Composite metal oxide heat storage material and preparation method thereof

Abstract

The present invention provides a copper-aluminum composite metal oxide heat storage material modified with magnesium oxide and a preparation method thereof. By further doping magnesium oxide into a copper oxide-doped aluminum oxide heat storage material system, the sintering problem of the copper oxide-doped aluminum oxide heat storage material is further improved, thereby enhancing its cycling performance. The composite metal oxide heat storage material is a heat storage material formed by combining copper oxide with aluminum oxide and magnesium oxide at high temperatures. Aluminum oxide and magnesium oxide form magnesium aluminate at high temperatures, and the magnesium aluminate coats the surface of the copper oxide particles. The preparation method of the composite metal oxide heat storage material comprises the following steps: Step S1: Weighing copper oxide, aluminum oxide, and magnesium oxide in proportion, grinding and mixing the raw materials; Step S2: calcining the mixed copper oxide powder, aluminum oxide, and magnesium oxide at high temperature, followed by cooling to obtain a calcined product; and grinding the calcined product into a powder to obtain the composite metal oxide heat storage material.

Description

Technical Field

[0001] The present invention relates to the technical field of heat storage materials, and in particular to a composite metal oxide heat storage material and a preparation method thereof. Background Art

[0002] Energy storage is a key technology supporting flexible power consumption. Large-scale high-temperature thermal energy storage is low-cost and highly secure, making it an effective means of ensuring the safe and stable operation of power systems, improving their overall efficiency, and ensuring the safety of flexible power consumption.

[0003] As for heat storage technology, it is currently divided into three forms: sensible heat, phase change latent heat, and thermochemical reaction heat storage. Sensible heat storage mainly uses the rise and fall of the medium temperature to achieve heat storage and release. The process is relatively simple, but the energy storage density is low and the temperature is not constant during heat release. Phase change heat storage uses the latent heat of the medium phase change process to achieve heat storage and release. The energy storage density is relatively high, but the phase change material usually needs to be encapsulated and has a low thermal conductivity and is prone to aging. Thermochemical reaction heat storage uses reversible chemical reactions to store and release heat. The energy storage density can be an order of magnitude higher than sensible heat, the applicable temperature range is wide, the storage / release temperature is relatively stable and concentrated, and seasonal long-term storage and long-distance transportation can be achieved. It can also achieve improved thermal energy quality and has great research and development and application prospects.

[0004] Among thermochemical reaction heat storage systems, high-temperature thermochemical heat storage technologies based on metal oxides (such as cobalt, manganese, copper, and iron) achieve energy storage through redox reactions between metal oxides of different valence states. These technologies offer high heat storage temperatures (>800°C), high heat storage densities (>500kJ / kg), and abundant resources (such as copper and manganese-based materials). Copper-based heat storage materials have a faster reaction rate and higher heat storage density, but suffer from the problem of decreased reaction performance due to sintering at high temperatures.

[0005] To address this issue, existing technologies have proposed doping copper oxide with aluminum oxide to improve its cycling performance. However, after 120 cycles, the reoxidation rate of this copper oxide-doped aluminum oxide system dropped to approximately 80%. Despite this improvement, the cycle life remained unsatisfactory. Summary of the Invention

[0006] In response to the deficiencies in the above-mentioned prior art, the present invention provides a copper-aluminum composite metal oxide heat storage material modified with magnesium oxide and a preparation method thereof, further doping magnesium oxide into the copper oxide-doped alumina heat storage material system to further improve the sintering problem of the copper oxide-doped alumina heat storage material and enhance its cycle performance.

[0007] On the one hand, the present invention provides a composite metal oxide heat storage material, which is a heat storage material formed by combining copper oxide, aluminum oxide and magnesium oxide at high temperature. Aluminum oxide and magnesium oxide generate magnesium aluminate at high temperature, and magnesium aluminate is coated on the surface of copper oxide particles.

