High performance of selenium cathode by encapsulating selenium into the micropores of chitosan-derived porous carbon framework

Abstract

Incorporating elemental selenium into parts of the micropores of a high surface area carbonaceous framework can simultaneously buffer volume variation and improve electronic conductivity of the resulting selenium/carbon composite for high-performance lithium-selenium (Li-Se) battery cathodes. In this paper, chitosan-derived porous carbon (CPC) framework has been constructed through a one-step carbonization/activation route, possessing oxygen- and nitrogen-containing functional groups and acquiring a high specific surface area of 2098.6 m2 g−1, a total pore volume of 1.04 cm3 g−1 and a micropore volume of 0.62 cm3 g−1. As a Li-Se battery cathode, at 0.1 C (1 C = 675 mA g−1) the composite cathode of Se-50.2/CPC (Se ∼ 50.2 wt%) delivers the ultrahigh discharge capacities of 801.2, 673.1 and 633.9 mAh g−1 in the 1st, 2nd and 100th cycles, respectively. The change of Se-loading amount proves the volume-buffering positive effect of residual voids on the cycling stability of Se-50.2/CPC composite cathode, and the galvanostatic cycling-dependent decrease of charge-transfer resistance interprets its high-capacity feature and good rate capability. In a word, a facile, low-cost and value-added transformation of chitosan into porous carbon framework may satisfy its potential application in Li-Se batteries.