Molten salt energy storage aluminum battery electrode and preparation method thereof

Abstract

The invention discloses a fused salt energy storage aluminum battery electrode and a preparation method thereof, the fused salt energy storage aluminum battery electrode is prepared by compounding cement, graphite particles, graphene and a fused salt stabilizer, the mass of a cement-based material accounts for 10%-50% of the total mass of the composite material, the mass of graphite accounts for 50%-80% of the total mass of the composite material, the mass of graphene accounts for 1%-5% of the total mass of the composite material, and the mass of the fused salt stabilizer accounts for 5%-15% of the total mass of the composite material. According to the design, high temperature resistance and corrosion resistance of cement, high conductivity of graphite and the characteristic that graphene forms a three-dimensional ion conductive network are fully utilized, an efficient and stable electrode material is constructed, and the problems that a traditional carbon-based electrode is prone to failure, a cement-based electrode is insufficient in conductivity and a metal-based electrode is high in cost are solved; and effective combination of low cost and high performance is realized.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology, specifically relating to a molten salt energy storage aluminum battery electrode and its preparation method. Background Technology

[0002] With the transformation of the global energy structure, the utilization rate of renewable energy has increased rapidly, but its intermittent and fluctuating characteristics pose a challenge to the stability of the power system. Energy storage technology, as a core means to solve this problem, has received widespread attention in recent years. Molten salt batteries, as an important large-scale energy storage technology, show great promise in the field of energy storage due to their high safety, long lifespan, low cost, and ability to adapt to extreme environments.

[0003] The basic principle of molten salt batteries is to use molten salt as an electrolyte to achieve efficient ion migration and electrochemical reactions. Compared with traditional lithium-ion batteries, molten salt batteries do not rely on scarce metal resources and have higher thermal stability. Currently, research on molten salt batteries mainly focuses on three major directions: sodium-sulfur batteries, magnesium-based molten salt batteries, and aluminum-based molten salt batteries. Among them, sodium-sulfur batteries are widely used in energy storage power stations due to their high energy density and mature technology. However, their high operating temperature of up to 300℃ leads to significant energy loss and poses certain safety hazards. Magnesium-based molten salt batteries have the advantages of abundant resources and high specific energy, but the poor cycle performance and chemical stability of their electrode materials limit their further promotion. In contrast, aluminum-based molten salt batteries are considered an important direction for future energy storage technology due to the abundance and low cost of aluminum resources, high theoretical specific capacity, and good electrochemical stability.

[0004] The core of aluminum-based molten salt batteries lies in the compatibility of their electrode materials and molten salt electrolytes. Traditional metal electrodes (such as nickel and molybdenum), while possessing high conductivity and mechanical strength, are costly and prone to corrosion, failing to meet the demands of large-scale applications. Carbon-based materials such as graphite, carbon nanotubes, and graphene have become important research directions due to their excellent conductivity and chemical stability. However, the chemical stability of single carbon-based materials in high-temperature molten salt environments is limited, especially during long-term cycling, where the conductive network is prone to damage. Therefore, recent research has increasingly shifted towards the design of composite materials, optimizing material structure and composition to improve the conductivity, stability, and ion migration performance of the electrodes.

[0005] Cement-based composite materials have shown significant potential in the field of molten salt battery electrodes. Cement, as the world's most widely used building material, possesses excellent high-temperature resistance, corrosion resistance, and low cost. Furthermore, its porous structure facilitates molten salt penetration and ion migration. However, traditional cement materials exhibit poor electrical conductivity, requiring improvement through the introduction of conductive fillers (such as graphite and carbon nanotubes). In addition, the hardening process and porous structure of cement significantly influence the material's mechanical strength and ion transport properties; therefore, optimizing the composition and manufacturing process of cement-based electrodes has become a key research focus. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing molten salt energy storage aluminum battery electrodes.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0010] Solid and liquid components are mixed and stirred evenly to obtain a slurry. The slurry is placed in a mold, cured at room temperature, and then heat-treated to obtain the molten salt energy storage aluminum battery electrode.

[0011] The solid component, by mass percentage, consists of 10% to 50% cement, 50% to 80% graphite particles, 1% to 5% graphene, and 1% to 5% molten salt stabilizer.

[0012] The liquid component is deionized water, and the mass ratio of the liquid component to the solid component is 0.3 to 0.5:1.

[0013] In this invention, cement provides ion transport channels by constructing a porous structure, while its high temperature resistance and corrosion resistance enhance the stability of the electrode.

