While energy storage within lithium ion batteries relies on the ability of an electrode phase to reversibly intercalate Li ions, critical performance metrics such as energy density, rate capability, and cycle life often depend on the nanocomposite electrode architecture which mediates electronic and ionic transport to the cathode particles. Delivering higher performance batteries depends not only on the discovery of novel materials but also on the optimization of the nanocomposite architecture. Notably, heterogeneity in the electrode reactivity can develop due to limitations in ionic and electronic conductivity. These can lead to incomplete cycling of parts of the electrode and ultimately limit capacity and device lifetime. Identifying the lengthscale and origin of such heterogeneity in the energy storage reaction is important to designing of improved battery electrodes.
This presentation will describe operando hard X-ray studies identifying reaction heterogeneity in the commercially-important layered transition metal oxide electrode (NCA) that impact performance from the first cycle towards failure.