In situ formed lithium sulfide/microporous carbon cathodes for lithium-ion batteries

Highly stable sulfur/microporous carbon (S/MC) composites are prepared by vacuum infusion of sulfur vapor into microporous carbon at 600 C, and lithium sulfide/microporous carbon (Li₂S/MC) cathodes are fabricated via a novel and facile in situ lithiation strategy, i.e., spraying commercial stabilized lithium metal powder (SLMP) onto a prepared S/MC film cathode prior to the routine compressing process in cell assembly. The in situ formed Li ₂S/MC film cathode shows high Coulombic efficiency and long cycling stability in a conventional commercial Li-ion battery electrolyte (1.0 M LiPF₆ + EC/DEC (1:1 v/v)). The reversible capacities of Li ₂S/MC cathodes remain about 650 mAh/g even after 900 charge/discharge cycles, and the Coulombic efficiency is close to 100% at a current density of 0.1C, which demonstrates the best electrochemical performance of Li ₂S/MC cathodes reported to date. Furthermore, this Li₂S/MC film cathode fabricated via our in situ lithiation strategy can be coupled with a Li-free anode, such as graphite, carbon/tin alloys, or Si nanowires to form a rechargeable Li-ion cell. As the Li₂S/MC cathode is paired with a commercial graphite anode, the full cell of Li₂S/MC-graphite (Li ₂S-G) shows a stable capacity of around 600 mAh/g in 150 cycles. The Li₂S/MC cathodes prepared by higherate sulfur infusion and SLMP prelithiation before cell assembly are ready to fit into current Li-ion batteries manufacturing processes and will pave the way to commercialize low-cost Li₂S-G Li-ion batteries.