生物质基锂硫电池正极材料的超临界制备及其电化学性能研究

Supercritical Preparation and Electrochemical Study of Lithium-Sulfur Battery Cathode Materials Derived from Biomass

摘要: 为了缓解锂硫电池的穿梭效应，提高其电化学性能，本研究利用橘皮为碳源合成了一种氮掺杂的纳米片状多孔碳(NNPC)，并通过超临界二氧化碳沉积技术合成了硫碳复合材料(C-S-CO₂)作为电池的正极材料，其载硫量达到64%。通过XRD、XPS、SEM、TEM、以及拉曼等方法对材料的表面形貌和特性进行了表征。电化学测试表明，在0.2 C的电流密度下，C-S-CO₂复合正极材料的初始比容量达到1065 mAh g⁻¹，远高于熔融渗透法合成的硫碳材料(C-S-M)的初始比容量773 mAh g⁻¹；并且经过200次循环之后，C-S-CO₂的保持率能达到70%左右。

Abstract: A nitrogen-doped nanosheet-like porous carbon (NNPC) was synthesized using orange peel. A method, supercritical CO₂ deposition, was used to synthesize carbon/sulfur (C-S-CO₂) composites for lithium-sulfur batteries cathode materials. The surface morphology and characteristics of the materials were characterized by XPS, SEM, TEM, and Raman. Electrochemical tests show that the initial specific capacity of C-S-CO₂ composite cathode material reaches 1065 mA h g⁻¹ at a current density of 0.2 C, which is significantly higher than carbon/sulfur composites (C-S-M) of 773 mA h g⁻¹ deposited by melting infiltration method. And after 200 cycles, the retention rate of C-S-CO₂ can reach about 70%. The improvement of the electrochemical performance of C-S-CO₂ is mainly at-tributed to the unique properties of supercritical CO₂ which have a better dispersion for sulfur.