[0008] According to this technical solution, first, after the copper-aluminum composite heat storage material is doped with magnesium oxide, since the reaction priority of magnesium oxide with aluminum oxide at high temperature is higher than the reaction of aluminum oxide with copper oxide or magnesium oxide with copper oxide, magnesium oxide can preferentially react with aluminum oxide to form magnesium aluminate crystals with more stable crystal form and stronger structure. Magnesium aluminate has a higher operating temperature than aluminum oxide and has more stable chemical properties. Therefore, even under high-temperature reaction conditions, the magnesium aluminate generated by the reaction of aluminum oxide and magnesium oxide will not undergo phase changes at high temperatures, nor will it react chemically with copper oxide like aluminum oxide. Therefore, it can still exist stably in multiple storage / release cycles while avoiding the reduction of the content of the main reaction substance (copper oxide).

[0009] Secondly, the applicant's experimental research found that there is a strong interaction between magnesium aluminate and copper oxide particles. Magnesium aluminate can be tightly wrapped on the surface of copper oxide particles and is not easy to fall off during multiple heat storage / release cycle reactions.

[0010] Finally, since magnesium aluminate can adhere to the surface of copper oxide particles, it can effectively block multiple copper oxide particles, prevent contact between the copper oxide particles, and avoid agglomeration and sintering of the copper oxide particles under high-temperature reaction conditions. In addition, during multiple cycles of heat storage / release reactions, magnesium aluminate can also be stably coated on the surface of the copper oxide particles. Therefore, the heat storage material provided by the present invention has excellent cyclic heat storage / release performance and can maintain a high heat storage / release density after multiple cycles.

[0011] As a preferred technical solution of the present invention, the mass fraction of copper oxide is 1-x, the mass fraction of magnesium aluminate is x, and the value range of x is 5%-20%.

[0012] According to this technical solution, copper oxide particles will agglomerate and sinter under high-temperature reaction conditions, and too little magnesium aluminate cannot effectively block the copper oxide particles, resulting in some copper oxide particles still agglomerating and sintering. Magnesium aluminate of more than 5% can effectively block most of the copper oxide particles. The higher the mass fraction of magnesium aluminate and the more uniform its distribution, the better the blocking effect on the agglomeration of copper oxide particles. When the mass ratio of magnesium aluminate reaches more than 5%, the reoxidation degree of the heat storage material can reach 99%. However, the higher the mass fraction of magnesium aluminate, the lower the mass fraction of copper oxide particles. The main reaction substance of the heat storage material is copper oxide particles. If the content of copper oxide particles is low, the energy density of the heat storage / release reaction of the material under the same mass conditions will be reduced. In addition, too much magnesium aluminate adheres to the surface of the copper oxide particles, which easily causes insufficient contact reaction area between the copper oxide particles and the air. Therefore, when the mass ratio of magnesium aluminate is 5%-20%, the heat storage / release density and cycle performance of the heat storage material can be taken into account.

[0013] As a preferred technical solution of the present invention, the value of x is 10%.

[0014] According to this technical solution, the applicant has experimentally found that when the ratio of copper oxide to magnesium aluminate in the heat storage material is 9:1, the mass change rate of the composite metal oxide heat storage material does not change much after 500 cycles, and the reoxidation degree can still reach more than 96%, which has better cyclic heat storage performance.

[0015] As a preferred technical solution of the present invention, the molar ratio of aluminum oxide to magnesium oxide is 1:1.

[0016] According to this technical solution, too little magnesium oxide will cause the remaining aluminum oxide to still combine with copper oxide to form copper-aluminum spinel, affecting the cycle performance and reducing the heat storage density. Too much magnesium oxide will cause the remaining magnesium oxide to react with copper oxide to form magnesium cuprate, which is not conducive to the reaction of copper oxide. When the molar ratio of aluminum oxide to magnesium oxide is 1:1, aluminum oxide and magnesium oxide can just react completely to form magnesium aluminate with more stable properties.

[0017] As a preferred technical solution of the present invention, magnesium aluminate is in the form of solid particles.

