In Situ Electrochemically Derived Amorphous-Li2S for High Performance Li2S/Graphite Full Cell

High-capacity Li 2 S cathode (1166 mAh g −1 ) is regarded as a promising candidate for the next-generation lithium ion batteries. However, its high potential barrier upon the initial activation process leads to a low utilization of Li 2 S. In this work, a Li 2 S/graphite full cell with the zero activation potential barrier is achieved through an in situ electrochemical conversion of Li 2 S 8 catholyte into the amorphous Li 2 S. Theoretical calculations indicate that the zero activation potential for amorphous Li 2 S can be ascribed to its lower Li extraction energy than that of the crystalline Li 2 S. The constructed Li 2 S/graphite full cell delivers a high discharge capacity of 1006 mAh g −1 , indicating a high utilization of the amorphous Li 2 S as a cathode. Moreover, a long cycle life with 500 cycles for this Li 2 S/graphite full cell is realized. This in situ electrochemical conversion strategy designed here is inspired for developing high energy Li 2 S-based full cells in future.