Precious potential regulation of carbon cathode enabling high-performance lithium-ion capacitors

Abstract For lithium-ion capacitors, electrode potential tuning has been widely regarded as an efficient technology to improve their performance where the anode is usually pre-lithiated for desired potentials. However, the attention on the cathode is quite rare which denies the further excavation of this promising strategy. Herein, we reported the precious regulation of the potential of a cathode made of nitrogen-doped carbon nanosheets to fully leverage the merit of the electrode materials and the electrolyte potential window. Specifically, the nitrogen-doped carbon nanosheets in the optimized potential range of 1.6–4.5 V vs Li/Li+ show a specific capacity of around 150 mA h g−1 at 0.2 A g−1, which is four-time higher than that of the typical activated carbon cathode without potential tuning, and could be stably cycled for over 10 000 cycles without obvious decay. After pairing with a pre-lithiated anode, the as-assembled lithium-ion capacitors based on such a cathode can lead to simultaneously optimize the specific capacitance and voltage window of the device that contributes to a 17-fold increase in energy density, large power density, and long-term stability. The simple and effective strategy demonstrated here may inspire an alternative avenue to regulate the real performance of hybrid energy storage devices.