[0014] Graphite, as the main conductive component, forms continuous conductive channels through optimized distribution, thereby significantly improving the overall conductivity of the electrode.

[0015] Graphene, as a functional additive, further enhances ion mobility and electrode cycling performance through its three-dimensional network structure.

[0016] Molten salt stabilizers can provide chemical compatibility between the electrode and the molten salt electrolyte, reduce electrolyte corrosion at high temperatures, and improve the stability of ion transport.

[0017] In a preferred embodiment of the preparation method of the molten salt energy storage aluminum battery electrode of the present invention, the curing time at room temperature is 12-24 hours.

[0018] In a preferred embodiment of the preparation method of the molten salt energy storage aluminum battery electrode of the present invention, the heat treatment temperature is 80-150°C.

[0019] In a preferred embodiment of the method for preparing the molten salt energy storage aluminum battery electrode of the present invention, the heat treatment time is 2 to 5 hours.

[0020] In a preferred embodiment of the preparation method of the molten salt energy storage aluminum battery electrode of the present invention, the cement includes silicate cement or sulfoaluminate cement with a particle size of 1-50 μm.

[0021] In a preferred embodiment of the preparation method of the molten salt energy storage aluminum battery electrode of the present invention, the molten salt stabilizer includes one or more of K2SO4, Na2CO3, MgO or CaO.

[0022] In a preferred embodiment of the method for preparing the molten salt energy storage aluminum battery electrode of the present invention, the method further includes spraying a 4-5 μm thick alumina coating onto the surface of the molten salt energy storage aluminum battery electrode.

[0023] Another object of the present invention is to provide a molten salt energy storage aluminum battery electrode.

[0024] Another object of the present invention is to provide a molten salt energy storage aluminum battery, comprising a positive electrode, a negative electrode, and a molten salt electrolyte, wherein the negative electrode is the electrode of the molten salt energy storage aluminum battery, and the molten salt comprises KCl-AlCl3 or a mixture thereof.

[0025] As a preferred embodiment of the molten salt energy storage aluminum battery of the present invention, the molten salt energy storage aluminum battery has an operating temperature range of 80 to 150°C and its electrochemical performance retention rate is >90% after 2000 charge-discharge cycles.

[0026] Beneficial effects of this invention:

[0027] (1) High conductivity and ion migration performance: Through the conductive channels of graphite and the three-dimensional ion conductive network formed by graphene, the overall conductivity of the electrode and the ion migration rate in the molten salt environment are effectively improved, and the electrochemical performance of the battery is significantly optimized.

[0028] (2) Low cost and high stability: The introduction of cement-based materials reduces the overall cost of the electrode and provides good high temperature resistance and corrosion resistance, enabling the electrode to operate stably for a long time in a molten salt environment of 80-150℃.

[0029] (3) Enhanced chemical compatibility: The addition of molten salt stabilizer improves the chemical compatibility between the electrode and the molten salt electrolyte, reduces corrosion at high temperatures, and improves the service life of the material.

[0030] (4) Excellent cycle life: After 10,000 charge-discharge cycles, the performance retention rate of the electrode is not less than 90%, which is significantly better than existing metal-based or single carbon-based electrode materials. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. 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. Wherein:

[0032] Figure 1 This is a physical image of the molten salt energy storage aluminum battery electrode prepared according to the present invention.

[0033] Figure 2 The diagram shows the structure and working principle of the molten salt energy storage aluminum battery using the electrode of the molten salt energy storage aluminum battery of the present invention. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0037] Unless otherwise specified, all raw materials used in this invention are commercially available in the art. Specifically, the silicate cement is PO 42.5 type silicate cement (Huaxin Cement Company, D).50 The graphite particles are flake graphite powder (Qingdao Huatai Graphite, model HT-GF100, particle size range 10–100μm); the graphene is reduced graphene oxide (Suzhou Carbon Element Technology Co., Ltd., model CE-RGO-500, number of layers 3–10); all other reagents are of analytical grade and commercially available.

[0038] The product electrode performance testing in this invention is performed using the following method:

[0039] 1. Electrochemical Cyclic Performance Testing

[0040] The electrode samples were placed in a KCl–AlCl3 eutectic salt system (molar ratio 1:1.5) and subjected to isothermal treatment in a 150℃ forced-air drying oven. Charge-discharge cycle testing was performed using an external constant current source. The cycle current density was 0.1 mA / cm². 2 Record the capacity retention rate and cycle stability during the cycle.