[0018] According to this technical solution, when granular magnesium aluminate adheres to the surface of copper oxide particles, it makes point contact with the surface of the copper oxide particles, ensuring a barrier effect between the copper oxide particles while providing a large reaction contact area between the copper oxide particles and the air. As a result, in multiple cycles of heat storage / release reactions, the heat storage material provided by the present invention has a large reaction area, further improving the reoxidation degree and reaction rate of the heat storage material in the heat storage / release reaction cycles.

[0019] As a preferred technical solution of the present invention, the particle size of the magnesium aluminate particles is smaller than that of the copper oxide particles, and a plurality of magnesium aluminate particles are evenly coated on the surface of the copper oxide particles.

[0020] According to this technical solution, magnesium aluminate with smaller particle size is evenly attached to the surface of copper oxide particles with larger particle size, so that the magnesium aluminate particles evenly distributed on the surface of the copper oxide particles can prevent the agglomeration of the copper oxide particles without affecting the reaction area between the copper oxide particles and the air, thereby maximizing the barrier effect of magnesium aluminate with the same mass proportion on the agglomeration phenomenon of copper oxide particles.

[0021] Another aspect of the present invention further provides a method for preparing the composite metal oxide heat storage material in any of the above technical solutions, comprising the following steps:

[0022] Step S1: Weigh copper oxide, aluminum oxide, and magnesium oxide in proportion, and grind and mix the raw materials;

[0023] Step S2: calcining the mixed copper oxide powder, aluminum oxide and magnesium oxide at high temperature and then cooling to obtain a calcined product, and grinding the calcined product into powder to obtain a composite metal oxide heat storage material.

[0024] According to this technical solution, uniformly mixed magnesium aluminate and copper oxide particles are compounded at high temperature. Under high temperature conditions, the solid interfaces undergo contact, reaction, nucleation, and crystal growth reactions to ultimately obtain a composite material. This preparation method has low cost, high output, simple equipment and preparation process, and high production efficiency.

[0025] In addition, during the high-temperature calcination of the uniformly mixed powdered copper oxide and magnesium aluminate in step S2, the magnesium aluminate powder can be evenly and firmly attached to the surface of the copper oxide powder, thereby effectively improving the agglomeration and sintering phenomenon of the copper oxide powder under high-temperature reaction conditions, and a copper-based composite metal oxide heat storage material with excellent cyclic heat storage / release performance can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of a method for preparing a magnesium oxide modified copper-aluminum composite metal oxide heat storage material provided in an embodiment of the present invention.

[0027] Figure 2 It is the SEM image of copper-aluminum composite metal oxide (control sample) under different cycle numbers.

[0028] Figure 3 This is a schematic diagram of the thermogravimetric curve of the copper-aluminum composite metal oxide heat storage material (control sample) under different cycle numbers.

[0029] Figure 43 is an X-ray diffraction analysis (XRD) diagram of the magnesium oxide modified copper-aluminum composite metal oxide heat storage material in an embodiment of the present invention.

[0030] Figure 5 3 is an SEM image of the magnesium oxide modified copper-aluminum composite metal oxide heat storage material under different cycle times in an embodiment of the present invention.

[0031] Figure 6 Schematic diagram of thermogravimetric curves of the magnesium oxide modified copper-aluminum composite metal oxide heat storage material under different cycle numbers in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of the present invention.

[0033] 1. Material Preparation

[0034] Figure 1 Flowchart of the preparation method of magnesium oxide modified copper-aluminum composite metal oxide heat storage material provided in the embodiment of the present invention. Figure 1 As shown, in this embodiment, the magnesium oxide modified copper-aluminum composite metal oxide heat storage material is prepared by the following steps:

[0035] Step S1: Weigh copper oxide, aluminum oxide, and magnesium oxide in proportion, and grind and mix the raw materials;

[0036] Step S2: calcining the mixed copper oxide powder, aluminum oxide and magnesium oxide at high temperature and then cooling to obtain a calcined product, and grinding the calcined product into powder to obtain a composite metal oxide heat storage material.

