A Hybrid Dual-Type Sulfur Cathode and a Lithiated Si/SiOx Nanosphere Anode for Li-Sulfur Full Cells

Abstract

Lithium−sulfur batteries could become an excellent alternative to replace the currently used lithium-ion batteries. 1 The natural abundance and low cost of sulfur, coupled with the high theoretical energy density of sulfur-based cathodes, namely, 1675 mAh g-1 and 2600 Wh kg-1, are the major advantages of this sulfur battery.2 However, commercialization of lithium−sulfur batteries has so far been limited due to the cyclability problems associated with both the sulfur cathode and the lithium−metal anode.3 Herein, we demonstrate a highly reliable lithium−sulfur battery showing cycle performance comparable to that of lithium-ion batteries; our design uses a highly reversible hybrid dual-type sulfur cathode (solid sulfur electrode and polysulfide catholyte) and a lithiated Si/SiOx nanosphere anode. Our result shows superior battery performance in terms of high specific capacity, excellent charge−discharge efficiency, and notable cycle life, delivering a specific capacity of ∼750 mAh g−1 over 500 cycles (85% of the initial capacity). These promising behaviors may arise from a synergistic effect of the enhanced electrochemical performance of the newly designed anode and the optimized layout of the cathode.