Insights into Lithium Surface: Stable Cycling by Controlled 10 μm Deep Surface Relief, Reinterpreting the Natural Surface Defect on Lithium Metal Anode

The future of next-generation rechargeable batteries, such as lithium metal, lithium–sulfur, and lithium–oxygen batteries, hinges on the utilization of metallic lithium as the anode. However, the practical application of lithium anodes has been challenging thus far due to the uncontrolled growth of lithium dendrites and extremely unstable interfaces between lithium and the electrolyte. Extensive investigations have been conducted to mitigate these limitations; nevertheless, there is a lack of fundamental insight into physical and chemical characteristics, the effect of thickness, and surface morphology of lithium anodes. Herein, an overview of the fundamental understanding of the effect of the shape of surface reliefs on lithium anode under the different cycling conditions is reported. Two different types of 10 μm deep surface reliefs, viz., continuous and discontinuous, were fabricated via soft lithography. It was newly found that the lithium-stripping behavior was significantly affected by the shape of surface reliefs. Furthermore, it is demonstrated that a 10 μm deep surface relief can not only be utilized on a thin lithium anode (20 μm) but also enhances the cell cycling stability. It is anticipated that the results will shed light on the practical utilization of lithium anodes by using the combination of other physical or chemical modification techniques.