Goaf sandwich type layered filling energy storage system and electrolyte circulation scheduling method

Abstract

The application discloses a goaf sandwich type layered filling energy storage system, which comprises an upper conductive filling electrode layer, a lower conductive filling electrode layer and an insulating isolation layer, the insulating isolation layer is arranged between the upper conductive filling electrode layer and the lower conductive filling electrode layer, and a conductive current collection anchor rod is arranged in each of the upper conductive filling electrode layer and the lower conductive filling electrode layer; the conductive current collection anchor rod is electrically connected with an external current conversion device through a current collection bus; a porous liquid injection pipe network is embedded in the insulating isolation layer; and the porous liquid injection pipe network is connected with a liquid storage tank group through a valve group and a circulating pump group. The application further discloses an electrolyte circulation scheduling method. The application solves the problems of uneven ion transmission of a filling body, long current collection path, high contact resistance and lack of a multi-working-condition electrolyte scheduling mechanism in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of underground space energy storage and filling mining technology, specifically involving a sandwich-type layered filling energy storage system for goaf areas, and also involving a method for electrolyte circulation scheduling using this system. Background Technology

[0002] Goaf areas, characterized by their large spatial volume, stable surrounding rock constraints, and high degree of coupling with the mining production system, possess the potential for constructing large-scale underground energy storage units. Combining backfill mining technology with electrochemical energy storage structures holds promise for achieving goaf management and ground pressure control while simultaneously providing energy storage and peak-shaving / frequency regulation functions.

[0003] Existing energy storage solutions based on infill bodies typically suffer from the following problems: First, the coupling between electron conduction and ion migration paths in a single-block infill structure is unclear, which can easily lead to uneven distribution of active areas and severe local polarization after large-scale construction. Second, traditional anchor bolts mainly serve a support function and lack effective current collection coordination with energy storage electrodes, resulting in high interfacial contact resistance. Third, the underground environment has large temperature differences and frequent changes in operating conditions. Different operating modes have significantly different requirements for electrolyte conductivity, fluidity, and antifreeze properties, and existing systems lack an electrolyte circulation scheduling mechanism to adapt to changes in operating conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a sandwich-type layered filling energy storage system for goaf areas, which solves the problems of uneven ion transport in the filling body, long current collection path, high contact resistance, and lack of multi-condition electrolyte scheduling mechanism in the prior art.

[0005] Another object of the present invention is to provide an electrolyte circulation scheduling method.

[0006] The technical solution adopted in this invention is a sandwich-type layered filling energy storage system for goaf areas, including an upper conductive filling electrode layer, a lower conductive filling electrode layer, and an insulating isolation layer. The insulating isolation layer is disposed between the upper and lower conductive filling electrode layers. Conductive current collecting anchors are respectively installed in the upper and lower conductive filling electrode layers. The conductive current collecting anchors are electrically connected to an external converter via a current collecting busbar. A porous liquid injection network is embedded in the insulating isolation layer. The porous liquid injection network is connected to a liquid storage tank group via a valve group and a circulating pump group.

[0007] The invention is further characterized by: Both the upper conductive filling electrode layer and the lower conductive filling electrode layer are located inside the surrounding rock layer of the goaf. The upper conductive filling electrode layer is located above the insulating isolation layer, and the lower conductive filling electrode layer is located below the insulating isolation layer. Both the upper and lower conductive filling electrode layers are composed of cementitious filling materials mixed with conductive fillers. The conductive fillers are one or more of graphite, carbon black, graphene, carbon fiber, and metal powder.

[0008] An ion-exchange composite membrane is attached to the upper and lower surfaces of the insulating layer. The ion-exchange composite membrane covers the junctions between the insulating layer and the upper conductive filling electrode layer, and between the insulating layer and the lower conductive filling electrode layer. The ion-exchange composite membrane allows ions to migrate in a directional manner and inhibits electron leakage and cross-diffusion of active materials between adjacent electrode layers.

[0009] The porous injection network is distributed in an S-shape, serpentine shape, or square shape within the insulating isolation layer, and the pipe wall of the porous injection network has outlet holes along the length direction.

[0010] One end of the conductive current-collecting anchor is anchored in the surrounding rock layer of the goaf, and the other end of the conductive current-collecting anchor is connected to the current-collecting busbar. The conductive current-collecting anchor has both surrounding rock support and current collection functions. The conductive current-collecting anchor forms conductive contact with the upper conductive filling electrode layer and the lower conductive filling electrode layer respectively. There are multiple conductive current-collecting anchors, which are arranged in the upper conductive filling electrode layer and the lower conductive filling electrode layer according to a preset spacing. The conductive current-collecting anchors are led out in groups along the roadway side and collected by the current-collecting busbar before being connected to the external converter.

