A tin-plated copper substrate for efficient cycling of lithium metal in an anode-free rechargeable lithium battery

Adhesion of Li plating to electrode substrate and chemical stability of plated Li against electrolyte components are two essential factors affecting the cycling performance of Li metal in a rechargeable Li battery. Poor adhesion results in high contact resistance and further the formation of dead Li. Aiming to improve the adhesion of Li plating to Cu substrate, we plate a very thin tin layer as the primer for Li plating on the Cu substrate. By this way, Li metal is first reacted with tin to form a Li-Sn alloy, and then Li is cycled on resultant Li-Sn alloy so that the Li-Sn alloy functions as an “electric glue” to electrically connect the Li plating and Cu substrate. Attributed to the strong affinity between Li and Li-Sn alloy, the pre-plated tin layer is shown not only to enhance the adhesion of the plated Li to electrode substrate but also to improve the morphology of Li plating. Using a 1.0 m (molality) LiPF6 1:4 (wt.) fluoroethylene carbonate/ethylmethyl carbonate electrolyte, in this paper the effect of the tin primer layer on the Li cycling performance in a Li/Cu cell and a Cu/LiNi0.85Co0.10Al0.05O2 cell is demonstrated and discussed.