A High‐Performance Dual‐Ion Battery‐Supercapacitor Hybrid Device Based on LiCl in Ion Liquid Dual‐Salt Electrolyte

Abstract A dual‐ion battery‐supercapacitor hybrid device (DIB‐SCHD), cleverly integrating a dual‐ion battery (DIB) and a supercapacitor (SC), is expected to endow both the high energy density of dual‐ion battery and the high power density of supercapacitor. Benefitting from the similar features of the electrolyte and symmetrical electrode configuration, a state‐of‐the‐art DIB‐SCHD is developed by using N‐doped micropores‐dominant carbon(N‐MPC) as the electrode and LiCl in a room‐temperature ion liquid hybrid as the electrolyte, which deliver an ultrahigh mass capacitance of 374 F g −1 with a high voltage of 3.5 V and a remarkable specific energy of 208 Wh kg −1 at 1144 W kg −1 and an ultrahigh specific power of 22834 W kg −1 at 77 Wh kg −1 . Combined with ex situ characterizations and theoretical calculations, the assembled DIB‐SCHD presents a synergistic energy storage mechanism simultaneously involving ion intercalation/deintercalation and adsorption/desorption processes, which can promote the reaction kinetics and achieve exceptional electrochemical performance. The perfect integration of the dual‐ion battery‐type and supercapacitor‐type electrodes provides a new strategy toward high energy and power density electrochemical energy storage devices.