Hierarchically porous carbon nanofibers loaded with Cu2O and Cu nanoparticles modified separator with strong adsorption and excellent catalysis of lithium polysulfide for lithium-sulfur batteries

In this study, we propose a strategy to modify Celgard separator through using a functional coating of hierarchically porous carbon nanofibers loaded with copper oxide and copper nanoparticles (Cu2O-Cu@PCNFs). The separator modified the Cu2O-Cu@PCNFs composite materials combines the advantages of high electrical conductivity of Cu nanoparticles, strong adsorption and conversion properties of Cu2O nanoparticles towards lithium polysulfides(LiPSs), and the enough space to accommodate the significant volume changes and excellent physical domain-limiting effect based on the three-dimensional networks of PCNFs. On the basis of these advantages of the modified Cu2O-Cu@PCNFs composite materials, the assembled LSBs demonstrate excellent intercepting and catalytic conversion capabilities towards LiPSs, finally exhibiting outstanding electrochemical performance. The LSBs exhibit high initial specific capacity (1096.6 mAh g-1 at 0.5 C and 1211.0 mAh g-1 at 1 C) and a capacity fading rate as low as 0.05% and 0.08% per cycle after 400 cycles. In addition, the assembled LSBs also have relatively high Coulomb efficiency with more than 97 %) excellent rate performance and outstanding cycle stability. This work will provide a novel strategy for the convenient preparation of modifying the separator of high-performance LSBs, where copper-based metals and their compounds can be applied in the design of various secondary batteries including LSBs.