Understanding lithium loss in a lithium metal anode with liquid electrolytes

Abstract

Li-ion batteries (LIBs) have powered society for decades since their first commercialization in 1991. However, the current Li-ion chemistry deploying traditional graphite anode is approaching its energy density limit and struggling to meet the growing demand. The use of pure metallic Li with almost ten folds of anodic specific capacity is therefore critical to realize a higher energy density Li metal battery (LMB). A pure Li metal anode faces great challenges before its readiness for commercial applications. In addition to safety issues, which are a subject researched and reviewed widely, drastic Li loss (including the loss from active utilization or storage) is often overlooked, resulting in reduced capacity and eventually limited battery longevity. The Li loss in conventional liquid electrolyte settings, refers to the proportion of Li not taking part in an electrochemically active role for generating energy, and can be mainly categorized as inactive metallic Li, solid–electrolyte interphase (SEI) dissolution, and Li corrosion. To date, the underlying mechanisms involving these Li loss pathways and their dependence on each other are subject of ongoing investigations. This paper summarizes the major forms of Li loss processes when using a Li metal anode in an LMB, and existing strategies to mitigate these losses.