Liquid metal battery based on high-entropy alloy electrode and preparation method thereof

Abstract

The invention discloses a liquid metal battery based on a high-entropy alloy electrode and a preparation method thereof, and belongs to the technical field of liquid metal battery electrode design, the liquid metal battery comprises a shell, and a positive current collector, a negative current collector and an electrolyte which are spread in the shell; a negative electrode material is adsorbed on the negative electrode current collector; the positive electrode current collector is provided with a positive electrode material, and the positive electrode material comprises more than three positive electrode active metals of Te, Se, Bi, Sb, Zn and Co and more than two additives X of Sn, Mo, Cu, Cd, Ga, In, W, Fe and Ni. The high-entropy alloy constructed by taking the tellurium-selenium metal as the core has a multi-metal structure and a uniform solid solution phase, so that the dissolution and side reaction of the tellurium-selenium metal and a product thereof in electrolyte are inhibited, the thermal runaway phenomenon is avoided, and the safety and coulombic efficiency of a high-temperature battery are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of designing liquid metal battery electrodes, and more specifically, relates to a liquid metal battery based on high entropy alloy electrodes and a preparation method thereof. Background Art

[0002] According to the International Energy Agency's "Electricity Mid-Year Update" report, global renewable energy generation will exceed coal-fired power plants for the first time in 2025. This shift is an important milestone in the global energy sector. In response to this trend, building a "new power / energy supply system" based on clean energy and making full use of renewable energy are important ways to achieve energy structure transformation and decarbonization, and are important development directions for energy storage technology and major national strategic needs.

[0003] At present, renewable energy generation is uncontrollable, unstable and unpredictable. In order to achieve efficient access to the grid for renewable energy, it is essential to develop a low-cost, high-energy-density and safe energy storage technology. So far, various battery technologies have been used for fast and efficient energy storage, especially lithium batteries, which have been widely used in various portable electronic devices and new energy vehicle power batteries. However, the capacity of lithium-ion batteries has reached its upper limit and the use of organic electrolytes causes great safety hazards to the batteries under conditions of thermal runaway and external forces. Therefore, finding alternatives with high energy density, cost-effectiveness and good safety remains an important part of battery research. Liquid metal battery (LMB) adopts a fully liquid design, consisting of two different liquid metal electrodes and molten salt electrolytes. The three-layer liquid is automatically stratified by the difference in density. During the cycle, there will be no structural changes due to the use of liquid electrodes; the characteristics of molten salt electrolysis also make liquid metal batteries without diaphragms; these characteristics of liquid metal batteries also make them have long cycle life, low energy storage cost, and easy to scale up production, making them an ideal choice for power energy storage.

[0004] As an alloy material composed of multiple elements, high entropy alloy can provide higher chemical stability and structural stability, which helps to extend the life of the battery. In addition, the complex chemical composition and unique phase structure of high entropy alloy can reduce the dissolution of positive electrode materials in molten salt electrolytes and improve the cycle stability of the battery. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a liquid metal battery based on high entropy alloy electrodes and a preparation method thereof, thereby solving the technical problem of poor cycle stability of the existing battery due to the dissolution of high-voltage materials in the electrolyte.

[0006] To achieve the above-mentioned purpose, according to one aspect of the present invention, a liquid metal battery based on a high entropy alloy electrode is provided, comprising a shell and a positive electrode collector, a negative electrode collector and an electrolyte spread in the shell; the negative electrode collector is adsorbed with a negative electrode material; the positive electrode collector is provided with a positive electrode material, and the positive electrode material includes more than three positive electrode active metals selected from Te, Se, Bi, Sb, Zn, and Co and more than two additives X selected from Sn, Mo, Cu, Cd, Ga, In, W, Fe, and Ni.

[0007] Preferably, the amount of the additive X accounts for 10% to 25% of the total amount of the positive electrode material.

[0008] Preferably, the electrolyte is an inorganic halide electrolyte.

[0009] Preferably, the electrolyte comprises LiCl, LiBr, LiI, NaCl, NaBr, NaI, KCl, KBr or KI.

[0010] Preferably, the negative electrode material includes at least one of Na and Li.

