To investigate the capacity fade over cycling, voltage and dQ/dV profiles were examined over 100 cycles at C/2 rate (Supplementary Figure ). The onset of lithiation in the 2 nd cycle occurs at a higher voltage than the first. This phenomenon was also observed in Nb16W5O55 and attributed to than cycling to 1.2 V (6.0%, 12.3 mA•h•g -1 ). Comparison of the dQ/dV curves (Supplementary Figure ) suggests that cycling to 1.0 V hinders delithiation of the particles; this manifests as a continuous suppression of the first lithium removal peak around 1.19 V and a 200 mV shift to continuously more positive voltages over 100 cycles. For cycling to a lower cutoff voltage of 1.2