Lithium Metal Anode Enabled by a Robust and Stable Artificial Surface Layer

Lithium (Li) metal batteries have higher energy density than the state-of-the-art Li-ion batteries and the potential utilization in transportation devices. However, their practical application is still hindered by poor performance in terms of cycling stability and safety, especially at high current densities. This is due to a number of reasons among which are reactions between the Li metal and the liquid electrolyte, and formation of dendrites. In this study, we develop a robust and stable artificial solid electrolyte interface (aSEI), which consists of a surface treated (S_T) PEO – Li_6.4Ga_0.2La₃Zr₂O₁₂ composite polymer layer (CPL) on Li metal anode. The aSEI developed in this study is characterized by a good combination of electrochemical and mechanical properties. Benefitting from these characteristics, S_TCPL@Li||NMC811 cells with 4.7 mAh cm^-2 cathode loading exhibit improved electrochemical cycling stability compared with the bare Li||NMC811 cells at high current densities of ~1.6 and ~2.4 mA cm^-2. A capacity retention of ~ 90% is obtained for S_TCPL@Li||NMC811 at ~1.6 mA cm^-2after 200 cycles compared with 60% for bare Li||NMC811. In addition, S_TCPL@Li||NMC811 demonstrates higher charge rate capacities at charge current densities compared with bare Li||NMC811. These findings suggest that S_TCPL is promising for high current density Li metal batteries.