Symmetric Supercapacitors Based on MnOOH-Coated Nanoporous Carbon toward High Energy-Storage Performance

Pseudocapacitors, one of the most efficient types of energy storage devices due to their high specific capacitance, could not provide adequate information for real applications with a half-cell device. Therefore, this contribution describes the facile synthesis of hybrid materials based on nanoporous carbon (NPC) and MnOOH with outstanding capacitive performance in symmetric devices. Interconnected NPC with large surface area served as a conductive substrate for deposition of tunable amounts of MnOOH. NPC-MnOOH electrodes can be scanned with a wide voltage window from 0 to 1.6 V without obvious hydrolysis. The two-electrode supercapacitor NPC-MnOOH//NPC-MnOOH with 26.7 wt% of MnOOH shows the highest specific capacitance of 410 F g(-1) and a maximum energy density of 33.5 Wh kg(-1). It also shows 86% retention even after 10000 cycles. The beneficial properties proved the hybrid materials are suitable for a high-voltage industrial device under optimal conditions.