A new covalently linked ferrocene-containing organosulfur cathode material for high stability lithium–sulfur batteries

Abstract

Organic sulfur cathodes which received a great deal of attention have still been limited by their poor electrical conductivity, poor redox kinetics and low loading in the field of lithium–sulfur (Li–S) batteries. Herein, a kind of cathode with ferrocene covalently linked to double-bond carbon nanotubes and sulfur (S–Ferrocene acetylene–dbCNT) has been obtained for the first time through a thermal treatment strategy. It is found that the cell with the S–Ferrocene acetylene–dbCNT cathode does not produce soluble long-chain polysulfides during the charging–discharging process, which can effectively mitigate the shuttle effect. Besides, thanks to the covalently linked structure and the absorption/catalysis of ferrocene, the cell with this cathode exhibits good capacity retention of 93.79% after 400 cycles. Even with a sulfur loading of 8.93 mg cm⁻², the cell can display good capacity. It is worth noting that the cell with the S–Ferrocene acetylene–dbCNT cathode can also show extraordinary performance at low temperature, which is rarely reported for lithium–sulfur batteries. This work can not only provide an effective strategy to inhibit the shuttle effect by the combination of covalently linking sulfur and promoting the conversion of LiPS, but also plays a guiding role in the preparation of Li–S batteries with high stability, high loading and excellent low-temperature performance.