High-performance S cathode through a decoupled ion-transport mechanism

A high-performance sulfur (S) cathode is essential for advanced lithium-sulfur (Li-S) batteries. Issues such as shuttle effect of polysulfides and low conductivity of S need to be resolved. Here, we report a S-cathode prepared via constructing unique decoupled ion-transport network formed from soy protein-based ionic conductor with well-dispersed graphene, leading to mitigated shuttle effect and excellent dual-conductive capabilities, i.e., high electronic and ionic conductivities. The decoupled ion-transport mechanism, which is unconventional in polymeric systems, is enabled by appropriately maintaining the denatured soy protein structure during the cathode preparation, facilitating polysulfide trapping and providing high adhesion for the S cathode, confirmed by the experiment and simulation results. Consequently, the Li-S battery with the protein-based S cathode demonstrates excellent rate performance and long cycling stability. In specific, the Li-S battery with the protein-based S cathode shows similar to 70 % capacity retention (similar to 504 mAh g(-1)) after 600 cycles under the current density of 0.5 A g(-1). This work will initiate new scientific studies on introducing an unconventional ion-transport mechanism into electrodes for producing high-performance batteries.