increasing the energy storage density. The first heat storage medium storage tank 105 and the second heat storage medium storage tank 106 are used to recover and reuse the heat and cold generated during the compression and expansion processes, improving the overall energy utilization efficiency of the system and reducing waste heat emissions. This method can not only provide high-power energy storage with short-term response but also support long-term energy storage requirements, and is suitable for various new energy scenarios, such as peak shaving and valley filling of wind energy and photovoltaic power generation and backup power supply requirements.

[0073] In an exemplary embodiment, as Figure 2 shown, the above-mentioned compression unit 102 includes a motor 1020, a first compressor 1021, and a second compressor 1022; the cooling unit 103 includes a first intercooler 1030 and a second intercooler 1031;

[0074] The motor 1020 is used to drive the first compressor 1021 and the second compressor 1022;

[0075] The carbon dioxide output port of the first compressor 1021 is connected to the carbon dioxide input port of the first intercooler 1030;

[0076] The carbon dioxide output port of the first intercooler 1030 is connected to the carbon dioxide input port of the second compressor 1022;

[0077] The carbon dioxide output port of the second compressor 1022 is connected to the carbon dioxide input port of the second intercooler 1031;

[0078] The carbon dioxide outlet of the second intercooler 1031 is connected to the carbon dioxide inlet of the liquefaction unit 104.

[0079] Exemplarily, the first compressor 1021 is responsible for initially compressing the low-pressure carbon dioxide, raising its pressure to a medium level, and discharging it to the first intercooler 1030 for temperature reduction. The second compressor 1022 further increases the pressure of the carbon dioxide to meet the requirements of the subsequent liquefaction process. Meanwhile, the heat generated during its compression process is cooled by the second intercooler 1031. The second intercooler 1031 is responsible for reducing the temperature of the high-pressure carbon dioxide, preventing the temperature from being too high and affecting the liquefaction efficiency, and reducing the heat dissipation loss of the system. The high-pressure carbon dioxide processed by the second intercooler 1031 enters the liquefaction unit 104 from its outlet to complete liquefied storage.

[0080] During the energy storage stage, the motor 1020 drives the first compressor 1021 and the second compressor 1022 to rotate, compresses the carbon dioxide in the first liquid carbon dioxide storage tank 100 in two stages, and performs inter-stage cooling through the first intercooler 1030 and the second intercooler 1031 to obtain supercritical carbon dioxide.

[0081] In this embodiment, through the two-stage compression method of the first compressor 1021 and the second compressor 1022, the carbon dioxide is gradually pressurized with lower power consumption, reducing the excessive temperature rise and energy loss caused by single-stage compression, and improving the overall efficiency of the system. The first intercooler 1030 and the second intercooler 1031 are used for staged cooling, so that the carbon dioxide reaches the optimal temperature and pressure before entering the liquefaction unit 104, ensuring the efficient progress of the liquefaction process and reducing the additional refrigeration energy consumption.

[0082] In an exemplary embodiment, as Figure 2 shown, the medium outlet of the above-mentioned first heat storage medium storage tank 105 is respectively connected to the medium inlet of the first intercooler 1030 and the medium inlet of the second intercooler 1031;

[0083] The medium inlet of the second heat storage medium storage tank 106 is respectively connected to the medium outlet of the first intercooler 1030 and the medium outlet of the second intercooler 1031.

[0084] Exemplarily, the first heat storage medium storage tank 105 and the second heat storage medium storage tank 106 form a heat exchange circuit with the first intercooler 1030 and the second intercooler 1031, so that the heat generated during the process of compressing carbon dioxide can be efficiently recovered and stored step by step, thereby improving the overall energy efficiency of the system and optimizing the utilization efficiency of the heat storage medium.

[0085] The first heat storage medium storage tank 105 stores a low-temperature heat storage medium, and its medium output ports are respectively connected to the medium input ports of the first intercooler 1030 and the second intercooler 1031. During the process of compressing carbon dioxide, the low-temperature heat storage medium enters the first intercooler 1030 and the second intercooler 1031, absorbs the heat released during the compression process, gradually increases in temperature, and is transformed into a high-temperature heat storage medium.

