Calcium carbonate-based inorganic battery separator and method of making same

Abstract

The application discloses a calcium carbonate-based inorganic battery diaphragm and a preparation method thereof. A calcium carbonate-based material and a composite porous structure additive are fully mixed and dispersed in water to obtain a slurry; the composite porous structure additive comprises a chemical foaming agent and a stabilizer; the calcium carbonate-based material is a calcium-containing material with carbonization activity; the slurry is uniformly applied to the surface of an inert carrier by a spraying, dipping or spin coating process; an inorganic skeleton and a porous structure are synchronously formed under the action of carbon dioxide and temperature rising and maintenance, and post-treatment is performed to obtain the calcium carbonate-based inorganic battery diaphragm; the calcium carbonate-based material is any one or mixture of steel slag, magnesium slag, calcium carbide slag, calcium silicate mineral, cement, lime, calcium oxide and calcium hydroxide; the inorganic skeleton is constructed by the calcium carbonate-based material, which serves as the structural core of the diaphragm to provide mechanical strength; and the composite porous structure additive is introduced to form a continuous and through porous pore network, so that the efficient transmission of ions is ensured.

Description

Technical Field

[0001] This invention belongs to the field of battery separator technology, specifically relating to a calcium carbonate-based inorganic battery separator and its preparation method. Background Technology

[0002] The global energy landscape is rapidly transitioning towards renewable energy sources, with solar and wind power at its core. However, despite the promising prospects of clean energy, its inherent instability, randomness, and intermittency make it difficult to synchronize power generation with demand. To effectively address this challenge, the development of energy storage systems is crucial. These systems can effectively smooth out fluctuations in renewable energy generation, minimize energy waste, and significantly improve the efficiency of renewable energy integration and utilization. Among numerous energy storage technologies, electrochemical energy storage technology has attracted considerable attention due to its superior performance, including high energy density, efficient energy conversion, high reliability, and wide range of applications.

[0003] In electrochemical energy storage systems, the performance of core components directly impacts overall efficiency and safety. Typically, these systems employ a stacked structure of "electrode-membrane-electrode," with the membrane playing a crucial role. The membrane must not only effectively physically isolate the positive and negative electrodes to prevent internal short circuits but also precisely regulate the selective migration of ions to ensure smooth charge transport during charge-discharge cycles. Therefore, an ideal membrane material should possess excellent electrical insulation, good mechanical strength, an open and uniform porous structure, and efficient ion conductivity. However, existing commercially available membranes suffer from insufficient mechanical strength and are easily punctured by dendrites formed during charge-discharge processes, posing serious safety hazards and limiting the performance improvement and widespread application of energy storage systems. Furthermore, organic membrane materials also face problems such as poor thermal stability and insufficient chemical resistance. Therefore, developing novel inorganic membrane materials with superior performance has significant research value and application prospects.

[0004] Calcium carbonate-based materials, with their inherent flame retardancy and electrical insulation, have shown great potential in the field of lithium-ion battery separators. However, ion transport performance, a key factor affecting electrochemical energy storage efficiency, remains insufficient in existing calcium carbonate-based battery separators. Although existing research has focused on using halogenated modified calcium carbonate as a coating material or employing self-supporting calcium carbonate nanoarray structures to improve ionic conductivity and mechanical properties, these strategies are still limited by the inherent ion transport efficiency of calcium carbonate materials. Furthermore, issues such as the long-term structural stability of coatings or nanoarrays, interfacial impedance control, and the complexity of fabrication processes remain challenges that urgently need to be addressed. Meanwhile, existing technologies that use spherical calcium carbonate templates to form through-pores often sacrifice the mechanical strength and thermal stability of the separator while optimizing porosity to promote ion transport, leading to a risk of damage or structural failure during battery cycle operation. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention prepares a calcium carbonate-based inorganic battery separator by introducing specific composite porous structure additives. This separator exhibits excellent ionic conductivity and mechanical strength, thereby significantly improving the safety performance and cycle life of the battery. Simultaneously, the separator possesses excellent carbon dioxide absorption capacity, effectively absorbing carbon dioxide during preparation and maintenance, promoting carbonization reactions, improving the mechanical strength of the material, and significantly enhancing its environmental performance and service life.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] A method for preparing a calcium carbonate-based inorganic battery separator includes the following steps:

[0008] (1) A slurry is obtained by fully mixing and dispersing calcium carbonate-based material and composite porous structure additive in water; the composite porous structure additive includes a chemical foaming agent and a stabilizer; the calcium carbonate-based material is a calcium-containing material with carbonation activity;

[0009] (2) The slurry is uniformly applied to the surface of an inert carrier by spraying, dipping or spin coating.

