Liquid metal battery electrolysis recovery device and method

Abstract

The invention discloses a liquid metal battery electrolysis recovery device and method, and relates to the technical field of liquid metal battery recovery, the liquid metal battery electrolysis recovery device comprises a reaction kettle which comprises a cabin body and a top cover arranged on the top of the cabin body; the cooling area surrounds the upper part of the cabin body; the anode assembly is arranged in the reaction kettle and comprises a molten salt resistant reaction container and an anode conductive lead embedded in the side wall of the molten salt resistant reaction container; the cathode assembly comprises a conducting rod penetrating through the top cover and an active metal adsorption body; a feeding port, a cathode replacement port and an inert gas inlet / outlet are integrated on the top cover of the reaction kettle, so that continuous feeding and cathode assembly replacement in an open environment are realized, and the dependence on a glove box is eliminated; thermal isolation is formed through the cooling area surrounding the side wall of the upper portion of the cabin body, the high-temperature electrolysis area and the operation area are effectively separated, safety is improved, and rapid curing of lithium products is promoted. By adopting the detachable active metal adsorption body cathode assembly and combining with the net-shaped fishing tool, deposited lithium and fused salt are efficiently separated, and the recovery efficiency is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of liquid metal battery recycling technology, and in particular to a liquid metal battery electrolytic recycling device and method. Background Technology

[0002] Liquid metal batteries, due to their unique three-liquid-layer self-assembly structure, possess advantages such as high safety, long cycle life, and low cost, and are considered an important technological route for large-scale energy storage systems. These batteries do not form solid interfaces during charging and discharging, avoiding dendrite growth problems. Furthermore, their highly simplified composition provides a theoretical basis for efficient closed-loop material recycling. In recent years, research on the recycling of liquid metal batteries in lithium-bismuth and sodium-antimony systems has gradually unfolded, mainly employing molten salt electrolysis to selectively reduce and separate active metals in failed cathode alloys at high temperatures, thereby achieving the regeneration and utilization of key resources.

[0003] However, existing recycling technologies are still limited to small-batch laboratory operations and generally suffer from drawbacks such as inability to operate continuously, high energy consumption, and stringent environmental requirements. Specifically, traditional methods are usually carried out in closed, inert environments such as glove boxes, with a single processing volume of only a few grams to tens of grams. Feeding, product collection, and electrode replacement all require interruption of the electrolysis process, making it difficult to achieve large-scale operations. At the same time, the lack of effective thermal management and product separation design leads to high energy consumption per unit mass of product, and the deposited metal is prone to being mixed with molten salt, resulting in low separation efficiency. These problems seriously restrict the engineering application of liquid metal battery recycling technology.

[0004] Based on the above problems, we propose a liquid metal battery electrolytic recovery device and method. Summary of the Invention

[0005] Therefore, the technical problem to be solved by this invention is: how to achieve continuous, batch, low-energy molten salt electrolytic recovery of failed liquid metal battery cathode alloys in an open system.

[0006] The above-mentioned technical problems are solved by the following technical solution: This invention proposes a liquid metal battery electrolysis and recovery device, which includes a reactor, a chamber, and a top cover on the top of the chamber; a cooling zone surrounding the upper part of the chamber; an anode assembly disposed in the reactor, including a molten salt reaction vessel and an anode conductive lead embedded in the side wall of the molten salt reaction vessel; a cathode assembly suspended in the molten salt reaction vessel, including a conductive rod penetrating the top cover and an active metal adsorbent disposed at one end of the conductive rod; the anode conductive lead and the conductive rod maintain an electrically isolated distance, and the anode conductive lead and the conductive rod are respectively led out through the top cover to the outside of the reactor.

[0007] In a preferred embodiment of the liquid metal battery electrolytic recovery device of the present invention: a molten salt layer is provided inside the molten salt reaction vessel, and the active metal adsorbent is immersed in the molten salt layer.

[0008] In a preferred embodiment of the liquid metal battery electrolysis recycling device of the present invention: the outer wall of the top cover is provided with an air inlet and an air outlet, which are respectively connected to the air supply pipe and the air outlet pipe.

[0009] In a preferred embodiment of the liquid metal battery electrolysis recycling device of the present invention: a feeding port is provided between the air inlet and the air outlet, and the conductive rod passes through the feeding port to connect to an external power supply device.