[0037] Preferably, the copper oxide, magnesium oxide, and aluminum oxide chemical reagents used to prepare the magnesium oxide-modified copper-aluminum composite metal oxide thermal storage material are all analytically pure, with relatively high purity and few interfering impurities. This minimizes the impact of impurities on the thermal storage / release chemical reactions of the thermal storage material, thereby preventing damage to the thermal storage / release reaction characteristics and cyclic performance of the thermal storage material.

[0038] In step S2, copper oxide, aluminum oxide, and magnesium oxide must first be thoroughly mixed. The specific mixing method is not limited here. In some embodiments, copper oxide, aluminum oxide, and magnesium oxide can be placed in a solvent for mixing and then dried to obtain a homogeneous mixture. In other embodiments, copper oxide powder, aluminum oxide, and magnesium oxide powder can also be placed in a ball mill for grinding and mixing; thereafter, the uniformly mixed powder is compounded by a high-temperature solid-phase method. Under the high-temperature calcination conditions of step S2, the interface between the copper oxide powder, aluminum oxide powder, and magnesium oxide powder undergoes contact, reaction, nucleation, and crystal growth reaction, ultimately obtaining the composite metal oxide heat storage material in this embodiment. This preparation method has the advantages of low cost, high output, simple equipment and preparation process, and high production efficiency, and is suitable for large-scale industrial production. In addition, the chemical properties of magnesium aluminate produced by high-temperature calcination are more stable, which can further improve the cyclic stability of the heat storage material.

[0039] Specifically, first weigh alumina and magnesium oxide according to a molar ratio of 1:1, and then weigh the copper oxide raw material according to different mass ratios based on the total mass of the weighed alumina and magnesium oxide raw materials. The weighed raw materials are ball milled for 30 minutes with a ball mill and fully mixed. Then, the fully mixed solid powder is placed in a box furnace, maintained at 900°C, and calcined for 4 hours at a heating rate of 10°C / min. Finally, after waiting to cool to room temperature, the calcined product is taken out and the taken out calcined product is ground into powder to obtain a magnesium oxide-modified copper-aluminum composite metal oxide heat storage material formed by a composite of alumina, magnesium oxide and copper oxide.

[0040] In addition, aluminum oxide and copper oxide were weighed in proportion, and a copper-aluminum composite metal oxide heat storage material was prepared according to the above steps as a control sample.

[0041] 2. Material Characterization

[0042] The following experiments were used to characterize the thermal storage material. Thermogravimetric analysis was performed using a STA449F3 synchronous thermal analyzer from NETZSCH (Germany), and X-ray diffraction (XRD) analysis was performed using an Xpert Powder X-ray diffractometer from PANalytical (Netherlands). The redox ratio of the sample was measured using thermogravimetric analysis (TG).

[0043] The simulation process of the heat storage cycle in the experiment is as follows: about 10 mg of sample is placed in an alumina crucible with a capacity of 50 ul. The temperature control program is to heat up from room temperature to 1100°C and then directly cool down to 700°C. The heating and cooling rates are both 20°C / min, and the air flow rate is 30 ml / min (pO2=0.21).

[0044] 2.1 Control samples

[0045] Figure 2 The following are SEM images of copper-aluminum composite metal oxide (control sample) at different cycle times. Figure 2 It can be seen that in the early stage of the cycle (30 cycles), the copper oxide particles did not sinter, and the aluminum oxide attached to the surface of the copper oxide, which played a certain anti-sintering role. However, as the number of cycles continued to increase, when it reached 60-90 cycles, the copper oxide particles still showed agglomeration and growth. Finally, when it reached 120 cycles, the copper oxide particles had undergone very serious agglomeration and sintering phenomena. Multiple copper oxide particles merged into agglomerates, and as the number of reactions increased, the densification became more serious. Due to the fusion of copper oxide particles, the specific surface area of copper oxide decreased, and a large amount of copper oxide material located in the agglomeration center could not be exposed to the air, and thus could not undergo reoxidation reaction. Therefore, the cyclic heat storage / heat release performance of the copper-aluminum composite metal oxide thermal storage material decreased seriously after multiple cycles.

