An Ultra-Long-Life Flexible Lithium–Sulfur Battery with Lithium Cloth Anode and Polysulfone-Functionalized Separator

Flexible and high-performance batteries are urgently required for powering flexible/wearable electronics. Lithium–sulfur batteries with a very high energy density are a promising candidate for high-energy-density flexible power source. Here, we report flexible lithium–sulfur full cells consisting of ultrastable lithium cloth anodes, polysulfone-functionalized separators, and free-standing sulfur/graphene/boron nitride nanosheet cathodes. The carbon cloth decorated with lithiophilic three-dimensional MnO2 nanosheets not only provides the lithium anodes with an excellent flexibility but also limits the growth of the lithium dendrites during cycling, as revealed by theoretical calculations. Commercial separators are functionalized with polysulfone (PSU) via a phase inversion strategy, resulting in an improved thermal stability and smaller pore size. Due to the synergistic effect of the PSU-functionalized separators and boron nitride–graphene interlayers, the shuttle of the polysulfides is significantly inhibited. Because of successful control of the shuttle effect and dendrite formation, the flexible lithium–sulfur full cells exhibit excellent mechanical flexibility and outstanding electrochemical performance, which shows a superlong lifetime of 800 cycles in the folded state and a high areal capacity of 5.13 mAh cm–2. We envision that the flexible strategy presented herein holds promise as a versatile and scalable platform for large-scale development of high-performance flexible batteries.