An electrochemical thermoelectric conversion method and device based on dynamic regulation of thermal responsive gel

Abstract

The present application relates to thermoelectrochemical thermoelectric technology field, concretely is a kind of electrochemical thermoelectric conversion method and device based on thermal response gel dynamic regulation, including TREC battery and the first regulating unit and the second regulating unit symmetrically arranged in TREC battery two sides, the regulating unit is by thermal response drive chamber, rigid porous isolation plate, buffer chamber and water molecule selective permeation membrane Composition.The thermal response drive chamber fills thermal response gel, the buffer chamber fills osmotic pressure buffer solution.The present application utilizes the reversible water absorption and drainage behavior of thermal response gel with temperature change, by changing the concentration of osmotic pressure buffer solution in buffer chamber, osmotic pressure difference with electrolyte in TREC battery is generated to drive water molecule directional migration, realizes passive, reversible regulation to TREC battery electrolyte concentration, makes concentration change and temperature change synergistic amplification net voltage output, without external energy input and additional operation.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric chemical thermoelectric power generation technology, specifically to an electrochemical thermoelectric conversion method and device based on dynamic regulation of thermally responsive gel. Background Technology

[0002] Against the backdrop of the global energy system's accelerated transition to a clean and low-carbon model, improving the comprehensive utilization efficiency of low-grade thermal energy has become a consensus. However, due to the difficulty and low efficiency of utilizing low-grade thermal energy, it has long remained underdeveloped, resulting in significant energy waste and environmental thermal pollution.

[0003] Thermal regenerative electrochemical cycle (TREC) technology, based on the temperature sensitivity of electrode potential, directly converts low-grade thermal energy into electrical energy through cyclic charging and discharging between high and low temperature conditions, and has attracted widespread attention in recent years. However, traditional TREC systems have limited thermoelectric potential output and low power generation in applications with small temperature differences. According to the Nernst equation, changing the electrolyte concentration can effectively regulate the electrode potential. Theoretically, if the concentration is adjusted in conjunction with temperature changes, it is expected to achieve higher electrical energy output than simply driving the process through temperature difference.

[0004] Existing methods for regulating electrolyte concentration all require additional operational steps and energy consumption, making it difficult to achieve synchronization and passive synergy with the thermal cycling process of TREC batteries. Although thermoresponsive gel materials have been proven to passively and reversibly absorb / drain water with temperature changes, current technologies mainly use them as (quasi)solid electrolytes rather than for regulating the concentration of liquid electrolytes. If thermoresponsive gel materials are directly mixed with electrolytes to change the concentration, it is easy to cause gel adsorption of active substances, breakage and shedding to block electrodes, and contamination of the electrolyte system, making it difficult to meet the requirements for long-term cycling stability. To address this, we propose an electrochemical thermoelectric conversion method and device based on the dynamic regulation of thermoresponsive gels. Summary of the Invention

[0005] The purpose of this invention is to provide an electrochemical thermoelectric conversion method and device based on dynamic regulation of thermally responsive gel, in order to solve the problems mentioned in the background art. Existing methods for regulating electrolyte concentration all require additional operating steps and energy consumption, making it difficult to achieve synchronization and passive coordination with the thermal cycling process of TREC batteries. Directly mixing thermally responsive gel materials with electrolyte to change concentration can easily cause gel adsorption of active substances, breakage and shedding to block electrodes, and contamination of the electrolyte system, making it difficult to meet the requirements of long-term cycling stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an electrochemical thermoelectric conversion device based on dynamic regulation of thermally responsive gel, comprising a TREC battery and a first regulation unit and a second regulation unit symmetrically arranged on both sides of the TREC battery. The first regulation unit and the second regulation unit are respectively connected to the positive electrolyte chamber and the negative electrolyte chamber of the TREC battery. The positive electrolyte chamber and the negative electrolyte chamber are respectively provided with positive electrolyte and negative electrolyte. The first regulation unit and the second regulation unit are respectively used to regulate the concentration of the positive electrolyte and the concentration of the negative electrolyte of the TREC battery. Both the first control unit and the second control unit include a thermal response driving chamber. A buffer chamber is provided between the thermal response driving chamber and the TREC battery. The thermal response driving chamber and the buffer chamber, as well as the buffer chamber and the TREC battery, are separated by a rigid porous separator and a water molecule selectively permeable membrane, respectively. The interiors of the thermal response driving chamber and the buffer chamber are respectively filled with thermal response gel and osmotic pressure buffer. The thermally responsive gel has a critical dissolution temperature. When the operating temperature of the TREC battery is higher than the critical dissolution temperature, the thermally responsive gel undergoes either reversible water absorption or water drainage behavior, causing a corresponding change in the concentration of the osmotic pressure buffer. The two buffer chambers generate an osmotic pressure difference with the positive and negative electrolytes of the TREC battery through the change in the concentration of the osmotic pressure buffer. This osmotic pressure difference drives the directional migration of water molecules through the water molecule selective permeation membrane, thereby dynamically adjusting the concentrations of the positive and negative electrolytes of the TREC battery.