[0010] In a preferred embodiment of the liquid metal battery electrolysis recycling device of the present invention: an anode wire inlet and outlet are provided between the air inlet and the feeding port, and the anode conductive lead passes through the anode wire inlet and outlet to connect to an external power supply device.

[0011] In a preferred embodiment of the liquid metal battery electrolysis and recycling device of the present invention: an observation port is provided between the feeding port and the vent.

[0012] In a preferred embodiment of the liquid metal battery electrolysis and recycling device of the present invention: rubber plugs are movably provided in the feeding port, the anode wire inlet and outlet, and the observation port.

[0013] In a preferred embodiment of the liquid metal battery electrolysis and recycling device of the present invention: the outer wall of the cooling zone is provided with a water inlet and a water outlet.

[0014] The present invention also proposes a method for electrolytic recovery of liquid metal batteries, which includes adding molten salt electrolyte to a molten salt resistant reaction vessel and introducing inert gas through an air inlet and an air outlet to replace the air in the reaction vessel and maintain an inert atmosphere. Heating causes the molten salt electrolyte to melt, and the failed liquid metal battery positive electrode alloy is added to the molten salt resistant reaction vessel through the feeding port; The anode conductive lead and the conductive rod are respectively connected to an external power supply device to apply electrochemical excitation to the electrolysis system, so that the active metal in the positive electrode alloy is reduced and deposited on the active metal adsorbent.

[0015] In a preferred embodiment of the liquid metal battery electrolytic recovery method of the present invention: when the deposited product exceeds the adsorption capacity of the active metal adsorbent, electrolysis is suspended, the cathode assembly is replaced through the feed port, and the overflowing liquid metal is recovered from the molten salt surface using a separation tool.

[0016] The beneficial effects of this invention are as follows: by integrating the feeding port, cathode replacement port, and inert gas inlet and outlet on the top cover of the reactor, continuous feeding and cathode component replacement are achieved in an open environment, eliminating the reliance on a glove box; the cooling zone surrounding the upper side wall of the chamber forms thermal isolation, effectively separating the high-temperature electrolysis zone from the operating zone, improving safety and promoting rapid solidification of lithium products; by using a detachable active metal adsorbent cathode component, combined with a mesh retrieval tool, deposited lithium and molten salt are efficiently separated, significantly improving recovery efficiency; the entire device supports kilogram-level batch processing, greatly reducing energy consumption and recovery costs per unit mass of product. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Figure 1 A schematic diagram of the recycling device connection is shown; Figure 2 The constant voltage electrolysis current curve is shown. Figure 3 The constant current electrolysis voltage curve is shown. Figure 4 The XRD pattern of the failed cathode material is shown; Figure 5 The XRD pattern of the recovered lithium-bismuth alloy is shown. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0019] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0020] Reference Figure 1This embodiment provides a liquid metal battery electrolysis and recovery device, including a reactor 1, comprising a chamber 11 and a top cover 12 located on the top of the chamber 11. The reactor is preferably made of high-temperature resistant and corrosion-resistant stainless steel, providing good airtightness. A cooling zone 2 surrounds the upper sidewall of the chamber 11, with internal cooling medium channels and external air-cooled / water-cooled chillers, forming an annular liquid-cooled area. This allows for thermal partitioning within the reactor 1: a lower high-temperature electrolysis zone (450-500°C) and an upper low-temperature operating zone. This not only improves operational safety (preventing high-temperature burns and seal aging) but also accelerates the cooling and solidification of cathode-deposited lithium, preventing it from re-mixing with molten salt due to high-temperature fluidity, thus improving product purity and recovery efficiency. An anode assembly 3 within the reactor 1 includes a molten salt-resistant reaction vessel 31 and anode conductive leads 32 embedded in the sidewall of the molten salt-resistant reaction vessel 31. The molten salt-resistant reaction vessel 31 holds the molten salt electrolyte and spent lithium-bismuth alloy, and can be made of high-temperature resistant materials such as ceramic crucibles or graphite crucibles. In this embodiment, the molten salt resistant reaction vessel 31 is preferably a graphite crucible. The anode conductive lead 32 is embedded in the side wall of the molten salt resistant reaction vessel 31 through a drilled hole, and is led out through the top cover 12 to the external power supply equipment 5, serving as the anode of the electrolysis circuit. The cathode assembly 4 suspended in the molten salt resistant reaction vessel 31 includes a conductive rod 41 penetrating the top cover 12 and an active metal adsorbent 42 located at one end of the conductive rod 41. The conductive rod 41 is preferably a threaded steel bar, and the active metal adsorbent 42 can be porous sintered nickel, foamed copper, or foamed iron-nickel alloy. In this embodiment, the active metal adsorbent 42 is preferably foamed iron-nickel alloy. The cathode assembly 4 uses a threaded steel bar to pass through a longitudinally stacked foamed iron-nickel alloy and a cathode product collection device fixed with nuts. The nuts are fixed at the upper and lower ends of the foamed iron-nickel alloy respectively. The anode conductive lead 32 and the conductive rod 41 maintain an electrical isolation distance, and the anode conductive lead 32 and the conductive rod 41 are respectively led out through the top cover 12 to the outside of the reactor 1.

