Focus on the Electroplating Chemistry of Li Ions in Nonaqueous Liquid Electrolytes: Toward Stable Lithium Metal Batteries

Lithium metal anodes (LMAs) show unique superiority for secondary batteries because they possess the lowest molar mass and reduction potential among metallic elements. It can diminish the large gap in energy density between secondary batteries and fossil fuels. However, notorious dendrite propagation gives rise to large volume expansion, low reversibility and potential safety hazards, making the commercial application of LMAs a perennial challenge. The booming development in material characterization deepens the understanding of the dendrite formation mechanism, and the great progress made via nanotechnology-based solutions hastens practical procedures. In this paper, we highlight the current understanding of lithium dendrites. We first illustrate different nucleation theories and growth patterns of lithium dendrites. According to the growth patterns, we classify dendrites into three categories to accurately describe their different formation mechanisms. Then, we concentrate on the factors that may lead to dendritic deposits in each electroplating step. The dendritic morphology originates from the inhomogeneity of Li atoms, electrons, mass transport in the bulk electrolyte and the solid electrolyte interphase. Different inducements lead to different growth patterns. Based on this understanding, strategies for controlling lithium plating are divided into five methodologies. Reasonable integration of the strategies is expected to provide new ideas for basic research and practical application of LMAs. Finally, current limitations and advice for future research are proposed, aiming at inspiring engaged contributors and new entrants to explore scalable solutions for early realization of industrialization.