Wire-type flexible micro-supercapacitor based on MOF-assisted sulfide nano-arrays on dendritic CuCoP and V2O5-polypyrrole/nanocellulose hydrogel

Wire/fiber-type micro-supercapacitors (micro-SCs) have great potentials in next-generation wearable and portable energy supply devices, due to their low weight, high flexibility, small size and excellent reliability. Herein, we designed 2D-3D S-doped CoZnNi-OH/CuCoP positive microelectrode with hierarchical structure on 1D metal fiber substrate for high-capacitance fibrous micro-SCs. Such unique architecture, which 2D S-doped CoZnNi-OH nanosheet arrays vertically aligned on 1D Cu wire garnished with 3D dendritic CuCoP through CoZn-MOF template, exposed ample electroactive sites, created robust electrical and mechanical joint between nanostructured material and metal fiber, and promote the transport/diffusion rate of ions. The achieved 2D-3D S-doped CoZnNi-OH/CuCoP/CW microelectrode exhibited the areal/volumetric/length capacitances of 2.9 F cm−2, 290.07 F cm−3, and 348 mF cm−1 at 4 mA cm−2, respectively, which is 18 times of the sulfide directly co-electrodeposited on 3D CuCoP foam without MOF template. Besides, negative microelectrode was prepared through electrochemical deposition of V2O5-PPy on 1D carbon fiber substrate decorated with rGO-nanocellulose (NC) hydrogel. The electrical double layer capacitance behavior combined with pseudocapacitive properties enhances charge storage performance of fibrous microelectrode in terms of specific capacitance, cycle stability and rate capability. The fabricated solid-state 2D-3D S-doped CoZnNi-OH/CuCoP/CW//V2O5-PPy/rGO-NC/CF micro-SC presents high areal energy density of 127.62 µWh cm−2 at a power density of 1.83 mW cm−2 and durability (93.7 % retention after 5000 cycles) with excellent mechanical flexibility. Giving the versatility of 1D carbon/metal fiber substrates, template-assisted 3D architecture, MOF-derived sulfide nanoarrays, and NC chemical reactivity, the proposed strategy can be used for construction of other next-generation miniaturized portable electronics.