A method, system, device, and medium for enhancing mass transfer in liquid metal batteries based on an external magnetic field of permanent magnets

Abstract

The application is suitable for the cross technical field of electrochemical energy storage and electromagnetic fluid mechanics, and discloses a method, system, device and medium for strengthening mass transfer of liquid metal batteries based on an external magnetic field of a permanent magnet, the method comprising: constructing a model of a liquid metal battery and externally arranging a permanent magnet on the model; obtaining a discharge current by discharging the liquid metal battery, and interacting the discharge current with an external magnetic field generated by the permanent magnet in a positive electrode region to obtain a Lorentz force in an azimuthal direction; generating Joule heat through the discharge current, performing iterative calculation of a fluid heat transfer physical field to obtain a converged temperature distribution, forming thermal-driven flow, and coupling vortex flow driven by the Lorentz force to calculate a flow velocity containing a rotating vortex flow characteristic; and based on the converged flow velocity, using a rare substance transfer physical field to strengthen the mass transfer process in the positive electrode region. The application effectively relieves the accumulation of negative electrode metal ions at the interface by externally arranging the permanent magnet, and improves the discharge performance of the battery.

Description

Technical Field

[0001] This invention relates to the interdisciplinary field of electrochemical energy storage and electromagnetic fluid dynamics, and in particular to a method, system, device and medium for enhancing mass transfer in liquid metal batteries based on an externally applied magnetic field to a permanent magnet. Background Technology

[0002] With the ongoing transition to clean energy, the proportion of photovoltaic and wind power generation is increasing, making the demand for large-scale, low-cost, and long-life energy storage systems more urgent. Liquid metal batteries, with their unique structure and excellent performance, are considered a highly promising next-generation large-scale energy storage solution.

[0003] Liquid metal batteries (LMBs) differ from traditional batteries due to their unique three-layer liquid structure. The fully liquid state eliminates dendrite growth issues and provides excellent high-rate performance, while the stable density stratification ensures stable operation. However, LMBs still face the inherent challenge of concentration polarization during discharge. Compared to the relatively fast electrochemical reactions at the electrode surface, mass transfer in the cathode is relatively slow. Furthermore, the lower density of lithium-bismuth alloys causes them to float on the cathode surface. This stable density stratification inhibits flow in the cathode, further slowing lithium mass transfer. A large amount of lithium accumulates at the cathode-electrolyte interface, causing severe concentration polarization. This manifests as a decrease in potential and reduced capacity utilization. This effect is particularly pronounced under low-temperature operation and high current density conditions, becoming a key bottleneck restricting further performance improvements in LMBs.

[0004] Due to the aforementioned shortcomings, further improvements are urgently needed in this field. To address the issues of slow mass transfer and severe concentration polarization within liquid metal batteries, a simple and effective method should be designed to reduce concentration polarization and improve battery discharge performance. Summary of the Invention

[0005] In view of the aforementioned existing problems, the present invention is proposed.

[0006] Therefore, this invention provides a method, system, device, and medium for enhancing mass transfer in liquid metal batteries using an external magnetic field on a permanent magnet to solve the problem of severe concentration polarization that commonly exists in existing liquid metal batteries during operation.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for enhancing mass transfer in a liquid metal battery based on an externally applied magnetic field using a permanent magnet, comprising: Construct a liquid metal battery model and attach an external permanent magnet to the model; The discharge current is obtained by discharging the liquid metal battery, and interacts with the external magnetic field generated by the permanent magnet in the positive pole region to obtain the Lorentz force in the azimuth direction. Joule heat is generated by the discharge current, and the convergent temperature distribution is obtained by performing iterative calculations of the fluid heat transfer physical field, forming a heat-driven flow. Coupled with the Lorentz force-driven vortex, the flow velocity containing the characteristics of rotating vortex is calculated. Based on the converged flow velocity, the mass transfer process inside the positive electrode region is enhanced by using rare matter to transfer the physical field.

[0008] As a preferred embodiment of the mass transfer method for liquid metal batteries based on an externally applied magnetic field to a permanent magnet as described in this invention, the method includes: constructing a liquid metal battery model and placing an external permanent magnet on the model, comprising: Construct a liquid metal battery model that includes a negative electrode region, an electrolyte region, and a positive electrode region; Define the boundary conditions for the liquid metal battery model, including that the negative electrode region is connected to the outside world through the negative electrode rod, and the positive electrode region is in direct contact with the metal shell.