[0041] 2. Conductivity test

[0042] Electrode conductivity was tested at room temperature using the four-probe method. After heat treatment and cooling, the samples were cut into 10mm × 10mm sheet-like specimens, and their volumetric conductivity (S / m) was calculated.

[0043] 3. High-temperature molten salt stability test

[0044] Electrode samples were immersed in KCl–AlCl3 molten salt at 150℃ for 200 hours. The changes in sample mass and structural integrity were observed to evaluate their corrosion resistance.

[0045] 4. Microstructure and Thermal Stability Analysis (Auxiliary)

[0046] Conventional material analysis methods such as SEM, EDS, XRD, and TG / DSC were used to assist in verifying the structural uniformity, pore morphology, compositional thermal stability, and ion pathway construction effect of the electrode.

[0047] Example 1

[0048] This embodiment provides a method for preparing an electrode for a molten salt energy storage aluminum battery, specifically:

[0049] 1) Weigh the raw material components according to the following mass percentages:

[0050] Solid components: 40% silicate cement, 55% graphite particles, 3% graphene, 3% K2SO4;

[0051] Liquid component: Deionized water in a mass ratio of 0.4:1 to solid component;

[0052] 2) Mix the solid and liquid components and stir until homogeneous to obtain a slurry. Place the slurry in a mold (a circular mold with a diameter of 20 mm and a thickness of 2 mm), cure at room temperature for 24 hours, and then heat-treat at 120°C for 3 hours to obtain the molten salt energy storage aluminum battery electrode. A physical image of the electrode is shown below. Figure 1 As shown, the heat-treated electrode exhibits a dense, smooth, circular structure with good self-supporting properties and structural integrity, making it suitable for directly constructing cathode materials in high-temperature energy storage systems.

[0053] A molten salt energy storage aluminum battery is constructed using the prepared molten salt energy storage aluminum battery electrode as the negative electrode. A schematic diagram of the structure and working principle of this molten salt energy storage aluminum battery is shown below. Figure 2 As shown in the figure, the basic structural components of the battery are illustrated, including an aluminum anode, a molten salt electrolyte, and a cement-graphite composite cathode. The arrows indicate the migration paths of AlCl4- / Al2Cl7- anions during discharge / charge. The enlarged inset in the upper right corner shows the microstructural features of the composite electrode. Graphite and the cement matrix form an intercalated structure, and the generated C–S–H gel provides a porous network, which is beneficial to the continuity and stability of ion channels.

[0054] The electrode prepared in this embodiment was tested for performance. After 2000 cycles of charge-discharge in the KCl-AlCl3 molten salt system, the capacity retention rate was 92% and the conductivity was 48 S / m.

[0055] Example 2

[0056] 1) Weigh the raw material components according to the following mass percentages:

[0057] Solid components: 25% cement, 70% graphite particles, 4% graphene, 1% MgO;

[0058] Liquid component: Deionized water at a mass ratio of 0.35:1 to solid component;

[0059] 2) Mix the solid and liquid components and stir evenly to obtain a slurry. Place the slurry in a mold and cure at room temperature for 24 hours. Then heat treat it at 150°C for 3 hours to obtain the molten salt energy storage aluminum battery electrode.

[0060] The electrode prepared in this embodiment was subjected to performance testing. After 1500 constant-temperature charge-discharge cycles at 150°C in the KCl-AlCl3 eutectic salt system, the capacity retention rate was >90%, demonstrating excellent chemical stability and structural integrity.

[0061] Example 3

[0062] A 5 μm thick aluminum oxide coating was sprayed onto the surface of the molten salt energy storage aluminum battery electrode prepared in Example 2 to further improve its oxidation resistance and corrosion resistance. The remaining steps and processes were the same as in Example 2 to obtain the molten salt energy storage aluminum battery electrode of this comparative example.

[0063] The performance of the molten salt energy storage aluminum battery electrode prepared in this embodiment was tested. After oxidation test, the electrode operated for more than 3,000 hours in the range of 80 to 150°C, and the conductivity retention rate exceeded 95%.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that the electrode material is prepared solely using graphite and cement-based materials as raw materials. Specifically:

[0066] 1) Weigh the raw material components according to the following mass percentages:

[0067] Solid components: 20% cement, 80% graphite particles;

[0068] Liquid component: Deionized water at a mass ratio of 0.35:1 to solid component;

[0069] 2) Mix the solid and liquid components and stir evenly to obtain a slurry. Place the slurry in a mold and cure at room temperature for 24 hours. Then heat treat it at 120°C for 3 hours to obtain the molten salt energy storage aluminum battery electrode.

