We have thus chosen to only discuss liquid and polymer electrolyte systems with added salt. Compared to polymer electrolytes with added salt, there is little information about dendrite morphologies obtained in polymeric single-ion conductors ( Cao et al., 2019 Dai et al., 2019). In principle, polymer electrolytes can also be single ion conductors if the anion is covalently linked to the polymer chain ( Bouchet et al., 2013). On the other hand, these concentration gradients are absent when current flows through inorganic solid electrolytes. The passage of current results in salt concentration gradients in liquid-and polymer-based electrolytes ( Chazalviel, 1990). In contrast, lithium ions are an integral part of the crystal structure of inorganic solid electrolytes. The lithium ions are present in both liquid- and polymer-based electrolytes due to the addition of a suitable salt. We focus on three classes of electrolytes: those based on organic liquids, organic polymers, and inorganic solids. Lithium metal protrusions have been observed in electrodeposition and cycling experiments conducted in a wide array of electrolytes ( Arakawa et al., 1993 Brissot et al., 1998 Ren et al., 2015). These protrusions are often referred to as “lithium dendrites.” Strictly, the word “dendrite” implies a branched structure we propose to not use this term as many non-dendritic morphologies have been reported in the literature. One of the main challenges is the nucleation and growth of protrusions during battery charging ( Selim and Bro, 1974 Besenhard and Eichinger, 1976 Epelboin, 2006), which limits the battery lifetime and compromises safety ( Yamaki et al., 1998 Aurbach et al., 2002). However, many fundamental challenges must be addressed before lithium electrodes can be deployed in practical devices ( Aurbach et al., 2000, 2002). There is growing interest in the nature of electrodeposition at lithium metal electrodes due to the current focus on increasing the energy density of rechargeable lithium batteries ( Girishkumar et al., 2010 Balsara and Newman, 2013). We show that specific morphologies are confined to contiguous regions on this two-dimensional plot. The main result of the study is a figure where the morphology of electrodeposited lithium is plotted as a function of two variables: shear modulus of the electrolyte and current density normalized by the limiting current density. These deposits were obtained in a variety of cell geometries using both unidirectional deposition and cell cycling. We find that the non-uniform deposits can be grouped into six classes: whiskers, moss, dendrites, globules, trees, and cracks. We have surveyed the literature on lithium electrodeposition through three classes of electrolytes: liquids, polymers and inorganic solids. These non-uniform deposits are often referred to as lithium “dendrites,” although their morphologies can vary. Lithium metal is a promising anode material for next-generation rechargeable batteries, but non-uniform electrodeposition of lithium is a significant barrier. 4Lawrence Berkeley National Laboratory, Joint Center for Energy Storage Research (JCESR), Berkeley, CA, United States.3Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, United States.2Lawrence Berkeley National Laboratory, Materials Science Division, Berkeley, CA, United States.1Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, United States.

Dendrite structure cubic