[0009] As a preferred embodiment of the mass transfer method for liquid metal batteries based on an externally applied permanent magnet magnetic field enhanced by the present invention, wherein obtaining a convergent temperature distribution and a flow velocity containing rotating eddy current characteristics includes: Based on the Joule heat generated by the discharge current of the liquid metal battery, the heat transfer equation of the fluid heat transfer physical field is executed to calculate the temperature distribution. Based on the temperature distribution, the material density in the fluid heat transfer physical field and the turbulent physical field is updated using the equation of state. The buoyancy term generated by the updated material density is combined with the Lorentz force, and the momentum equation of the turbulent physical field is used to drive the fluid to form a rotating vortex, and the flow velocity is calculated. The flow velocity is fed back into the convection term of the fluid heat transfer physical field, and the temperature distribution is recalculated.

[0010] As a preferred embodiment of the mass transfer method for liquid metal batteries based on an externally applied magnetic field of a permanent magnet as described in this invention, the method includes: enhancing the mass transfer process within the positive electrode region using a rare-material transfer physical field based on the converged flow velocity, comprising: Based on the Lorentz force, a rotating vortex is formed in the positive electrode region of the liquid metal battery, which increases the Reynolds number of the flow and thus elevates the flow state to turbulence. Based on the physical field of rare matter transfer, the strong convection effect of rotating eddies is used to transport the discharge products accumulated at the positive electrode-electrolyte interface to the positive electrode region, thereby reducing the concentration gradient of discharge products at the positive electrode-electrolyte interface.

[0011] As a preferred embodiment of the mass transfer method for liquid metal batteries based on an externally applied magnetic field enhanced by a permanent magnet as described in this invention, wherein: the calculation of temperature distribution and updating of material density includes: Based on the Joule heat generated by the discharge current of the liquid metal battery, the heat transfer equations of the fluid heat transfer physics field are applied to calculate the temperature distribution. : In the formula, The density of the material; It is a constant pressure heat capacity; Indicates partial derivative; Indicates time; For flow velocity; For temperature gradient; For gradient operators; This refers to the heat dissipation power of convective heat transfer; It is Joule fever; This refers to the electrode current; Electrode conductivity; Based on the temperature distribution, the material density in the fluid heat transfer physical field and the turbulence physical field is updated using the equation of state: In the formula, The coefficient of thermal expansion of the material; This is the material reference density; This is the internal reference temperature of the liquid metal battery.

[0012] As a preferred embodiment of the mass transfer method for liquid metal batteries based on an externally applied magnetic field enhanced by a permanent magnet as described in this invention, the buoyancy term generated by the updated material density is combined with the Lorentz force, and the momentum equation of the turbulent physical field is used to drive the fluid to form a rotating vortex, and the flow velocity is calculated, including: Using the Navier-Stokes equations as the momentum equations, the flow process of a liquid metal battery is obtained: In the formula, It is the identity matrix; For fluid dynamic viscosity; Turbulent viscosity; It is the acceleration due to gravity; This is the buoyancy term; For Lorentz force.

[0013] As a preferred embodiment of the mass transfer method for liquid metal batteries based on an externally applied permanent magnet magnetic field enhanced according to the present invention, the mass transfer process within the enhanced positive electrode region includes: Based on the mass transfer process inside a liquid metal battery, the Planck-Nernst equation is used to derive the mass transfer process: In the formula, This refers to ion flux; This represents the diffusion coefficient of ion i; Indicates the dynamic viscosity of the fluid; Indicates the electrolyte potential; express The number of charges carried by ions; express The concentration of ions; It represents ion mobility; It is Planck's constant.

[0014] Secondly, the present invention provides a mass transfer system for liquid metal batteries based on an externally applied permanent magnet magnetic field to enhance mass transfer, comprising: The model building module is used to build a liquid metal battery model and attach an external permanent magnet to the model; The first calculation module is used to obtain the discharge current through the discharge of the liquid metal battery and to interact with the external magnetic field generated by the permanent magnet in the positive pole region to obtain the Lorentz force in the azimuth direction. The coupled calculation module is used to generate Joule heat through discharge current, perform iterative calculation of fluid heat transfer physical field to obtain converged temperature distribution, form heat-driven flow, couple Lorentz force driven eddies, and calculate flow velocity including rotating eddy characteristics. The mass transfer calculation module is used to enhance the mass transfer process within the cathode region by utilizing the physical field of rare matter transfer based on the converged flow velocity.