[0011] According to another aspect of the present invention, a method for preparing a liquid metal battery based on a high entropy alloy electrode is provided, the method comprising the following steps:

[0012] S1, mixing three or more positive electrode active metals of Te, Se, Bi, Sb, Zn, and Co with two or more additives X of Sn, Mo, Cu, Cd, Ga, In, and W in proportion, and then putting them into a ball mill for ball milling to uniformly mix the metals to obtain a metal mixture; mixing three or more positive electrode active metals of Te, Se, Bi, Sb, Zn, and Co with two or more additives X of Sn, Mo, Cu, Cd, Ga, In, and W in proportion, and then putting them into a ball mill for ball milling to uniformly mix the metals to obtain a metal mixture;

[0013] S2, melting the metal mixture in a vacuum environment and annealing to obtain a positive electrode material;

[0014] S3, placing the positive electrode material on the positive electrode current collector, and placing the molten electrolyte and the negative electrode current collector adsorbed with the negative electrode material into the shell in sequence, thereby completing the preparation of the liquid metal battery.

[0015] Preferably, the ball milling time in step S1 is 4 to 9 hours, and the ball milling speed is 300 to 500 rpm.

[0016] Preferably, anhydrous ethanol is added as a dispersant during the mixing of the positive electrode active metal and the additive X to prevent the metals from agglomerating during the ball milling process.

[0017] Preferably, step S3 specifically includes:

[0018] S21, placing the metal mixture into a muffle furnace, and evacuating the muffle furnace or introducing an inert gas;

[0019] S22, slowly raising the temperature of the muffle furnace from room temperature to 200-300° C. and maintaining it for 1 hour to remove residual moisture and volatile impurities in the metal mixture;

[0020] S23, continue to heat up to 600-1000°C at a rate of 2°C / min and keep warm for 2 hours to allow the metal components to fully melt and undergo a complete alloying reaction. The molten alloy is annealed at 400°C for 3 hours and then slowly cooled to room temperature to obtain a positive electrode material.

[0021] Preferably, the positive electrode active metal and the additive X are both in powder form.

[0022] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0023] 1. The liquid metal battery based on high entropy alloy electrodes proposed in the present invention has a high entropy alloy constructed with tellurium selenide metal as the core, which has a multi-metal structure and a uniform solid solution phase composition, so that it inhibits the dissolution of tellurium selenide metal and its products in the electrolyte and the occurrence of side reactions, avoids the occurrence of thermal runaway, and improves the safety and coulombic efficiency of high-temperature batteries.

[0024] 2. In the liquid metal battery based on high entropy alloy electrodes proposed in the present invention, the use of additive X enables the high entropy alloy electrode material to maintain low ion migration impedance in a high temperature environment, significantly improves the conductivity, reduces the influence of internal resistance on the charging and discharging process, and can improve the contact between the electrode and the current collector, thereby improving the charging and discharging efficiency and power density of the battery.

[0025] 3. The preparation method of the liquid metal battery based on high entropy alloy electrodes proposed in the present invention realizes the uniform distribution and stable structure of multiple elements by adding nano-scale metal powder and strictly controlling the high-temperature sintering process, so that the electrode has excellent cycle stability under high temperature and high pressure conditions, avoiding material expansion and cracking caused by temperature changes, thereby extending the cycle life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of a method for preparing a liquid metal battery based on a high entropy alloy electrode of the present invention;

[0027] Figure 2 is a charge and discharge performance curve diagram of the liquid metal battery in Example 1 of the present invention;

[0028] Figure 3 is a cycle performance diagram of the liquid metal battery in Example 3 of the present invention;

[0029] Figure 4 is a charge and discharge performance curve diagram of the liquid metal battery in Example 3 of the present invention;

[0030] Figure 5 It is a charge and discharge performance curve diagram of the liquid metal battery of Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The present invention proposes a liquid metal battery based on a high entropy alloy electrode, comprising a shell and a positive electrode current collector, a negative electrode current collector and an electrolyte spread in the shell; the negative electrode current collector is adsorbed with a negative electrode material; the positive electrode current collector is provided with a positive electrode material, and the positive electrode material comprises more than three positive electrode active metals selected from Te, Se, Bi, Sb, Zn and Co and more than two additives X selected from Sn, Mo, Cu, Cd, Ga, In, W, Fe and Ni.

[0033] To further illustrate, the ratio of the positive electrode active metal to the additive X is close.

[0034] In further explanation, the electrolyte is an inorganic halide electrolyte. As a preferred embodiment of the present invention, the electrolyte includes LiCl, LiBr, LiI, NaCl, NaBr, NaI, KCl, KBr or KI.

