Controlling Li deposition below the interface

The desire for high-energy-density batteries calls for the revival of the Li metal anode. However, its application is hindered by enormous challenges associated with Li deposition/desolvation behaviors, such as side reactions, volume change, and dendrite formation. To overcome these challenges, Li deposition must be controlled to remain below the separator. Further, to enable longer cycle life, Li deposition should be constrained below the solid electrolyte interphase (SEI). To achieve these goals, it is critical to have a deep theoretical understanding and corresponding strategies. This paper examines Li plating/stripping in terms of behaviors, mechanisms, and influencing factors, and it proposes general strategies to control Li deposition. Comprehensive design strategies for the electrode, electrolyte, and their interface are essential. Three dimensional (3D) anodes are recommended to store most of the Li deposited below the surface of the anode. Artificial interface engineering can reduce the risk of Li deposition outside of the 3D anode, while electrolyte engineering favors Li transport, regulates Li deposition, and suppresses dendrites, serving as the final barrier to uncontrolled Li deposition. This paper reviews systemic theories and solutions to control Li deposition below the interface, paving the way for a promising route to build safer lithium metal batteries.