[0015] Thirdly, the present invention provides an electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the method for enhancing the mass transfer of liquid metal batteries based on an external magnetic field applied to a permanent magnet.

[0016] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the method for enhancing mass transfer in a liquid metal battery based on an externally applied permanent magnet magnetic field.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention does not alter the shape or upper structure of the battery body, nor does it require any additional complex operations; it can be achieved simply by adding a permanent magnet to the bottom of the battery. This not only simplifies the structure and facilitates implementation, but also significantly improves battery performance. The external magnetic field generated by the bottom permanent magnet interacts with the battery discharge current to produce a Lorentz force in the angular direction, causing rotating eddy currents at the positive electrode. This promotes mass transfer, enhances the battery's discharge performance, and ensures that the eddy current amplitude is not too large, thus avoiding problems such as interface deformation and reduced battery stability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall process of a method for enhancing mass transfer in a liquid metal battery based on an external magnetic field applied to a permanent magnet, according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the simulated structure of a liquid metal battery based on a permanent magnet external magnetic field to enhance mass transfer in an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the lithium concentration at the cathode-electrolyte interface of a 20Ah liquid metal battery under the action of permanent magnets of different sizes, based on the mass transfer method of liquid metal battery enhanced by external magnetic field on a permanent magnet according to an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the potential of 20Ah liquid metal under the action of permanent magnets of different sizes, based on the mass transfer method of liquid metal battery enhanced by external magnetic field on permanent magnets according to an embodiment of the present invention. Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0024] Example 1, referring to Figure 1 As one embodiment of the present invention, a method for enhancing mass transfer in a liquid metal battery based on an externally applied magnetic field using a permanent magnet is provided, comprising: S100: Construct a liquid metal battery model and attach an external permanent magnet to the model; S200: The discharge current is obtained by discharging through the liquid metal battery, and interacts with the external magnetic field generated by the permanent magnet in the positive pole region to obtain the Lorentz force in the azimuth direction; S300: Joule heat is generated by the discharge current, and the convergent temperature distribution is obtained by performing iterative calculation of the fluid heat transfer physical field, forming a heat-driven flow, coupled with the Lorentz force-driven vortex, and the flow velocity containing the characteristics of rotating vortex is calculated. S400: Based on the converged flow velocity, the mass transfer process inside the positive electrode region is enhanced by using rare matter to transfer the physical field.

[0025] It should be noted that during the discharge process of liquid metal batteries, the mass transfer process in the positive electrode region mainly relies on diffusion, which is relatively slow. As discharge progresses, negative electrode metal ions continuously enter the positive electrode, easily accumulating in large quantities at the positive electrode-electrolyte interface, forming a significant concentration gradient, i.e., concentration polarization, which leads to a decrease in battery output voltage and a reduction in energy efficiency.

[0026] Therefore, to address the aforementioned problems, steps S100-S400 involve placing a permanent magnet at the bottom of the battery, generating a ring-shaped magnetic field in the positive electrode region. When this magnetic field interacts with the vertical current of the cathode during discharge, a significant Lorentz force in the azimuth direction is generated within the positive electrode, disrupting the existing stable density stratification. This creates a high-speed rotating eddy current in the azimuth direction within the positive electrode, accompanied by a vertical component of a certain amplitude, with a flow intensity comparable to thermal convection under conventional operating conditions. This type of eddy current significantly promotes mass migration within the positive electrode, effectively mitigating the accumulation of metal ions at the interface of the negative electrode, thus greatly reducing concentration polarization and improving the battery's discharge voltage and energy utilization rate.

[0027] Example 2, refer to Figures 1-2 As an embodiment of the present invention, based on the above embodiment, a method for enhancing mass transfer in liquid metal batteries by applying an external magnetic field to a permanent magnet is provided.

