Abstract
Exhibiting high specific energy and low cost, lithium–sulfur batteries are considered promising candidates for the next-generation battery. However, its wide applications are limited by the insulating nature of the sulfur, dissolution of polysulfide species, and large volume change of the sulfur cathode. In this work, a conductive binder, crosslinked polyfluorene (C-PF) is synthesized and employed in Li–S batteries to enhance the overall electrochemical performance from the following three aspects: 1) possessing high electronic conductivity, C-PF facilitates lowered areal resistance for the sulfur electrode and leads to an improved rate capability; 2) owing to the cross-linked polymer structure, favorable mechanical properties of the electrode can be achieved, hence the well-preserved electrode integrity; 3) forming strong binding with various polysulfide species, C-PF manages to trap them from diffusing to the Li anode, which greatly improves the cycling stability of Li–S cells. Through designing a multifunctional binder to comprehensively enhance the Li–S cathode, this proposed approach could be broadly applied to fully harness the energy from S redox in addition to cathode material modifications.