[0021] In one embodiment provided in this application, a molten salt layer 311 is provided inside the molten salt reaction vessel 31, and an active metal adsorbent 42 is immersed in the molten salt layer 311 to ensure that the active metal adsorbent 42 is in direct contact with the molten electrolyte, providing an effective reaction interface for the electrochemical reduction of lithium ions. During the electrolysis process, lithium ions migrate from the molten salt layer 311 to the surface of the active metal adsorbent 42 and are reduced to metallic lithium, which is then adsorbed and deposited by the high specific surface area structure of the substrate. The immersion arrangement ensures uniform current distribution, high deposition efficiency, and avoids uncontrolled precipitation of lithium on the liquid surface, thereby improving the purity and controllability of the recovered product.

[0022] In one embodiment provided in this application, the outer wall of the top cover 12 is provided with an air inlet 121 and an air outlet 122, which are respectively connected to the air supply pipe 123 and the air outlet pipe 124, for introducing inert gas during the reaction process to replace the air in the reactor 1 and maintain a positive pressure inert atmosphere inside the chamber 11; the inert gas is high-purity argon (purity ≥99.999%), which can effectively remove residual oxygen and moisture in the reactor 1.

[0023] In one embodiment provided in this application, a feeding port 125 is provided between the air inlet 121 and the air outlet 122. The conductive rod 41 passes through the feeding port 125 and is connected to the external power supply device 5. A removable rubber plug 129 is provided in the annular gap between the feeding port 125 and the conductive rod 41. The rubber plug 129 tightly covers the conductive rod 41 in the non-feeding state to achieve airtight sealing. When it is necessary to add the failed lithium bismuth alloy into the reactor 1, the rubber plug 129 can be temporarily loosened or partially removed. With the conductive rod 41 still connected, solid or molten alloy raw materials are added along its circumferential gap. Then the rubber plug 129 is tightened again to restore the inert environment.

[0024] In one embodiment provided in this application, an anode conductor inlet / outlet 126 is provided between the air inlet 121 and the feed inlet 125. The anode conductive lead 32 is led out from the side wall of the molten salt resistant reaction vessel 31, passes through the anode conductor inlet / outlet 126 and is connected to the external power supply equipment 5, serving as the anode input terminal of the electrolysis circuit. In the non-operating state, a removable rubber plug 129 or a high-temperature resistant sealing ring is provided inside the anode conductor inlet / outlet 126, the inner hole of which is tightly fitted with the outer wall of the anode conductive lead 32 to ensure the overall airtightness of the reactor 1. During installation or maintenance, the rubber plug 129 can be temporarily loosened to adjust the position of the conductor, and then re-tightened and sealed after the operation is completed.

[0025] In one embodiment provided in this application, an observation port 128 is provided between the feeding port 125 and the vent 122. The observation port 128 is a transparent or open tubular channel that passes through the end cap 12. It can be a high-temperature resistant quartz glass window or a stainless steel tube with a removable rubber stopper 129. In this embodiment, a stainless steel tube with a removable rubber stopper 129 is preferred. It is used to observe the molten salt state, lithium metal deposition and bubble generation inside the reactor 1 in real time during the electrolysis process.

[0026] In one embodiment provided in this application, rubber plugs 129 are movably provided in the feeding port 125, the anode wire inlet / outlet 126, and the observation port 128. The rubber plugs 129 are made of heat-resistant silicone rubber or fluororubber and have good elasticity, sealing performance, and the ability to withstand short-term heat radiation of 450~500℃. In the non-operating state, the rubber plugs 129 are tightly embedded in the corresponding pipe openings, effectively preventing the leakage of high-purity argon gas and the infiltration of air. When a specific operation needs to be performed, the corresponding rubber plugs 129 can be temporarily pulled out or loosened.

