A pre-lithiation method for sulfur cathode used for future lithium metal free full battery

Lithium metal free sulfur battery paired by lithium sulfide (Li₂S) is a hot point in recent years because of its potential for relatively high capacity and its safety advantage. Due to the insulating nature and high sensitivity to moisture of Li₂S, it calls for new way to introduce Li ion into S cathode besides the method of directly using the Li₂S powder for the battery pre-lithiation. Herein, we proposed a pre-lithiation method to lithiate the polypyrrole (PPy)/S/Ketjenblack (KB) electrode into PPy/Li₂S/KB cathode at room temperature. By this process, the fully lithiated PPy/Li₂S/KB cathode showed facilitated charge transfer than the original PPy/S/KB cathode, leading to better cycling performance at high C-rates and disappearance of over potential phenomenon. In this work, the ion-selective PPy layer has been introduced on the cathode surface by an electrodeposition method, which can suppress the polysulfide dissolution from the cathode source. The lithium metal free full battery coupled by the prepared Li₂S/KB cathode and graphite anode exhibited excellent cycling performance. Hence, we believe this comprehensive fabrication approach of Li₂S cathode will pave a way for the application of new type lithium metal free secondary battery.