A low-cost performance-enhanced Na2ZrO3-based heat storage agent, a preparation method and applications thereof

Abstract

This invention discloses a low-cost, performance-enhanced Na2ZrO3-based thermal storage agent, its preparation method, and its applications, belonging to the field of energy storage materials technology. This invention uses sodium, zirconium, and extracts from retired lithium-manganese button batteries as raw materials to prepare a Na2ZrO3-based thermal storage agent simultaneously doped with lithium and manganese. Na2ZrO3 forms the basis of thermochemical energy storage. The multivalent nature of manganese can introduce lattice defects and distortions into the crystal, increasing the diffusion channels of CO2 gas in the solid phase product layer, thereby significantly improving the carbonization conversion rate and reaction rate of the material. Lithium can partially replace sodium sites during synthesis to form a solid solution, which helps stabilize the crystal structure and improve the material's resistance to sintering during long-term cycling. In addition, manganese, as a transition metal oxide, can enhance the material's absorption rate of sunlight and improve photothermal conversion efficiency. Ultimately, a Na2ZrO3-based thermal storage agent with excellent light absorption and thermochemical thermal storage performance is obtained.

Description

Technical Field

[0001] This invention belongs to the field of energy storage materials technology, and particularly relates to a low-cost, high-performance Na2ZrO3-based thermal energy storage agent, its preparation method, and its application. Background Technology

[0002] Over-reliance on fossil fuels such as coal, oil, and natural gas has led to a dual crisis of energy depletion and environmental degradation, posing a significant challenge to global sustainable development. The transition to renewable energy has become an urgent priority. Solar energy, characterized by its abundance, cleanliness, and sustainable development, is a preferred candidate for this transition. Concentrated solar power (CSP) technology has become the main method for large-scale solar energy utilization. However, the intermittency and instability of solar energy limit its widespread application. Therefore, combining CSP with reliable energy storage technologies is a prerequisite for stable power supply from CSP systems. Thermochemical energy storage (TCES) technology is a thermal energy storage technology that effectively stores and releases energy by breaking and rearranging molecular bonds through reversible chemical reactions. Commonly used thermochemical thermal storage media include CaO and Li₄SiO₄.

[0003] Sodium zirconate (Na2ZrO3) is a rarely reported TCES material. It releases heat through the reaction of Na2ZrO3 with CO2 in a carbonization furnace, followed by the storage of the carbonization products Na2CO3 and ZrO2 in a specific material tank. Finally, during the energy supply phase, it is transferred to a calcining furnace to regenerate Na2ZrO3 while simultaneously storing heat. The Na2ZrO3 / Na2CO3 / ZrO2 material continuously circulates and fluidizes between the carbonization furnace, storage tank, and calcining furnace during the cyclic heat storage process, achieving efficient and stable cyclic heat storage / release. However, pure Na2ZrO3 powder is white, which significantly limits the solar radiation absorption capacity of Na2ZrO3-based heat storage agents. Furthermore, unmodified Na2ZrO3-based heat storage agents do not possess strong industrial application adaptability, specifically exhibiting low energy storage density and a rapid performance degradation rate. Therefore, modifying the properties of Na2ZrO3-based thermal storage agents to improve their light absorption and thermal storage performance is a necessary prerequisite for their practical application.

[0004] On the other hand, with the rapid development of the Internet of Things, microelectronic devices, and disposable medical devices, lithium-manganese button batteries have been widely used due to their high energy density, stable discharge platform, and low cost, leading to a sharp increase in their disposal volume. These batteries contain valuable metals such as manganese and lithium; if discarded indiscriminately, they will cause serious heavy metal pollution and resource waste. Traditional recycling methods suffer from complex processes, high energy consumption, and the potential for secondary pollution. Therefore, there is an urgent need to develop a new technology for the efficient, low-carbon, and high-value recycling of retired lithium-manganese button batteries. Summary of the Invention

[0005] To address the bottlenecks of low heat storage density and weak light absorption performance of Na2ZrO3-based materials in thermochemical heat storage, this invention proposes a low-cost, performance-enhanced Na2ZrO3-based heat storage agent, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a low-cost, performance-enhancing Na2ZrO3-based thermal storage agent, the raw materials of which include sodium source, zirconium source and extract from retired lithium manganese button batteries; The molar ratio of sodium in the sodium source, zirconium in the zirconium source, and manganese in the extract of retired lithium manganese button batteries is 2:(0.9~0.975):(0.025~0.1).

