Three-dimensional carbon foam-metal oxide-based asymmetric electrodes for high-performance solid-state micro-supercapacitors.

A three-dimensional carbon foam (CF)-based asymmetric planar micro-supercapacitor is fabricated by the direct spray patterning of active materials on an array of interdigital electrodes. The solid-state asymmetric micro-supercapacitor comprises the CF network with pseudocapacitive metal oxides (manganese oxide (MnO), iron oxide (Fe2O3)), where CF-MnO composite as a positive electrode, and CF-Fe2O3 as negative electrode for superior electrochemical performance. The micro-supercapacitor, CF-MnO//CF-Fe2O3, attains an ultrahigh supercapacitance of 18.4 mF cm−2 (2326.8 mF cm−3) at a scan rate of 5 mV s−1. A wider potential window of 1.4 V is achieved with a high energy density of 5 μW h cm−2. The excellent cyclic stability is confirmed by 86.1% capacitance retention after 10 000 electrochemical cycles.