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

Abstract

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 3M_x 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.