[0011] The storage tank assembly includes a mine water storage tank, an enhanced electrolyte storage tank, and an antifreeze electrolyte storage tank. The mine water storage tank contains mine water or a low-concentration inorganic salt solution. The enhanced electrolyte storage tank contains an inorganic salt solution, an acidic electrolyte, or a liquid medium containing redox active couples. The antifreeze electrolyte storage tank contains an antifreeze electrolyte containing polyols or low-freezing-point solvents.

[0012] It also includes a sensor group, a controller, and a heat exchange unit. The sensor group includes a temperature sensor, a voltage sensor, an internal resistance monitoring unit, and a liquid level sensor. The temperature sensor is disposed in the upper conductive filling electrode layer and the lower conductive filling electrode layer. The voltage sensor is electrically connected to the upper conductive filling electrode layer and the lower conductive filling electrode layer, respectively. The internal resistance monitoring unit is electrically connected to the upper conductive filling electrode layer and the lower conductive filling electrode layer, respectively. The liquid level sensor is disposed in the liquid storage tank group. The sensor group is electrically connected to the controller. The controller is controlled by the valve group, the circulating pump group, and the heat exchange unit.

[0013] Another technical solution adopted in this invention is an electrolyte circulation scheduling method, comprising the following steps: Step 1: Collect the operating parameters of the energy storage unit; Step 2: Select the target electrolyte from the storage tank group based on the collected operating parameters; Step 3: Switch the control valve group to the storage tank corresponding to the target electrolyte, and control the circulation pump group to inject the target electrolyte into the porous injection network; Step 4: Adjust the injection flow rate, pulse frequency, and return cycle during the charging and discharging process; Step 5: Recover the original electrolyte and inject a suitable electrolyte.

[0014] Another feature of the technical solution adopted in this invention is that: Step 1 specifically involves: collecting the energy storage unit's operating mode, ambient temperature, terminal voltage and equivalent internal resistance between the upper and lower conductive filling electrode layers, as well as the liquid level information in the storage tank group through the sensor group, and transmitting the collected parameters to the controller. Step 2 is as follows: The controller determines the target operating condition based on the collected operating mode and ambient temperature. When the system is in conventional energy storage or peak shaving and valley filling mode, it selects mine water or low-concentration inorganic salt electrolyte from the mine water storage tank as the working medium. When the system is in high-rate frequency modulation mode, it selects an enhanced electrolyte with a higher ion mobility than the mine water electrolyte from the enhanced electrolyte storage tank as the working medium. Step 3 is as follows: The controller controls the valve group to switch to the storage tank corresponding to the target electrolyte, and controls the circulating pump group to operate in pulse injection mode, injecting the target electrolyte into the insulating layer through the porous injection pipeline. The target electrolyte permeates into the insulating layer through the outlet holes on the pipe wall of the porous injection pipeline, and diffuses upward into the conductive filling electrode layer through the ion exchange composite membrane on the upper surface of the insulating layer, and at the same time diffuses downward into the conductive filling electrode layer through the ion exchange composite membrane on the lower surface of the insulating layer.

[0015] Step 4 specifically involves the controller dynamically adjusting the pulse frequency and duty cycle of the circulating pump group based on the real-time feedback from the sensor group regarding the equivalent internal resistance, terminal voltage difference, and temperature changes between the upper and lower conductive filling electrode layers. The adjustment amplitude of the pulse frequency and duty cycle is positively correlated with the detected values ​​of the equivalent internal resistance and terminal voltage difference. Step 5 is as follows: When the system stops or the operating condition changes, the controller controls the valve group to switch to the return pipeline, and the circulating pump group recovers the original electrolyte in the upper conductive filling electrode layer, the insulating isolation layer and the lower conductive filling electrode layer through the porous injection network to the corresponding storage tank; when the sensor group detects that the ambient temperature is lower than the preset threshold, the controller controls the valve group to recover the aqueous electrolyte and switches from the antifreeze electrolyte storage tank to the antifreeze electrolyte injection network. At the same time, the heat exchange unit is started to maintain the target temperature range to reduce the impact of freezing expansion on the structural stability of the filling body.

[0016] In step 4, when the system is in high-rate frequency modulation mode, the controller controls the circulating pump group to operate in pulse injection mode. The peak flow rate of pulse injection mode is higher than the constant injection flow rate in conventional energy storage mode. The interval of pulse injection mode is used to release the concentration polarization in the upper conductive filling electrode layer and the lower conductive filling electrode layer.

[0017] The beneficial effects of this invention are: The sandwich-style layered filling energy storage system and electrolyte circulation scheduling method for goaf areas provided by this invention, through the sandwich-style layered configuration of an upper conductive filling electrode layer, an insulating isolation layer, and a lower conductive filling electrode layer, separates the electron collection channel and the ion migration channel, effectively reducing local polarization in large-scale filling bodies and improving the uniformity of ion transport. At the same time, by utilizing a conductive current-collecting anchor array that combines surrounding rock support and current collection functions, the current collection path is shortened, and the interface contact resistance and current output loss are reduced. In addition, through the multi-source electrolyte switching strategy and the coordinated cooperation of the heat exchange unit, the system has good operational adaptability under various operating conditions such as conventional energy storage, high-rate frequency regulation, and low-temperature shutdown, achieving a balance between ion mass transfer efficiency, system energy consumption, and structural stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the sandwich-type layered filling energy storage system for goaf areas of the present invention; Figure 2 This is a schematic diagram of the synergistic mechanism between the conductive current-collecting anchor array and the support in this invention; Figure 3 This is a schematic flowchart of the electrolyte circulation scheduling method of the present invention.

