All-Solid-State Flexible Asymmetric Supercapacitor with Good Cycling Performance and Ultra-Power Density by Electrode Materials of Core-Shell CoNiO2@NiAl-Layered Double Hydroxide and Hollow Spherical \u03b1-Fe2O3

Huifang Lv,Yan Wang,Zexiang Chen,Xinyu Yan,Zhiyu Zhou,Jijun Zhang

doi:10.1186/s11671-019-2910-5

Abstract

High electrochemical performance of asymmetric supercapacitor (ASC) depends on exquisite nanostructure design and synthesis of electrodes, including structural controllable design and synthesis of high theoretical performance materials and nanocomposite materials. Herein, a template-free hierarchical core-shell nanostructure of CoNiO2@NiAl-layered double hydroxide (NiAl-LDH) and α-Fe2O3 with a hollow spherical structure composed of nanoparticles are successfully prepared. The CoNiO2@NiAl-LDH as the cathode electrode and the hollow spherical α-Fe2O3 as the anode electrode of the ASC devices exhibit superior electrochemical performance. The gel of polyvinyl alcohol (PVA) and KOH acts as the solid electrolyte and the separator to assemble into the all-solid-state flexible ASC devices. Two of the CoNiO2@NiAl-LDH//α-Fe2O3 ASC devices in series are fabricated to meet the voltage requirement of mobile energy equipment, which exhibit a maximum energy density of 65.68 Wh kg−1 at the power density of 369.45 W kg−1. Interestingly, in addition to many advantages that the solid electrolyte in ASC devices already have, we find that it can be an alternative way of solving the problem of iron oxide cycling performance, and of course it can also be used as a reference for other materials with poor cycling performance.

Highlights

With the development of electric vehicles, traditional energy storage equipment has been difficult to meet the demand of high-energy density and high-power density
Based on the above consideration, we report a hierarchical CoNiO2@NiAl-layered double hydroxides (LDHs) core-shell nanosheet as the cathode electrode and the hollow sphere of α-Fe2O3 as the anode electrode of all-solid-state supercapacitor, which polyvinyl alcohol (PVA)&KOH was introduced as the solid electrolyte and separator
The all-solid-state Asymmetric supercapacitors (ASCs) device was fabricated by the CoNiO2@NiAl-LDH as the cathode material, the α-Fe2O3 as the anode material, the foamed nickel as the current collect collector, and the PVA&KOH as the electrolyte and the separator

Summary

Introduction

With the development of electric vehicles, traditional energy storage equipment has been difficult to meet the demand of high-energy density and high-power density. Lithium-ion battery has high energy density, its intrinsic factors limit its power density, which is hard to meet the requirement of the output of high power in practical application of electric vehicle. Supercapacitor is the energy storage device between dielectric capacitor and rechargeable battery exhibiting fast charge-discharge rate, high power density, low cost and good cycling. In the same specific surface area, the pseudocapacitors can provide more than ten times storage capacity than the electric double-layer capacitance which have attracted great interest in increasing their energy densities of the pseudocapacitors to partially replace the current commercialized two-time battery. The pseudocapacitors suffer from the low conductivity of active materials with poor power characteristics and poor cyclic stability caused by volumetric expansion during the charge and discharge processes

Methods

Results

Conclusion