[0035] like Figure 1 As shown, the present invention proposes a method for preparing a liquid metal battery based on a high entropy alloy electrode, the method comprising the following steps:

[0036] Step S1:

[0037] Preparation of high entropy alloy electrodes

[0038] 1. Metal mixing and ball milling

[0039] Accurately weigh metal elements such as Bi, Sb, Te, Cu, Se, etc. according to the proportion of alloy design to ensure accurate ratio to achieve the expected alloying effect. Place the weighed metal elements in a wear-resistant ball mill and add 1% to 5% anhydrous ethanol as a dispersant to prevent metal powders from agglomerating during ball milling and reduce the risk of oxidation. Ball milling is carried out under the protection of high-purity argon. The ball milling time is controlled at 4 to 9 hours and the ball milling speed is 300 to 500 rpm to achieve uniform mixing of the metal elements. This step aims to achieve preliminary microscopic mixing through mechanical force to improve the uniformity and reactivity of the material.

[0040] 2. Alloy melting and vacuum treatment

[0041] The ball-milled metal mixture is placed in a muffle furnace with a high vacuum function. By vacuuming or protecting with high-purity inert gas, oxidation and volatilization loss of metal elements during subsequent heating are prevented. The furnace temperature is slowly raised from room temperature to 200-300°C and maintained for 1 hour to remove residual volatile impurities such as moisture and organic matter, reducing the risk of contamination during subsequent melting. When the temperature is stable, the temperature is continued to rise at a rate of 2°C / min, gradually rising to 600-1000°C to prevent excessive volatilization of elements caused by too fast heating and ensure the effective retention of metal components. After reaching the target temperature, keep warm for 2 hours to ensure that all metal components are fully melted and complete alloying reaction occurs, thereby forming a single-phase uniform high-entropy alloy structure. The melted alloy is annealed at 400°C for 3 hours to eliminate internal stress and improve the grain structure of the material. Then slowly cool down to room temperature to prevent cracks or structural instability in the alloy during cooling.

[0042] Step S2: Battery Assembly

[0043] After placing the positive electrode material on the positive electrode current collector, the negative electrode material is adsorbed on the negative electrode current collector, and then the electrolyte is heated to melt, and the electrolyte and the negative electrode current collector are placed in the shell in turn, and then the battery is welded into a whole to complete the battery assembly.

[0044] The technical solution of the present invention is further illustrated by specific embodiments below.

[0045] Example 1

[0046] Embodiment 1 of the present invention provides a liquid metal battery based on a high entropy alloy electrode and a preparation method thereof, comprising the following steps:

[0047] (1) Selecting metal Na as the negative electrode material;

[0048] (2) Using 20:20:20:20:20 mol% Bi-Te-Sb-Cu-Sn high entropy alloy as the positive electrode material, weighing the corresponding mass of metal powder according to the molar ratio composition of the positive electrode material using a balance, and preparing the required positive electrode material according to the aforementioned steps;

[0049] (3) The electrolyte material is NaCl-LiCl-KCl ternary mixed cationic molten salt, and the molar ratio of NaCl-LiCl-KCl is 6:59:36. The preparation process of the electrolyte is: different electrolytes are heated to 200°C in a vacuum oven to remove the crystal water in the electrolyte, and then the corresponding masses are weighed according to the molar ratio of the electrolyte components and mixed, and then melted in a glove box electric furnace, cooled and crushed to obtain a usable electrolyte;

[0050] (4) The negative electrode current collector and negative electrode material, the positive electrode current collector and positive electrode material, and the electrolyte are assembled into a liquid metal battery according to the above steps. The assembled liquid metal battery is placed in an electric furnace and heated to 470°C. It is tested at a charge and discharge current of 0.3A. The test results are as follows: Figure 2 , Figure 3 As shown, the battery capacity is 0.53Ah. The battery operates stably during the test without short circuit, showing a higher voltage platform. The coulombic efficiency is finally stabilized at 97%, indicating that the battery maintains good electrochemical stability and high energy conversion efficiency over multiple cycles.

[0051] Example 2

[0052] Embodiment 2 of the present invention provides a liquid metal battery based on a high entropy alloy electrode and a preparation method thereof, comprising the following steps:

[0053] (1) Selecting metal Na as the negative electrode material;

[0054] (2) Using 25:25:20:20:10 mol% Cu-Ni-Fe-Cr-Mn high entropy alloy as the positive electrode material, weighing the corresponding mass of metal powder on a balance according to the molar ratio composition of the positive electrode material, and preparing the required positive electrode material according to the above steps;

[0055] (3) The electrolyte material is NaCl-LiCl-KCl ternary mixed cationic molten salt, and the molar ratio of NaCl-LiCl-KCl is 6:59:36. The preparation process of the electrolyte is: different electrolytes are heated to 200°C in a vacuum oven to remove the crystal water in the electrolyte, and then the corresponding masses are weighed according to the molar ratio of the electrolyte components and mixed, and then melted in a glove box electric furnace, cooled and crushed to obtain a usable electrolyte;

[0056] (4) The negative electrode current collector and negative electrode material, the positive electrode current collector and positive electrode material, and the electrolyte are assembled into a liquid metal battery according to the above steps. The assembled liquid metal battery is placed in an electric furnace and heated to 470° C. and tested at a charge and discharge current of 0.3 A, and the process is the same as in Example 1.