[0007] Preferably, the osmotic pressure of the osmotic buffer solution is initially in equilibrium with the osmotic pressure of the positive and negative electrolytes in the TREC battery. The initial operating temperature of the electrochemical thermoelectric conversion device is set to the average of the high-temperature and low-temperature operating temperatures of the TREC battery, and the osmotic pressure difference across the TREC battery is zero in the initial state. Preferably, the thermal response driving chamber is a rigid container, the buffer chamber is a sealed cavity, and the thermal response gel can be replaced by an adsorbent. The adsorbent is a moisture adsorption-thermal desorption type, and the regeneration temperature of the adsorbent corresponds to the critical dissolution temperature of the thermal response gel. The adsorbent includes, but is not limited to, any one of metal-organic framework materials, inorganic hygroscopic materials, and organic composite hygroscopic materials. Both the critical dissolution temperature of the thermal response gel and the regeneration temperature of the adsorbent are located between the high-temperature and low-temperature operating temperatures of the TREC battery.

[0008] Preferably, the thermally responsive gel is a thermally responsive hydrogel, which has one of the following characteristics: a low critical dissolution temperature (LCT) and a high critical dissolution temperature (HCT). The LCT exhibits water absorption swelling and water drainage shrinkage at temperatures below and above the LCT, respectively. The HCT exhibits water drainage shrinkage and water absorption swelling at temperatures below and above the HCT, respectively. The thermally responsive hydrogel can be conventionally modified by adjusting the critical dissolution temperature using one of the following methods: chemical grafting, copolymerization, doping, and crosslinking degree control, and is suitable for low-grade thermal energy applications with multiple temperature ranges.

[0009] Preferably, when the TREC battery is a membrane-free system and has the same positive and negative electrode control requirements, the two thermally responsive gels are set to the same type; when the TREC battery is a membrane-based system and has opposite positive and negative electrode control requirements, the two thermally responsive gels are set to LCST type and UCST type, respectively. The water absorption and drainage behavior of the thermally responsive gel, in conjunction with the temperature change direction of the TREC battery, affects the electrode potentials of the positive and negative electrodes. The change in the concentration of the positive and negative electrolytes causes the voltage change of the TREC battery to be in the same direction as the thermoelectric potential of the temperature change, thus achieving amplified output of the net voltage.

[0010] Preferably, the outer surface of the rigid porous separator is provided with densely packed small pores, which are used to provide channels for water molecule migration in the thermally responsive gel and the osmotic pressure buffer. The water molecule selectively permeable membrane is a two-dimensional material membrane with sub-nanometer pore size. The effective pore size of the water molecule selectively permeable membrane is between the diameter of water molecules and the diameter of hydrated ions. The water molecule selectively permeable membrane satisfies the transmembrane transport of water molecules and retains hydrated cations and hydrated anions in the solutions on both sides.

[0011] Preferably, the TREC battery has two high-position electrodes installed inside. The two high-position electrodes are respectively the positive electrode and the negative electrode and are disposed in the upper part of the positive electrode electrolyte chamber and the negative electrode electrolyte chamber. There are installation gaps between the two high-position electrodes and the water molecule selective permeable membrane, the bottom of the positive electrode electrolyte chamber and the negative electrode electrolyte chamber. The installation gaps are used to avoid the high-position electrodes blocking the water molecule permeation equilibrium process and to allow the trace bubbles generated in the electrochemical reaction to float up and be discharged naturally.

[0012] A method for controlling an electrochemical thermoelectric conversion device based on dynamic regulation of a thermally responsive gel includes the following steps: S1: Set the initial operating temperature of the electrochemical thermoelectric conversion device to an intermediate temperature T0 between the high-temperature operating temperature and the low-temperature operating temperature. Prepare the osmotic pressure buffer and balance its osmotic pressure at the intermediate temperature T0 with the osmotic pressure of the positive and negative electrolytes of the TREC battery. S2: When the TREC cell is above the critical dissolution temperature T of the thermally responsive gel a High temperature operating conditions T H During operation, the thermally responsive gel undergoes either water drainage or water absorption, altering the concentration of the osmotic buffer and driving the directional migration of water molecules until a new equilibrium is reached in the osmotic pressure across the membrane where water molecules selectively permeate. This allows for the adjustment of the electrolyte concentration, and subsequently, discharge and charge operations are performed based on the temperature coefficient of the redox pair. S3: When the TREC cell is below the critical dissolution temperature T of the thermally responsive gel a Low temperature operating conditions T L When the thermo-responsive gel is in operation, it exhibits either the opposite water absorption or water drainage behavior and changes the concentration of the osmotic pressure buffer, thereby driving water molecules to migrate in the opposite direction until the osmotic pressure on both sides of the selective permeation membrane by water molecules reaches a new equilibrium, thereby adjusting the electrolyte concentration. Then, it performs the charge and discharge operation opposite to that under high temperature conditions. S4: Restore the TREC battery to the intermediate temperature T0, and the electrochemical thermoelectric conversion device returns to the initial equilibrium state. Repeat the continuous thermoelectric conversion operation of the TREC battery under high temperature and low temperature conditions.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes the temperature response characteristics of the thermally responsive gel itself to automatically complete the reversible change of electrolyte concentration when the TREC battery switches between high and low temperature conditions. No external pumps, heaters or manual intervention are required. It achieves passive synergy between concentration regulation and temperature change, which significantly reduces the system's energy consumption and operational complexity. Moreover, through the synergistic effect of temperature change and concentration change, it breaks through the limitation of traditional TREC systems that rely solely on the temperature coefficient of the electrode itself, and obtains higher net voltage output under the same temperature difference conditions, thereby improving power generation efficiency. 2. This invention isolates the thermally responsive gel from the electrolyte, avoiding adsorption, clogging, and contamination that can occur when the gels are directly mixed. Furthermore, the intermediate isolation design of the buffer chamber further prevents the selective permeation of the TREC battery electrolyte and water molecules from being directly affected by changes in the volume of the thermally responsive gel. This results in high long-term system stability. Independent control units are set on both sides of the TREC battery, allowing for separate control of the positive and negative electrode electrolyte concentrations by flexibly selecting either LCST or UCST type thermally responsive gels, thus adapting to different application requirements. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a diagram illustrating an embodiment of the device for dynamically controlling KI / KI3-K3 / 4Fe(CN)6 full cells based on LCST-type thermoresponsive gel according to the present invention. Figure 3 This is a diagram illustrating an embodiment of the device for dynamically controlling Cu / Cu(NO3)2-CuHCF / KNO3 full cells based on LCST-type and UCST-type thermally responsive gels according to the present invention. Figure 4 This is a flowchart illustrating the control process of the electrochemical thermoelectric conversion device of the present invention; Figure 5 This is a flowchart of the electrochemical thermoelectric conversion method of the present invention.

