Cathodes for Long Cycle Life and High Power Density Lithium Ion Batteries

wileyonlinelibrary.com lower than counterpart anodes. [ 5–7 ] The energy density of current lithium ion batteries is mainly limited by cathode materials. Due to a high theoretical capacity of 1672 mAh g −1 , sulfur has been considered as the next generation cathode for high energy Li-ion batteries, [ 8–12 ] and it has attracted considerable research interest from both academy and industry. However, lithium sulfur batteries suffer from two major problems: [ 13 ] (1) low utilization of sulfur and poor power density due to the insulating property of sulfur and lithium sulfi de; (2) the dissolution of polysulfi de intermediates triggers severe shuttle reaction, resulting in rapid capacity fading during lithiation/delithiation process. Nevertheless, the dissolution of insulating polysulfi de intermediates into electrolytes also allows full lithiation of sulfur, thus increasing the sulfur utilization and capacity. The current strategy to achieve both long cycling stability and high capacity is to use highly polysulfi desoluble electrolyte, but physically restrict dissolved polysulfi des inside sulfur cathode to prevent shuttle reaction. The most effective method is to employ conductive porous carbon as a host to constrain polysulfi de intermediates and enhance the conductivity of sulfur. [ 14,15 ]