On-Site Fluorination for Enhancing Utilization of Lithium in a Lithium–Sulfur Full Battery

The rechargeability of the lithium anode in lithium–sulfur (Li–S) batteries is an issue for this type of battery. In this work, we demonstrate a Li–S full battery comprising a protected anode scaffold and a Li2S cathode. The stabilized performance is attained by an on-site fluorination strategy, using BiF3 for the interfacial coating of the anode. Unlike previously reported LiF protective coating derived from the vapor/solution depositions, BiF3 nanocrystals would be lithiated on-site to the anode surface and server as the protective layer. The chemically inertial Li3Bi alloy can provide additional ion-conductive paths and stitch the LiF to form a seamless protective layer, thereby suppressing the dendrite propagation and parasitic reactions effectively. With the designed anode structures and compositions, the high-loading full battery (8.05 mg cm–2) can achieve an exceptional utilization of both sulfur (898 mAh gS–1) and lithium (1533 mAh gLi–1) over 200 cycles, marking a step toward cyclable Li metal batteries at a high capacity.