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

Sen Wang,Xiaoyu Shi,Jieqiong Qin,Shuanghao Zheng,Feng Zhou,Zhong-Shuai Wu,Chenglin Sun,Xinhe Bao,Han Xiao

doi:10.1038/s41699-018-0052-8

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.

Highlights

With speeding development of wearable and portable electronics, microscale energy storage devices with innovative characteristics of lightweight, miniaturization, flexibility, and compact energy have gained ever-increasing attentions.[1]
Enormous advances have been made on the development of high-peformance electrodes in sandwich-like hybrid supercapacitors (HSCs), such as positive electrodes of capacitive counterparts (e.g., active carbon (AC),[9] graphite,[10] and graphene11), redox-active metal oxides/ hydroxides (e.g., MnO2,12,13 Co3O4,14 Co(OH)[2,15] Ni(OH)216), electrically conducting polymers[17] and their hybrids,[18] and negative electrode materials covering all types of nanocarbons (AC,[19] porous carbon,[20] CNT,[21] graphene13,16), metal oxides (e.g., Mn3O4,22 MoO3,23 Fe2O324), and metal nitrides (e.g., titanium nitride,[25] vanadium nitride (VN)26)
Highpatterned microelectrodes on single substrate were directly manufactured through vacuum filtration of high-conducting electrochemically exfoliated graphene (EG) nanosheets as metalconducting EG patterns with in-plane interdigital geometry were prepared as current collectors by vacuum filtration of EG dispersion (0.5 mL, 0.1 mg mL−1), with the help of a customized free current collectors, and subsequent filtration of patterned films mask with four digital fingers on each side (Fig. 1a)

Summary

Introduction

With speeding development of wearable and portable electronics, microscale energy storage devices with innovative characteristics of lightweight, miniaturization, flexibility, and compact energy have gained ever-increasing attentions.[1]. Based on the above evaluation of capacity and potential windows, we constructed VN//Co(OH)2-PHMSs based on porous VN nanosheets as negative electrode and Co(OH)[2] nanoflowers as positive electrode, operated at an optimized working voltage of 1.5 V (Fig. 3a, b).

Results

Conclusion