[0046] Figure 3 The figure is a schematic diagram of the thermogravimetric curve of the copper-aluminum composite metal oxide heat storage material (control sample) at different cycle times. Figure 3 As shown in the figure, the reoxidation degree of the control sample is greatly reduced at the 90th and 120th cycles. Figure 2 and Figure 3 From the results, it can be seen that between the 90th cycle and the 120th cycle, copper oxide underwent more serious sintering, which also led to a large amount of copper oxide agglomeration, a reduction in specific surface area, and an inability to undergo reoxidation reaction. Therefore, the reoxidation degree of the heat storage material was greatly reduced.

[0047] 2.2 Magnesium oxide modified copper-aluminum composite metal oxide thermal storage material

[0048] Figure 4 This is an X-ray diffraction analysis (XRD) diagram of the magnesium oxide modified copper-aluminum composite metal oxide heat storage material prepared by the preparation method provided in this embodiment. Figure 4 The phases of the magnesium oxide modified copper-aluminum composite metal oxide heat storage material at room temperature are mainly two crystal phases of copper oxide and magnesium aluminate, indicating that under high temperature conditions, alumina and magnesium oxide react to form magnesium aluminate; and the composite reaction between alumina and magnesium oxide takes precedence over the reaction between alumina and copper oxide or magnesium oxide and copper oxide; the generated magnesium aluminate has a more stable crystal form and a stronger structure than alumina, and has a higher operating temperature and stable chemical properties, so it can exist stably at high temperatures and will not react with copper oxide particles to form new substances.

[0049] Therefore, the use of magnesium oxide to modify the copper-aluminum composite metal oxide heat storage material can avoid the reaction between aluminum oxide and copper oxide at high temperatures, thereby avoiding the problem of reducing the content of the main reaction substance (copper oxide) of the composite metal oxide heat storage material and damaging the reaction activity of the copper oxide metal oxide, ensuring that the heat storage material has a higher heat storage / release density.

[0050] Figure 5 : is the SEM image of the magnesium oxide modified copper-aluminum composite metal oxide heat storage material obtained in this embodiment at different cycle times. Figure 5 The magnesium aluminate particles are coated on the surface of the copper oxide particles. This effectively blocks contact between the copper oxide particles, preventing them from agglomerating and sintering under high-temperature reaction conditions. Furthermore, the magnesium aluminate can stably coat the surface of the copper oxide particles during multiple cycles of heat storage and release reactions. As a result, the heat storage material provided by the present invention has excellent cyclic heat storage and release performance, and can maintain a high heat storage and release density after multiple cycles.

[0051] In particular, Figure 5 It can be seen that the particle size of the copper oxide particles after 100 cycles is not much different from that after 200 cycles. After the 300th cycle, driven by the surface energy difference of different grain sizes (Ostwald ripening theory), small grains and large grains aggregate and merge, and the grain size begins to grow. However, the particle size after the 400th and 500th cycles did not change much compared with the 300th cycle, which shows that the magnesium aluminate on the surface of the copper oxide particles effectively inhibited the agglomeration of copper oxide particles; and even after 500 cycles, magnesium aluminate was still coated on the surface of the copper oxide particles, further proving that even under high temperature conditions and multiple cycles of heat storage / exothermic reactions, there is still a strong interaction force between magnesium aluminate and copper oxide particles, and it is not easy to fall off. It can play a barrier role between multiple copper oxide particles, preventing the copper oxide particles from agglomerating and sintering under high temperature conditions, thereby improving the cyclic heat storage performance of the composite metal oxide heat storage material.