[0019] In the diagram, 1. Surrounding rock layer; 2. Upper conductive filling electrode layer; 3. Ion exchange composite membrane; 4. Insulation layer; 5. Porous injection network; 6. Lower conductive filling electrode layer; 7. Conductive current collecting anchor; 8. Current collecting busbar; 9. Converter; 10. Storage tank group; 11. Circulating pump group; 12. Heat exchange unit; 13. Sensor group; 14. Controller. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] The sandwich-style layered filling energy storage system for goaf areas provided by this invention, such as Figure 1As shown, the structure includes an upper conductive filling electrode layer 2, a lower conductive filling electrode layer 6, and an insulating isolation layer 4. The insulating isolation layer 4 is located between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. Conductive current collecting anchors 7 are respectively installed inside the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The conductive current collecting anchors 7 are electrically connected to an external converter device 9 via a current collecting busbar 8. A porous liquid injection network 5 is embedded in the insulating isolation layer 4. The porous liquid injection network 5 is connected to a liquid storage tank group 10 via a valve group and a circulating pump group 11. The upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are both located inside the surrounding rock layer 1 of the goaf. The upper conductive filling electrode layer 2 is located above the insulating isolation layer 4, and the lower conductive filling electrode layer 6 is located below the insulating isolation layer 4. Both the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are composed of a cementitious filling material incorporating conductive fillers, which are one or more of graphite, carbon black, graphene, carbon fiber, and metal powder. Ion exchange composite membranes 3 are respectively attached to the upper and lower surfaces of the insulating isolation layer 4. The ion exchange composite membranes 3 cover the junctions between the insulating isolation layer 4 and the upper conductive filling electrode layer 2, and between the insulating isolation layer 4 and the lower conductive filling electrode layer 6. The ion exchange composite membranes 3 allow ions to migrate directionally and inhibit electron leakage and cross-diffusion of active materials between adjacent electrode layers. A porous injection network 5 is distributed in an S-shape, serpentine shape, or a U-shape within the insulating isolation layer 4. The walls of the porous injection network 5 have outlet holes along their length. One end of the conductive current-collecting anchor rod 7 is anchored to the perimeter of the goaf. Within rock stratum 1, the other end of the conductive current-collecting anchor 7 is connected to the current-collecting busbar 8. The conductive current-collecting anchor 7 serves both as surrounding rock support and current collection. The conductive current-collecting anchor 7 forms conductive contact with the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, respectively. Multiple conductive current-collecting anchors 7 are arranged in zones according to preset spacing within the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The conductive current-collecting anchors 7 are led out in groups along the roadway side 18 and collected by the current-collecting busbar 8 before being connected to the external converter device 9. The liquid storage tank group 10 includes a mine water storage tank, an enhanced electrolyte storage tank, and an antifreeze electrolyte storage tank. The mine water storage tank contains mine water or a low-concentration inorganic salt solution, while the enhanced electrolyte storage tank contains an inorganic salt solution, an acidic electrolyte, or an oxidizing solution. The liquid medium for reducing active redox couples includes an antifreeze electrolyte storage tank containing an antifreeze electrolyte containing polyols or low-freezing-point solvents; it also includes a sensor group 13, a controller 14, and a heat exchange unit 12. The sensor group 13 includes a temperature sensor, a voltage sensor, an internal resistance monitoring unit, and a liquid level sensor. The temperature sensor is disposed in the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The voltage sensor is electrically connected to the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, respectively. The internal resistance monitoring unit is electrically connected to the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, respectively. The liquid level sensor is disposed in the storage tank group 10. The sensor group 13 is electrically connected to the controller 14. The controller 14 is controlled by the valve group, the circulating pump group 11, and the heat exchange unit 12.A porous liquid injection network 5 is pre-embedded in the insulating layer, and the injection, circulation, recovery, and switching of different electrolyte media are realized through the liquid storage tank group 10, valve group, circulation pump group 11, heat exchange unit 12, and controller 14. Multiple conductive current collection anchors 7 mainly undertake the functions of shortening the current collection path and providing support coordination.

