Choi Sinho, Su Dawei, Shin Myoungsoo, Park Soojin, Wang Guoxiu
Centre for Clean Energy Technology, Faculty of Science, University of Technology Sydney, NSW, 2007, Australia.
Department of Energy Engineering, School of Energy and Chemical Engineering, UNIST, Ulsan, 44919, Republic of Korea.
Chem Asian J. 2018 Mar 2;13(5):568-576. doi: 10.1002/asia.201701759. Epub 2018 Feb 13.
Porous materials have many structural advantages for energy storage and conversion devices such as rechargeable batteries, supercapacitors, and fuel cells. When applied as a host material in lithium-sulfur batteries, porous silica materials with a pomegranate-like architecture can not only act as a buffer matrix for accommodating a large volume change of sulfur, but also suppress the polysulfide shuttle effect. The porous silica/sulfur composite cathodes exhibit excellent electrochemical performances including a high specific capacity of 1450 mA h g , a reversible capacity of 82.9 % after 100 cycles at a rate of C/2 (1 C=1672 mA g ) and an extended cyclability over 300 cycles at 1 C-rate. Furthermore, the high polysulfide adsorption property of porous silica has been proven by ex-situ analyses, showing a relationship between the surface area of silica and polysulfide adsorption ability. In particular, the modified porous silica/sulfur composite cathode, which is treated by a deep-lithiation process in the first discharge step, exhibits a highly reversible capacity of 94.5 % at 1C-rate after 300 cycles owing to a formation of lithiated-silica frames and stable solid-electrolyte-interphase layers.
多孔材料对于诸如可充电电池、超级电容器和燃料电池等储能及能量转换装置具有许多结构优势。当作为主体材料应用于锂硫电池时，具有石榴状结构的多孔二氧化硅材料不仅可以作为缓冲基体来容纳硫的大幅体积变化，还能抑制多硫化物穿梭效应。多孔二氧化硅/硫复合阴极表现出优异的电化学性能，包括1450 mA h g的高比容量、在C/2倍率（1 C = 1672 mA g）下100次循环后82.9%的可逆容量以及在1 C倍率下超过300次循环的长循环稳定性。此外，通过非原位分析证明了多孔二氧化硅具有高多硫化物吸附性能，显示出二氧化硅表面积与多硫化物吸附能力之间的关系。特别地，在首次放电步骤中通过深度锂化处理的改性多孔二氧化硅/硫复合阴极，由于形成了锂化二氧化硅框架和稳定的固体电解质界面层，在300次循环后1 C倍率下表现出94.5%的高可逆容量。