[0010] (3) The inorganic framework and porous structure are formed simultaneously by heating and curing in a carbon dioxide atmosphere, and the calcium carbonate-based inorganic battery separator is obtained by post-processing.

[0011] According to the above scheme, the calcium carbonate-based material mentioned in step (1) is any one or a mixture of steel slag, magnesium slag, carbide slag, calcium silicate minerals, cement, lime, calcium oxide, and calcium hydroxide. The calcium silicate minerals include, for example, γ-2CaO•SiO2 (γ-C2S), 3CaO•2SiO2 (C3S2), and CaO•SiO2 (CS).

[0012] According to the above scheme, the chemical foaming agent mentioned in step (1) is sodium carbonate or sodium bicarbonate.

[0013] According to the above scheme, the stabilizer mentioned in step (1) is cellulose or nano-silica.

[0014] According to the above scheme, the mass ratio of the chemical foaming agent to the stabilizer in step (1) is (2-10):1.

[0015] According to the above scheme, the mass ratio of the calcium carbonate-based material to the composite porous structure additive in step (1) is 1:(2-8); the amount of water used is 3-5 wt% of the mass of the calcium carbonate-based material.

[0016] According to the above scheme, in step (1), high-speed dispersion or ultrasonic treatment is used to promote the full effect of the additives and improve the rheological properties and stability of the porous structure of the slurry.

[0017] According to the above plan, the curing temperature in step (3) is 40 ℃-80 ℃, the relative humidity is 40 %-90%, and the curing time is 1-24h.

[0018] According to the above scheme, the carbon dioxide atmosphere concentration in step (3) should not be less than 5%, and the pressure should be set within the range of 0.1 to 0.3 MPa.

[0019] According to the above scheme, the post-processing in step (3) includes drying and sanding or cutting. Sanding methods include one or more of sandpaper sanding, automatic polishing machines and manual polishing machines.

[0020] This invention provides a calcium carbonate-based inorganic battery separator, prepared using the aforementioned method. It is a porous material, primarily composed of a calcium carbonate-based inorganic framework that serves as the structural core of the separator, providing mechanical strength. By introducing composite porous structure additives, a chemical foaming agent decomposes to generate gas, inducing bubble nucleation and growth; while a stabilizer regulates matrix viscosity, reduces interfacial tension, and strengthens bubble walls, effectively inhibiting bubble coalescence and collapse, thereby ensuring uniform gas dispersion and the formation of stable, fine bubbles. This synergistic effect controls the porosity, pore size, and distribution of the porous material, forming a continuous, interconnected composite porous network, thus greatly ensuring efficient ion transport and significantly improving ionic conductivity.

[0021] To address the problems of flammability, insufficient mechanical strength, and poor thermal stability inherent in traditional organic separators, the calcium carbonate-based inorganic battery separator provided by this invention possesses a high-strength inorganic framework structure and a highly interconnected porous network, significantly improving the mechanical strength and pore connectivity of the separator, thereby effectively enhancing the ionic conductivity of the electrochemical energy storage device. Furthermore, this invention employs a carbonization curing process, which not only optimizes the overall performance of the separator but also achieves efficient absorption and storage of carbon dioxide, enhancing the material's environmental friendliness and sustainable development potential.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) Compared with traditional membranes, calcium carbonate-based inorganic membranes prepared by introducing specific composite porous structure additives can significantly improve their ionic conductivity and mechanical strength, which is expected to extend the service life and safety stability of electrochemical energy storage devices.