[0015] In the figure: 1. Thermal response drive chamber; 2. Thermal response gel; 3. Rigid porous separator; 4. Buffer chamber; 5. Osmotic pressure buffer; 6. Water molecule selective permeation membrane; 7. TREC cell; 8. High-position electrode. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] Please see Figures 1 to 3 The present invention provides three embodiments: Example 1: An electrochemical thermoelectric conversion device based on dynamic regulation of thermally responsive gel, comprising a TREC cell 7 and a first regulation unit and a second regulation unit symmetrically arranged on both sides of the TREC cell 7. Both the first and second regulation units include a thermally responsive driving chamber 1. A buffer chamber 4 is provided between the thermally responsive driving chamber 1 and the TREC cell 7. The thermally responsive driving chamber 1 is a rigid container, and the buffer chamber 4 is a sealed cavity. The thermally responsive driving chamber 1 and the buffer chamber 4, as well as the buffer chamber 4 and the TREC cell 7, are respectively connected through a rigid porous separator 3 and a water molecule selectively permeable membrane 6. The interior of the thermally responsive driving chamber 1 and the buffer chamber 4 are respectively filled with thermally responsive gel 2 and osmotic buffer solution 5. The outer surface of the rigid porous isolation plate 3 is provided with dense small pores, which are used to provide channels for the migration of water molecules in the thermally responsive gel 2 and the osmotic buffer solution 5. The water molecule selective permeable membrane 6 is a two-dimensional material membrane with sub-nanometer pore size. The effective pore size of the water molecule selective permeable membrane 6 is between the diameter of water molecules and the diameter of hydrated ions. The water molecule selective permeable membrane 6 satisfies the transmembrane transport of water molecules and retains hydrated cations and hydrated anions in the solutions on both sides. The TREC battery 7 has two high-level electrodes 8 installed inside. The two high-level electrodes 8 are the positive electrode and the negative electrode, respectively, and are located at the top of the positive electrode electrolyte chamber and the negative electrode electrolyte chamber. There are installation gaps between the two high-level electrodes 8 and the water molecule selective permeable membrane 6, the bottom of the positive electrode electrolyte chamber and the negative electrode electrolyte chamber. The installation gaps are used to prevent the high-level electrodes 8 from blocking the permeation balance of water molecules and to allow the trace bubbles generated in the electrochemical reaction to rise and be discharged naturally.

[0018] Furthermore, the first control unit and the second control unit are respectively connected to the positive electrolyte chamber and the negative electrolyte chamber of the TREC battery 7. The positive electrolyte chamber and the negative electrolyte chamber are respectively provided with positive electrolyte and negative electrolyte. The first control unit and the second control unit are respectively used to control the concentration of positive electrolyte and negative electrolyte of TREC battery 7. The thermally responsive gel 2 has a critical dissolution temperature. When the operating temperature of the TREC battery 7 is higher than the critical dissolution temperature, the thermally responsive gel 2 undergoes either reversible water absorption or water drainage behavior, causing a corresponding change in the concentration of the osmotic pressure buffer 5. The two buffer chambers 4 generate an osmotic pressure difference with the positive and negative electrolytes of the TREC battery 7 through the change in the concentration of the osmotic pressure buffer 5. The osmotic pressure difference drives the water molecules to migrate in a directional manner through the water molecule selective permeation membrane 6, so as to dynamically adjust the concentration of the positive and negative electrolytes of the TREC battery 7. In the initial state, the osmotic pressure of the osmotic pressure buffer 5 is in equilibrium with the osmotic pressure of the positive and negative electrolytes in the TREC battery 7. The initial operating temperature of the electrochemical thermoelectric conversion device is set to the average of the high-temperature operating temperature and the low-temperature operating temperature of the TREC battery 7. The osmotic pressure difference between the two sides of the TREC battery 7 is zero in the initial state. When the TREC battery 7 is a membrane-free system and one of the positive and negative electrode control requirements is the same, the two thermally responsive gels 2 are set to the same type. When the TREC battery 7 is a membrane-based system and the positive and negative electrode control requirements are opposite, the two thermally responsive gels 2 are set to LCST type and UCST type respectively. The water absorption and drainage behavior of the thermally responsive gel 2, one of them, works in conjunction with the temperature change direction of the TREC battery 7 to affect the electrode potential of the positive and negative electrodes. The change in the concentration of the positive and negative electrolytes causes the voltage change of the TREC battery 7 to be in the same direction as the thermoelectric potential of the temperature change, thus realizing the amplification of the net voltage output.

