On the utilisation of the pseudo-capacitive capabilities of Li-ion cells for the provision of frequency response services

•A method to identify pseudo-capacitive limits from EIS measurements is developed.•The threshold between pseudo-capacitance and diffusion is independent of current.•The threshold is highly dependent on cell architecture and SoC.•Frequency response provision can utilise pseudo-capacitive properties.•A reduction in ageing through primary use of pseudo-capacitance is reasonable.