A liquid metal battery based on high-entropy alloy electrodes and a method of making the same

Abstract

The application discloses a liquid metal battery based on high-entropy alloy electrodes and a preparation method thereof, and belongs to the technical field of designing electrodes of liquid metal batteries, and comprises a shell, 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 three or more than three positive electrode active metals in Te, Se, Bi, Sb, Zn and Co and two or more than two additives X in Sn, Mo, Cu, Cd, Ga, In, W, Fe and Ni. The high-entropy alloy constructed with tellurium-selenium metal as a core has a multi-metal structure and a uniform solid solution phase composition, so that the dissolution of tellurium-selenium metal and its products in the electrolyte and the occurrence of side reactions are inhibited, the generation of thermal runaway is avoided, and the safety and coulomb efficiency of the high-temperature battery are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of designing liquid metal battery electrodes, and more particularly relates to a liquid metal battery based on a high-entropy alloy electrode and a preparation method thereof. BACKGROUND

[0002] According to the International Energy Agency's website, the report "Mid-year update on electricity", the global renewable energy power generation will exceed that of coal-fired power plants for the first time in 2025. This change is an important milestone in the global energy field, in order to respond to this trend, to build a "new power / energy supply system" dominated by clean energy, and to make full use of renewable energy power is an important way to realize the energy structure transformation and decarbonization, and is an important development direction of energy storage technology and a major national strategic demand.

[0003] At present, renewable energy power generation is uncontrollable, unstable and difficult to predict, in order to realize the efficient grid connection of renewable energy, it is crucial 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 the upper limit and the use of organic electrolyte has caused great safety hazards in the condition of thermal runaway and external force. Therefore, finding a substitute with high energy density, cost-effectiveness and good safety is still an important part of battery research. Liquid metal battery (LMB) adopts a full-liquid design, which is composed of two different liquid metal electrodes and a molten salt electrolyte, and relies on the difference in density to achieve three-layer liquid automatic stratification. In the cycle process, there will be no structural change due to the use of liquid electrodes; the characteristics of molten salt electrolysis also make liquid metal battery unnecessary for diaphragm; these characteristics of liquid metal battery also make it have long cycle life, low energy storage cost and easy to scale production, which is an ideal choice for power storage.

[0004] As an alloy material composed of multiple elements, high-entropy alloy can provide higher chemical stability and structural stability, which helps to prolong the life of the battery; and the complex chemical composition of high-entropy alloy and the unique phase structure formed can reduce the dissolution of the positive electrode material in the molten salt electrolyte and improve the cycle stability of the battery. SUMMARY

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

[0006] To achieve the above object, according to one aspect of the present application, there is provided a liquid metal battery based on 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 adsorbs a negative electrode material; the positive electrode current collector is provided with a positive electrode material, the positive electrode material comprising three or more positive electrode active metals of Te, Se, Bi, Sb, Zn, Co and two or more additives X of Sn, Mo, Cu, Cd, Ga, In, W, Fe, Ni.

[0007] Preferably, the amount of substance of the additive X accounts for 10% to 25% of the total amount of substance 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 comprises at least one of Na and Li.

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

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

[0013] S2, the metal mixture is melted in a vacuum environment, and the positive electrode material is obtained after annealing;

[0014] S3, the positive electrode material is placed in the positive electrode current collector, the electrolyte in a molten state and the negative electrode current collector adsorbing the negative electrode material are sequentially placed in the shell, 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 aggregation of the metals during the ball milling.

[0017] Preferably, step S3 specifically comprises:

[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, thereby inhibiting the dissolution of tellurium selenide metal and its products in the electrolyte and the occurrence of side reactions, avoiding the occurrence of thermal runaway, and improving 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 improving conductivity, reducing the impact of internal resistance on the charge and discharge process, and improving the contact between the electrode and the current collector, thereby improving the battery's charge and discharge efficiency and power density.