[0007] Furthermore, the sodium source is selected from sodium carbonate, and the zirconium source is selected from zirconium dioxide.

[0008] Furthermore, the molar ratio of sodium in the sodium source, zirconium in the zirconium source, and manganese in the extract of retired lithium manganese button batteries is 2:0.975:0.025, 2:0.95:0.05, 2:0.925:0.075, or 2:0.9:0.1.

[0009] Furthermore, the preparation method of the retired lithium manganese button battery extract includes: after pre-treating the retired lithium manganese button battery by discharge, prying open the steel shell along the sealed edge of the battery, taking out the internal stacked structure, and then scraping and collecting the black electrode material in the stacked structure to obtain the retired lithium manganese button battery extract.

[0010] Furthermore, the low-cost, performance-enhanced Na2ZrO3-based thermal storage agent is a lithium- and manganese-co-doped Na2ZrO3-based thermal storage agent.

[0011] This invention provides a method for preparing a low-cost, performance-enhancing Na2ZrO3-based thermal storage agent as described above, comprising the following steps: Sodium source, zirconium source and extract from retired lithium manganese button batteries were mixed and ground to obtain precursor powder; The precursor powder was calcined and then ground again to obtain the low-cost, high-performance Na2ZrO3-based thermal storage agent.

[0012] Furthermore, the calcination temperature is 800~950℃, the calcination time is 240~360min, and the calcination atmosphere is air.

[0013] This invention also provides an application of the low-cost, performance-enhancing Na2ZrO3-based thermal energy storage agent as described above as a thermochemical energy storage material in solar collectors.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects: This invention uses sodium source, zirconium source, and extracts from decommissioned lithium-manganese button batteries as raw materials to prepare a Na2ZrO3-based thermal storage agent simultaneously doped with lithium and manganese. Na2ZrO3 is the basis for thermochemical energy storage, and manganese has multiple valence states (Mn). 2+ / Mn 3+ / Mn 4+ The synthesis process can introduce lattice defects and distortions into the crystal, increasing the diffusion channels of CO2 gas in the solid product layer, thereby significantly improving the carbonization conversion rate and reaction rate of the material. Lithium can partially replace sodium sites during the synthesis process to form a solid solution, which helps to stabilize the crystal structure and improve the anti-sintering ability of the material in long-term cycling. In addition, manganese, as a transition metal oxide, can enhance the absorption rate of sunlight and improve the photothermal conversion efficiency. Finally, a Na2ZrO3-based heat storage agent with excellent light absorption and thermochemical heat storage performance was obtained.

[0015] The low-cost, performance-enhanced Na2ZrO3-based thermal energy storage agent provided by this invention exhibits an average absorptivity across the entire solar spectrum that is approximately 12.6 times higher than that of pure Na2ZrO3, and its energy storage density is also improved compared to unmodified pure Na2ZrO3. This invention not only utilizes the large quantities of waste from retired lithium-manganese button batteries currently stockpiled, but also achieves a combined enhancement of the thermochemical thermal energy storage and light absorption properties of Na2ZrO3-based materials. Furthermore, the preparation method is convenient, providing a novel technical approach for the industrial application of thermochemical energy storage. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The image shows the XRD pattern of the extract from the retired lithium manganese button battery used in this invention. Figure 2 XRD patterns of the Na2ZrO3-based thermal storage agents prepared in Example 1, Comparative Example 2, and Comparative Example 5; Figure 3 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared for Comparative Example 1 with the number of cycles; Figure 4 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared in Example 1 with the number of cycles; Figure 5 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared for Comparative Example 2 with the number of cycles; Figure 6The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared for Comparative Example 3 with the number of cycles; Figure 7 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared in Comparative Example 4 with the number of cycles. Figure 8 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared in Example 2 with the number of cycles; Figure 9 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared in Example 3 with the number of cycles; Figure 10 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared in Example 4 with the number of cycles; Figure 11 The change in energy storage density of the Na2ZrO3-based thermal energy storage agent prepared in Comparative Example 5 with the number of cycles; Figure 12 The results of ultraviolet-visible-near-infrared absorption tests of the Na2ZrO3-based thermal storage agent prepared in Example 1; Figure 13 The results of UV-Vis-NIR absorption tests on the Na2ZrO3-based thermal storage agent prepared in Comparative Example 2 are shown. Figure 14 The results of ultraviolet-visible-near-infrared absorption tests are shown for the Na2ZrO3-based thermal storage agent prepared in Comparative Example 5. Figure 15 The average absorption rate of the Na2ZrO3-based thermal storage agents prepared in Examples 1, 2, and 5 in the wavelength range of 300–800 nm. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] This invention provides a low-cost, performance-enhancing Na₂ZrO₃-based thermal storage agent, using sodium, zirconium, and extracts from retired lithium-manganese button batteries as raw materials. The manganese and lithium from the retired lithium-manganese button battery extract are incorporated into the Na₂ZrO₃ matrix, effectively improving the material's light absorption and thermochemical thermal storage performance.

