In situ synthesized Li2S@porous carbon cathode for graphite/Li2S full cells using ether-based electrolyte

Abstract

Lithium-sulfur (Li-S) batteries have been recognized as one of the promising next-generation energy storage devices owing to their high energy density, low cost and eco-friendliness. As for cathode’s performance, the main challenges for developing highly-efficient and long-life Li-S batteries are to retard the polysulfides diffusion into electrolyte and the reaction with metallic lithium (Li). Especially, the safety issues, derived from metallic Li in anode, must be overcome. Herein, we fabricated lithium sulfide@porous carbon composites (Li2S@PC) by an in-situ reaction between the lithium sulfate (Li2SO4) and the pyrolytic carbon from glucose. The nanosized Li2S particles were uniformly distributed in the carbon matrix, which not only significantly improve electronic conductivity of the electrode but also effectively trap the dissolved polysulfides. Furthermore, on the basis of the graphite’s electrochemical features in ether-based electrolyte, we assembled graphite-Li2S@PC full cells using the obtained Li2S@PC composites as the cathode, graphite as the anode and the DOL/DME with LiNO3 additive as the electrolyte. A unique strategy was proposed to activate the full-cells in descending order using constant voltage and current to charge the cut-off voltage. This Li-S full cell exhibits stable cycling performance at 0.5 C over 100 cycles. Because graphite-Li2S batteries are suitable to the lithium-ion batteries industry, our preliminary results here will shed a new light on the cell design and industrial production.