[0028] In this embodiment of the application, step S100, which involves constructing a liquid metal battery model and placing an external permanent magnet on the model, includes: Specifically, finite element simulation software is used for analysis to construct a liquid metal battery model, and an external permanent magnet is placed at its bottom, such as... Figure 2 The model shown is a two-dimensional axisymmetric model. Rotating the entire battery around the left axis of symmetry creates a three-dimensional model. Inside the battery, the top layer is the negative electrode material lithium (Li), the middle layer is the LiCl-KCl electrolyte molten salt, and the bottom layer is the positive electrode material bismuth (Bi). The negative electrode is connected to the outside world through a negative electrode rod, while the positive electrode is in direct contact with the metal casing. Both the negative electrode rod and the metal casing are made of stainless steel, and they are insulated from each other by ceramic.

[0029] In an optional implementation, the model in step S100 uses lithium, bismuth, and LiCl-KCl as materials, or a lithium-antimony-lead (Li||Sb-Pb) alloy system. Specifically, the positive electrode material is set as an antimony-lead alloy, and the negative electrode material is liquid lithium. Since the alloy density differs from that of pure metals, the resulting buoyancy term also changes. Simulation verification shows that this method can also generate effective stirring eddies in the alloy positive electrode, demonstrating the applicability of this method to low-cost alloy systems.

[0030] In another optional implementation, the model in step S100 uses lithium, bismuth, and LiCl-KCl as materials, and a sodium-bismuth (Na||Bi) system can also be used. Specifically, the negative electrode material is set to liquid sodium, the positive electrode material is set to liquid bismuth, and the electrolyte is a sodium-based molten salt. This aims to verify that the method of enhancing mass transfer with an external magnetic field is not only applicable to lithium-based batteries, but also to sodium-based liquid metal battery systems, which have more abundant resources and lower costs.

[0031] Meanwhile, the left side of the model is an axisymmetric boundary, the negative electrode lead is grounded, the outer shell on the upper surface of the positive electrode has a constant current, the negative electrode-electrolyte interface and the positive electrode-electrolyte interface are set with equilibrium potentials, and the other interfaces are electrically insulating interfaces.

[0032] Furthermore, the magnetic field distribution of the liquid metal battery is described using the physical field of magnetic fields. Therefore, by placing an external permanent magnet at the bottom of the model, a ring-shaped magnetic field can be generated in the positive electrode region.

[0033] In an alternative implementation, the external permanent magnet at the bottom of the model in step S100 can also be placed on the side of the liquid metal battery, around the side wall, or on the top, as long as it can generate a magnetic field that passes through the positive electrode region.

[0034] In another optional implementation, the shape of the permanent magnet in step S100 is not limited to a ring shape. A ring structure with a hollow center can also be used and placed at the bottom of the battery. Compared to a solid cylindrical magnet, a ring magnet alters the magnetic field distribution gradient within the positive electrode region, making the magnetic field strength relatively stronger at the edge region and weaker in the central region. Since the edge region of a liquid metal battery is often a critical area with high current density and prone to polarization during high-current discharge, using a ring magnet can specifically enhance the Lorentz force and eddy current intensity in the edge region, thereby improving the mass transfer effect in the edge region.

[0035] It should be noted that the preferred permanent magnet of the present invention is sintered AlNiCo, which can operate at a temperature of up to 550°C.

[0036] In an optional embodiment, the permanent magnet in step S100 can be sintered AlNiCo, or it can be samarium cobalt (SmCo) permanent magnet material, etc. Specifically, considering that liquid metal batteries typically operate at high temperatures of 400°C to 500°C, samarium cobalt magnets have extremely high Curie temperatures (approximately 700-800°C) and excellent thermal stability.

[0037] In another optional implementation, the permanent magnet in step S100 can be sintered AlNiCo permanent magnet material, or an AlNiCo permanent magnet material. Specifically, for certain high-temperature molten salt battery systems with higher operating temperatures (e.g., exceeding 500°C), AlNiCo magnets provide optimal temperature resistance.

[0038] In this embodiment of the application, step S200 involves obtaining a discharge current through the discharge of a liquid metal battery, which interacts with an external magnetic field generated by a permanent magnet in the positive electrode region to obtain a Lorentz force in the azimuth direction, including: Specifically, the potential current during the discharge process of a liquid metal battery is described using a three-dimensional current distribution physical field. The vertical discharge current at the negative electrode, generated by the liquid metal battery discharge, interacts with the external magnetic field produced by the permanent magnet in the positive electrode region. The permanent magnet then generates magnetic fields along the three directions r, phi, and z. , , Current in three directions , , The interaction generates a Lorentz force in the positive electrode region. : In the formula, , , There are three directions.