[0020] In a preferred embodiment, the sodium source is selected from sodium carbonate, and the zirconium source is selected from zirconium dioxide.

[0021] In a preferred embodiment, the molar ratio of sodium in the sodium source, zirconium in the zirconium source, and manganese in the extract of retired lithium manganese button batteries is 2:(0.9~0.975):(0.025~0.1), more preferably 2:0.975:0.025, 2:0.95:0.05, 2:0.925:0.075, or 2:0.9:0.1, and even more preferably 2:0.975:0.025.

[0022] In a preferred embodiment, the preparation method of the retired lithium manganese button battery extract includes: after pre-treating the retired lithium manganese button battery by discharge, prying open the steel shell along the sealed edge of the battery, removing the internal stacked structure, and then scraping and collecting the black electrode material in the stacked structure to obtain the retired lithium manganese button battery extract; more preferably: immersing the retired lithium manganese button battery in a 10wt% sodium chloride solution, letting it stand at room temperature for 24 hours, then rinsing it with deionized water and drying it; subsequently, using diagonal pliers to pry open the steel shell along the sealed edge of the battery, removing the stacked structure containing the black electrode material, metal mesh, separator and sealing ring, and then scraping and collecting the black electrode material in the stacked structure to obtain the retired lithium manganese button battery extract.

[0023] In a preferred embodiment, the extract of the decommissioned lithium manganese button battery contains 50.59% Mn and 4.999% Li by mass.

[0024] In a preferred embodiment, the low-cost, performance-enhanced Na2ZrO3-based thermal storage agent is a lithium- and manganese-co-doped Na2ZrO3-based thermal storage agent.

[0025] This invention provides a method for preparing a low-cost, performance-enhancing Na2ZrO3-based thermal storage agent as described above, comprising the following steps: Sodium source, zirconium source and extract from retired lithium manganese button batteries were mixed and ground to obtain precursor powder; The precursor powder was calcined and then ground again to obtain the low-cost, high-performance Na2ZrO3-based thermal storage agent.

[0026] In a preferred embodiment, the calcination temperature is 800~950℃, more preferably 900℃; the calcination time is 240~360min, more preferably 300min; and the calcination atmosphere is air. During the calcination process, the synthesis of the Na2ZrO3 matrix and the incorporation of manganese and lithium elements are achieved.

[0027] This invention also provides an application of the low-cost, performance-enhancing Na2ZrO3-based thermal energy storage agent as described above as a thermochemical energy storage material in solar collectors.

[0028] In this embodiment of the invention, room temperature refers to "25±2℃".

[0029] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0030] The composition of the retired lithium-manganese button battery extract used in this invention was analyzed by inductively coupled plasma optical emission spectroscopy (IPC-OES) and X-ray fluorescence spectroscopy (XRF), and the results are shown in Tables 1 and 2, respectively. The IPC-OES test results (Table 1) show that the main metallic element in the material is Mn, with a mass fraction as high as 50.59%, confirming it as the core component of the retired lithium-manganese button battery extract, while the mass fraction of Li is 4.999%. Further XRF test results (Table 2) show that Mn mainly exists in the form of manganese oxide (MnO), accounting for over 95%, while the total content of other impurities such as silicon, chlorine, and sulfur is low and within an acceptable range, allowing it to be directly used in the preparation of Na2ZrO3-based thermal storage agents without complex purification steps.