[0022] The electrolyte circulation scheduling method provided by this invention, based on the aforementioned sandwich-type layered filling energy storage system for goaf areas, includes the following steps: Step 1: Collect the operating parameters of the energy storage unit; Step 1 specifically involves: collecting the energy storage unit's operating mode, ambient temperature, terminal voltage and equivalent internal resistance between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, as well as the liquid level information in the storage tank group 10 through the sensor group 13, and transmitting the collected parameters to the controller 14. Step 2: Select the target electrolyte from the storage tank group based on the collected operating parameters; Step 2 is as follows: The controller 14 determines the target operating condition based on the collected operating mode and ambient temperature. When the system is in conventional energy storage or peak shaving and valley filling mode, it selects mine water or low-concentration inorganic salt electrolyte from the mine water storage tank as the working medium. When the system is in high-rate frequency modulation mode, it selects an enhanced electrolyte with a higher ion mobility than the mine water electrolyte from the enhanced electrolyte storage tank as the working medium. Step 3: Switch the control valve group to the storage tank corresponding to the target electrolyte, and control the circulation pump group to inject the target electrolyte into the porous injection network; Step 3 is as follows: The controller 14 controls the valve group to switch to the storage tank corresponding to the target electrolyte, and controls the circulating pump group 11 to operate in pulse injection mode, injecting the target electrolyte into the insulating layer 4 through the porous injection network 5. The target electrolyte permeates into the insulating layer 4 through the outlet holes on the wall of the porous injection network 5, and diffuses upward into the conductive filling electrode layer 2 through the ion exchange composite membrane 3 on the upper surface of the insulating layer 4, and diffuses downward into the conductive filling electrode layer 6 through the ion exchange composite membrane 3 on the lower surface of the insulating layer 4. Step 4: Adjust the injection flow rate, pulse frequency, and return cycle during the charging and discharging process; Step 4 is as follows: The controller 14 dynamically adjusts the pulse frequency and duty cycle of the circulating pump group 11 based on the equivalent internal resistance, terminal voltage difference and temperature change between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 fed back in real time by the sensor group 13. The adjustment amplitude of the pulse frequency and duty cycle is positively correlated with the detected values ​​of the equivalent internal resistance and terminal voltage difference. In step 4, when the system is in high-rate frequency modulation mode, the controller 14 controls the circulating pump group 11 to operate in pulse injection mode. The peak flow rate of pulse injection mode is higher than the constant injection flow rate in conventional energy storage mode. The interval of pulse injection mode is used to release the concentration polarization in the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. Step 5: Recover the original electrolyte and inject a suitable electrolyte; Step 5 is as follows: When the system stops or the operating condition changes, the controller 14 controls the valve group to switch to the return pipeline 15, and the circulation pump group 11 recovers the original electrolyte in the upper conductive filling electrode layer 2, the insulating isolation layer 4 and the lower conductive filling electrode layer 6 through the porous injection network 5 to the corresponding storage tank; when the sensor group 13 detects that the ambient temperature is lower than the preset threshold, the controller 14 controls the valve group to recover the aqueous electrolyte and switches from the antifreeze electrolyte storage tank to the antifreeze electrolyte injection network 5. At the same time, the heat exchange unit 12 is started to maintain the target temperature range to reduce the impact of freezing expansion on the structural stability of the filling body.

[0023] By separating electron collection channels and ion migration channels as much as possible through a layered configuration, local polarization in large-volume filling structures is reduced. Conductive current-collecting anchor arrays connect the support components to external circuits, reducing current conduction losses. Multi-source electrolyte switching and heat exchange synergy enhance the system's adaptability to conventional energy storage, high-rate frequency regulation, and cold-weather shutdown conditions. Fluid circuit adjustment parameters can be adjusted in real time according to changes in temperature, internal resistance, and terminal voltage, more closely aligning with actual operational needs. This system improves the uniformity of ion transport in large-scale filling bodies, reduces interfacial contact resistance, balances surrounding rock support and current collection, and enhances the system's operational adaptability under high-rate frequency regulation and low-temperature conditions.

[0024] Example 1 The sandwich-style layered filling energy storage system for goaf proposed in this embodiment, such as Figure 1 As shown, it includes an upper conductive filling electrode layer 2, a lower conductive filling electrode layer 6, and an insulating isolation layer 4. The insulating isolation layer 4 is disposed between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. Conductive current collecting anchor rods 7 are respectively installed in the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The conductive current collecting anchor rods 7 are electrically connected to an external converter device 9 via a current collecting busbar 8. A porous liquid injection network 5 is embedded in the insulating isolation layer 4. The porous liquid injection network 5 is connected to a liquid storage tank group 10 via a valve group and a circulating pump group 11. The upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are both disposed inside the surrounding rock layer 1 of the goaf. The upper conductive filling electrode layer 2 is located above the insulating isolation layer 4, and the lower conductive filling electrode layer 6 is located below the insulating isolation layer 4. The upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are both composed of a cementitious filling material mixed with conductive filler. The conductive filler is one or more of graphite, carbon black, graphene, carbon fiber, and metal powder.

