Novel cell designs and methods for characterizing lithium protective membranes for lithium metal batteries

Abstract

Battery systems employing a lithium metal negative electrode are attractive due to their high theoretical specific energy. However, it is necessary to protect the lithium electrode from crossover species such as polysulfides in Li-S systems, redox mediators in Li-O2 cells, or dissolved cathode species or electrolyte oxidation products in high voltage Li-ion batteries. One approach to tackling these issues is the use of a lithium-ion selective conducting membrane to protect the lithium metal electrode. Such a membrane allows passage of lithium ions, but is impermeable to other species. As well as ability to block crossover species, key requirements of any material used in this way are high Li+ conductivity and high Li+ transport number (together with low interfacial impedance, wide electrochemical stability window, good chemical, thermal and mechanical stability, low cost and ease of processing/device integration). This paper discusses a novel cell design and method developed to characterize lithium-protective membranes in lithium metal batteries, specifically their ability to block crossover species.