[0019] Among them, thermally responsive gel 2 can be replaced by an adsorbent. The adsorbent is of the water adsorption-thermal desorption type. The regeneration temperature of the adsorbent corresponds to the critical dissolution temperature of thermally responsive gel 2. The adsorbent includes, but is not limited to, any one of metal-organic framework materials, inorganic hygroscopic materials and organic composite hygroscopic materials. The critical dissolution temperature of thermally responsive gel 2 and the regeneration temperature of the adsorbent are both located between the high temperature and low temperature operating temperature of TREC battery 7. Thermoresponsive gel 2 is a thermoresponsive hydrogel. Thermoresponsive hydrogel has one of the following characteristics: low critical dissolution temperature and high critical dissolution temperature. Thermoresponsive hydrogel with low critical dissolution temperature exhibits water absorption swelling and water drainage shrinkage at temperatures below and above the low critical dissolution temperature, respectively. Thermoresponsive hydrogel with high critical dissolution temperature exhibits water drainage shrinkage and water absorption swelling at temperatures below and above the high critical dissolution temperature, respectively. Thermoresponsive hydrogel can be conventionally modified by adjusting the critical dissolution temperature through one of the following methods: chemical grafting, copolymerization, doping, and crosslinking degree control, and is suitable for low-grade thermal energy application scenarios with multiple temperature ranges.

[0020] Please see Figure 4 A method for controlling an electrochemical thermoelectric conversion device based on dynamic regulation of a thermally responsive gel includes the following steps: S1: Set the initial operating temperature of the electrochemical thermoelectric conversion device to the intermediate temperature T0 between the high temperature and the low temperature, prepare the osmotic pressure buffer 5 and balance its osmotic pressure at the intermediate temperature T0 with the osmotic pressure of the positive and negative electrolytes of the TREC battery 7. S2: When TREC battery 7 is above the critical dissolution temperature T of the thermally responsive gel a High temperature operating conditions T H When the working state is reversed, the thermally responsive gel 2 undergoes either water drainage or water absorption and changes the concentration of the osmotic buffer 5, thereby driving the directional migration of water molecules until the osmotic pressure on both sides of the selectively permeable membrane 6 reaches a new equilibrium, thereby adjusting the electrolyte concentration. Then, discharge and charge operations are performed according to the temperature coefficient of the redox pair. S3: When TREC battery 7 is below the critical dissolution temperature T of the thermally responsive gel a Low temperature operating conditions T L When working, the thermally responsive gel 2 exhibits either the opposite water absorption or water drainage behavior and changes the concentration of the osmotic pressure buffer 5, thereby driving water molecules to migrate in the opposite direction until the osmotic pressure on both sides of the water molecule selectively permeates the membrane 6 and reaches a new equilibrium, thereby adjusting the electrolyte concentration. Then, it performs the charge and discharge operation opposite to the high-temperature condition. S4: Restore TREC battery 7 to the intermediate temperature T0, and the electrochemical thermoelectric conversion device returns to the initial equilibrium state. Repeat the continuous thermoelectric conversion operation of TREC battery 7 under high temperature and low temperature conditions.