[0025] 3. The preparation method of liquid metal batteries based on high-entropy alloy electrodes proposed in the present invention achieves uniform distribution of multiple elements and a stable structure by adding nano-scale metal powder and a strictly controlled high-temperature sintering process, so that the electrodes have 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 This is a flow chart of a method for preparing a liquid metal battery based on a high entropy alloy electrode according to the present invention;

[0027] Figure 2 is a charge and discharge performance curve 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 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 objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining 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 may 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 high-entropy alloy electrodes, 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 includes three or more positive electrode active metals selected from Te, Se, Bi, Sb, Zn, and Co and two or more 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] For 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 proportions of the alloy design to ensure accurate ratios to achieve the desired 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 the metal powder from agglomerating during the ball milling process 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 equipped with a high vacuum function. Vacuuming or using a high-purity inert gas shield prevents oxidation and volatilization of metallic elements during subsequent heating. The furnace temperature is slowly raised from room temperature to 200-300°C and held for one hour to remove residual volatile impurities such as moisture and organic matter, reducing the risk of contamination during the subsequent melting process. Once the temperature stabilizes, the temperature is gradually increased at a rate of 2°C / min to 600-1000°C. This prevents excessive volatilization of elements caused by rapid heating and ensures effective retention of metallic components. Once the target temperature is reached, the mixture is held for two hours to ensure full melting and complete alloying of the metallic components, resulting in a single-phase, homogeneous high-entropy alloy structure. The melted alloy is annealed at 400°C for three hours to eliminate internal stresses and improve the material's grain structure. The temperature is then slowly cooled to room temperature to prevent cracking or structural instability 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 below through specific embodiments.

[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 a 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 a ternary mixed cationic molten salt of NaCl-LiCl-KCl, with a molar ratio of NaCl-LiCl-KCl of 6:59:36. The electrolyte preparation process is as follows: 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. The mixture is then melted in a glove box electric furnace, cooled, and crushed to obtain a usable electrolyte.

[0050] (4) Assemble the negative electrode current collector and negative electrode material, positive electrode current collector and positive electrode material, and electrolyte 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 finally stabilizes 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 a 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 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;

[0055] (3) The electrolyte material is a ternary mixed cationic molten salt of NaCl-LiCl-KCl, with a molar ratio of NaCl-LiCl-KCl of 6:59:36. The electrolyte preparation process is as follows: 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. The mixture is 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. The test is carried out at a charge and discharge current of 0.3A, following the same process 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 a 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 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;

[0061] (3) The electrolyte material is a ternary mixed cationic molten salt of NaCl-LiCl-KCl, with a molar ratio of NaCl-LiCl-KCl of 6:59:36. The electrolyte preparation process is as follows: 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. The mixture is 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. The test is carried out at a charge and discharge current of 0.3A, following the same process 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 a 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 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;

[0067] (3) The electrolyte material is a ternary mixed cationic molten salt of NaCl-LiCl-KCl, with a molar ratio of NaCl-LiCl-KCl of 6:59:36. The electrolyte preparation process is as follows: 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. The mixture is 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. The test is carried out at a charge and discharge current of 0.3A, following the same process 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 a 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 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;

[0073] (3) The electrolyte material is a ternary mixed cationic molten salt of LiBr-LiCl-KBr, with a molar ratio of LiBr-LiCl-KBr of 31:37:32. The electrolyte preparation process is as follows: 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. The mixture is then melted in a glove box electric furnace, cooled, and crushed to obtain a usable electrolyte.

[0074] (4) Assemble the negative electrode current collector and negative electrode material, the positive electrode current collector and positive electrode material, and the electrolyte according to the above steps to form a liquid metal battery. The assembled liquid metal battery is placed in an electric furnace and heated to 390°C. The test is carried out at a charge and discharge current of 0.3A, following the same process 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, weigh the corresponding mass of metal powder using a balance and add it to the positive electrode current collector;

[0079] (3) The electrolyte material is a ternary mixed cationic molten salt of NaCl-LiCl-KCl, with a molar ratio of NaCl-LiCl-KCl of 6:59:36. The electrolyte preparation process is as follows: 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. The mixture is 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. The test is carried out at a charge and discharge current of 0.3A, following the same process 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 merely 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 scope of protection of the present invention.

Claims

1. A liquid metal battery based on high entropy alloy electrodes, characterized in that: The invention comprises 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 includes one or more positive electrode active metals selected from Te, Se, Bi, Sb, Zn, and Co and two or more 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. The liquid metal battery based on high entropy alloy electrodes according to claim 1, characterized in that: The electrolyte is an inorganic halide electrolyte.

4. The 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 electrodes 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 according to 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 selected from Te, Se, Bi, Sb, Zn, and Co with two or more additives X selected from Sn, Mo, Cu, Cd, Ga, In, W, Fe, and Ni in a certain proportion, and then placing the mixture 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 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.

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 process 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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