Electrodeposition of \u03b1-MnO2/\u03b3-MnO2 on Carbon Nanotube for Yarn Supercapacitor

Duck Weon Lee,Jong Woo Park,Jae-Hun Jeong,Seon Jeong Kim,Ray H Baughman

doi:10.1038/s41598-019-47744-x

Duck Weon Lee, Jong Woo Park + Show 3 more

Open Access

https://doi.org/10.1038/s41598-019-47744-x

Copy DOI

Abstract

Yarn supercapacitors have attracted renewed interest as promising energy storage for wearable devices due to their lightweight, long cycling lifetime and excellent weavability. There has been much effort to fabricate high performance yarn supercapacitor by depositing pseudo-capacitive materials on the outer surface of the carbon fibers. However, a key challenge still remains to achieve high capacitance and high mass loading without sacrificing the cycling stability. Herein, we perform a phase-controlled of MnO2 at various deposition temperatures with ultrahigh mass loading of 11 mg/cm2 on a MWNT sheets and fabricate it to yarn structure to achieve high capacitance without decreasing in the electrochemical performance. The structure of optimized sample (MnO2/CNTs-60, deposition at 60 °C) consists of the composite of primary α-MnO2 nanosheets and secondary γ-MnO2 nanoparticles. The heteronanostructures of MnO2 provide facile ionic and electric transport in the yarn electrode, resulting in improvement of electrochemical performance and cycling stability. The MnO2/CNTs-60 yarn electrode with ultrahigh mass loading delivers a high areal capacitance of 3.54 F/cm2 at 1 mA/cm2 and an excellent rate capability. Finally, the MnO2/CNTs-60 device exhibits an outstanding high areal energy density of 93.8 μWh/cm2 at the power density of 193 μW/cm2, which is superior to previously reported symmetric yarn supercapacitors.

Highlights

With the rapid development of portable devices and wearable electronics, the yarn supercapacitors has been continuously demanded because of their high power density, lightweight, long cycling lifetime and excellent weavability[1,2,3]
The MnO2 was directly deposited on the multiwalled carbon nanotubes (MWNTs) sheets through the electrodeposition at different temperatures and its morphologies of the all yarn samples, as presented in Figs 1b–e and S1, were observed through the SEM
At 25 °C of deposition temperature, interconnected MnO2 nanosheets grown on the surface of the MWNTs sheets are shown in Fig. 1b (MnO2/CNTs-25)

Summary

Introduction

With the rapid development of portable devices and wearable electronics, the yarn supercapacitors has been continuously demanded because of their high power density, lightweight, long cycling lifetime and excellent weavability[1,2,3]. The increase in the loading active material significantly reduces the charge storage capacity, including specific capacitances and rate performance because of the low electrical conductivity, slow ion diffusion and poor mechanical stability of the MnO2 active material. The MnO2/CNTs-60 yarn electrode exhibits excellent areal capacitance of 3.54 F/cm[2] at 1 mA/cm[2] It is one of the highest values reported for MnO2-based yarn supercapacitors in gel electrolytes. The MnO2/ CNTs-60 device shows high areal energy density of 93.8 μWh/cm[2] at the power density of 193 μW/cm[2] This performance is the highest value in the most of the symmetric yarn supercapacitors

Methods

Results

Conclusion