[0039] Furthermore, the potential during battery discharge... Determined by the equilibrium potentials of the positive and negative electrodes and the overpotential, it can be expressed as: In the formula, , These are the equilibrium potentials of the positive and negative electrodes, respectively, with the reference equilibrium potential of the negative electrode defined as 0. This represents the Ohmic polarization overpotential. This is the concentration polarization overpotential; This represents the electrochemical polarization overpotential.

[0040] in, , Calculated using the Nernst equation: In the formula, It is the ideal gas constant; Temperature distribution in a liquid metal battery; It is Planck's constant; It indicates the activity of Li, which is transported by electrons in the positive and negative electrodes and by ions in the electrolyte; The equilibrium potential of a battery can be obtained by coulometric titration. The calculation yielded: At the same time, charge conservation is satisfied everywhere in the electrolyte: In the formula, express The number of charges carried by ions; express The concentration of ions; It is the summation symbol.

[0041] The electrochemical reaction rate at the cathode-electrolyte interface can be expressed as: In the formula, This represents the local current density at the positive electrode-electrolyte interface; The anode transfer coefficient; The cathode transfer coefficient; This is the overpotential at the positive electrode-electrolyte interface; For exchange current density.

[0042] In this embodiment of the application, in step S300, Joule heating is generated by the discharge current, and a convergent temperature distribution is obtained by performing iterative calculations of the fluid heat transfer physical field, forming a heat-driven flow. A vortex driven by the Lorentz force is coupled, and the flow velocity containing the characteristics of the rotating vortex is calculated, including the following steps A1-A4: A1: Based on the Joule heat generated by the discharge current of the liquid metal battery, execute the heat transfer equation of the fluid heat transfer physical field to calculate the temperature distribution; Specifically, during the discharge process of a liquid metal battery, Joule heating is generated due to the discharge current. Since the conductivity of the molten salt electrolyte is much lower than that of the positive and negative electrode materials, Joule heating is mainly generated in the electrolyte region.

[0043] Heat transfer inside a liquid metal battery is described by a fluid heat transfer physics field. Furthermore, the temperature distribution inside the battery is also affected by the external environment (which can be described using boundary conditions). The heat transfer equations of the fluid heat transfer physics field are executed to calculate the temperature distribution. : In the formula, The density of the material; It is a constant pressure heat capacity; Indicates partial derivative; Indicates time; For flow velocity; For temperature gradient; For gradient operators; This refers to the heat dissipation power of convective heat transfer; It is Joule fever; This refers to the electrode current; Electrode conductivity; is the thermal conductivity.

[0044] A2: Based on the temperature distribution, update the material density in the fluid heat transfer physical field and the turbulent physical field using the equation of state; In the formula, The coefficient of thermal expansion of the material; This is the material reference density; This is the internal reference temperature of the liquid metal battery.

[0045] It should be noted that because temperature distribution affects density, the higher the temperature of a material, the lower its density, and it will float; conversely, the lower the temperature, the higher the density, and it will sink. This density difference between different temperature regions creates a buoyancy term. This drives the fluid to generate natural convection.

[0046] A3: The buoyancy term generated by the updated material density is combined with the Lorentz force, and the momentum equation of the turbulent physical field is used to drive the fluid to form a rotating vortex, and the flow velocity is calculated. Specifically, the flow inside a liquid metal battery is described using turbulent physics.

[0047] Using the Navier-Stokes equations from the RANS-EVM k-ε turbulence model as the momentum equations, the flow process of the liquid metal battery is obtained: In the formula, ; It is the identity matrix; For fluid dynamic viscosity; Turbulent viscosity; This is the acceleration due to gravity.

[0048] Among them, turbulent viscosity Solve using the following formulas: get : In the formula, It is turbulent kinetic energy; This is the term representing the generation of turbulent kinetic energy caused by the average velocity gradient; The turbulent kinetic energy loss rate; , , , , These are empirical constants in the standard k-ε turbulence model, using the Launder-Spalding standard values, which are 1.44, 1.92, 0.09, 1.0, and 1.3, respectively.