[0086] The second heat storage medium storage tank 106 is mainly used to store the high-temperature heat storage medium that has absorbed heat and increased in temperature. Its medium input ports are respectively connected to the medium output ports of the first intercooler 1030 and the second intercooler 1031, so that the heat storage medium that has increased in temperature during the cooling process can be efficiently recovered and stored for use in subsequent gasification and expansion work processes, ensuring the efficient energy conversion of the energy storage system.

[0087] During the process of compressing carbon dioxide, both the temperature and pressure will gradually increase. The low-temperature heat storage medium is output from the first heat storage medium storage tank 105 and enters the first intercooler 1030 and the second intercooler 1031 respectively to cool the carbon dioxide, while absorbing heat and increasing in temperature itself, and is gradually transformed into a high-temperature heat storage medium. The heated high-temperature heat storage medium flows into the second heat storage medium storage tank 106 for storage, providing a heat source for the subsequent energy release stage of the energy storage system.

[0088] In this embodiment, by storing the heat released during the compression stage and using it for gasification and expansion in the energy release stage, the thermal energy utilization rate of the energy storage system is improved, the additional heating demand is reduced, and the overall efficiency is increased. Through the first heat storage medium storage tank 105 and the second heat storage medium storage tank 106, the temperature of the heat storage medium is dynamically regulated to ensure the efficient transfer of heat and improve the thermal exchange stability. By recovering and recycling waste heat, the consumption of external energy is reduced, the operating cost is lowered, and the economy of the energy storage system is improved. The reasonable thermal energy management system avoids high-temperature accumulation, reduces the risk of system overheating, and at the same time improves the service life and operating reliability of the equipment through the stable circulation of the heat storage medium.

[0089] In an exemplary embodiment, as Figure 2 shown, the above-mentioned expansion unit 109 includes a first expander 1090, a second expander 1091 and a generator 1092; the heating unit 108 includes a first reheater 1080 and a second reheater 1081;

[0090] The first expander 1090 and the second expander 1091 are used to drive the generator 1092 to output electric energy;

[0091] The carbon dioxide output port of the gasification unit 107 is connected to the carbon dioxide input port of the first reheater 1080;

[0092] The carbon dioxide outlet of the first reheater 1080 is connected to the carbon dioxide inlet of the first expander 1090;

[0093] The carbon dioxide outlet of the first expander 1090 is connected to the carbon dioxide inlet of the second reheater 1081;

[0094] The carbon dioxide outlet of the second reheater 1081 is connected to the carbon dioxide inlet of the second expander 1091.

[0095] Exemplarily, the first expander 1090 and the second expander 1091 are connected in series in a cascaded manner for grading the expansion work process of carbon dioxide to ensure more uniform energy release of the gas, thereby optimizing the power generation efficiency and system stability. The gasification unit 107 is responsible for converting liquid carbon dioxide into gaseous carbon dioxide and outputting it to the first reheater 1080 for preliminary heating to a temperature suitable for entering the first expander 1090 for expansion work.

[0096] The first expander 1090 releases part of the pressure and temperature of carbon dioxide through expansion, drives the generator 1092 to output electric energy, and conveys the expanded carbon dioxide gas to the second reheater 1081 for secondary heating. At this time, since the carbon dioxide has completed partial expansion and the temperature has decreased, the second reheater 1081 further increases the temperature of the gas so that it can enter the second expander 1091 for secondary expansion to maximize energy release.

[0097] In this embodiment, through the two-stage expansion design of the first expander 1090 and the second expander 1091, carbon dioxide is graded and expanded at different pressure stages, improving the energy conversion efficiency of the generator 1092 and reducing the energy loss caused by single expansion. The first reheater 1080 and the second reheater 1081 are used for graded heating to ensure that the carbon dioxide always maintains a suitable temperature before expansion, avoiding the temperature drop problem caused by too fast expansion and improving the stability of system operation. The reheater recovers waste heat from the heat storage system instead of relying on additional energy input, thereby reducing the external heating demand and improving the economy of the entire energy storage system. The reasonable graded expansion and heating process helps to smoothly release the energy of high-pressure carbon dioxide, reduce the impact caused by instantaneous pressure changes, extend the service life of the equipment, and improve the long-term operation reliability of the system.