[0052] Among them, preferably, Figure 5 As shown, magnesium aluminate is a solid particle. When the granular magnesium aluminate is wrapped around the surface of the copper oxide particles, it makes point contact with the surface of the copper oxide particles, thereby ensuring a barrier effect between the copper oxide particles. At the same time, the copper oxide particles have a larger reaction contact area with the air. Therefore, in multiple cycles of heat storage / exothermic reactions, the magnesium oxide-modified copper-aluminum composite metal oxide heat storage material provided in this embodiment has a larger reaction area, further improving the reoxidation degree and reaction rate of the copper-aluminum composite metal oxide heat storage material in the cycle of heat storage / exothermic reactions.

[0053] Among them, preferably, Figure 5As shown, the particle size of the magnesium aluminate particles is smaller than that of the copper oxide particles, and multiple magnesium aluminate particles are evenly coated on the surface of the copper oxide particles. The smaller magnesium aluminate particles are evenly attached to the surface of the larger copper oxide particles. This prevents the copper oxide particles from agglomerating without affecting the reaction area between the copper oxide particles and air. This maximizes the effect of magnesium aluminate on preventing copper oxide particles from agglomerating when the mass ratio is the same.

[0054] Furthermore, the applicant also provided the thermal storage performance test results of magnesium oxide-modified copper-aluminum composite metal oxide thermal storage materials prepared by the above-mentioned preparation method using different proportions of copper oxide, aluminum oxide, and magnesium oxide. The experiment found that the mass fraction of magnesium aluminate should not be too low. Too low a magnesium aluminate cannot effectively block copper oxide particles. Specifically, the mass fraction of magnesium aluminate should not be less than 5% of the mass of the thermal storage material. Furthermore, the mass fraction of magnesium aluminate should not be too high. Excessive magnesium aluminate will affect the content of the main reaction substance (copper oxide) in the thermal storage material, resulting in a decrease in the thermal storage density of the thermal storage material. Specifically, the mass fraction of copper oxide is 1-x, the mass fraction of magnesium aluminate is x, and the value range of x is 5%-20%.

[0055] Table 1 shows the weight loss rate during heat storage and the weight gain rate during heat release of the magnesium oxide modified copper-aluminum composite metal oxide heat storage material obtained by the above preparation method with different proportions of copper oxide, aluminum oxide and magnesium oxide.

[0056] Table 1

[0057]

[0058]

[0059] As shown in Table 1, when the mass ratio of copper oxide to magnesium aluminate is between 19:1 and 8:2, that is, the mass fraction x of magnesium aluminate is in the range of 5% to 20%, the ratio of the weight gain rate to the weight loss rate of the composite metal oxide thermal storage material reaches 99%. This means that the reoxidation degree of the composite metal oxide thermal storage material formed by the composite of copper oxide particles and magnesium aluminate in the mass ratio of 19:1 to 8:2 can reach 99%. Therefore, magnesium aluminate with a mass ratio greater than 5% can effectively block the copper oxide particles and prevent the copper oxide particles from agglomerating and sintering under high temperature reaction conditions. However, when the mass fraction of magnesium aluminate continues to increase, the mass fraction of copper oxide particles continues to decrease, and the weight loss rate of the thermal storage material will also decrease. The energy density of the heat storage / release reaction of the material under the same mass conditions is reduced. In addition, excessive magnesium aluminate adheres to the surface of the copper oxide particles, which easily causes insufficient contact reaction area between the copper oxide particles and the air. Therefore, as a preferred method, when the mass fraction of magnesium aluminate is 5% to 20%, the heat storage / release performance and cycle performance of the thermal storage material can be taken into account.

[0060] Further preferably, when the mass proportion of magnesium aluminate is 10%, the ratio of the weight gain rate and weight loss rate of the composite metal oxide heat storage material reaches the highest value. Therefore, as a preference, when the mass proportion of magnesium aluminate is 10%, the composite metal oxide heat storage material can have better heat storage / heat release performance.

