Construction of nanoporous Mo2C shell/MoO3 core composite by converting MoO3 and its superior performance in lithium sulfur battery

Abstract

• Mo 2 C/MoO 3 prepared by the combination of synthesis of MoO 3 particle and its surface conversion (reduction and carbonization) to Mo 2 C. • Mo 2 C/MoO 3 -modified separator. • Wasted CFRP acts as the carbon source for Mo 2 C, and CF is simultaneously reclaimed. • The core–shell structured Mo 2 C/MoO 3 has high capability to anchor LiPS and prompt the electrochemistry of S. • The Li-S battery with Mo 2 C/MoO 3 -modified separator owns excellent electrochemical performance. The lithium-sulfur (Li-S) battery is a promising energy storage device in the future. However, its performance is strongly affected by the shuttle effect and inherent sluggish kinetics. Herein, Mo 2 C/MoO 3 -modified separator is constructed, in which MoO 3 particles are derived by the decomposition of Mo source and simultaneously their surfaces are converted (reduced and carbonized) into Mo 2 C, i.e., Mo 2 C shell/MoO 3 core. In addition, the resin matrix of the waste CFRP (Carbon fiber reinforced polymer) acts as the carbon source for the change from MoO 3 to Mo 2 C, while CF is claimed from CFRP. The synergistic effect of conductive Mo 2 C-shell and polar MoO 3 -core anchors lithium polysulfide to promote the conversion of sulfur. Benefited from block effect on the soluble lithium polysulfide (LiPS) and catalytic effect on sulfur, Li-S battery with Mo 2 C/MoO 3 -modified separator owns excellent electrochemical performance: A high initial discharge specific capacity of 1288 mAh g −1 at 0.2C and an initial capacity of 670 mAh g −1 at 4C, as well as the average decay rate per cycle of 0.039% over 250 times.