[0070] The electrode prepared in this comparative example was subjected to cyclic charge-discharge tests in a KCl–AlCl3 eutectic salt system at a constant temperature of 150℃ and a current density of 0.1 mA / cm². 2 Tests showed that the comparative electrode exhibited a capacity decay rate exceeding 20% ​​after 500 cycles, a room temperature conductivity of 32 S / m, and slight erosion and pulverization on its surface after molten salt immersion. This indicates that its conductivity and structural stability are poor and it cannot meet the requirements of long-term molten salt energy storage environments.

[0071] Comparative Example 2

[0072] The difference between this comparative example and the previous examples is that the electrode material was prepared using only graphite and graphene as raw materials. Specifically:

[0073] 1) Weigh the raw material components according to the following mass percentages:

[0074] Solid composition: 95% graphite particles, 5% graphene;

[0075] Liquid component: Deionized water at a mass ratio of 0.35:1 to solid component;

[0076] 2) Mix the solid and liquid components and stir evenly to obtain a slurry. Place the slurry in a mold and cure at room temperature for 24 hours. Then heat treat it at 120°C for 3 hours to obtain the molten salt energy storage aluminum battery electrode.

[0077] The electrode prepared in this comparative example was subjected to cyclic charge-discharge tests in a KCl–AlCl3 eutectic salt system at a constant temperature of 150℃ and a current density of 0.1 mA / cm². 2 The results showed that after working in molten salt for 200 hours, the electrode exhibited significant surface expansion, cracking, and edge powdering; its electrochemical cycling performance deteriorated significantly, with a capacity retention rate of less than 75% after 500 cycles; and its conductivity, initially 51 S / m, dropped to 34 S / m after high-temperature operation. This indicates that without a cement support structure, the electrode's chemical stability in a high-temperature molten salt environment is severely compromised, the conductive network is easily damaged, and its practical application is limited.

[0078] Example 4

[0079] The difference between this embodiment and Embodiment 1 is that the content of graphite particles was adjusted to 40%, 50wt%, 60wt%, 70wt%, 80wt%, and 90wt%, and the content of cement was adjusted accordingly to keep the total content of solid components at 100%. The remaining steps and processes were the same as in Embodiment 1. Electrode materials with different graphite particle contents were obtained in this embodiment, and the relevant properties were measured. The results are shown in Table 1.

[0080] Table 1

[0081] Graphite content (wt%) 2000-cycle capacity retention rate / % Conductivity (S / m) Structural integrity after soaking 40 89 39 whole 50 91 42 whole Example 1 (55) 92 48 whole 60 92 46 whole 70 91 49 Microcracks at the edges 80 87 51 Surface micro-peeling 90 76 53 Noticeable powdering

[0082] The test results show that conductivity increases with increasing graphite content, but capacity retention and structural stability gradually decrease above 70%, indicating that excessively high graphite content weakens the support network formed by cement and affects the integrity of the ion channel structure. Therefore, 60–70 wt% graphite is the optimal range.

[0083] Example 5

[0084] The difference between this embodiment and Embodiment 1 is that the graphene content was adjusted to 1%, 2%, 3%, 4%, 5%, and 6%, and the cement content was adjusted accordingly to keep the total content of solid components at 100%. The remaining steps and processes were the same as in Embodiment 1. Electrode materials with different graphite particle contents were obtained in this embodiment, and the relevant properties were measured. The results are shown in Table 2.

[0085] Table 2

[0086]

[0087]

[0088] As shown in Table 2, the appropriate introduction of graphene can form a three-dimensional conductive network in the cement-graphite structure, improving electron migration efficiency and interface stability. With an addition of 4%, conductivity and cycle performance reach their optimal levels. However, when the content exceeds 5%, uneven dispersion or structural stress concentration leads to an increase in microcracks and a decrease in stability, indicating that the use of graphene needs to be controlled within a reasonable range (recommended 2–4 wt%).

[0089] Example 6

[0090] The difference between this embodiment and Example 1 is that the content of the molten salt stabilizer K2SO4 was adjusted to 1%, 2%, 3%, 4%, 5%, and 6%, respectively, and the content of cement was adjusted accordingly to keep the total content of solid components at 100%. The remaining steps and processes were the same as in Example 1. Electrode materials with different graphite particle contents were obtained in this embodiment, and the relevant properties were measured. The results are shown in Table 3.

