Perovskite Lithium Lanthanum Titanate-Modified Separator As Both Adsorbent And Converter Of Soluble Polysulfides Toward High-Performance Li-S Battery

A novel separator constructed by coating a layer of perovskite lithium lanthanum titanate (LLTO)/Super P (SP) composite over a commercial PE membrane was employed for the first time in the Li-S battery (LLTO@Li-S). It was found that the LLTO@Li-S battery possessed an obviously lower impedance but higher Li-ion diffusion than the Li-S battery employing the uncoated separator (Pristine@Li-S). This enabled the soluble polysulfides to be effectively immobilized and further electrochemically transformed into Li 2 S via the formation of thiosulfate/polythionate intermediates over the LLTO/SP-coated separator during the discharge of the battery. As a result, the shuttle effect was effectively inhibited, and particularly the passivation of both the cathode and "dead S" over the separator was largely decreased. These properties ensured that the LLTOPLi-S battery displayed a significantly high specific capacity and rate capability as well as good cycling stability. For the LLTO@Li-S battery with a S loading of 2 mg cm(-2), an initial specific capacity of 1491 mAh g(-1) at 0.1C and a residual specific capacity of 459 mAh g - at 1C after 1200 cycles had been achieved, while for the LLTO@Li-S battery with a S loading of 5 mg cm(-2), an initial specific capacity of 1046 mAh g(-1) and a residual specific capacity of more than 800 mAh g(-1 )at 0.1C after 50 cycles could be delivered.