[0025] Example 2 The sandwich-style layered filling energy storage system for goaf proposed in this embodiment, such as Figure 1 As shown, the structure includes an upper conductive filling electrode layer 2, a lower conductive filling electrode layer 6, and an insulating isolation layer 4. The insulating isolation layer 4 is located between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. Conductive current collecting anchors 7 are respectively installed inside the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The conductive current collecting anchors 7 are electrically connected to an external converter device 9 via a current collecting busbar 8. A porous liquid injection network 5 is embedded in the insulating isolation layer 4. The porous liquid injection network 5 is connected to a liquid storage tank group 10 via a valve group and a circulating pump group 11. The upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are both located inside the surrounding rock layer 1 of the goaf. The upper conductive filling electrode layer 2 is located above the insulating isolation layer 4, and the lower conductive filling electrode layer 6 is located below the insulating isolation layer 4. Both the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are composed of a gelling filling material doped with conductive filler. The conductive filler is one or more of graphite, carbon black, graphene, carbon fiber, and metal powder. Ion exchange composite membranes 3 are attached to the upper and lower surfaces of the insulating isolation layer 4, respectively. The ion exchange composite membranes 3 cover the junctions between the insulating isolation layer 4 and the upper conductive filling electrode layer 2, and between the insulating isolation layer 4 and the lower conductive filling electrode layer 6. The ion exchange composite membranes 3 allow ions to migrate in a directional manner and inhibit electron leakage and cross-diffusion of active materials between adjacent electrode layers. The porous liquid injection network 5 is distributed in an S-shape, serpentine shape, or U-shape within the insulating isolation layer 4. Liquid outlet holes are opened along the length direction on the wall of the porous liquid injection network 5.

[0026] Example 3 The sandwich-style layered filling energy storage system for goaf proposed in this embodiment, such as Figure 1As shown, the structure includes an upper conductive filling electrode layer 2, a lower conductive filling electrode layer 6, and an insulating isolation layer 4. The insulating isolation layer 4 is located between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. Conductive current collecting anchors 7 are respectively installed inside the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The conductive current collecting anchors 7 are electrically connected to an external converter device 9 via a current collecting busbar 8. A porous liquid injection network 5 is embedded in the insulating isolation layer 4. The porous liquid injection network 5 is connected to a liquid storage tank group 10 via a valve group and a circulating pump group 11. The upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are both located inside the surrounding rock layer 1 of the goaf. The upper conductive filling electrode layer 2 is located above the insulating isolation layer 4, and the lower conductive filling electrode layer 6 is located below the insulating isolation layer 4. Both the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 are composed of a cementitious filling material incorporating conductive fillers, which are one or more of graphite, carbon black, graphene, carbon fiber, and metal powder. Ion exchange composite membranes 3 are respectively attached to the upper and lower surfaces of the insulating isolation layer 4. The ion exchange composite membranes 3 cover the junctions between the insulating isolation layer 4 and the upper conductive filling electrode layer 2, and between the insulating isolation layer 4 and the lower conductive filling electrode layer 6. The ion exchange composite membranes 3 allow ions to migrate directionally and inhibit electron leakage and cross-diffusion of active materials between adjacent electrode layers. A porous injection network 5 is distributed in an S-shape, serpentine shape, or a U-shape within the insulating isolation layer 4. The walls of the porous injection network 5 have outlet holes along their length. One end of the conductive current-collecting anchor rod 7 is anchored to the perimeter of the goaf. Within rock stratum 1, the other end of the conductive current-collecting anchor 7 is connected to the current-collecting busbar 8. The conductive current-collecting anchor 7 serves both as surrounding rock support and current collection. The conductive current-collecting anchor 7 forms conductive contact with the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, respectively. Multiple conductive current-collecting anchors 7 are arranged in zones according to preset spacing within the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The conductive current-collecting anchors 7 are led out in groups along the roadway side 18 and collected by the current-collecting busbar 8 before being connected to the external converter device 9. The liquid storage tank group 10 includes a mine water storage tank, an enhanced electrolyte storage tank, and an antifreeze electrolyte storage tank. The mine water storage tank contains mine water or a low-concentration inorganic salt solution, while the enhanced electrolyte storage tank contains an inorganic salt solution, an acidic electrolyte, or an oxidizing solution. The liquid medium for reducing active redox couples includes an antifreeze electrolyte storage tank containing an antifreeze electrolyte containing polyols or low-freezing-point solvents; it also includes a sensor group 13, a controller 14, and a heat exchange unit 12. The sensor group 13 includes a temperature sensor, a voltage sensor, an internal resistance monitoring unit, and a liquid level sensor. The temperature sensor is disposed in the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. The voltage sensor is electrically connected to the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, respectively. The internal resistance monitoring unit is electrically connected to the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, respectively. The liquid level sensor is disposed in the storage tank group 10. The sensor group 13 is electrically connected to the controller 14. The controller 14 is controlled by the valve group, the circulating pump group 11, and the heat exchange unit 12.