[0031] Table 1

[0032] Table 2

[0033] Example 1 A method for preparing a low-cost, performance-enhancing Na2ZrO3-based thermal storage agent, comprising the following specific steps: (1) Place 0.1 mol sodium carbonate (Na2CO3, Guoyao reagent), 0.0975 mol zirconium dioxide (ZrO2, Maclean reagent) and the powder of retired lithium manganese button battery extract containing 0.0025 mol manganese in a mortar and grind for 10 min until the mixture is uniform in color and there are no visible particles to the naked eye, and obtain the precursor powder. (2) The precursor powder obtained in step (1) is calcined at 900°C in air atmosphere for 300 min to obtain a low-cost performance-enhanced Na2ZrO3-based heat storage agent.

[0034] Comparative Example 1 A method for preparing a Na2ZrO3-based thermal storage agent, the specific steps of which are as follows: (1) Place 0.1 mol sodium carbonate (Na2CO3, Guoyao reagent), 0.0975 mol zirconium dioxide (ZrO2, Maclean's reagent) and 0.0025 mol manganese dioxide (MnO2, 85%, Maclean's reagent) in a mortar and grind them evenly to obtain precursor powder; (2) The precursor powder obtained in step (1) is calcined at 900°C in air atmosphere for 300 min to obtain Na2ZrO3-based heat storage agent.

[0035] Examples 2-4 A method for preparing a low-cost, performance-enhancing Na2ZrO3-based thermal storage agent differs from Example 1 in that the amounts of zirconium dioxide and the extract from decommissioned lithium manganese button batteries are different, while the rest is the same as in Example 1; the specific amounts of zirconium dioxide and the extract from decommissioned lithium manganese button batteries are shown in Table 3.

[0036] Comparative Examples 2-5 A method for preparing a Na2ZrO3-based heat storage agent differs from Comparative Example 1 in that the amounts of zirconium dioxide and manganese dioxide are different, while the other aspects are the same as in Comparative Example 1; the specific amounts of zirconium dioxide and manganese dioxide are shown in Table 3.

[0037] Table 3

[0038] Figure 1 This is the XRD pattern of the extract from the retired lithium-manganese button battery used in this invention. Figure 1 It can be seen that the XRD diffraction peaks of the extract from retired lithium manganese button batteries are mixed and weak, indicating that its crystallinity is low and its composition is mixed.

[0039] Figure 2 The XRD patterns are of the Na2ZrO3-based thermal storage agents prepared in Examples 1, 2, and 5. Figure 2 The results showed that both Example 1 and Comparative Example 2 exhibited strong diffraction peaks at diffraction angles of 16.13°, 33.62°, and 38.76°, which perfectly matched the characteristic peaks of standard Na₂ZrO₃, confirming that the main crystalline phase of the synthesized material was Na₂ZrO₃. Meanwhile, no obvious impurity phase diffraction peaks were observed, indicating that the doping process did not alter the main structure of the material.

[0040] The cyclic thermal storage performance of the Na2ZrO3-based thermal storage agents prepared in Examples 1-4 and Comparative Examples 1-5 under specific thermal storage conditions was tested using a dual-temperature-controlled fixed-bed reactor. The thermal storage conditions were: thermal storage temperature 950℃, thermal storage time 40 min, and atmosphere of 100 vol.% N2; the exothermic conditions were: exothermic temperature 800℃, heat release time 15 min, and atmosphere of 100 vol.% CO2. Ten cycles were performed. The mass of CO2 adsorbed in each cycle was calculated based on the difference in adsorbent mass before and after each cycle. The energy storage density was calculated using the heat of reaction (ΔH = -158.3 kJ / kg). The change in energy storage density with increasing cycle number was illustrated graphically. The results are shown below. Figures 3-11 As shown, the horizontal axis represents the number of heat storage-heat release cycles, and the vertical axis represents the energy storage density. From Figures 3-11 As can be seen, the energy storage densities of the thermal storage agents prepared from sodium carbonate, zirconium dioxide, and extracts from retired lithium-manganese button batteries (Examples 1-4) are generally higher than those of the thermal storage agents prepared from sodium carbonate, zirconium dioxide, and manganese dioxide (Comparative Examples 1-4) and pure Na2ZrO3 (Comparative Example 5). The Na2ZrO3-based thermal storage agent prepared in Example 1 exhibits the best energy storage stability, achieving an energy density of 673 kJ / kg after 10 cycles. Notably, the pure Na2ZrO3 thermal storage agent prepared in Comparative Example 5 shows poor energy storage stability, with an energy density of 554 kJ / kg after 10 cycles, demonstrating that the energy storage stability of the Na2ZrO3-based thermal storage agent is improved compared to undoped pure Na2ZrO3.