[0027] In one embodiment provided in this application, the outer wall of the cooling zone 2 is provided with an inlet 21 and an outlet 22, and the interior of the cooling zone 2 is provided with an annular cooling channel to form a thermal isolation barrier during the reaction process, effectively separating the lower high-temperature electrolysis zone from the upper operating zone. The inlet 21 is connected to the low-temperature cooling water output terminal of an external air-cooled water chiller. The cooling water flows into the annular channel of the cooling zone 2 through the inlet 21, absorbs heat from the reactor body, and then flows back to the condensation system from the outlet 22, forming a closed loop. By adjusting the water flow rate and temperature, the temperature of the top cover 12 and the upper interface area can be controlled within a safe range (e.g., <150℃), effectively preventing aging of the seals, burns to operators, and excessive volatilization of lithium metal caused by high temperatures. At the same time, it promotes rapid solidification of deposited lithium, facilitating subsequent collection.

[0028] In operation, molten salt electrolyte is first added to the molten salt resistant reaction vessel 31, and the reaction vessel 1 is sealed. Inert gas is introduced through the air inlet 121 and air outlet 122 to replace the air in the reaction vessel 1 and maintain an inert atmosphere. Subsequently, the molten salt electrolyte is melted by heating, and the depleted liquid metal battery positive electrode alloy is added to the reaction vessel 1 through the feed port 125. After the system stabilizes, the anode conductive lead 32 and the conductive rod 41 of the cathode assembly 4 are respectively connected to the external power supply device 5 to apply electrochemical excitation to the electrolysis system, causing the active metal in the positive electrode alloy to be reduced and deposited on the surface of the active metal adsorbent 42. When the deposited product exceeds the adsorption capacity of the active metal adsorbent 42, electrolysis is stopped, the cathode assembly 4 is replaced through the feed port 125, and the surface tension of lithium metal is used to achieve phase separation and recover the overflowing liquid metal from the molten salt surface by using a separation tool (the separation tool is a mesh scooping tool for separating liquid lithium and molten salt, whose mesh size is configured to allow molten salt to pass through while trapping liquid lithium) to recover the overflowing liquid metal from the molten salt surface, thereby achieving continuous batch recovery.

[0029] Reference Figures 1-5 This embodiment provides a liquid metal battery electrolytic recovery method, which includes adding molten salt electrolyte to a molten salt resistant reaction vessel 31 and introducing inert gas through an air inlet 121 and an air outlet 122 to replace the air in the reaction vessel 1 and maintain an inert atmosphere. Heating causes the molten salt electrolyte to melt, and the failed liquid metal battery positive electrode alloy is added to the molten salt resistant reaction vessel 31 through the feeding port 125. The anode conductive lead 32 and the conductive rod 41 are respectively connected to the external power supply device 5 to apply electrochemical excitation to the electrolysis system, so that the active metal in the positive electrode alloy is reduced and deposited on the active metal adsorbent 42.

[0030] In one embodiment provided in this application, when the deposited product exceeds the adsorption capacity of the active metal adsorbent 42, electrolysis is suspended, the cathode assembly 4 is replaced through the feed port 125, and the overflowing liquid metal is recovered from the molten salt surface using a separation tool.

[0031] In actual operation, taking the recovery of 1.5 kg of failed lithium bismuth alloy as an example: First, add the LiCl-LiBr-KBr ternary eutectic molten salt (molar ratio 33:29:38) into the graphite molten salt resistant reaction vessel 31, cover the top cover 12, and insert rubber plugs 129 into the feeding port 125, the anode wire inlet and outlet 126, the observation port 128, and the cathode wire inlet and outlet to ensure airtightness.

[0032] Then, high-purity argon gas (purity ≥99.999%) is introduced through the air inlet 121 at a flow rate of 0.5~1 L / min for 1 hour to replace the air in reactor 1; after replacement, the argon gas flow rate is adjusted to 0.1~0.2 L / min to maintain a slightly positive pressure inert atmosphere. The external heating furnace is started, and the temperature of reactor 1 is raised to 450~500℃ and held for 1 hour to allow the molten salt to completely melt and form a uniform molten salt layer 311. The rubber plug 129 is pulled out through the feeding port 125, 1.5 kg of degraded lithium bismuth alloy is added, and then it is immediately resealed. After standing for 1 hour, the alloy is fully dispersed and compatible with the molten salt. Then, the anode conductive lead 32 and the conductive rod 41 of the cathode assembly 4 are connected to a constant current / constant voltage power supply, respectively. A constant current of 2~10 A is applied for electrolysis for 1 hour, and then the constant voltage of 1.4 V is switched to continue electrolysis until the current decays to below 0.1 A, indicating that Li3Bi has been basically completely decomposed.

