Single-crystalline integrated 4H-SiC nanochannel array electrode: toward high-performance capacitive energy storage for robust wide-temperature operation

Abstract

The exploration of energy conversion and storage devices for wide-temperature operation is presently a grand challenge. Herein, the single-crystalline integrated energy-storage units based on highly-oriented 4H-SiC nanochannel arrays (NCAs) were fabricated via an improved electrochemical anodic oxidation technique from 4H-SiC wafers. The as-prepared SiC NCAs electrode exhibits an areal capacitance of 14.8 mF cm⁻² at 10 mV s⁻¹, which is the highest for SiC electrodes ever reported and also 6-fold higher in comparison to that of SiC nanowire array electrode (NWAs, 2.32 mF cm⁻²). Moreover, the resultant 4H-SiC NCAs exhibit an extremely stable cycling performance in aqueous electrolytes, with higher than 95% retention of initial capacitance regardless of being serviced under low, high or cross-fade temperatures for 11 000 charge–discharge cycles, demonstrating that they are nearly full-featured for robust wide-temperature operation.