[0021] Please see Figure 5 An electrochemical thermoelectric conversion method based on dynamic regulation of thermally responsive gels includes the following steps: A1: System initialization, prepare the electrolyte for TREC battery 7 and fill it into the electrolyte chamber. Record the initial liquid level height through the transparent observation window and scale on the side wall of the electrolyte chamber. Then determine the intermediate temperature T0. Prepare the osmotic pressure buffer 5 and fill it into the buffer chamber 4. Put the thermal response gel 2 into the thermal response drive chamber 1. Ensure that the thermal response drive chamber 1 is in liquid communication with the buffer chamber 4 through the rigid porous isolation plate 3. Check the integrity and sealing status of the water molecule selective permeation membrane 6 and confirm that there is no leakage at each connection. A2: Regulation under high-temperature conditions, when TREC battery 7 is under high-temperature conditions T H When working, if the thermally responsive gel 2 is of the LCST type, it exhibits chain extension and water absorption swelling behavior at low temperatures; if the thermally responsive gel 2 is of the UCST type, it exhibits chain curling and drainage shrinkage behavior at low temperatures. If the thermally responsive gel 2 is of the LCST type, it undergoes chain extension and water absorption swelling at low temperatures. It absorbs water from the buffer chamber 4 through the rigid porous separator 3. The osmotic pressure buffer 5 in the buffer chamber 4 is concentrated, and the osmotic pressure rises, exceeding the osmotic pressure of the electrolyte in the TREC battery 7. Driven by the osmotic pressure difference, water molecules migrate directionally from the electrolyte chamber of the TREC battery 7 to the buffer chamber 4 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium, ultimately achieving an increase in electrolyte concentration. If a water adsorption-thermal desorption type adsorbent is used, the adsorbent adsorbs water when the temperature is lower than the regeneration temperature, effectively achieving the gel water absorption effect. If the thermally responsive gel 2 is of the UCST type, it will undergo chain coiling and drainage shrinkage behavior at low temperature, and drain the pure water stored inside the gel into the buffer chamber 4 through the rigid porous isolation plate 3. The osmotic pressure buffer 5 in the buffer chamber 4 will be diluted, and the osmotic pressure will drop, which will be lower than the osmotic pressure of the electrolyte in the TREC battery 7. Driven by the osmotic pressure difference, water molecules will migrate directionally from the buffer chamber 4 to the electrolyte chamber of the TREC battery 7 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium, and finally the electrolyte concentration will be reduced. If the thermally responsive gel 2 is of the LCST type, it undergoes chain coiling and drainage shrinkage behavior at high temperature, draining the pure water stored inside the gel into the buffer chamber 4 through the rigid porous isolation plate 3. The osmotic pressure buffer 5 in the buffer chamber 4 is diluted, and the osmotic pressure decreases, falling below the osmotic pressure of the electrolyte in the TREC battery 7. Driven by the osmotic pressure difference, water molecules migrate directionally from the buffer chamber 4 to the electrolyte chamber of the TREC battery 7 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium, ultimately achieving a reduction in electrolyte concentration. If a water adsorption-thermal desorption adsorbent is used, the adsorbent completes water desorption, effectively achieving the gel drainage effect. If the thermally responsive gel 2 is of the UCST type, it will exhibit chain extension and water absorption swelling behavior at high temperature. It will absorb water from the buffer chamber 4 through the rigid porous isolation plate 3. The osmotic pressure buffer 5 in the buffer chamber 4 will be concentrated, and the osmotic pressure will rise, which will be higher than the osmotic pressure of the electrolyte in the TREC battery 7. Driven by the osmotic pressure difference, water molecules will migrate directionally from the electrolyte chamber of the TREC battery 7 to the buffer chamber 4 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium, and finally the electrolyte concentration will be increased. A3: Under high-temperature conditions, after a new osmotic equilibrium is established, the electrolyte stabilizes at a new concentration value. At this time, the direction of concentration change is the same as the direction of thermoelectric potential caused by temperature change, thus amplifying the effective voltage. The charging and discharging operation is performed according to the temperature coefficient sign of the redox pair used in TREC battery 7. When the temperature coefficient is positive, it discharges under high-temperature conditions and outputs electrical energy through the external circuit. When the temperature coefficient is negative, it charges under high-temperature conditions and stores chemical energy. A4: Regulation under low-temperature conditions, when TREC battery 7 is under low-temperature condition T L When working, depending on the type of thermally responsive gel 2, its water absorption and drainage behaviors are opposite; A5: Under low-temperature conditions, after the electrolyte concentration stabilizes at a new value, the charging and discharging operation is reversed compared to that under high-temperature conditions, based on the sign of the temperature coefficient. When the temperature coefficient is positive, charging occurs under low-temperature conditions; when the temperature coefficient is negative, discharging occurs under low-temperature conditions, outputting electrical energy to the external circuit. A6: System recovery. After the charging and discharging operations under high and low temperature conditions are completed, the TREC battery 7 is restored to the intermediate temperature T0. The temperature of the thermal response drive chamber 1 is restored accordingly. The thermal response gel 2 gradually returns to its initial state during the temperature recovery process. The concentration of the osmotic pressure buffer 5 is restored to a state of equilibrium with the electrolyte osmotic pressure. Finally, the system returns to its initial state. The above steps A2 to A5 can be repeated for continuous thermoelectric conversion.

[0022] Please see Figure 2 Example 2: Dynamic regulation of thermoelectric conversion in KI / KI3-K3 / 4Fe(CN)6 full cells based on LCST-type thermoresponsive gel.

[0023] Battery system composition: TREC battery 7 is a KI / KI3-K3 / 4Fe(CN)6 full cell with a positive temperature coefficient. An ion exchange membrane is set between the positive and negative electrode chambers of TREC battery 7. The positive electrode uses a KI / KI3 redox couple and the positive electrode electrolyte is a mixed aqueous solution of KI and KI3. The negative electrode uses a K3 / 4Fe(CN)6 redox couple and the negative electrode electrolyte is a mixed aqueous solution of K3Fe(CN)6 and K4Fe(CN)6.

[0024] Control unit setup: A first control unit is set on the KI / KI3 redox pair side, and a second control unit is set on the K3 / 4Fe(CN)6 redox pair side. Both the first and second control units use LCST type thermoresponsive gel, specifically poly(N-isopropylacrylamide) hydrogel 2. The buffer chamber 4 is filled with a certain concentration of KNO3 solution as an osmotic pressure buffer 5.

[0025] Concentration-potential response: The electrode potential of the KI / KI3 couple decreases with increasing concentration; the electrode potential of the K3 / 4Fe(CN)6 couple increases with increasing concentration. Since the temperature coefficient of the KI / KI3-K3 / 4Fe(CN)6 full cell is positive, its operating mode is high-temperature discharge and low-temperature charging.

[0026] In summary, to achieve the goal of outputting more electrical energy during discharge, it is necessary to increase the full battery voltage under high-temperature conditions. Therefore, the control targets are: lowering the concentration of KI / KI3 at the positive electrode and lowering the concentration of K3 / 4Fe(CN)6 at the negative electrode. To achieve the goal of consuming less electrical energy during charging, it is necessary to reduce the full battery voltage under low-temperature conditions. Therefore, the control targets are: increasing the concentration of KI / KI3 at the positive electrode and increasing the concentration of K3 / 4Fe(CN)6 at the negative electrode.

