High-safety lithium-sulfur battery with prelithiated Si/C anode and ionic liquid electrolyte

A Li-S battery with safety configuration has been constructed by employing electrochemically prelithiated Si/C microspheres as an anode, S/C composites as a cathode, and a room temperature ionic liquid of n-Methyl-n-Allylpyrrolidinium bis(trifluoromethanesulfonyl)imide (RTIL P1A3TFSI) as an electrolyte. Galvanostatic discharge–charge tests show that the as-assembled Li-S battery could deliver a high discharge specific capacity of 1457 mA h g−1 (based on the sulfur cathode) at 0.1 C, indicating the high Li electroactivity of the system. The reversible capacity is 926.4 mA h g−1 in the first cycle, and could remain as high as 670 mA h g−1 after 50 cycles, revealing the favorable compatibility between the RTIL P1A3TFSI electrolyte and the two electrode materials in the Li-S battery. The as-assembled Li-S battery in the charged state can be used for energy output without activation process by charging. This green rechargeable Li-S battery typically gives an output voltage of 1.5 V per cell, which raises the potential for directly replacing the widely used 1.5 V primary alkaline batteries and dry cells without any change of external circuits of current electronic devices but more rechargeable and powerful.