Mesoporous vanadium nitride as anion storage electrode for reverse dual-ion hybrid supercapacitor

In traditional dual-ion systems, the cathode usually is employed as anion-storage materials. Herein, we propose a new dual-ion hybrid supercapacitor with reverse anion/cation-storage mechanism, consisting of a mesoporous (MPs) VN anode as a pivotal anion-storage material and K(2-x)Mn(8)O(16) nanosheet arrays grown on carbon cloth (NSs/CC) as (K-storage) cathode. During charge/discharge, the anode and cathode reversibly store/release OH(−) ions and K(+) ions, respectively. Herein, the MPs VN as anion-storage electrode can operate in an alkaline condition and deliver a high capacitance of 251 mF cm(−2) with desired low-voltage plateau. More importantly, benefiting from unique reverse dual-ion mechanism, the (MPs VN-K(2-x)Mn(8)O(16) NSs/CC) hybrid device displays excellent rate performance and satisfying area capacitance along with good durability of 92.2% after 10,000 cycles at a scan rate of 100 mV s(−1). It offers new ideas to expand the range of anion-storage materials in dual-ion hybrid supercapacitors.