[0027] Example 4 The electrolyte circulation scheduling method proposed in this embodiment, based on the above-mentioned sandwich-type layered filling energy storage system for goaf areas, includes the following steps: Step 1: Collect the operating parameters of the energy storage unit; Step 2: Select the target electrolyte from the storage tank group based on the collected operating parameters; Step 3: Switch the control valve group to the storage tank corresponding to the target electrolyte, and control the circulation pump group to inject the target electrolyte into the porous injection network; Step 4: Adjust the injection flow rate, pulse frequency, and return cycle during the charging and discharging process; Step 5: Recover the original electrolyte and inject a suitable electrolyte.

[0028] Example 5 The electrolyte circulation scheduling method proposed in this embodiment, based on the above-mentioned sandwich-type layered filling energy storage system for goaf areas, includes the following steps: Step 1: Collect the operating parameters of the energy storage unit; Step 1 specifically involves: collecting the energy storage unit's operating mode, ambient temperature, terminal voltage and equivalent internal resistance between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, as well as the liquid level information in the storage tank group 10 through the sensor group 13, and transmitting the collected parameters to the controller 14. Step 2: Select the target electrolyte from the storage tank group based on the collected operating parameters; Step 2 is as follows: The controller 14 determines the target operating condition based on the collected operating mode and ambient temperature. When the system is in conventional energy storage or peak shaving and valley filling mode, it selects mine water or low-concentration inorganic salt electrolyte from the mine water storage tank as the working medium. When the system is in high-rate frequency modulation mode, it selects an enhanced electrolyte with a higher ion mobility than the mine water electrolyte from the enhanced electrolyte storage tank as the working medium. Step 3: Switch the control valve group to the storage tank corresponding to the target electrolyte, and control the circulation pump group to inject the target electrolyte into the porous injection network; Step 3 is as follows: The controller 14 controls the valve group to switch to the storage tank corresponding to the target electrolyte, and controls the circulating pump group 11 to operate in pulse injection mode, injecting the target electrolyte into the insulating layer 4 through the porous injection network 5. The target electrolyte permeates into the insulating layer 4 through the outlet holes on the wall of the porous injection network 5, and diffuses upward into the conductive filling electrode layer 2 through the ion exchange composite membrane 3 on the upper surface of the insulating layer 4, and diffuses downward into the conductive filling electrode layer 6 through the ion exchange composite membrane 3 on the lower surface of the insulating layer 4. Step 4: Adjust the injection flow rate, pulse frequency, and return cycle during the charging and discharging process; Step 4 is as follows: The controller 14 dynamically adjusts the pulse frequency and duty cycle of the circulating pump group 11 based on the equivalent internal resistance, terminal voltage difference and temperature change between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 fed back in real time by the sensor group 13. The adjustment amplitude of the pulse frequency and duty cycle is positively correlated with the detected values ​​of the equivalent internal resistance and terminal voltage difference. In step 4, when the system is in high-rate frequency modulation mode, the controller 14 controls the circulating pump group 11 to operate in pulse injection mode. The peak flow rate of pulse injection mode is higher than the constant injection flow rate in conventional energy storage mode. The interval of pulse injection mode is used to release the concentration polarization in the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6. Step 5: Recover the original electrolyte and inject a suitable electrolyte; Step 5 is as follows: When the system stops or the operating condition changes, the controller 14 controls the valve group to switch to the return pipeline 15, and the circulation pump group 11 recovers the original electrolyte in the upper conductive filling electrode layer 2, the insulating isolation layer 4 and the lower conductive filling electrode layer 6 through the porous injection network 5 to the corresponding storage tank; when the sensor group 13 detects that the ambient temperature is lower than the preset threshold, the controller 14 controls the valve group to recover the aqueous electrolyte and switches from the antifreeze electrolyte storage tank to the antifreeze electrolyte injection network 5. At the same time, the heat exchange unit 12 is started to maintain the target temperature range to reduce the impact of freezing expansion on the structural stability of the filling body.

[0029] Example 6 Conventional energy storage modes; see Figure 1 An upper conductive filling electrode layer 2, an insulating isolation layer 4, and a lower conductive filling electrode layer 6 are sequentially cast between the surrounding rock layers 1 in the goaf. The upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6 can be formed using cementitious filling materials incorporating graphite, carbon black, graphene, or carbon fiber. The insulating isolation layer 4 is used to physically separate the positive and negative electrode areas, and ion exchange composite membranes 3 are set on its upper and lower surfaces. An S-shaped porous liquid injection network 5 is pre-embedded inside the insulating isolation layer to make the electrolyte diffuse more evenly in the cross-sectional direction of the goaf. Conductive current collecting anchor bolts 7 extend into the upper and lower conductive filling electrode layers along the roadway side and are connected to the converter device 9 through the current collecting busbar 8 to complete the current collection and output during the charging and discharging process.

