Layered carbon-based pseudocapacitive materials for lithium/sodium-ion capacitor with high energy-power densities and long cycle life

Hybrid ion capacitors that combined high-power density of supercapacitor and high-energy density of battery are drawing attention to insufficient power densities of currently-used lithium-ion batteries (LIBs). Two kinds of layered carbon-based pseudocapacitive materials were used as both anode and cathode for lithium/sodium ion capacitors (LICs/NICs) with balanced energy/power properties. As-assembled NIC and LIC could deliver the energy densities of 125.7 Wh kg(-1) and 119.6 Wh k(-1) at the power density of 7941.2 W kg(-1) and 8823.5 W kg(-1), respectively. The electrochemical properties of NICs were better than that of LICs when the current density was below 4 A g(-1), although the working voltage of LIC is higher than that of NICs, and the size of Na+ is larger than that of Li+. Using an instantaneous potential technique, it is found that the increase of the capacity for anode material in low potential region will effectively enhance the electrochemical performance for the full device.