Prospects for Dendrite-Free Cycling of Li Metal Batteries

We discuss the general origins of three-dimensional (3D) growth and morphology instability that can occur during homoepitaxial electrodeposition on initially planar single crystal surfaces and then focus on specific issues relevant to polycrystalline Li metal electrode dissolution/deposition cycling. During dissolution, pitting of Li metal electrodes can occur owing to a variety of causes including pinholes in the solid-electrolyte interphase (SEI) layer, second-phase impurities within the Li electrode and dislocations or grain boundaries that intersect with the Li metal/SEI interface. We demonstrate that pits can serve as nucleation sites for dendrite growth and suggest ways in which this particular cause of dendrite formation may be mitigated. However, in general we conclude that prospects for the elimination of 3D or dendrite growth during "high-rate" cycling of Li are poor without the discovery of new stable high Li solubility electrolytes. (C) 2015 The Electrochemical Society. All rights reserved.