[0030] Example 7 Support-collection collaborative mode; see Figure 2 One end of the conductive current-collecting anchor 7 is anchored to the surrounding rock layer 1, and the other end is connected to the current-collecting busbar 8. When electrons in the conductive filling body are conducted outward from the conductive particle / slurry interface, they can be collected to the current-collecting busbar 8 through the conductive current-collecting anchor 7 and the conductive contact area. The key point of this arrangement is to shorten the effective current-collecting path between the inside of the filling body and the external circuit, while more specific structures such as the conductive coating, roughened interface, or sensing unit on the surface of the anchor can be further realized by independent component schemes.

[0031] Example 8 Multi-source electrolyte circulation scheduling mode; see Figure 3 The storage tank group 10 includes at least a mine water storage tank, an enhanced electrolyte storage tank, and an antifreeze electrolyte storage tank. Based on the ambient temperature, internal resistance, voltage, and liquid level information collected by the sensor group 13, the controller 14 controls the valve group to switch to the target storage tank and delivers the appropriate electrolyte to the underground energy storage unit via the circulating pump group 11 and the heat exchange unit 12. After completing ion transfer, the electrolyte returns to the storage tank group 10 via the return pipeline, forming a closed loop.

[0032] When the system needs to undertake the task of automatic power grid generation control and frequency regulation, a 2.0 mol / L H2SO4 enhanced electrolyte can be selected, and the circulating pump group 11 can be controlled to operate in pulse mode to reduce polarization. Tests show that under this condition, the equivalent internal resistance of the energy storage body can be reduced from 150 Ω in the static mine water mode to about 12 Ω, and the response speed is improved accordingly.

[0033] In cold, high-altitude mining areas in northern China, during low-temperature standby or winter shutdown conditions, the system can recover conventional aqueous electrolyte and switch to a propylene glycol-based inorganic salt antifreeze electrolyte. This electrolyte remains liquid and ionicly conductive at -30°C, and, in conjunction with a heat exchange unit, maintains a suitable operating temperature to reduce the adverse effects of freezing expansion on the filling material.

[0034] The pulse frequency, duty cycle, and return cycle of the circulating pump group 11 can be dynamically corrected based on the voltage difference, equivalent internal resistance, and temperature changes between the upper conductive filling electrode layer 2 and the lower conductive filling electrode layer 6, thereby achieving a more practical balance between ion mass transfer efficiency, system energy consumption, and local temperature rise control.

Claims

1. A sandwich-style layered filling energy storage system for goaf areas, characterized in that, It includes an upper conductive filling electrode layer (2), a lower conductive filling electrode layer (6) and an insulating isolation layer (4). The insulating isolation layer (4) is disposed between the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6). Conductive current collecting anchor rods (7) are respectively installed in the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6). The conductive current collecting anchor rods (7) are electrically connected to an external converter device (9) via a current collecting bus (8). A porous liquid injection network (5) is embedded in the insulating isolation layer (4). The porous liquid injection network (5) is connected to a liquid storage tank group (10) via a valve group and a circulating pump group (11).

2. The sandwich-type layered filling energy storage system for goaf areas according to claim 1, characterized in that, The upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6) are both located inside the surrounding rock layer (1) of the goaf. The upper conductive filling electrode layer (2) is located above the insulating isolation layer (4), and the lower conductive filling electrode layer (6) is located below the insulating isolation layer (4). The upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6) are both composed of a cementitious filling material mixed with conductive filler. The conductive filler is one or more of graphite, carbon black, graphene, carbon fiber and metal powder.

3. The goaf sandwich-type layered filling energy storage system according to claim 1, characterized in that, The upper and lower surfaces of the insulating isolation layer (4) are respectively attached with ion exchange composite membranes (3). The ion exchange composite membranes (3) cover the junctions between the insulating isolation layer (4) and the upper conductive filling electrode layer (2) and between the insulating isolation layer (4) and the lower conductive filling electrode layer (6). The ion exchange composite membranes (3) allow ions to migrate in a directional manner and inhibit electron leakage and cross-diffusion of active materials between adjacent electrode layers.

4. The sandwich-type layered filling energy storage system for goaf areas according to claim 1, characterized in that, The porous injection network (5) is distributed in an S-shape, serpentine shape or a square shape within the insulating isolation layer (4), and the porous injection network (5) has an outlet hole along its length on the pipe wall.

5. The goaf sandwich-type layered filling energy storage system according to claim 1, characterized in that, One end of the conductive current-collecting anchor (7) is anchored in the surrounding rock layer (1) of the goaf area, and the other end of the conductive current-collecting anchor (7) is connected to the current-collecting busbar (8). The conductive current-collecting anchor (7) has both surrounding rock support and current collection functions. The conductive current-collecting anchor (7) forms conductive contact with the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6) respectively. There are multiple conductive current-collecting anchors (7) arranged in the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6) according to a preset spacing. The conductive current-collecting anchors (7) are led out in groups along the roadway side (18) and collected by the current-collecting busbar (8) before being connected to the external converter device (9).

