Designing the Electrochemical Interface to Enable Lithium Metal Batteries

Although Li-ion battery is one of the most widely used energy storage devices, there have been extensive efforts to push its limit to meet the ever-increasing demands to improve its energy density for applications such as electric vehicles, portable electronics, and grid storages. Here, Li metal anode plays a key role in the next generation energy storage devices, ultimately enabling the anode-free configuration. However, there are major challenges that need to be overcome for a successful deployment of anode-free batteries. These include designing a competitive SEI, low Coulombic efficiency, and the formation of dendrites. To realize an effective anode-free configuration modifying the copper collector, adding a 3D host and tuning the electrolyte of the key. In this work, we adopted gallium-based liquid metal (LM) as a coating layer on a copper current collector to uniformly deposit Li and prevent the dendrite formation to improve the cycle performance. The effect of the LM coating was confirmed by in situ transmission electron microscopy and optical microscopy observations. LM reduced the charge/discharge overpotentials with its high affinity with Li. It also contributed to decompose the dendritic Li in the discharge process reducing the dead Li disconnected from the current collector. The LM coating was further fortified by graphene oxide (GO) overlayer to prevent the direct contact of electrolyte with uniformly deposited Li. The GO overlayer acted as a barrier and as a 3D host for the deposited Li. Furthermore, we combined in situ TEM and first principles calculations to investigate the electrochemical stability of the solid electrolyte and the structural evolution in contact with Li to study a potential direction to mitigate Li dendrites and enable Li metal anode