[0041] The Na2ZrO3-based thermal storage agents prepared in Example 1, Comparative Example 2, and Comparative Example 5 were subjected to ultraviolet-visible-near-infrared absorbance tests. The test results are as follows: Figures 12-14 As shown. From Figures 12-14 As can be seen, Example 1 and Comparative Example 2 show similar absorbance trends. Specifically, an absorption peak (>65%) appears near 300 nm, and then the absorbance of both materials shows a continuous and gradual decreasing trend with increasing wavelength, maintaining an absorbance of over 15% at 800 nm. Comparative Example 5 (pure Na2ZrO3), however, exhibits significantly different behavior, showing extremely low absorbance across the entire test wavelength range (300~800 nm), with a peak value of less than 7%, and no significant fluctuation with increasing wavelength. This result demonstrates that the light absorption performance of the Na2ZrO3-based thermal storage agent is significantly improved by doping pure Na2ZrO3.

[0042] To quantitatively compare the absorbance properties of Example 1, Comparative Example 2, and Comparative Example 5, the average absorbance of each sample in the wavelength range of 300–800 nm was calculated. The calculation results are as follows: Figure 15 As shown, the calculation formula is as follows: ; In the formula, λ is the wavelength, in nm; A(λ) is the absorbance of the sample at λ, expressed as a percentage; I AM1.5D (λ) represents the standard AM1.5D solar spectral irradiance.

[0043] Figure 15 The average absorbance of the Na2ZrO3-based thermal storage agents prepared in Examples 1, 2, and 5 in the wavelength range of 300–800 nm. Figure 15 It can be seen that the average absorption rate of the Na2ZrO3-based thermal storage agent prepared in Example 1 is 34.75%, while the average absorption rate of the Na2ZrO3-based thermal storage agent prepared in Comparative Example 5 is 2.76%. Therefore, the average absorption rate of Example 1 is approximately 12.6 times higher than that of Comparative Example 5.

[0044] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-cost, performance-enhanced Na2ZrO3-based thermal storage agent, characterized in that, The raw materials include sodium source, zirconium source and extracts from retired lithium manganese button batteries; The molar ratio of sodium in the sodium source, zirconium in the zirconium source, and manganese in the extract of retired lithium manganese button batteries is 2:(0.9~0.975):(0.025~0.1).

2. The low-cost, performance-enhanced Na2ZrO3-based thermal storage agent according to claim 1, characterized in that, The sodium source is selected from sodium carbonate, and the zirconium source is selected from zirconium dioxide.

3. The low-cost, performance-enhanced Na2ZrO3-based thermal storage agent according to claim 1, characterized in that, The molar ratio of sodium in the sodium source, zirconium in the zirconium source, and manganese in the extract of retired lithium manganese button batteries is 2:0.975:0.025, 2:0.95:0.05, 2:0.925:0.075, or 2:0.9:0.

1.

4. The low-cost, performance-enhanced Na2ZrO3-based thermal storage agent according to claim 1, characterized in that, The preparation method of the retired lithium manganese button battery extract includes: after discharging the retired lithium manganese button battery, prying open the steel shell along the sealed edge of the battery, taking out the internal stacked structure, and then scraping and collecting the black electrode material in the stacked structure to obtain the retired lithium manganese button battery extract.

5. The low-cost, performance-enhanced Na2ZrO3-based thermal storage agent according to claim 1, characterized in that, The low-cost, performance-enhanced Na2ZrO3-based thermal storage agent is a lithium- and manganese-co-doped Na2ZrO3-based thermal storage agent.

6. A method for preparing a low-cost, performance-enhancing Na2ZrO3-based thermal storage agent as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Sodium source, zirconium source and extract from retired lithium manganese button batteries were mixed and ground to obtain precursor powder; The precursor powder was calcined and then ground again to obtain the low-cost, high-performance Na2ZrO3-based thermal storage agent.

7. The preparation method according to claim 6, characterized in that, The calcination temperature is 800~950℃, the calcination time is 240~360min, and the calcination atmosphere is air.

8. The application of a low-cost, performance-enhancing Na2ZrO3-based thermal energy storage agent as described in any one of claims 1 to 5 as a thermochemical energy storage material in a solar collector.

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