[0027] Detailed operating procedures: B1: Concentration control under high temperature conditions. When the temperature of TREC battery 7 is higher than the critical dissolution temperature of PNIPAM hydrogel, the PNIPAM hydrogel in the first control unit and the second control unit simultaneously change from an expanded state to a contracted state. During the gel contraction process, the water stored inside is discharged into the buffer chamber 4 through the rigid porous isolation plate 3, which dilutes the KNO3 osmotic pressure buffer 5 in the buffer chamber 4, causing its osmotic pressure to drop and become lower than the osmotic pressure of the positive electrode KI / KI3 electrolyte and the negative electrode K3 / 4Fe(CN)6 electrolyte. Driven by the new osmotic pressure difference, water molecules migrate directionally from the buffer chamber 4 to the electrolyte chamber of the TREC battery 7 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium. This process reduces the concentration of the positive electrode KI / KI3 electrolyte and the negative electrode K3 / 4Fe(CN)6 electrolyte, ultimately leading to an increase in the positive electrode potential and a decrease in the negative electrode potential, thus increasing the overall battery voltage. B2: Performs discharge operation under high temperature conditions. The KI / KI3-K3 / 4Fe(CN)6 full cell has a higher voltage at high temperature and performs discharge operation to output more electrical energy through the external circuit. B3: Concentration control under low temperature conditions. When the temperature of TREC battery 7 is lower than the critical dissolution temperature of PNIPAM hydrogel, the PNIPAM hydrogel in the first control unit and the second control unit simultaneously change from a contracted state to an expanded state. During the gel expansion process, water is absorbed from the buffer chamber 4 through the rigid porous isolation plate 3, causing the osmotic pressure of KNO3 osmotic buffer 5 in the buffer chamber 4 to rise, which is higher than the osmotic pressure of the positive electrode KI / KI3 electrolyte and the negative electrode K3 / 4Fe(CN)6 electrolyte. Driven by the new osmotic pressure difference, water molecules migrate directionally from the electrolyte chamber of the TREC battery 7 to the buffer chamber 4 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium. This process increases the concentration of both the positive electrode KI / KI3 electrolyte and the negative electrode K3 / 4Fe(CN)6 electrolyte. The increased concentration leads to a decrease in the positive electrode potential and an increase in the negative electrode potential, thus reducing the overall battery voltage. B4: Under low-temperature conditions, the KI / KI3-K3 / 4Fe(CN)6 full cell has a low voltage at low temperatures. It performs a charging operation to consume electrical energy to restore the electrolyte to its initial state and store chemical energy for the next round of high-temperature discharge.

[0028] Please see Figure 3 Example 3: Dynamic regulation of thermoelectric conversion in Cu-CuHCF full cells based on LCST-type and UCST-type thermoresponsive gels.

[0029] Battery system composition: TREC battery 7 is a Cu-CuHCF full cell with a negative temperature coefficient. The positive and negative electrode chambers of TREC battery 7 are separated by an ion exchange membrane. The positive electrode uses a CuHCF / KNO3 redox couple and the positive electrode electrolyte is an aqueous solution of KNO3. The negative electrode uses a Cu / Cu(NO3)2 redox couple and the negative electrode electrolyte is an aqueous solution of Cu(NO3)2.

[0030] Control unit setup: A first control unit is set on the CuHCF / KNO3 redox couple side, and a second control unit is set on the Cu / Cu(NO3)2 redox couple side. The first control unit adopts LCST type thermal responsive gel, specifically poly(N-isopropylacrylamide) hydrogel, and the second control unit adopts UCST type thermal responsive gel, specifically polyacrylamide (PNAGA) hydrogel. The buffer chamber 4 of each control unit is filled with a certain concentration of KNO3 solution as osmotic pressure buffer 5.

[0031] Concentration-potential response relationship and regulation target: The electrode potentials of both the Cu / Cu(NO3)2 couple and the CuHCF / KNO3 couple increase with increasing concentration. Since the temperature coefficient of the Cu-CuHCF full cell is negative, its operating mode is high-temperature charging and low-temperature discharging.

[0032] In summary, based on the aforementioned potential response characteristics, to reduce charging energy consumption during high-temperature charging, the full battery voltage needs to be reduced under high-temperature conditions. The control target is to lower the concentration of the positive electrode electrolyte and increase the concentration of the negative electrode electrolyte. To output more electrical energy during low-temperature discharge, the full battery voltage needs to be increased under low-temperature conditions. The control target is to increase the concentration of the positive electrode electrolyte and decrease the concentration of the negative electrode electrolyte.