[0024] (2) Compared with ordinary cement, the use of calcium carbonate-based materials can effectively reduce carbon dioxide emissions;

[0025] (3) Compared with ordinary cement curing methods, carbonation curing can not only save curing time, but also allow it to absorb and seal carbon dioxide.

[0026] (4) The method of the present invention is reasonably designed and easy to operate. It not only meets the requirements of green development, but also has significant economic value. Attached Figure Description

[0027] Figure 1 Pore ​​structure of calcium carbonate-based inorganic battery separators with different ratios of composite porous additives.

[0028] Figure 2 Pore ​​structure of calcium carbonate-based inorganic battery separators with different amounts of composite porous additives.

[0029] Figure 3 : Polarization voltage curve of implementation 1.

[0030] Figure 4 Polarization voltage curve of implementation 2.

[0031] Figure 5 : Polarization voltage curve of implementation 3. Detailed Implementation

[0032] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0033] The calcium carbonate-based materials provided in the specific embodiments are calcium-containing materials with carbonation activity, such as lunar soil and Martian soil; industrial by-products, such as steel slag, magnesium slag, carbide slag, and other slag-like materials; calcium silicate minerals, such as γ-2CaO•SiO2 (γ-C2S), 3CaO•2SiO2 (C3S2), and CaO•SiO2 (CS); and one or more of cement, lime, calcium oxide, and calcium hydroxide. The chemical foaming agents used are such as sodium carbonate and sodium bicarbonate, and the stabilizers used are such as cellulose and nano-silica, with a mass ratio between the two ranging from 2:1 to 10:1. Unless otherwise specified, all other chemicals used in the specific embodiments are commercially available.

[0034] Example 1

[0035] First, a composite porous structure additive was prepared: sodium bicarbonate (a chemical foaming agent) and nano-silica (a stabilizer) were weighed at a mass ratio of 4:1 and thoroughly mixed in a mixer. Then, γ-C2S and water were added, with the mass ratio of γ-C2S to the composite porous structure additive being 1:3, and the water content being 3% of the mass of the calcium carbonate-based material. High-speed dispersion was then performed to obtain a uniform slurry. The resulting slurry was uniformly coated onto the surface of an inert carrier using a dip-coating process. Next, the coated sample was placed in a carbonation device at 60 ℃ and 60% relative humidity, and cured at a CO2 concentration of 5% and a pressure of 0.3 MPa to allow the inorganic framework and porous structure to form simultaneously. After one day of curing, the sample was removed, dried, and trimmed to obtain a calcium carbonate-based inorganic battery separator with a stable porous structure, high carbon fixation efficiency, and excellent ionic conductivity.

[0036] Example 2

[0037] The preparation process in this embodiment is basically the same as that in Example 1, except that the chemical foaming agent sodium bicarbonate and the stabilizer nano silica are in a mass ratio of 3:1.

[0038] Example 3

[0039] The preparation process in this embodiment is basically the same as that in Example 1, except that the chemical foaming agent sodium bicarbonate and the stabilizer nano silica are in a mass ratio of 5:1.

[0040] Example 4

[0041] The preparation process in this embodiment is basically the same as that in Example 1, except that the mass ratio of γ-C2S to the composite porous structure additive is 1:2.

[0042] Example 5

[0043] The preparation process in this example is basically the same as that in Example 1, except that the mass ratio of γ-C2S to the composite porous structure additive is 1:4.

[0044] Example 6

[0045] The preparation process in this embodiment is basically the same as that in Example 1, except that the chemical foaming agent is sodium carbonate.

[0046] Example 7

[0047] The preparation process in this embodiment is basically the same as that in Example 1, except that the stabilizer is cellulose.

[0048] Example 8

[0049] The preparation process in this embodiment is basically the same as that in Example 1, except that the calcium carbonate-based material is carbide slag.

[0050] Example 9

[0051] The preparation process in this embodiment is basically the same as that in Example 1, except that the calcium carbonate-based material is simulated lunar soil.

[0052] Example 10

[0053] The preparation process in this embodiment is basically the same as that in Example 1, except that the calcium carbonate-based material is magnesium slag.