[0057] Example 3

[0058] Embodiment 3 of the present invention provides a liquid metal battery based on a high entropy alloy electrode and a preparation method thereof, comprising the following steps:

[0059] (1) Selecting metal Na as the negative electrode material;

[0060] (2) Using 15:30:20:15:10:10 mol% Bi-Te-Se-Sb-Cu-Mo high entropy alloy as the positive electrode material, weighing the corresponding mass of metal powder on a balance according to the molar ratio composition of the positive electrode material, and preparing the required positive electrode material according to the above steps;

[0061] (3) The electrolyte material is NaCl-LiCl-KCl ternary mixed cationic molten salt, and the molar ratio of NaCl-LiCl-KCl is 6:59:36. The preparation process of the electrolyte is: different electrolytes are heated to 200°C in a vacuum oven to remove the crystal water in the electrolyte, and then the corresponding masses are weighed according to the molar ratio of the electrolyte components and mixed, and then melted in a glove box electric furnace, cooled and crushed to obtain a usable electrolyte;

[0062] (4) The negative electrode current collector and negative electrode material, the positive electrode current collector and positive electrode material, and the electrolyte are assembled into a liquid metal battery according to the above steps. The assembled liquid metal battery is placed in an electric furnace and heated to 470° C. and tested at a charge and discharge current of 0.3 A, and the process is the same as in Example 1.

[0063] Example 4

[0064] Embodiment 4 of the present invention provides a liquid metal battery based on a high entropy alloy electrode and a preparation method thereof, comprising the following steps:

[0065] (1) Selecting metal Na as the negative electrode material;

[0066] (2) Using 35:25:20:10:10 mol% Bi-Sb-Te-Mo-W high entropy alloy as the positive electrode material, weighing the corresponding mass of metal powder on a balance according to the molar ratio composition of the positive electrode material, and preparing the required positive electrode material according to the above steps;

[0067] (3) The electrolyte material is NaCl-LiCl-KCl ternary mixed cationic molten salt, and the molar ratio of NaCl-LiCl-KCl is 6:59:36. The preparation process of the electrolyte is: different electrolytes are heated to 200°C in a vacuum oven to remove the crystal water in the electrolyte, and then the corresponding masses are weighed according to the molar ratio of the electrolyte components and mixed, and then melted in a glove box electric furnace, cooled and crushed to obtain a usable electrolyte;

[0068] (4) The negative electrode current collector and negative electrode material, the positive electrode current collector and positive electrode material, and the electrolyte are assembled into a liquid metal battery according to the above steps. The assembled liquid metal battery is placed in an electric furnace and heated to 470° C. and tested at a charge and discharge current of 0.3 A, and the process is the same as in Example 1.

[0069] Example 5

[0070] Embodiment 5 of the present invention provides a liquid metal battery based on a high entropy alloy electrode and a preparation method thereof, comprising the following steps:

[0071] (1) Selecting metal Na as the negative electrode material;

[0072] (2) Using 30:25:20:15:10 mol% Sn-In-Bi-Ga-Te high entropy alloy as the positive electrode material, weighing the corresponding mass of metal powder with a balance according to the molar ratio composition of the positive electrode material, and preparing the required positive electrode material according to the above steps;

[0073] (3) The electrolyte material is LiBr-LiCl-KBr ternary mixed cation molten salt, and the molar ratio of LiBr-LiCl-KBr is 31:37:32. The preparation process of the electrolyte is: different electrolytes are heated to 200°C in a vacuum oven to remove the crystal water in the electrolyte, and then the corresponding masses are weighed according to the molar ratio of the electrolyte components and mixed, and then melted in a glove box electric furnace, cooled and crushed to obtain a usable electrolyte;

[0074] (4) The negative electrode current collector and negative electrode material, the positive electrode current collector and positive electrode material, and the electrolyte are assembled into a liquid metal battery according to the above steps. The assembled liquid metal battery is placed in an electric furnace and heated to 390° C. and tested at a charge and discharge current of 0.3 A, and the process is the same as in Example 1.