[0098] In an exemplary embodiment, as Figure 2 shown, the medium outlet of the second heat storage medium storage tank 106 is respectively connected to the medium inlet of the first reheater 1080 and the medium inlet of the second reheater 1081;

[0099] The medium input ports of the first heat storage medium storage tank 105 are respectively connected to the medium output ports of the first reheater 1080 and the second reheater 1081.

[0100] Exemplarily, the medium output ports of the second heat storage medium storage tank 106 are respectively connected to the medium input ports of the first reheater 1080 and the second reheater 1081, and are used to provide high-temperature heat storage medium as the main heat source for reheating carbon dioxide. During the expansion work process, the temperature of carbon dioxide gradually decreases. Therefore, it is necessary to heat it through a reheater, and the heat required for heating is provided by the second heat storage medium storage tank 106 to keep carbon dioxide at a relatively high temperature and ensure the efficient work of the expander.

[0101] The medium input ports of the first heat storage medium storage tank 105 are respectively connected to the medium output ports of the first reheater 1080 and the second reheater 1081, ensuring that during the heating process, the low-temperature heat storage medium that has released heat and decreased in temperature can be recovered and stored, so as to re-absorb heat during the subsequent carbon dioxide compression and cooling process and realize the closed-loop cycle of the heat storage medium.

[0102] Before the carbon dioxide expands to do work, the high-temperature heat storage medium from the second heat storage medium storage tank 106 is transported to the first reheater 1080 and the second reheater 1081 to heat the carbon dioxide before expansion, increase the temperature and pressure of the gas, and make it reach the optimal expansion state. The high-temperature carbon dioxide heated by the first reheater 1080 enters the first expander 1090, releases energy during the expansion process and drives the generator 1092 to output electric energy. Subsequently, the expanded carbon dioxide enters the second reheater 1081 for secondary heating to compensate for the temperature drop caused by expansion and provide heat energy support for entering the second expander 1091 for secondary expansion work. During the reheating process, the high-temperature heat storage medium provided by the second heat storage medium storage tank 106 releases heat and its temperature decreases, gradually converting into low-temperature heat storage medium. The cooled low-temperature heat storage medium flows out from the first reheater 1080 and the second reheater 1081 and flows into the first heat storage medium storage tank 105 for storage, so as to re-absorb heat during the next round of carbon dioxide compression and cooling process and realize the efficient recycling of the heat storage medium.

[0103] In this embodiment, the high-temperature heat storage medium provided by the second heat storage medium storage tank 106 is used to heat carbon dioxide, improving the expansion efficiency and making the energy release process of the energy storage system more stable and efficient. Through the heat transfer between the first heat storage medium storage tank 105 and the second heat storage medium storage tank 106, the high-temperature heat storage medium releases heat and is converted into a low-temperature heat storage medium, which then flows back to the first heat storage medium storage tank 105 for storage, improving the heat management efficiency. The reheating process mainly relies on the heat storage medium to provide heat rather than an additional external energy input, thus effectively reducing the heating energy consumption of the system and improving the economy of the system. A reasonable heat management system ensures that the expander operates within a stable temperature range, avoiding the influence of temperature fluctuations on the expander efficiency and improving the operation life and safety of the equipment.

[0104] In an exemplary embodiment, as Figure 2 shown, the above-mentioned compressed carbon dioxide energy storage subsystem 10 further includes a throttle valve 110 and a cold accumulator 111;

[0105] The carbon dioxide outlet of the first liquid carbon dioxide storage tank 100 is connected to the compression unit 102 through the cold accumulator 111;

[0106] The carbon dioxide outlet of the first liquid carbon dioxide storage tank 100 is connected to the cold accumulator 111 through the throttle valve 110;

[0107] The carbon dioxide inlet of the first liquid carbon dioxide storage tank 100 is connected to the expansion unit 109 through the cold accumulator 111.