[0033] Detailed operating procedures: C1: Concentration control under high temperature conditions. When the temperature of TREC battery 7 is higher than the critical dissolution temperature of PNIPAM hydrogel and PNAGA hydrogel, the PNIPAM gel in the first control unit on the positive electrode side changes from an expanded state to a contracted state, and discharges the water stored inside into the buffer chamber 4 through the rigid porous separator 3, diluting the KNO3 osmotic pressure buffer 5 in the buffer chamber 4, causing its osmotic pressure to drop and become lower than the osmotic pressure of the positive electrode KNO3 electrolyte. The PNAGA gel in the second control unit on the negative electrode side changes from a contracted state to an expanded state, and absorbs water from the buffer chamber 4 through the rigid porous separator 3, causing the KNO3 osmotic pressure buffer 5 in the buffer chamber 4 to be concentrated, and the osmotic pressure to rise and become higher than the osmotic pressure of the negative electrode Cu(NO3)2 electrolyte. Driven by the new osmotic pressure difference, water molecules on the positive electrode side migrate directionally from the buffer chamber 4 to the positive electrode electrolyte chamber through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium. This process lowers the concentration of KNO3 electrolyte at the positive electrode. Water molecules on the negative electrode side migrate directionally from the negative electrode electrolyte chamber to the buffer chamber 4 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium. This process raises the concentration of Cu(NO3)2 electrolyte at the negative electrode, ultimately leading to a decrease in the positive electrode potential and an increase in the negative electrode potential, thus reducing the overall cell voltage. C2: Performs charging operation under high temperature conditions. The voltage of Cu-CuHCF full cell is lower at high temperatures, so it performs charging operation and consumes less energy. C3: Concentration control under low temperature conditions. When the temperature of TREC battery 7 is lower than the critical dissolution temperature of PNIPAM hydrogel and PNAGA hydrogel, the PNIPAM gel in the first control unit on the positive electrode side changes from a contracted state to an expanded state. It absorbs water from the buffer chamber 4 through the rigid porous separator 3, which concentrates the KNO3 osmotic buffer solution 5 in the buffer chamber 4 and increases the osmotic pressure, which is higher than the osmotic pressure of the positive electrode KNO3 electrolyte. The PNAGA gel in the second control unit on the negative electrode side changes from an expanded state to a contracted state and discharges the water stored inside into the buffer chamber 4 through the rigid porous separator 3, which dilutes the KNO3 osmotic buffer solution 5 in the buffer chamber 4 and decreases its osmotic pressure, which is lower than the osmotic pressure of the negative electrode Cu(NO3)2 electrolyte. Driven by the new osmotic pressure difference, water molecules on the positive electrode side migrate directionally from the positive electrode electrolyte chamber to the buffer chamber 4 through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium. This process increases the concentration of the positive electrode KNO3 electrolyte. On the negative electrode side, water molecules migrate directionally from the buffer chamber 4 to the negative electrode electrolyte chamber through the water molecule selective permeation membrane 6 until the osmotic pressure on both sides reaches a new equilibrium. This process decreases the concentration of the negative electrode Cu(NO3)2 electrolyte. Ultimately, this leads to an increase in the positive electrode potential and a decrease in the negative electrode potential, thereby increasing the overall cell voltage. C4: Performs discharge operation under low temperature conditions. The Cu-CuHCF full cell has a higher voltage at low temperatures, so it performs discharge operation and outputs more electrical energy through the external circuit.

[0034] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An electrochemical thermoelectric conversion device based on dynamic regulation of thermally responsive gel, comprising a TREC cell (7) and a first regulation unit and a second regulation unit symmetrically arranged on both sides of the TREC cell (7), characterized in that: The first control unit and the second control unit are respectively connected to the positive electrolyte chamber and the negative electrolyte chamber of the TREC battery (7). The positive electrolyte chamber and the negative electrolyte chamber are respectively provided with positive electrolyte and negative electrolyte. The first control unit and the second control unit are respectively used to control the concentration of the positive electrolyte and the concentration of the negative electrolyte of the TREC battery (7). Both the first control unit and the second control unit include a thermal response drive chamber (1). A buffer chamber (4) is provided between the thermal response drive chamber (1) and the TREC battery (7). The thermal response drive chamber (1) and the buffer chamber (4) and the buffer chamber (4) and the TREC battery (7) are separated by a rigid porous separator (3) and a water molecule selective permeable membrane (6), respectively. The interior of the thermal response drive chamber (1) and the buffer chamber (4) is filled with thermal response gel (2) and osmotic pressure buffer (5), respectively. The thermally responsive gel (2) has a critical dissolution temperature. When the operating temperature of the TREC battery (7) is higher than the critical dissolution temperature, the thermally responsive gel (2) undergoes either reversible water absorption or water drainage behavior, causing the concentration of the osmotic pressure buffer (5) to change accordingly. The two buffer chambers (4) generate an osmotic pressure difference with the positive and negative electrolytes of the TREC battery (7) by means of the concentration change of the osmotic pressure buffer (5). The osmotic pressure difference drives the water molecules to migrate in a directional manner through the water molecule selective permeation membrane (6) to dynamically adjust the concentration of the positive and negative electrolytes of the TREC battery (7).

2. The electrochemical thermoelectric conversion device based on dynamic control of thermally responsive gel according to claim 1, characterized in that: The osmotic pressure of the osmotic pressure buffer (5) is initially balanced with the osmotic pressure of the positive and negative electrolytes in the TREC battery (7). The initial operating temperature of the electrochemical thermoelectric conversion device is set to the average of the high-temperature and low-temperature operating temperatures of the TREC battery (7). The osmotic pressure difference between the two sides of the TREC battery (7) is zero in the initial state.

3. The electrochemical thermoelectric conversion device based on dynamic control of thermally responsive gel according to claim 2, characterized in that: The thermal response drive chamber (1) is a rigid container, the buffer chamber (4) is a sealed cavity, the thermal response gel (2) can be replaced by an adsorbent, the adsorbent is a water adsorption-thermal desorption type, the regeneration temperature of the adsorbent corresponds to the critical dissolution temperature of the thermal response gel (2), the adsorbent includes but is not limited to any one of metal-organic framework materials, inorganic hygroscopic materials and organic composite hygroscopic materials, the critical dissolution temperature of the thermal response gel (2) and the regeneration temperature of the adsorbent are both located between the high temperature operating temperature and the low temperature operating temperature of the TREC battery (7).

