Advanced Materials for Lithium Batteries

Abstract

Advanced lithium battery materials promise some combination of higher energy density, lower cost, longer lifetime, and faster charging rates compared to traditional lithium-ion batteries. This work studies lithium-metal anodes in “anode-free cells” which aim to increase cell energy density, and cutting edge cathode materials that can extend cell lifetime or reduce cost. Lithium-metal anodes are yet to be used in commercial products at a large scale since they lose capacity at a much faster rate than traditional lithium-ion batteries. Here a method is developed to quantify the surface area of lithium-metal electrodes by argon gas adsorption. Methods are also developed to analyze electrolyte from lithium-metal cells in order to understand the extent and type of reactions occurring with the lithium-metal electrode. These studies are used to develop an optimized electrolyte that extends cell lifetime.

Advanced cathode materials are then studied. Resistance growth is monitored in pouch cells with LiNi0.80Co0.15Al0.5O2 cathode, a material that is used in commercial cells today. The crystal structure is studied versus lithium content, x, for single-crystal LixNi0.5Mn0.3Co0.2O2, a recently developed cathode material that extends cell lifetime and has very little resistance growth. Lastly, synthesis is studied using in-situ high temperature diffraction for new lithium-transition metal-oxide cathode materials that are the focus of electrochemical studies by others in our laboratory.