All-solid-state high-energy planar hybrid micro-supercapacitors based on 2D VN nanosheets and Co(OH)2 nanoflowers

Abstract Planar micro-supercapacitors are recognized as one of the most competitive on-chip power sources for integrated electronics. However, most reported symmetric micro-supercapacitors suffer from low energy density. Herein, we demonstrate the facile mask-assisted fabrication of new-type all-solid-state planar hybrid micro-supercapacitors with high energy density, based on interdigital patterned films of porous vanadium nitride nanosheets as negative electrode and Co(OH) 2 nanoflowers as positive electrode. The resultant planar hybrid micro-supercapacitors display high areal capacitance of 21 mF cm −2 and volumetric capacitance of 39.7 F cm −3 at 0.2 mA cm −2 , and exhibit remarkable energy density of 12.4 mWh cm −3 and power density of 1750 mW cm −3 , based on the whole device, outperforming most reported planar hybrid micro-supercapacitors and planar asymmetric micro-supercapacitors. Moreover, all-solid-state planar hybrid micro-supercapacitors show excellent cyclability with 84% capacitance retention after 10000 cycles, and exceptionally mechanical flexibility. Therefore, our proposed strategy for the simplified construction of planar hybrid micro-supercapacitors will offer numerous opportunities of utilizing graphene and other 2D nanosheets for high-energy microscale supercapacitors for electronics.