[0061] Figure 6 Schematic diagram of thermogravimetric curve of magnesium oxide modified copper-aluminum composite metal oxide heat storage material obtained by the preparation method of composite metal oxide heat storage material in this embodiment under different cycle numbers. Figure 6 As shown, in the heat storage material composed of 90% copper oxide and 10% magnesium aluminate, during multiple heat storage / release processes, compared with the first cycle, the mass change rate of the heat storage material composed of magnesium aluminate and copper oxide particles after 500 cycles is not much changed, and the reoxidation degree can still reach more than 96%. Therefore, the heat storage material provided in this embodiment can maintain a high reoxidation degree after multiple cycles, and has better cyclic heat storage / release performance. In particular, when the mass proportion of magnesium aluminate is 10%, the composite metal oxide heat storage material also has good cycle performance.

[0062] In this embodiment, first, after the copper-aluminum system heat storage material is doped with magnesium oxide, since the reaction priority of magnesium oxide with aluminum oxide at high temperature is higher than the reaction of aluminum oxide with copper oxide and magnesium oxide with copper oxide, magnesium oxide can preferentially react with aluminum oxide to form magnesium aluminate crystals with more stable crystal form and stronger structure. Magnesium aluminate has a higher operating temperature than aluminum oxide and has stable chemical properties. Therefore, even under high-temperature reaction conditions, the magnesium aluminate generated by the reaction of aluminum oxide and magnesium oxide will not undergo phase changes at high temperatures, nor will it react chemically with copper oxide like aluminum oxide. This avoids the reduction of the content of the main reaction substance (copper oxide) and can stably exist in multiple storage / release cycles.

[0063] Secondly, the applicant's experimental research found that there is a strong interaction between magnesium aluminate and copper oxide particles. Magnesium aluminate can be tightly wrapped on the surface of copper oxide particles and is not easy to fall off during multiple heat storage / release cycle reactions.

[0064] Finally, since magnesium aluminate can adhere to the surface of copper oxide particles, it can effectively block contact between copper oxide particles and prevent the agglomeration and sintering of copper oxide particles under high-temperature reaction conditions. Moreover, during multiple cycles of heat storage / release reactions, magnesium aluminate can also be stably coated on the surface of copper oxide particles. Therefore, the heat storage material provided by the present invention has excellent cyclic heat storage / release performance and can maintain a high heat storage / release density after multiple cycles.

[0065] The technical solutions of the present invention have been described above in conjunction with the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is not limited to the above specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A composite metal oxide heat storage material, characterized in that: The composite metal oxide heat storage material is a heat storage material formed by uniformly mixing copper oxide, aluminum oxide and magnesium oxide and then calcining them at high temperature. The molar ratio of the aluminum oxide to the magnesium oxide is 1:

1. The aluminum oxide and the magnesium oxide generate magnesium aluminate at high temperature, and the magnesium aluminate is wrapped on the surface of the copper oxide particles.

2. The composite metal oxide heat storage material according to claim 1, wherein The mass fraction of the copper oxide is 1-x, the mass fraction of the magnesium aluminate is x, and the value range of x is 5%-20%.

3. The composite metal oxide heat storage material according to claim 2, characterized in that: The value of x is 10%.

4. The composite metal oxide heat storage material according to claim 1, wherein The magnesium aluminate is in the form of solid particles.

5. The composite metal oxide heat storage material according to claim 4, characterized in that The particle size of the magnesium aluminate particles is smaller than that of the copper oxide particles, and a plurality of the magnesium aluminate particles are uniformly wrapped on the surface of the copper oxide particles.

6. A method for preparing the composite metal oxide heat storage material according to any one of claims 1 to 5, characterized in that: The steps include: Step S1: weighing the copper oxide, the aluminum oxide, and the magnesium oxide in proportion, and grinding and mixing the raw materials; Step S2: calcining the mixed copper oxide, aluminum oxide and magnesium oxide at high temperature and then cooling to obtain a calcined product, and grinding the calcined product into powder to obtain the composite metal oxide heat storage material.

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