4. The electrochemical thermoelectric conversion device based on dynamic control of thermally responsive gel according to claim 3, characterized in that: The thermally responsive gel (2) is a thermally responsive hydrogel. The thermally responsive hydrogel has one of the following characteristics: low critical dissolution temperature and high critical dissolution temperature. The thermally responsive hydrogel with low critical dissolution temperature undergoes water absorption swelling and water drainage shrinkage in the state below and above the low critical dissolution temperature, respectively. The thermally responsive hydrogel with high critical dissolution temperature undergoes water drainage shrinkage and water absorption swelling in the state below and above the high critical dissolution temperature, respectively. The thermally responsive hydrogel can be conventionally modified by chemical grafting, copolymerization, doping and crosslinking degree control to offset the critical dissolution temperature, and is suitable for low-grade thermal energy application scenarios with multiple temperature ranges.

5. The electrochemical thermoelectric conversion device based on dynamic control of thermally responsive gel according to claim 4, characterized in that: When the TREC battery (7) is a membrane-free system and has the same positive and negative electrode control requirements, the two thermal response gels (2) are set to the same type. When the TREC battery (7) is a membrane-based system and has opposite positive and negative electrode control requirements, the two thermal response gels (2) are set to LCST type and UCST type respectively. The water absorption and drainage behavior of the thermally responsive gel (2) synergistically affects the electrode potentials of the positive and negative electrodes with the temperature change direction of the TREC battery (7). The change in the concentration of the positive and negative electrolytes causes the voltage change direction of the TREC battery (7) to be the same as the thermoelectric potential direction of the temperature change, thus achieving amplified output of the net voltage.

6. The electrochemical thermoelectric conversion device based on dynamic control of thermally responsive gel according to claim 5, characterized in that: The outer surface of the rigid porous separator (3) is provided with dense small pores, which are used to provide water molecule migration channels in the thermally responsive gel (2) and the osmotic pressure buffer (5). The water molecule selectively permeable membrane (6) is a two-dimensional material membrane with sub-nanometer pore size. The effective pore size of the water molecule selectively permeable membrane (6) is between the diameter of water molecules and the diameter of hydrated ions. The water molecule selectively permeable membrane (6) satisfies the transmembrane transport of water molecules and retains hydrated cations and hydrated anions in the solutions on both sides.

7. The electrochemical thermoelectric conversion device based on dynamic control of thermally responsive gel according to claim 6, characterized in that: The TREC battery (7) has two high-position electrodes (8) installed inside. The two high-position electrodes (8) are respectively the positive electrode and the negative electrode and are located at the top of the positive electrode electrolyte chamber and the negative electrode electrolyte chamber. There are installation gaps between the two high-position electrodes (8) and the water molecule selective permeable membrane (6), the bottom of the positive electrode electrolyte chamber and the negative electrode electrolyte chamber. The installation gaps are used to avoid the high-position electrodes (8) blocking the water molecule permeation balance process and to allow the micro bubbles generated in the electrochemical reaction to float up and be discharged naturally.

8. An electrochemical thermoelectric conversion method based on dynamic regulation of a thermo-responsive gel, and an electrochemical thermoelectric conversion device based on dynamic regulation of a thermo-responsive gel according to any one of claims 1-7, characterized in that, Includes the following steps: A1: System initialization, prepare the electrolyte for TREC battery 7 and fill it into the electrolyte chamber. Record the initial liquid level height through the transparent observation window and scale on the side wall of the electrolyte chamber. Then determine the intermediate temperature T0. Prepare the osmotic pressure buffer 5 and fill it into the buffer chamber 4. Put the thermal response gel 2 into the thermal response drive chamber 1. Ensure that the thermal response drive chamber 1 is in liquid communication with the buffer chamber 4 through the rigid porous isolation plate 3. Check the integrity and sealing status of the water molecule selective permeation membrane 6 and confirm that there is no leakage at each connection. A2: Regulation under high-temperature conditions, when TREC battery 7 is under high-temperature conditions T H When working, if the thermally responsive gel 2 is of the LCST type, it exhibits chain extension and water absorption swelling behavior at low temperatures; if the thermally responsive gel 2 is of the UCST type, it exhibits chain curling and drainage shrinkage behavior at low temperatures. A3: Under high-temperature conditions, after a new osmotic equilibrium is established during charging and discharging, the electrolyte stabilizes at a new concentration value. At this time, the direction of concentration change is the same as the direction of thermoelectric potential caused by temperature change, thus amplifying the effective voltage. The charging and discharging operation is performed according to the temperature coefficient sign of the redox pair used in TREC battery 7. A4: Regulation under low-temperature conditions, when TREC battery 7 is under low-temperature condition T L When working, depending on the type of thermally responsive gel 2, its water absorption and drainage behaviors are opposite; A5: Under low-temperature conditions, after the electrolyte concentration stabilizes at a new value, the charging and discharging operation is reversed compared to that under high-temperature conditions, based on the sign of the temperature coefficient. When the temperature coefficient is positive, charging occurs under low-temperature conditions; when the temperature coefficient is negative, discharging occurs under low-temperature conditions, outputting electrical energy to the external circuit. A6: System recovery. After the charging and discharging operations under high and low temperature conditions are completed, the TREC battery 7 is restored to the intermediate temperature T0. The temperature of the thermal response drive chamber 1 is restored accordingly. The thermal response gel 2 gradually returns to its initial state during the temperature recovery process. The concentration of the osmotic pressure buffer 5 is restored to a state of equilibrium with the electrolyte osmotic pressure. Finally, the system returns to its initial state. The above steps A2 to A5 can be repeated for continuous thermoelectric conversion.

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