The ‘use-by date’ for lithium-ion battery components

Lithium-ion battery (LIB) manufacturing is based around the slurry tape casting of electrodes followed by the assembly of the dried electrodes into cells with a separator and electrolyte. Many aspects of the manufacturing process can affect the performance of a lithium-ion cell. One of the least understood aspects in academia is the effect of degradation of the materials during the manufacturing processes or the 'shelf-life' of the materials and components. Here, we discuss some of the time limitations and degradation issues observed during the manufacturing and testing of the components from an industrially sourced LiNiMnCoO (NMC-622)//graphite cell, and the affect that the component storage has, upon both the performance and the properties of the materials and cells. The materials are stored either in a dry room, vacuum oven or in a laboratory environment and the effect of the atmosphere upon the degradation components of the electrodes and electrolyte is characterized by analytical surface techniques and electrochemical analysis. We note that all storage affects the electrochemical performance, even storage in a vacuum oven or dry room. We propose that the electrodes and electrolytes should be used immediately after manufacture; however, we propose alternative methods for storage in case this is not possible. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.