[0049] A4: Flow velocity The temperature distribution is recalculated in the convection term of the fluid heat transfer physical field.

[0050] In this embodiment of the application, step S400, based on the converged flow velocity, utilizes a rare matter transfer physical field to enhance the mass transfer process within the positive electrode region, including: Specifically, based on the Lorentz force, a rotating vortex is formed in the positive electrode region of the liquid metal battery, which increases the Reynolds number of the flow and thus elevates the flow state to turbulence. The mass transfer process inside the liquid metal battery is described by the physical field of rare matter transfer. The strong convection effect of the rotating vortex is used to transport the discharge products accumulated at the positive electrode-electrolyte interface to the positive electrode region, thereby reducing the concentration gradient of discharge products at the positive electrode-electrolyte interface.

[0051] Furthermore, the transfer of rare matter, i.e., the mass transfer process, in the negative electrode region can be described by the Planck-Nernst equation: In the formula, This refers to ion flux; This represents the diffusion coefficient of ion i; Indicates the electrolyte potential; It represents ion mobility; Indicates the diffusion term; Indicates electromigration term; Indicates the convection term; Since there are no ions in the positive electrode, there is no electromigration process; that is, the mass transfer process in the positive electrode region can be represented as: At the same time, charge conservation is satisfied everywhere in the electrolyte: Furthermore, in the electrolyte, it functions as lithium ions, meaning that at this time... for The solution is then performed, and the electrolyte is generated at the negative electrode-electrolyte interface and consumed at the positive electrode-electrolyte interface. The mass transfer process in the electrolyte is mediated by the source term. Couple: In the formula, Indicates the mobility of lithium; This represents the current density at the interface; This represents the number of charges carried by the ion.

[0052] As the battery discharges, lithium is continuously transferred to the bismuth cathode. The diffusion coefficient of lithium in the cathode... The density is measured using a constant current intermittent titration method. During lithium transport, the composition of the cathode changes accordingly, thus affecting the cathode density. And with the changes: In the formula, This indicates the molar percentage of lithium in the positive electrode; This indicates the molar percentage of bismuth in the positive electrode; and These represent the molar masses of lithium and bismuth, respectively. and These are the densities of lithium and bismuth, respectively.

[0053] It should be noted that since the positive electrode is Bi before discharge, as the discharge proceeds, Li is reduced at the positive electrode and gradually increases, and begins to mix with Bi to form a mixture of LiBi. Therefore, the proportion and density of the mixture also change in real time.

[0054] Example 3, referring to Figures 3-4 As an embodiment of the present invention, based on the above embodiment, a simulation experiment is provided to enhance the mass transfer of liquid metal batteries by applying an external magnetic field to a permanent magnet, so as to verify its feasibility and effect. By changing the size of the permanent magnet, the battery was discharged at a rate of 0.5C to obtain the magnetic field strength generated by the permanent magnet in the positive electrode, as shown in Table 1.

[0055] Table 1

[0056] In a 20Ah liquid metal battery, after externally placing permanent magnets 1-4 of different sizes, the resulting lithium concentration at the positive electrode-electrolyte interface was observed. ,like Figure 3 As shown: Compared to the case without permanent magnets, the larger the diameter and thickness of the permanent magnet, the higher the lithium concentration at the positive electrode-electrolyte interface. The smaller.

[0057] Therefore, when an external permanent magnet is used, lithium is transferred to the depth of the positive electrode, and the lithium concentration at the positive electrode-electrolyte interface can be effectively reduced.

[0058] After externally placing permanent magnets 1-4 of different sizes on a 20Ah liquid metal battery, the potential of the liquid metal battery is as follows: Figure 4 As shown, compared to the case without permanent magnets, the larger the diameter and thickness of the permanent magnet, the greater the potential.

[0059] Therefore, with the external permanent magnet, the concentration polarization limiting the battery discharge voltage is weakened due to the reduced lithium concentration at the positive electrode-electrolyte interface, thus effectively increasing the battery discharge voltage. It should be noted that this approach is also applicable to process strategies that apply a strong magnetic field for short periods to facilitate short-circuit self-repair.

