Activation-free synthesis of microporous carbon from polyvinylidene fluoride as host materials for lithium-selenium batteries

Abstract

Microporous carbon (MPC) was synthesized from polyvinylidene fluoride (PVDF) using an activation-free approach and used as a selenium host for high-performance lithium-selenium (Li-Se) batteries. The microporous carbon/selenium (MPC/Se) composites were applied a cathode in Li-Se batteries with a carbonate-based electrolyte. The influences of PVDF carbonization temperature (600 °C, 700 °C and 800 °C) and Se content (50 wt%, 60 wt%, and 70 wt%) in the cathode were investigated in order to establish correlation between MPC structure and MPC/Se electrochemical performance. The results revealed that the MPC/Se composite cathode, with MPC synthesized at 800 °C and with a Se content of 50 wt%, exhibited a superior reversible capacity of 508.8 mAh g−1 at 0.1C after 100 cycles. Moreover, the MPC/Se maintained a capacity retention of 354.0 mAh g−1 at 0.5C for 200 cycles. The reason for the excellent performance could be attributed to the dominant microporous feature of MPC, which could effectively confine Se and reduce side reactions with electrolytes. Furthermore, increasing Se content from 50 wt% to 70 wt% leaded to decrease in the specific capacity and rate capability of MPC/Se cathode, due to significantly reduced Li-ion diffusion coefficient. This work suggested the effectiveness of MPC derived from commercial PVDF through an activation-free and scalable approach as Se hosts for high-performance Li-Se batteries.