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

Summary: 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 K2-xMn8O16 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-K2-xMn8O16 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.