[0033] During electrolysis, lithium metal preferentially deposits on the active metal adsorbent 42 (such as foamed iron-nickel); when the deposition exceeds its adsorption capacity, some liquid lithium overflows onto the molten salt surface. At this point, electrolysis is paused, the cathode assembly 4 is removed and replaced with a new cathode, and a stainless steel wire mesh strainer (mesh aperture 0.1~1 mm) is used to retrieve the overflowed lithium metal from the molten salt surface. By repeating the "electrolysis-replacement-retrieval" operation, batch recovery of 1.5 kg of spent lithium-bismuth alloy can be efficiently completed.

[0034] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A liquid metal battery electrolytic recovery device, characterized in that: include, The reactor (1) includes a chamber (11) and a top cover (12) located on the top of the chamber (11). A cooling zone (2) surrounding the upper part of the cabin (11); The anode assembly (3) located in the reactor (1) includes a molten salt reaction vessel (31) and an anode conductive lead (32) embedded in the side wall of the molten salt reaction vessel (31). The cathode assembly (4) suspended in the molten salt reaction vessel (31) includes a conductive rod (41) penetrating the top cover (12) and an active metal adsorbent (42) disposed at one end of the conductive rod (41). The anode conductive lead (32) and the conductive rod (41) maintain an electrically isolated distance, and the anode conductive lead (32) and the conductive rod (41) are respectively led out through the top cover (12) to the outside of the reactor (1).

2. The liquid metal battery electrolytic recovery device according to claim 1, characterized in that: The molten salt reaction vessel (31) is provided with a molten salt layer (311), and the active metal adsorbent (42) is immersed in the molten salt layer (311).

3. The liquid metal battery electrolytic recovery device according to claim 1, characterized in that: The outer wall of the top cover (12) is provided with an air inlet (121) and an air outlet (122), which are respectively connected to the air supply pipe (123) and the air outlet pipe (124).

4. The liquid metal battery electrolysis and recovery device according to claim 3, characterized in that: A feeding port (125) is provided between the air inlet (121) and the air outlet (122), and the conductive rod (41) passes through the feeding port (125) to connect to an external power supply device (5).

5. The liquid metal battery electrolytic recovery device according to claim 4, characterized in that: An anode wire inlet / outlet (126) is provided between the air inlet (121) and the feeding port (125), and the anode conductive lead (32) passes through the anode wire inlet / outlet (126) to connect to an external power supply device (5).

6. The liquid metal battery electrolytic recovery device according to claim 5, characterized in that: An observation port (128) is provided between the feeding port (125) and the air outlet (122).

7. The liquid metal battery electrolytic recovery device according to claim 6, characterized in that: Rubber plugs (129) are movably provided inside the feeding port (125), the anode wire inlet / outlet (126), and the observation port (128).

8. The liquid metal battery electrolytic recovery device according to claim 1, characterized in that: The cooling zone (2) has an inlet (21) and an outlet (22) on its outer wall.

9. A method for electrolytic recycling of liquid metal batteries, characterized in that: The liquid metal battery electrolysis and recycling device as described in any one of claims 1 to 8 further includes, Molten salt electrolyte is added to the molten salt reaction vessel (31), and inert gas is introduced through the air inlet (121) and air outlet (122) to replace the air in the reaction vessel (1) and maintain an inert atmosphere; Heating causes the molten salt electrolyte to melt, and the failed liquid metal battery positive electrode alloy is added to the molten salt resistant reaction vessel (31) through the feeding port (125); The anode conductive lead (32) and the conductive rod (41) are respectively connected to an external power supply device (5) to apply electrochemical excitation to the electrolysis system, so that the active metal in the positive electrode alloy is reduced and deposited on the active metal adsorbent (42).

10. The method for electrolytic recovery of liquid metal batteries according to claim 9, characterized in that: When the deposited product exceeds the adsorption capacity of the active metal adsorbent (42), electrolysis is suspended, the cathode assembly (4) is replaced through the feed port (125), and the overflowing liquid metal is recovered from the molten salt surface using a separation tool.

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