[0108] Exemplarily, when the low-pressure liquid carbon dioxide in the first liquid carbon dioxide storage tank 100 flows towards the system, it first passes through the throttle valve 110 for pressure regulation, reducing its outlet pressure and thereby lowering the temperature of the carbon dioxide. This process utilizes the throttling effect (Joule-Thomson effect) to lower the temperature of the liquid carbon dioxide without additional heat exchange, thereby improving the cooling efficiency of the system. To make full use of the cold energy released during this cooling process, the cold accumulator 111 is used to store it, that is, the low-pressure liquid carbon dioxide released from the first liquid carbon dioxide storage tank 100, after being cooled by the throttle valve 110, releases the cold energy to the cold accumulator 111 for storage, which is used for the liquefaction of the carbon dioxide gas after the energy release of the expansion unit 109. That is, after the expansion work is completed, the carbon dioxide gas discharged from the expansion unit 109 is usually in a low-temperature and low-pressure state and needs to be further cooled and liquefied in order to re-enter the liquid carbon dioxide storage link. The cold accumulator 111 releases the stored cold energy to pre-cool the expanded carbon dioxide gas, reducing its temperature to reach the liquefaction condition and improving the efficiency of the liquefaction process. The cooled carbon dioxide gas is efficiently liquefied with lower energy consumption and finally flows back to the first liquid carbon dioxide storage tank 100 to complete the energy storage cycle.

[0109] In this embodiment, the carbon dioxide is precooled by the throttle valve 110, and the cold energy is stored by the cold accumulator 111, reducing the dependence on external cooling during the liquefaction process of carbon dioxide gas, thereby reducing additional refrigeration energy consumption and improving the liquefaction efficiency. The cold accumulator 111 recovers and stores cold energy and dynamically releases cold energy during the operation of the system, making the temperature management of the energy storage system more efficient, reducing the dependence on additional cooling equipment, and improving the system stability. By reasonably utilizing the cold energy during the throttling cooling process, the carbon dioxide gas discharged from the expansion unit 109 can be quickly liquefied under low energy consumption conditions, improving the recovery efficiency of carbon dioxide and reducing the system cycle loss. The internal cold energy cycle storage and reuse of the system reduce the demand for external refrigeration systems, thereby reducing the operating cost of the system and improving the overall economy.

[0110] In an exemplary embodiment, as Figure 3 shown, the above-mentioned cooling subsystem 200 includes a high-pressure pump 2001, a heat accumulator 2002, and a cooling pipeline;

[0111] The second liquid carbon dioxide storage tank 101 is connected to the cooling pipeline through the high-pressure pump 2001;

[0112] The first liquid carbon dioxide storage tank 100 is connected to the cooling pipeline through the heat accumulator 2002.

[0113] Exemplarily, the high-pressure pump 2001 is responsible for pumping liquid carbon dioxide from the second liquid carbon dioxide storage tank 101 and sending it into the cooling subsystem 200 through the cooling pipeline to achieve the thermal management of the battery compartment. This design enables carbon dioxide to enter the cooling circuit in a high-pressure state, improving the cooling efficiency and ensuring that the liquid carbon dioxide can maintain stable flow characteristics when flowing through the cooling subsystem 200. When the high-pressure liquid carbon dioxide flows through the interior of the battery compartment, it exchanges heat with the battery surface, absorbing the heat generated during the operation of the battery and keeping the battery temperature within a safe range.

[0114] The first liquid carbon dioxide storage tank 100 is connected to the cooling pipeline through the heat accumulator 2002 to optimize the heat exchange process of the cooling medium. In the cooling cycle, the liquid carbon dioxide that has cooled the battery takes away heat from the battery compartment, evaporates into gaseous carbon dioxide, and flows through the heat accumulator 2002, releasing part of the heat and liquefying during this process, enabling the heat storage system to effectively store the excess thermal energy and improving the overall thermal management efficiency of the system. The cooled liquid carbon dioxide returns to the first liquid carbon dioxide storage tank 100 through the pipeline to complete the cooling cycle, providing a cooling medium for the next energy storage cycle.

