Microwave Processed, Onionlike Carbon and Fluoropolymer Passivated Lithium Metal Electrode for Enhanced Li Stripping/Plating Performance

One key limitation of lithium metal electrodes is their propensity for dendrite formation that limits their use in commercial batteries. Here, a simple surface modification method was demonstrated to improve the electrochemical stability of the lithium metal electrode through direct coating of onionlike carbon (OC) and a fluoropolymer onto the lithium metal electrode. Selective and rapid microwave heating of the OC resulted in the in situ formation of a LiF-rich composite with the simultaneous infiltration of lithium into the OC. The electrochemical stability of the modified electrode was compared with a neat lithium metal electrode using symmetric stripping/plating cells. The microwave processed surface coating acted as a robust and stable passivation layer to prevent electrolyte decomposition, while also suppressing fast dendrite growth. The potential stability during the stripping and plating was enhanced at all rates examined (0.5-2 mA/cm²) by this passivation layer. With the stripping/plating capacity of 1 mA h/cm², the microwave processed lithium metal electrode can be cycled over 1000 h at a current density of 0.5 mA/cm². These results demonstrated that microwave treatment is a promising method for selective modification of the lithium metal electrode to improve its performance in energy storage applications.