Chemical prelithiation of Al for use as an ambient air compatible and polysulfide resistant anode for Li-ion/S batteries

Abstract

Lithium-ion/sulfur (Li-ion/S) batteries consisting of metallic lithium-free anodes and sulfur cathodes are promising energy storage solutions. Anode prelithiation enables a Li-ion/S battery assembly with the extensively-developed sulfur cathodes. However, it's very challenging owing to the low lithiation potentials of anode materials (e.g. Al, 0.32 V vs. Li/Li⁺). Here, a free-standing LiAl alloy anode (c-LiAl) is prepared via an easy-to-implement chemical prelithiation, by using a newly exploited reagent of lithium 9,9-dimethylfluorene (Li-DiMF) with a lower redox potential of 0.22 V vs. Li/Li⁺. Compared with the LiAl anode prepared by electrochemical prelithiation (e-LiAl) and the lithium metal anode by electrodeposition (e-Li/Cu), c-LiAl displays a superior cyclability in the half cell test and high resistance towards polysulfide or ambient-air corrosion. When paired with a sulfur cathode, the resulting Li-ion/S battery with c-LiAl demonstrates a much better cycling performance than the Li-ion/S battery with e-LiAl and the lithium/sulfur battery with e-Li/Cu.