A thin LiGa alloy layer from in-situ electroreduction to suppress anode dendrite formation in lithium-sulfur pouch cell

Abstract

Lithium metal is considered to be the “Holy Grail” of battery anodes. However, the inhomogeneous deposition of lithium ions on the anode surface readily generates lithium dendrites, which leads to severe hidden danger. Particularly in lithium-sulfur batteries, the insulated Li2S caused by the reaction of lithium and polysulfide lithium aggravates the one-dimensional deposition of lithium ions. Meanwhile, the corrosion of lithium metal is the main reason for the decrease in lithium-sulfur capacity. Anodes made from alloys are an effective solution, while they sacrifice energy density. Here, we adopted an in-situ electrochemical reduction method for fabricating a very thin, low-resistance, low-reactivity LiGa alloy layer with uniform Li deposition sites on the Li metal surface in order to suppress side reactions with sulfides and dendrites. Furthermore, excellent electrochemical kinetics, high specific capacity, and high stability are also obtained in lithium-sulfur batteries with the LiGa layer. The alloy layer-based cells delivered a long cycle lifespan and a high capacity under high sulfur-loading, low Electrolyte/Sulfur ratio (5.0 µL mg−1) and thin lithium flakes (50 µm). This surface regulation engineering could be applied to the high-load systems and pouch cells, which provides a new solution for the prospect of industrialization.