Design and Regulation of Novel MnFe2O4@C Nanowires as High Performance Electrode for Supercapacitor.

Lei Geng,Fengfeng Yan,Cuihua An,Chenhao Dong

doi:10.3390/nano9050777

Abstract

Bimetallic oxides have been considered as potential candidates for supercapacitors due to their relatively high electric conductivity, abundant redox reactions and cheapness. However, nanoparticle aggregation and huge volume variation during charging-discharging procedures make it hard for them to be applied widely. In this work, one-dimensional (1D) MnFe2O4@C nanowires were in-situ synthesized via a simply modified micro-emulsion technique, followed by thermal treatment. The novel 1D and core-shell architecture, and in-situ carbon coating promote its electric conductivity and porous feature. Due to these advantages, the MnFe2O4@C electrode exhibits a high specific capacitance of 824 F·g−1 at 0.1 A·g−1 and remains 476 F·g−1 at 5 A·g−1. After 10,000 cycles, the capacitance retention of the MnFe2O4@C electrode is up to 93.9%, suggesting its excellent long-term cycling stability. After assembling with activated carbon (AC) to form a MnFe2O4@C//AC device, the energy density of this MnFe2O4@C//AC device is 27 W·h·kg−1 at a power density of 290 W·kg−1, and remains at a 10 W·h·kg−1 energy density at a high power density of 9300 W·kg−1.

Highlights

Electrochemical supercapacitors have been in the research spotlight owing to their intriguing characteristics, such as high power density, wide temperature ranges, long cycling stability and safety [1,2,3,4]
Despitethe aforementioned prominent advantages, the large-scale utilization for supercapacitors is restricted by their low energy density [5,6,7]
On account of the TG results, the calcinated condition was maintained at 350 ◦C for 2 h to ensure its complete decomposition

Summary

Introduction

Electrochemical supercapacitors have been in the research spotlight owing to their intriguing characteristics, such as high power density, wide temperature ranges, long cycling stability and safety [1,2,3,4]. The detailed process for the fabrication of the working electrode was as follows: 1) 24 mg active materials MnFe2O4@C, 3 mg acetylene black (AB) and 3 mg polyvinylidene fluoride (PVDF) were. The detailed process for the fabrication of the working electrode was as follows: 1) 24 mg active materials MnFe2O4@C, 3 mg acetylene black (AB) and 3 mg polyvinylidene fluoride (PVDF) were mixed in a mortar. Mv(Vf − Vi) Vi where C (F·g−1) is the specific capacitance, m (g) is the mass of the active materials (MnFe2O4@C) of the electrode or the total mass of the device, v (V·s−1) is the scan rate, Vi and Vf (V) are the initial and final potentials in the CV curves, respectively, and I (A) is the corresponding current. Where C (F·g−1) is the specific capacitance, t (s) is the discharging time, m (g) is the mass of the electrode or the total mass of the device, and V (V) is the working voltage window

Results and Discussion

Conclusions