Development and Optimization of Thin‐Lithium‐Metal Anodes with a Lithium Lanthanum Titanate Stabilization Coating for Enhancement of Lithium–Sulfur Battery Performance

Lithium‐ion batteries are dominating high‐energy‐density energy storage for 30 years. However, their development approaches theoretical limits, spurring the development of lithium–sulfur cells that achieve high energy densities through reversible electrochemical conversion reactions. Nevertheless, the commercialization of lithium–sulfur cells is hindered by practical challenges associated primarily with the use of thick‐lithium anodes, low‐loading sulfur cathodes, and high electrolyte‐to‐sulfur ratios, which prevent realization of the cells’ full potential in terms of electrochemical and material performance. To solve these extrinsic and intrinsic problems, the effect of lithium‐metal thickness on the electrochemical behavior of lithium–sulfur cells with high‐loading sulfur cathodes in lean‐electrolyte configurations is investigated. Specifically, lithium lanthanum titanate (LLTO), a solid electrolyte, is utilized to form an ionically/electronically conductive coating to stabilize lithium‐metal anodes, thereby enhancing their lithium‐ion pathways and interfacial charge transfer. Electrochemical analyses reveal that an LLTO coating significantly reduces excessive reactions between lithium metal and an electrolyte, thereby minimizing lithium consumption and electrolyte depletion. Further, LLTO‐stabilized lithium anodes improve lithium–sulfur cell performance, and most importantly, allow the fabrication of thin‐lithium, high‐loading‐sulfur cells that open a pathway toward high‐energy‐density batteries. This study addresses key battery‐technology challenges by stabilizing lithium‐metal electrodes with a layer of ionically/electronically conductive lithium lanthanum titanate (LLTO) coating. It details development of LLTO coatings with adjustable thicknesses and investigates the effects of lithium‐foil thickness involving lithium//lithium symmetric cell; lithium//copper half cell; and lithium–sulfur full cell evaluation, demonstrating excellent performance of the LLTO‐stabilized thin‐lithium anode.