Bulk electronic conductivity of NMC is orders of magnitude larger than previously reported. It's because contact resistances were not properly excluded from measurements. We also find a significant carbon-related impedance component in porous electrodes, as resistive as the charge-transfer resistance but at an even lower frequency.
We explain why conventional GITT (Galvanostatic Intermittent Titration Technique) measurements do not work as intended.
Our work unraveling the strange phase separation in single-phase lithium-intercalating layered oxides appears in Nature Materials. We also reveal that most battery particles are reaction-limited rather than diffusion-limited.