[0115] In this embodiment, liquid carbon dioxide is transported by the high-pressure pump 2001, enabling it to enter the cooling subsystem 200 at a high flow rate, improving the cooling efficiency and ensuring that the battery can maintain a stable temperature during high-power operation. The heat accumulator 2002 absorbs the heat released during the cooling process, enabling the cooling subsystem 200 to dynamically adjust the heat load, reduce temperature fluctuations, and improve the long-term stability of the system. The closed-loop cooling method is adopted to enable the recycling of carbon dioxide after heat exchange, reduce the loss of the cooling medium, and improve the economic efficiency of the system. By managing heat storage, the additional refrigeration demand is reduced, enabling the system to maintain efficient cooling under lower energy consumption conditions, reducing the overall operating cost, and improving the economic benefits.

[0116] In an exemplary embodiment, as Figure 3 shown, the above cooling pipeline includes an inlet pipeline 2003, an outlet pipeline 2004, a regulating valve 2005 provided on the inlet pipeline 2003, and a check valve 2006 provided on the outlet pipeline 2004.

[0117] Exemplarily, the inlet pipeline 2003 is responsible for transporting the low-temperature liquid carbon dioxide provided by the high-pressure pump 2001, enabling it to enter the cooling circuit and flow through the battery compartment for heat exchange. The regulating valve 2005 is provided on the inlet pipeline 2003 and is used to precisely control the carbon dioxide flow rate entering the battery compartment, ensuring that the cooling process can be dynamically adjusted according to the heat load demand of the battery and preventing overcooling or insufficient cooling.

[0118] The outlet pipeline 2004 is responsible for guiding the carbon dioxide that has completed the cooling cycle out of the battery compartment, transporting it to the heat accumulator 2002 for heat recovery treatment, and then returning it to the first liquid carbon dioxide storage tank 100 to complete the closed-loop cooling cycle. The check valve 2006 is provided on the outlet pipeline 2004 and is mainly used to prevent the reverse flow of the cooling medium, ensure the stable operation of the cooling subsystem 200, and avoid gas backflow or pressure fluctuations in the system, which may affect the cooling effect.

[0119] It should be noted that regulating valves 2005 are provided on the branches of the inlet pipeline 2003 leading to each battery pack; check valves 2006 are provided on the branches of each battery pack leading to the outlet pipeline 2004.

[0120] In this embodiment, the flow rate of carbon dioxide entering the battery compartment is controlled by the regulating valve 2005, enabling the cooling process to adapt to different power load conditions, achieving precise temperature regulation, and enhancing the adaptability of the cooling subsystem 200. The check valve 2006 ensures the unidirectional flow of the carbon dioxide cooling medium, preventing pressure fluctuations or coolant backflow, improving the stability of the cooling subsystem 200, and avoiding hydrodynamic interference from affecting the cooling effect. After absorbing heat, the carbon dioxide flows through the heat accumulator 2002, releases heat, and recovers it to the heat storage system, reducing the cooling energy consumption, enhancing the system's thermal energy utilization rate, and reducing the overall energy loss.

[0121] In an exemplary embodiment, as Figure 3 shown, the above-mentioned cooling subsystem 200 further includes a stop valve 2007; the cooling pipeline also leads to the inside of the energy storage battery compartment 201 through the stop valve 2007.

[0122] Exemplarily, the above-mentioned cooling subsystem 200 further includes a stop valve 2007, which is used to release carbon dioxide gas in case of thermal runaway or fire in the battery, playing a role in emergency fire extinguishing and temperature suppression to ensure the safety of the energy storage system.

[0123] The stop valve 2007 is installed on the pipeline inside the battery pack and is connected to the carbon dioxide cooling pipeline. When the battery temperature rises abnormally or even thermal runaway leads to a fire, the stop valve 2007 can be triggered automatically or manually, quickly releasing carbon dioxide into the inside of the energy storage battery compartment 201 for emergency fire extinguishing and temperature suppression.