[0060] In summary, this invention does not alter the battery's main shape or upper structure, nor does it require any additional complex operations; it only requires adding a permanent magnet to the bottom of the battery. When the annularly distributed external magnetic field generated by the permanent magnet at the bottom of the liquid metal battery interacts with the vertical current of the cathode during discharge, a significant Lorentz force in the azimuth direction is generated inside the positive electrode, thereby breaking the original stable density stratification. This forms a high-speed rotating eddy current in the azimuth direction within the positive electrode, accompanied by a vertical component of a certain amplitude, with a flow intensity comparable to thermal convection under conventional operating conditions. This type of eddy current significantly promotes material migration inside the positive electrode, effectively alleviating the accumulation of metal ions at the interface of the negative electrode, thus greatly weakening the concentration polarization effect and improving the battery's discharge voltage and energy utilization rate.

[0061] Example 3 illustrates a schematic scheme for a method of enhancing mass transfer in a liquid metal battery using an externally applied permanent magnet magnetic field. It should be noted that the technical solution of this system for enhancing mass transfer in a liquid metal battery using an externally applied permanent magnet magnetic field is based on the same concept as the aforementioned method. Details not described in detail in this embodiment can be found in the description of the aforementioned method.

[0062] This embodiment also provides a mass transfer system for liquid metal batteries based on an externally applied magnetic field enhanced by a permanent magnet, including: The model building module is used to build a liquid metal battery model and attach an external permanent magnet to the model; The first calculation module is used to obtain the discharge current through the discharge of the liquid metal battery and to interact with the external magnetic field generated by the permanent magnet in the positive pole region to obtain the Lorentz force in the azimuth direction. The coupled calculation module is used to generate Joule heat through discharge current, perform iterative calculation of fluid heat transfer physical field to obtain converged temperature distribution, form heat-driven flow, couple Lorentz force driven eddies, and calculate flow velocity including rotating eddy characteristics. The mass transfer calculation module is used to enhance the mass transfer process within the cathode region by utilizing the physical field of rare matter transfer based on the converged flow velocity.

[0063] This embodiment also provides an electronic device applicable to the situation of enhancing mass transfer of liquid metal batteries based on an external magnetic field applied by a permanent magnet, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to realize the method of enhancing mass transfer of liquid metal batteries based on an external magnetic field applied by a permanent magnet as proposed in the above embodiment.

[0064] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the mass transfer method for liquid metal batteries based on an external magnetic field enhanced by a permanent magnet, as proposed in the above embodiments.

[0065] The storage medium proposed in this embodiment and the method for enhancing the mass transfer of liquid metal batteries based on an external magnetic field of a permanent magnet proposed in the above embodiments belong to the same inventive concept. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0066] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for enhancing mass transfer in a liquid metal battery using an externally applied magnetic field on a permanent magnet, characterized in that, include: Construct a liquid metal battery model and attach an external permanent magnet to the model; The discharge current is obtained by discharging the liquid metal battery, and interacts with the external magnetic field generated by the permanent magnet in the positive pole region to obtain the Lorentz force in the azimuth direction. Joule heat is generated by the discharge current, and the convergent temperature distribution is obtained by performing iterative calculations of the fluid heat transfer physical field, forming a heat-driven flow. Coupled with the Lorentz force-driven vortex, the flow velocity containing the characteristics of rotating vortex is calculated. Based on the converged flow velocity, the mass transfer process inside the positive electrode region is enhanced by using rare matter to transfer the physical field.

2. The method for enhancing mass transfer in a liquid metal battery based on an externally applied magnetic field using a permanent magnet as described in claim 1, characterized in that, Constructing a liquid metal battery model and attaching an external permanent magnet to the model includes: Construct a liquid metal battery model that includes a negative electrode region, an electrolyte region, and a positive electrode region; Define the boundary conditions for the liquid metal battery model, including that the negative electrode region is connected to the outside world through the negative electrode rod, and the positive electrode region is in direct contact with the metal shell.

3. The method for enhancing mass transfer in a liquid metal battery based on an externally applied magnetic field using a permanent magnet as described in claim 2, characterized in that, The convergent temperature distribution and flow velocity containing rotating vortex characteristics are obtained, including: Based on the Joule heat generated by the discharge current of the liquid metal battery, the heat transfer equation of the fluid heat transfer physical field is executed to calculate the temperature distribution. Based on the temperature distribution, the material density in the fluid heat transfer physical field and the turbulent physical field is updated using the equation of state. The buoyancy term generated by the updated material density is combined with the Lorentz force, and the momentum equation of the turbulent physical field is used to drive the fluid to form a rotating vortex, and the flow velocity is calculated. The flow velocity is fed back into the convection term of the fluid heat transfer physical field, and the temperature distribution is recalculated.

