An In Vivo Formed Solid Electrolyte Surface Layer Enables Stable Plating of Li Metal

We describe an efficient yet facile strategy to stabilize Li plating by forming a single Li+-ion solid electrolyte layer in vivo on the Li surface using a rationally designed electrolyte additive. This amorphous, homogeneous layer not only reduces the direct contact and parasitic reactions of Li with the liquid electrolyte but also avoids ion depletion and electric field inhomogeneity at the vicinity of the Li surface, thus eliminating dendrite formation. This is evidenced by a 50-fold lower interfacial charge transfer resistance and an 8-fold longer Sand time in LijLi symmetric cells. The protection layer maintains chemical and electrochemical stability over repeated plating/stripping cycles. We demonstrate stable Li plating/stripping for 2,500 hr at 1 mA cm(-2) in symmetric cells, and efficient Li cycling at high current densities up to 8 mA cm(-2). Over 400 cycles were achieved at 5-C rate in cells with a Li4Ti5O12 counter electrode at close to 100% coulombic efficiency.