6. The sandwich-type layered filling energy storage system for goaf areas according to claim 1, characterized in that, The storage tank group (10) includes a mine water storage tank, an enhanced electrolyte storage tank, and an antifreeze electrolyte storage tank. The mine water storage tank contains mine water or a low-concentration inorganic salt solution. The enhanced electrolyte storage tank contains an inorganic salt solution, an acidic electrolyte, or a liquid medium containing redox active couples. The antifreeze electrolyte storage tank contains an antifreeze electrolyte containing polyols or low-freezing-point solvents.

7. The sandwich-type layered filling energy storage system for goaf areas according to claim 1, characterized in that, It also includes a sensor group (13), a controller (14), and a heat exchange unit (12). The sensor group (13) includes a temperature sensor, a voltage sensor, an internal resistance monitoring unit, and a liquid level sensor. The temperature sensor is disposed in the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6). The voltage sensor is electrically connected to the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6) respectively. The internal resistance monitoring unit is electrically connected to the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6) respectively. The liquid level sensor is disposed in the liquid storage tank group (10). The sensor group (13) is electrically connected to the controller (14). The controller (14) is controlled to be connected to the valve group, the circulating pump group (11), and the heat exchange unit (12).

8. An electrolyte circulation scheduling method, characterized in that, The goaf sandwich-type layered filling energy storage system according to any one of claims 1-7 includes the following steps: Step 1: Collect the operating parameters of the energy storage unit; Step 2: Select the target electrolyte from the storage tank group based on the collected operating parameters; Step 3: Switch the control valve group to the storage tank corresponding to the target electrolyte, and control the circulation pump group to inject the target electrolyte into the porous injection pipeline network; Step 4: Adjust the injection flow rate, pulse frequency, and return cycle during the charging and discharging process; Step 5: Recover the original electrolyte and inject a suitable electrolyte.

9. The electrolyte circulation scheduling method according to claim 8, characterized in that, Step 1 specifically involves: collecting the energy storage unit's operating mode, ambient temperature, terminal voltage and equivalent internal resistance between the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6), as well as the liquid level information in the storage tank group (10) through the sensor group (13), and transmitting the collected parameters to the controller (14). Step 2 specifically involves the controller (14) determining the target operating condition based on the collected operating mode and ambient temperature. When the system is in conventional energy storage or peak shaving and valley filling mode, it selects mine water or low-concentration inorganic salt electrolyte from the mine water storage tank as the working medium. When the system is in high-rate frequency modulation mode, it selects an enhanced electrolyte with a higher ion mobility than the mine water electrolyte from the enhanced electrolyte storage tank as the working medium. Step 3 specifically involves the controller (14) controlling the valve group to switch to the storage tank corresponding to the target electrolyte, and controlling the circulating pump group (11) to operate in pulse injection mode, injecting the target electrolyte into the insulating layer (4) through the porous injection network (5), and the target electrolyte permeating into the insulating layer (4) through the outlet hole on the wall of the porous injection network (5), and diffusing upward through the ion exchange composite membrane (3) on the upper surface of the insulating layer (4) to the conductive filling electrode layer (2), and simultaneously diffusing downward through the ion exchange composite membrane (3) on the lower surface of the insulating layer (4) to the conductive filling electrode layer (6); Step 4 specifically involves the controller (14) dynamically adjusting the pulse frequency and duty cycle of the circulating pump group (11) based on the equivalent internal resistance, terminal voltage difference, and temperature changes between the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6) fed back in real time by the sensor group (13). The adjustment amplitude of the pulse frequency and duty cycle is positively correlated with the detected values ​​of the equivalent internal resistance and the terminal voltage difference. Step 5 specifically involves the following steps: When the system stops or the operating condition is switched, the controller (14) controls the valve group to switch to the return pipeline (15), and the circulating pump group (11) recovers the original electrolyte in the upper conductive filling electrode layer (2), the insulating isolation layer (4), and the lower conductive filling electrode layer (6) through the porous injection network (5) to the corresponding storage tank; when the sensor group (13) detects that the ambient temperature is lower than the preset threshold, the controller (14) controls the valve group to recover the aqueous electrolyte and switches from the antifreeze electrolyte storage tank to inject antifreeze electrolyte into the porous injection network (5), while starting the heat exchange unit (12) to maintain the target temperature range in order to reduce the impact of freezing expansion on the structural stability of the filling body.

10. The electrolyte circulation scheduling method according to claim 8, characterized in that, In step 4, when the system is in high-rate frequency modulation mode, the controller (14) controls the circulating pump group (11) to operate in pulse injection mode. The peak flow rate of the pulse injection mode is higher than the constant injection flow rate in the conventional energy storage mode. The interval of the pulse injection mode is used to release the concentration polarization in the upper conductive filling electrode layer (2) and the lower conductive filling electrode layer (6).

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