Multifunctional binder 3Mx for improving the cycle stability of rechargeable Li–S batteries

Lithium–sulfur batteries have been recognized as one of the most promising next-generation energy storage technologies due to their ultra-high theoretical capacity and energy density. However, their practical application is still hampered by several issues, including the shuttle effect of polysulfides, the volume expansion of sulfur cathodes during charging/discharging process, etc. Rational design of multifunctional binders is one of the effective strategies to overcome the mentioned issues. In this work, a series of 3Mx binders were prepared by combining the inorganic material silica (SiO2) with the well-conductive 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane (3M). Excellent mechanical properties as well as good affinity to lithium polysulfide were obtained with the prepared 3M90 binder with a 3M content of 90%. The assembled battery with a 3M90 binder exhibited remarkable cycle performance. The lithium–sulfur battery with the 3M90 binder could achieve a reversible capacity retention of 77.4% after 500 cycles at a current density of 0.5 C. Even at a higher C-rate of 1 C, a capacity decay rate of 0.069% per cycle can be achieved after 300 cycles. The excellent electrochemical properties revealed that the 3M90 binder could make remarkable improvement in delivering the specific capacity and cycle stability of lithium–sulfur batteries.