[0124] When the temperature inside the battery pack exceeds the safety threshold, or when the monitoring system detects thermal runaway or fire, the stop valve 2007 is triggered (automatically controlled by a temperature sensor, a smoke sensor, or the system control logic). After the stop valve 2007 is opened, the carbon dioxide gas is quickly released from the cooling subsystem 200 and directly enters the inside of the energy storage battery compartment 201 along the pipeline, filling the battery compartment space. As a fire extinguishing medium, carbon dioxide first rapidly reduces the temperature inside the battery compartment through a cooling effect, preventing the spread of the fire. At the same time, since carbon dioxide can effectively isolate oxygen and inhibit the combustion reaction, it achieves the fire extinguishing effect. During the fire extinguishing process, carbon dioxide can be continuously released to ensure that the temperature inside the battery compartment drops rapidly and prevent the battery from reigniting. Since carbon dioxide is non-conductive and will not cause additional corrosive damage to the inside of the battery pack, compared with traditional fire extinguishing agents (such as water or foam fire extinguishing systems), this solution has less impact on the energy storage equipment, and the system can resume operation quickly after fire extinguishing.

[0125] In this embodiment, the shut-off valve 2007 automatically opens during a fire, quickly releases carbon dioxide for fire extinguishing, reduces the internal temperature of the battery compartment, effectively inhibits the combustion reaction, and reduces equipment damage and property losses. Carbon dioxide can not only extinguish fires, but also reduce the oxygen concentration, prevent re-ignition of the energy storage battery caused by residual internal heat or short circuit, and improve the fire safety level of the system. Compared with water-cooled or foam fire extinguishing systems, carbon dioxide fire extinguishing will not cause secondary damage to the battery or energy storage system, enabling the system to quickly resume operation after fire extinguishing, improving the maintainability and service life of the energy storage system. The shut-off valve 2007 can be linked with intelligent monitoring systems such as temperature sensors and smoke sensors to achieve automatic response, improve safety, and reduce the risk of manual intervention. At the same time, since the refrigeration medium and the fire extinguishing medium are both carbon dioxide, a set of pipeline systems can be shared without separate configuration, reducing complexity and control difficulty, and lowering the system operation and maintenance costs.

[0126] In an exemplary embodiment, the present application provides an operation method for an energy storage system that couples electrochemistry and compressed carbon dioxide, including:

[0127] In response to a first control instruction, controlling the operation of the electrochemical energy storage subsystem and the compression unit in the compressed carbon dioxide energy storage subsystem;

[0128] In response to a second control instruction, controlling the operation of the compressed carbon dioxide energy storage subsystem;

[0129] In response to a third control instruction, controlling the operation of the compressed carbon dioxide energy storage subsystem and the electrochemical energy storage subsystem.

[0130] Exemplarily, when power-type energy storage and short-term energy-type energy storage are required, a first control instruction is generated to enable the electrochemical energy storage system to operate alone, and only the compression unit of the compressed air energy storage system operates to provide high-pressure liquid carbon dioxide required for battery cooling. When the electrochemical energy storage subsystem is shut down for maintenance and long-term energy-type energy storage is required, a second control instruction is generated to enable the compressed air energy storage system to operate alone and the electrochemical energy storage system not to operate. When services such as peak shaving, valley filling, and auxiliary frequency modulation are required for the power system, a third control instruction is generated to enable the electrochemical energy storage subsystem and the compressed air energy storage subsystem to operate in a coupled manner, coordinate and cooperate, and jointly play the role of energy storage and release to effectively ensure the stability and reliability of the power system.

[0131] In this embodiment, it is possible to select single or coupled mode operation according to different requirements, which is applicable to various scenarios such as short-term, long-term energy storage and backup power supply. In the electrochemical energy storage mode, the compressed carbon dioxide energy storage system is used to provide cooling support to reduce the battery temperature and improve the system safety and battery life. When the electrochemical energy storage subsystem is shut down, the compressed carbon dioxide energy storage subsystem can operate independently to ensure that the energy storage function is not interrupted and improve the operation reliability of the system. By flexibly switching different operation modes, the energy storage system is prevented from operating in an inefficient state, thus enhancing the overall economy. Combining the advantages of fast response speed of electrochemical energy storage and long energy storage time of compressed carbon dioxide energy storage, it not only increases the total energy storage capacity of the system but also meets the different application requirements of the power grid for power-type and energy-type energy storage.

[0132] In the description of this specification, the descriptions referring to the terms "some embodiments", "other embodiments", 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 application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0133] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in the present application.

