Preparation method of all-solid-state lithium battery positive electrode material

Abstract

The invention relates to a preparation method of an all-solid-state lithium battery positive electrode material. According to the method, the polyaniline derivative and the organic sulfide are compounded, so that the compatibility of the polyaniline derivative and the organic sulfide is better than that of polyaniline, and the interaction of a molecular level is achieved. Part of nitrogen-substituted polyaniline is used, the alkalinity of the polyaniline is higher than that of polyaniline, a better catalytic effect on organic sulfides is achieved, and the positive electrode material with higher catalytic energy than that of polyaniline can be obtained. In an organic solvent such as N-methyl pyrrolidone, a composite solution of a polyaniline derivative and an organic sulfide is prepared, and conductive carbon black is added. The composite solution is coated or brushed on the surface of a current collector, such as copper, aluminum, platinum or stainless steel, so that the lithium secondary battery positive electrode with high specific energy is obtained. The method is simple to operate, is suitable for the field of high-specific-energy lithium batteries, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a method for preparing an all-solid-state lithium battery cathode material. Background Technology

[0002] With increasing global focus on energy issues, the demand for low-cost, high-energy-density, and rechargeable chemical power sources has become increasingly urgent. This demand is particularly strong in the context of the rapid development of the automotive industry, where the need for chemical power sources suitable for electric vehicles is growing rapidly. In 1989, American scholars SJ Visco et al. published research on using organic sulfides as cathode materials for lithium-ion batteries, a discovery that garnered widespread attention from scholars and industry worldwide. Organic sulfides are valued for their high energy density (exceeding 900 Wh / kg) and their ability to be used in a temperature range from room temperature to 150°C. In laboratory-assembled lithium / solid electrolyte / dithiazole batteries, an energy density of 140 Wh / kg can be achieved at 100°C. During battery charging and discharging, the redox reactions of organic sulfides, compared to polymerization and depolymerization processes—specifically, the formation and breaking of SS bonds—have a more significant impact on battery performance.

[0003] Although organosulfur compounds (OSCs) offer advantages in energy density, their relatively slow redox reaction rate at room temperature is a key factor limiting their application. In 1995, Japanese scholars N. Oyama et al. proposed a solution in their paper "Dimercapton-Polyaniline Composite Electrodes for Lithium Batteries with High Energy Density" (published in *Nature*, Vol. 373, 1995): using a composite of polyaniline and OSCs as the cathode material for lithium-ion batteries. This composite material significantly improved the redox reaction rate and reversibility of OSCs, achieving an energy density of 185 Ah / kg. At room temperature, the energy density was 0.1 mA / cm². 2 Under controlled current density during charge-discharge cycles, the battery can operate stably for 83 cycles while maintaining stable capacity. Polyaniline not only acts as an electrochemical catalyst to promote the reaction but also serves as one of the positive electrode active materials capable of energy storage, jointly enhancing the overall performance of the battery. Summary of the Invention

[0004] This invention provides a method for preparing an all-solid-state lithium battery cathode material, the technical solution of which is as follows:

[0005] The preparation method of the all-solid-state lithium battery cathode material adopts the method of composite of polyaniline derivatives and organic sulfides. This method combines solution blending and physical mixing steps to improve the compatibility between the catalyst and organic sulfides. Through this composite, the combination of polyaniline derivatives and organic sulfides is closer to the molecular level than that of polyaniline and organic sulfides, thereby enhancing the catalytic effect.