4. The method for enhancing mass transfer in a liquid metal battery based on an externally applied magnetic field using a permanent magnet as described in claim 3, characterized in that, Based on the converged flow velocity, the mass transfer process within the cathode region is enhanced using a rare matter transfer physical field, including: Based on the Lorentz force, a rotating vortex is formed in the positive electrode region of the liquid metal battery, which increases the Reynolds number of the flow and thus elevates the flow state to turbulence. Based on the physical field of rare matter transfer, the strong convection effect of rotating eddies is used to transport the discharge products accumulated at the positive electrode-electrolyte interface to the positive electrode region, thereby reducing the concentration gradient of discharge products at the positive electrode-electrolyte interface.

5. The method for enhancing mass transfer in a liquid metal battery based on an externally applied magnetic field using a permanent magnet as described in claim 3, characterized in that, The calculation of temperature distribution and updating of material density includes: Based on the Joule heat generated by the discharge current of the liquid metal battery, the heat transfer equations of the fluid heat transfer physics field are applied to calculate the temperature distribution. : In the formula, The density of the material; It is a constant pressure heat capacity; Indicates partial derivative; Indicates time; For flow velocity; For temperature gradient; For gradient operators; This refers to the heat dissipation power of convective heat transfer; It is Joule fever; This refers to the electrode current; Electrode conductivity; Based on the temperature distribution, the material density in the fluid heat transfer physical field and the turbulence physical field is updated using the equation of state: In the formula, The coefficient of thermal expansion of the material; This is the material reference density; This is the internal reference temperature of the liquid metal battery.

6. The method for mass transfer in a liquid metal battery based on an externally applied permanent magnet magnetic field as described in claim 5, characterized in that, The buoyancy term generated by the updated material density, combined with the Lorentz force, is used to drive the fluid to form a rotating vortex using the momentum equation of turbulent physics, and the flow velocity is calculated, including: Using the Navier-Stokes equations as the momentum equations, the flow process of a liquid metal battery is obtained: In the formula, It is the identity matrix; For fluid dynamic viscosity; Turbulent viscosity; It is the acceleration due to gravity; This is the buoyancy term; For Lorentz force.

7. The method for enhancing mass transfer in a liquid metal battery based on an externally applied magnetic field using a permanent magnet as described in claim 6, characterized in that, The enhanced mass transfer process within the positive electrode region includes: Based on the mass transfer process inside a liquid metal battery, the Planck-Nernst equation is used to derive the mass transfer process: In the formula, This refers to ion flux; This represents the diffusion coefficient of ion i; Indicates the dynamic viscosity of the fluid; Indicates the electrolyte potential; express The number of charges carried by ions; express The concentration of ions; It represents ion mobility; It is Planck's constant.

8. A mass transfer system for liquid metal batteries based on an externally applied magnetic field enhanced by a permanent magnet, using the method as described in any one of claims 1-7, characterized in that, include: The model building module is used to build a liquid metal battery model and attach an external permanent magnet to the model; The first calculation module is used to obtain the discharge current through the discharge of the liquid metal battery and to interact with the external magnetic field generated by the permanent magnet in the positive pole region to obtain the Lorentz force in the azimuth direction. The coupled calculation module is used to generate Joule heat through discharge current, perform iterative calculations of the fluid heat transfer physical field to obtain a converged temperature distribution, form a heat-driven flow, couple the Lorentz force-driven eddies, and calculate the flow velocity including the characteristics of rotating eddies; The mass transfer calculation module is used to enhance the mass transfer process within the cathode region by utilizing the physical field of rare matter transfer based on the converged flow velocity.

9. An electronic device, characterized in that, include: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the mass transfer method for liquid metal batteries based on permanent magnet external magnetic field enhancement as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It includes storing computer-executable instructions that, when executed by a processor, implement the steps of the mass transfer method for liquid metal batteries based on an externally applied permanent magnet magnetic field as described in any one of claims 1 to 7.

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