[0075] Comparative Example 1

[0076] Comparative Example 1 of the present invention provides a liquid metal battery based on a pure Te electrode and a preparation method thereof, comprising the following steps:

[0077] (1) Selecting metal Na as the negative electrode material;

[0078] (2) Using metal Te as the positive electrode material, weighing the corresponding mass of metal powder with a balance and adding it to the positive electrode current collector;

[0079] (3) The electrolyte material is NaCl-LiCl-KCl ternary mixed cationic molten salt, and the molar ratio of NaCl-LiCl-KCl is 6:59:36. The preparation process of the electrolyte is: different electrolytes are heated to 200°C in a vacuum oven to remove the crystal water in the electrolyte, and then the corresponding masses are weighed according to the molar ratio of the electrolyte components and mixed, and then melted in a glove box electric furnace, cooled and crushed to obtain a usable electrolyte;

[0080] (4) The negative electrode current collector and negative electrode material, the positive electrode current collector and positive electrode material, and the electrolyte are assembled into a liquid metal battery according to the above steps. The assembled liquid metal battery is placed in an electric furnace and heated to 470° C. and tested at a charge and discharge current of 0.3 A, and the process is the same as in Example 1.

[0081] The above results show that the liquid metal battery prepared in the present invention overcomes the limitations of traditional alloy positive electrode materials through reasonable component design and preparation process optimization, and exhibits excellent electrochemical performance and stability.

[0082] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid metal battery based on high entropy alloy electrodes, characterized in that: It comprises a shell and a positive electrode collector, a negative electrode collector and an electrolyte spread in the shell; the negative electrode collector is adsorbed with a negative electrode material; the positive electrode collector is provided with a positive electrode material, and the positive electrode material comprises more than three positive electrode active metals selected from Te, Se, Bi, Sb, Zn and Co and more than two additives X selected from Sn, Mo, Cu, Cd, Ga, In, W, Fe and Ni.

2. A liquid metal battery based on high entropy alloy electrodes according to claim 1, characterized in that: The amount of the additive X accounts for 10% to 25% of the total amount of the positive electrode material.

3. A liquid metal battery based on high entropy alloy electrodes according to claim 1, characterized in that: The electrolyte is an inorganic halide electrolyte.

4. A liquid metal battery based on high entropy alloy electrodes according to claim 3, characterized in that: The electrolyte includes LiCl, LiBr, LiI, NaCl, NaBr, NaI, KCl, KBr or KI.

5. The liquid metal battery based on high entropy alloy electrode according to claim 1, characterized in that: The negative electrode material includes at least one of Na and Li.

6. A method for preparing a liquid metal battery based on a high entropy alloy electrode as claimed in any one of claims 1 to 5, characterized in that: The method comprises the following steps: S1, mixing three or more positive electrode active metals of Te, Se, Bi, Sb, Zn, and Co with two or more additives X of Sn, Mo, Cu, Cd, Ga, In, W, Fe, and Ni in proportion, and then placing them in a ball mill for ball milling to uniformly mix the metals to obtain a metal mixture; S2, melting the metal mixture in a vacuum environment and annealing to obtain a positive electrode material; S3, placing the positive electrode material on the positive electrode collector, and placing the molten electrolyte and the negative electrode collector adsorbed with the negative electrode material into the shell in sequence, thereby completing the preparation of the liquid metal battery.

7. The preparation method according to claim 6, characterized in that: The ball milling time in step S1 is 4 to 9 hours, and the ball milling speed is 300 to 500 rpm.

8. The preparation method according to claim 6, characterized in that: Anhydrous ethanol is added as a dispersant during the mixing of the positive electrode active metal and the additive X to prevent the metals from agglomerating during the ball milling process.

9. The preparation method according to claim 6, characterized in that: Step S3 specifically includes: S21, placing the metal mixture into a muffle furnace, and evacuating the muffle furnace or introducing an inert gas; S22, slowly raising the temperature of the muffle furnace from room temperature to 200-300° C. and maintaining it for 1 hour to remove residual moisture and volatile impurities in the metal mixture; S23, continue to heat up to 600-1000°C at a rate of 2°C / min and keep warm for 2 hours to allow the metal components to fully melt and undergo a complete alloying reaction. The molten alloy is annealed at 400°C for 3 hours and then slowly cooled to room temperature to obtain a positive electrode material.

10. The preparation method according to claim 6, characterized in that: The positive electrode active metal and the additive X are both in powder form.

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