Lithium deposition in single-ion conducting polymer electrolytes

Abstract

Lithium (Li)-metal is considered as promising anode material for high-energy-density rechargeable batteries, although its application is hampered by inhomogeneous Li deposition and dendritic Li morphologies that could eventually result in contact losses of bulk and deposited Li as well as cell short circuits. Based on theoretical investigations, recent works on polymer electrolytes particularly focus on the design of single-ion conducting electrolytes and improvement of bulk Li + transport properties, including enhanced Li + transference numbers, ionic conductivity, and mechanical stability, thereby affording safer and potentially “dendrite-free” cycling of Li-metal batteries. In the present work, it is revealed that the spatial microstructures, localized chemistry, and corresponding distributions of properties within the electrolyte are also decisive for achieving superior cell performances. Thus, targeted modification of the electrolyte microstructures should be considered as further critical design parameters for future electrolyte development and to actually control Li deposition behavior and longevity of Li-metal batteries. Li deposition in single-ion conducting polymer cells is analyzed in various ways Agglomeration of dense Li deposits/deformation of the polymer membrane observed Microphase separation in electrolytes induces preferential Li + transport paths Electrolyte morphology is revealed as critical parameter for Li deposition behavior Combined galvanostatic cycling, scanning electron microscopy, and X-ray tomography imaging techniques are applied by Borzutzki et al. They reveal the impact of microstructural electrolyte features on the Li deposition behavior in a single-ion conducting blend-type polymer electrolyte, thereby identifying a previously neglected critical parameter for future electrolyte design and subsequent control of Li deposition.