[0006] Specifically, the derivatives of polyaniline have the following structure:

[0007] -R1 = -CnH2n+1 (n = 1~12) or -H

[0008] -R2 = -H, -Cl, -OCnH2n+1 or -CnH2n+1 (n = 1~12)

[0009] -x = 0 to 1;

[0010] In the preparation process, the molar ratio of polyaniline derivative to organosulfur compound is 1 / 0.5 to 1.2, and the compound is dissolved in an organic solvent under electromagnetic stirring. These organic solvents include tetrahydrofuran, propylene carbonate, and N-methylpyrrolidone. Subsequently, 0 to 15% conductive carbon black is added, and stirring is continued for 4 to 12 hours. Then, the mixture is ultrasonically vibrated for 2 to 12 hours, followed by treatment with a colloid mill or vibrator for 1 to 6 hours. The resulting mixture is uniformly coated on the surface of a current collector by printing or casting. The current collector can be made of copper, aluminum, platinum, or stainless steel. After evaporating the solvent in air, the mixture is dried in a vacuum for 12 to 48 hours.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] This invention provides a simple method for preparing composite cathodes of polyaniline derivatives and organosulfur compounds without complex industrial equipment or special operational requirements. By using polyaniline derivatives, a tighter composite with organosulfur compounds can be achieved, with near-molecular-level interactions. Partially nitrogen-substituted polyaniline derivatives exhibit stronger basicity and superior catalytic performance towards organosulfur compounds compared to polyaniline, thus producing cathodes with higher catalytic energy than polyaniline. This cathode material can be prepared using various methods such as casting, printing, and spraying, and different thicknesses can be obtained by adjusting the concentration. The simplicity and flexibility of this method make it suitable for large-scale production, and the thickness of the cathode material can be customized as needed. Detailed Implementation

[0013] Example 1

[0014] To prepare the composite cathode material, we first mixed 0.3 g of N-methylpolyaniline (x = 0.79) and 0.37 g of 2,5-dimercaptothiadiazole in a molar ratio of 1:0.84. Under stirring, 5 mL of N-methylpyrrolidone was gradually added to the mixture to prepare a mixed solution. Next, 0.06 g of conductive carbon black (9.0% of the mixture) was added, and stirring continued for 12 hours. Subsequently, the mixture was ultrasonically vibrated for 4 hours and then treated with a colloid mill for 1 hour. The treated mixture was coated onto the surface of a copper foil current collector, then dried in air using infrared spectroscopy and under vacuum for 48 hours. Cyclic voltammetry curves showed large oxidation and reduction peak currents, with a potential difference of 30 mV between the oxidation and reduction peaks, indicating good reversibility and high electrochemical activity. Based on the area of ​​the oxidation or reduction peaks, the specific capacity of the complex of N-methylpolyaniline (x value 0.79) and 2,5-dimercaptothiadiazole is 5 times that of N-methylpolyaniline (x value 0.79). However, if polyaniline is used as the catalyst, the specific capacity of the polyaniline-2,5-dimercaptothiadiazole complex is 1.9 times that of polyaniline.

Claims

1. A method for preparing an all-solid-state lithium battery cathode material, characterized in that, A method combining polyaniline derivatives with organosulfur compounds was adopted, which combines solution blending and physical mixing steps to improve the compatibility between the catalyst and organosulfur compounds. Through this method, the combination of polyaniline derivatives and organosulfur compounds is closer to the molecular level than that of polyaniline and organosulfur compounds, thereby enhancing the catalytic effect. Specifically, the derivatives of polyaniline have the following structure: -R1 = -CnH2n+1 (n = 1~12) or -H -R2 = -H, -Cl, -OCnH2n+1 or -CnH2n+1 (n = 1~12) -x＝0～1； In the preparation process, the molar ratio of polyaniline derivative to organosulfur compound is 1 / 0.5 to 1.2, and the compound is dissolved in an organic solvent under electromagnetic stirring. These organic solvents include tetrahydrofuran, propylene carbonate, and N-methylpyrrolidone. Subsequently, 0 to 15% conductive carbon black is added, and stirring is continued for 4 to 12 hours. Then, the mixture is ultrasonically vibrated for 2 to 12 hours, followed by treatment with a colloid mill or vibrator for 1 to 6 hours. The resulting mixture is uniformly coated on the surface of a current collector by printing or casting. The current collector can be made of copper, aluminum, platinum, or stainless steel. After evaporating the solvent in air, the mixture is dried in a vacuum for 12 to 48 hours.