Equal contents of intrinsic defects and oxygen-containing defects promote carbon electrodes to achieve high sulfur loads

High sulfur-loading is the key to achieve high lithium–sulfur battery performance. Defects (such as intrinsic defects and oxygen-containing defects) on biomass carbon surface are benefit for capturing sulfur. Two defects play different roles during reaction process. The limited loading capacity of one kind of defect forces researchers to combine two defects to achieve high sulfur-loading. Activation process of biomass carbon can lead to increasing contents of two defects on carbon surface to achieve high sulfur loads (> 80 wt%). However, the role of activation process on defects and polysulfide conversion abilities of activated carbon still needs to be solved. Studying defect changes of activated carbon on polysulfide-capturing and transforming abilities becomes essential. In our work, high-temperature carbonization process is used to obtain biomass carbon. Defect contents change after activation process and polysulfide conversion abilities are also studied. Results show that carbon materials with equal contents of intrinsic defects and oxygen-containing defects possess enhanced abilities to capture and transform polysulfides on their surface. Intrinsic defects promote conversion abilities of polysulfides and oxygen-containing defects promote capturing abilities of polysulfides. Under synergy effects of two defects, carbon electrodes possess high capacities in P2 parts (conversion process from Li2Sx to Li2S) under conditions of high sulfur loads (80 wt%) and high 4 current densities (20 C), achieving excellent rate performance.