Advanced Li-SexSy battery system: Electrodes and electrolytes

The worldwide energy shortage has led to numerous researches for the exploration of new-type battery materials to deal with the energy crisis. To achieve a great leap in energy density, the study of high capacity electrode materials plays a major role. As a replacement to the energy accumulation system of lithium–sulfur (Li–S) and lithium–selenium (Li–Se) batteries, great concern is generated over lithium/selenium−sulfur (Li–SexSy) batteries as they combine the advantages of S (high capacity) and Se (improved electrical conductivity), consequently stands for extensive new cathode materials. In recent years, widespread researches have been conducted and great achievements have been published. This review sums up the research status on Li–SexSy batteries and concentrates on the outstanding work of SexSy cathode materials. The reaction mechanism and capacity fading mechanism are discussed. The performance-structure relationship is stated in regard of different cathode structures, including a variety of carbon hosts, conducting polymer hosts, transition metal-doped carbon electrodes and various Se/S ratio. The compatibilities of frequently-used carbonate-based and ether-based electrolyte and other new-type electrolytes for Li-SexSy battery are demonstrated. Prospects for the future developments of Li–SexSy batteries are finally proposed.