[0054] The performance indicators of the obtained calcium carbonate-based inorganic battery separator are shown in Table 1. Compressive strength was determined according to GB11968-2008 "Test Methods for Autoclaved Aerated Concrete", with the loading rate controlled at 0.20±0.05 kN / s. Polarization performance test: The sample was placed in a zinc-metallic symmetric battery, charged for 1 hour and discharged for 1 hour at a current of 0.5 mA, and cycled to test its anti-polarization performance.

[0055] Table 1

[0056]

[0057] Table 1 shows that by changing the ratio and amount of composite porous additives, the compressive strength and interconnected porosity of the calcium carbonate-based inorganic battery separator can be significantly controlled, thereby affecting the cycle life and polarization voltage of the separator. Meanwhile, the selection of chemical foaming agents, stabilizers, and calcium carbonate-based materials also influences its compressive strength, cycle life, and polarization voltage.

[0058] Figure 1 The effects of different ratios of composite porous structure additives on the pore structure of calcium carbonate-based inorganic membranes were demonstrated. The results showed that changes in the ratio of composite porous structure additives led to significant changes in the pore structure of the membrane.

[0059] Figure 2 The effects of different amounts of composite porous structure additives on the pore structure of calcium carbonate-based inorganic membranes were demonstrated. The results showed that changes in the amount of composite porous structure additives led to significant changes in the pore structure of the membrane.

[0060] Figure 3 Example 1 demonstrates excellent anti-polarization performance with a polarization voltage of only 5.03 mV, and the voltage-time graph remains excellent during cycling, indicating that the battery separator prepared in Example 1 has excellent ionic conductivity.

[0061] Figure 4Example 2 exhibits poor anti-polarization performance, with a polarization voltage as high as 105.28 mV, and the voltage-time graph shows severe polarization during cycling, indicating that the battery separator prepared in Example 2 has poor ionic conductivity.

[0062] Figure 5 Example 3 demonstrates good anti-polarization performance with a polarization voltage of 10.11 mV, and the voltage-time graph shows moderate polarization during cycling, indicating that the battery separator prepared in Example 3 has good ionic conductivity.

Claims

1. A method for preparing a calcium carbonate-based inorganic battery separator, characterized in that... Includes the following steps: (1) A slurry is obtained by fully mixing and dispersing calcium carbonate-based materials and composite porous structure additives in water; the composite porous structure additives include chemical foaming agents and stabilizers; The calcium carbonate-based material is any one or a mixture of steel slag, magnesium slag, carbide slag, calcium silicate mineral, cement, lime, calcium oxide, and calcium hydroxide; the mass ratio of the calcium carbonate-based material to the composite porous structure additive is 1:(2-8). The chemical foaming agent is sodium carbonate or sodium bicarbonate; the stabilizer is cellulose or nano-silica; the mass ratio of the chemical foaming agent to the stabilizer is (2-10):1; (2) The slurry is uniformly applied to the surface of an inert carrier by spraying, dipping or spin coating. (3) The inorganic framework and porous structure are formed simultaneously by heating and curing in a carbon dioxide atmosphere, and the calcium carbonate-based inorganic battery separator is obtained by post-treatment; the curing temperature is 40 ℃-80 ℃, the relative humidity is 40 %-90%, and the curing time is 1-24h.

2. The method for preparing the calcium carbonate-based inorganic battery separator as described in claim 1, characterized in that... In step (1), the amount of water used is 3-5 wt% of the mass of the calcium carbonate-based material.

3. The method for preparing the calcium carbonate-based inorganic battery separator as described in claim 1, characterized in that... In step (3), the carbon dioxide atmosphere concentration shall not be less than 5%, and the pressure shall be set in the range of 0.1 to 0.3 MPa.

4. The method for preparing the calcium carbonate-based inorganic battery separator as described in claim 1, characterized in that... The post-processing in step (3) includes drying and polishing; the polishing method includes one or more of sandpaper polishing, automatic polishing machine polishing and manual polishing machine polishing.

5. A calcium carbonate-based inorganic battery separator, prepared by the method for preparing a calcium carbonate-based inorganic battery separator according to any one of claims 1-4.

Images