[0091] Table 3

[0092] <![CDATA[K2SO4 content / %]]> 2000-cycle capacity retention rate / % Conductivity (S / m) High temperature structural stability 1 86 44 Partial edge corrosion 2 89 45 Basically complete 3 92 48 Complete, without peeling 4 91 45 Complete, slightly roughened 5 89 43 Localized cracking 6 86 41 Porous structure instability and edge pulverization

[0093] As shown in Table 3, the chemical stability and cycle performance of the electrode are significantly improved as the molten salt stabilizer dosage increases from 1% to 3%. However, when the dosage continues to increase to above 5%, the conductivity and structural stability decrease due to the reduced compatibility between components and the destruction of the microporous structure. Therefore, the optimized dosage range of this invention is 2–4 wt%, which can effectively balance high-temperature chemical stability and the continuity of the conductive channel.

[0094] Example 7

[0095] The difference between this embodiment and Example 1 is that the types of molten salt stabilizers are K2SO4, Na2CO3, MgO or CaO, and the remaining steps and processes are the same as in Example 1. Electrode materials with different graphite particle contents were obtained in this embodiment, and the relevant properties were measured. The results are shown in Table 4.

[0096] Table 4

[0097]

[0098]

[0099] Table 4 shows that the mechanisms of action of different types of molten salt stabilizers in the composite electrode are significantly different. When K2SO4 is used as a stabilizer, it can synergistically form a dense protective layer with cement hydration products, effectively blocking the erosion of high-temperature molten salt and maintaining good conductivity. In contrast, alkaline oxide stabilizers (such as CaO and MgO) may react with Cl- in high-temperature molten salt to form a loose layer, leading to structural instability. This indicates that the stabilizer system preferred in this invention has significant technical advantages.

[0100] In summary, this invention designs a molten salt energy storage aluminum battery electrode and its preparation method. This design fully utilizes the high temperature resistance and corrosion resistance of cement, the high conductivity of graphite, and the characteristics of graphene in forming a three-dimensional ion-conducting network to construct an efficient and stable electrode material. It overcomes the problems of easy failure of traditional carbon-based electrodes, insufficient conductivity of cement-based electrodes, and high cost of metal-based electrodes, and achieves an effective combination of low cost and high performance.

[0101] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended 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 preparing an electrode for a molten salt energy storage aluminum battery, characterized in that: include, Solid and liquid components are mixed and stirred evenly to obtain a slurry. The slurry is placed in a mold, cured at room temperature, and then heat-treated to obtain the molten salt energy storage aluminum battery electrode. The solid component, by mass percentage, consists of 10% to 50% cement, 50% to 80% graphite particles, 1% to 5% graphene, and 1% to 5% molten salt stabilizer. The liquid component is deionized water, and the mass ratio of the liquid component to the solid component is 0.3 to 0.5:

1.

2. The method for preparing the molten salt energy storage aluminum battery electrode as described in claim 1, characterized in that: The curing time for room temperature curing is 12 to 24 hours.

3. The method for preparing the molten salt energy storage aluminum battery electrode as described in claim 1, characterized in that: The heat treatment temperature is 80–150°C, and the treatment time is 2–5 hours.

4. The method for preparing the molten salt energy storage aluminum battery electrode as described in claim 1, characterized in that: The cement includes silicate cement or sulfoaluminate cement, with a particle size of 1–50 μm.

5. The method for preparing the molten salt energy storage aluminum battery electrode as described in claim 1, characterized in that: The graphite particles have a particle size of 10–100 μm.

6. The method for preparing the molten salt energy storage aluminum battery electrode as described in claim 1, characterized in that: The molten salt stabilizer includes one or more of K2SO4, Na2CO3, MgO, or CaO.

7. The method for preparing the molten salt energy storage aluminum battery electrode as described in claim 1, characterized in that: It also includes spraying a 4-5 μm thick aluminum oxide coating onto the surface of the molten salt energy storage aluminum battery electrode.

8. Molten salt energy storage aluminum battery electrode prepared by any one of the preparation methods described in claims 1 to 7.

9. A molten salt energy storage aluminum battery, characterized in that: include, The battery comprises a positive electrode, a negative electrode, and a molten salt electrolyte, wherein the negative electrode is the molten salt energy storage aluminum battery electrode according to claim 7, and the molten salt includes KCl-AlCl3 or a mixture thereof.

10. The molten salt energy storage aluminum battery as described in claim 9, characterized in that: The molten salt aluminum energy storage battery operates in the temperature range of 80–150°C, and its electrochemical performance retention rate is >90% after 2000 charge-discharge cycles.

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