[0134] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. An energy storage system coupling electrochemistry and compressed carbon dioxide, characterized in that, The system includes: a compressed carbon dioxide energy storage subsystem and an electrochemical energy storage subsystem; the compressed carbon dioxide energy storage subsystem includes a first liquid carbon dioxide storage tank and a second liquid carbon dioxide storage tank; the electrochemical energy storage subsystem includes a cooling subsystem and an energy storage battery compartment composed of battery packs; The cooling subsystem is respectively connected to the first liquid carbon dioxide storage tank and the second liquid carbon dioxide storage tank.

2. The system according to claim 1, characterized in that The compressed carbon dioxide energy storage subsystem further includes a compression unit, a cooling unit, a liquefaction unit, a first heat storage medium storage tank, a second heat storage medium storage tank, a gasification unit, a heating unit and an expansion unit; The first liquid carbon dioxide storage tank is also respectively connected to the compression unit and the expansion unit; The cooling unit is respectively connected to the compression unit, the first heat storage medium storage tank, the second heat storage medium storage tank and the liquefaction unit; The second liquid carbon dioxide storage tank is also respectively connected to the liquefaction unit and the gasification unit; The heating unit is respectively connected to the gasification unit, the first heat storage medium storage tank, the second heat storage medium storage tank and the expansion unit.

3. The system according to claim 2, wherein The compression unit includes a motor, a first compressor and a second compressor; the cooling unit includes a first intercooler and a second intercooler; The motor is used to drive the first compressor and the second compressor; The carbon dioxide output port of the first compressor is connected to the carbon dioxide input port of the first intercooler; The carbon dioxide output port of the first intercooler is connected to the carbon dioxide input port of the second compressor; The carbon dioxide output port of the second compressor is connected to the carbon dioxide input port of the second intercooler; The carbon dioxide output port of the second intercooler is connected to the carbon dioxide input port of the liquefaction unit.

4. The system according to claim 3, wherein The medium output port of the first heat storage medium storage tank is respectively connected to the medium input port of the first intercooler and the medium input port of the second intercooler; The medium input port of the second heat storage medium storage tank is respectively connected to the medium output port of the first intercooler and the medium output port of the second intercooler.

5. The system according to claim 2, wherein The expansion unit includes a first expander, a second expander and a generator; the heating unit includes a first reheater and a second reheater; The first expander and the second expander are used to drive the generator to output electric energy; The carbon dioxide output port of the gasification unit is connected to the carbon dioxide input port of the first reheater; The carbon dioxide output port of the first reheater is connected to the carbon dioxide input port of the first expander; The carbon dioxide output port of the first expander is connected to the carbon dioxide input port of the second reheater; The carbon dioxide output port of the second reheater is connected to the carbon dioxide input port of the second expander.

6. The system according to claim 5, wherein The medium output port of the second heat storage medium storage tank is respectively connected to the medium input port of the first reheater and the medium input port of the second reheater; The medium input port of the first heat storage medium storage tank is respectively connected to the medium output port of the first reheater and the medium output port of the second reheater.

7. The system according to any one of claims 2 to 6, characterized in that The compressed carbon dioxide energy storage subsystem further includes a throttle valve and a cold accumulator; The carbon dioxide outlet of the first liquid carbon dioxide storage tank is connected to the compression unit through the cold accumulator; The carbon dioxide outlet of the first liquid carbon dioxide storage tank is connected to the cold accumulator through the throttle valve; The carbon dioxide inlet of the first liquid carbon dioxide storage tank is connected to the expansion unit through the cold accumulator.

8. The system according to claim 1, wherein The cooling subsystem includes a high-pressure pump, a heat accumulator, and a cooling pipeline; The second liquid carbon dioxide storage tank is connected to the cooling pipeline through the high-pressure pump; The first liquid carbon dioxide storage tank is connected to the cooling pipeline through the heat accumulator.

9. The system according to claim 8, wherein The cooling pipeline includes an inlet pipeline, an outlet pipeline, a regulating valve provided on the inlet pipeline, and a check valve provided on the outlet pipeline.

10. The system according to claim 8, characterized in that, The cooling subsystem further includes a stop valve; the cooling pipeline also leads to the inside of the energy storage battery compartment through the stop valve.

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