An efficient chemical reduction-induced assembly of Fe_(3)O_(4)@graphene fiber for wire-shaped supercapacitors with ultrahigh volumetric energy density

摘要

Benefiting from high flexibility and weavability,the wire-shaped supercapacitors(SCs)arouse tremendous interests for the applications in wearable/portable electronics.Graphene fiber(GF)is considered as a promising linear electrode for wire-shaped SCs.However,the bottleneck is how to develop the GF-based linear electrode with facile fabrication process while wellmaintaining satisfactory electrochemical performance.Herein,a novel Fe_(3)O_(4)@GF composite linear electrode is proposed via a chemical reduction-induced assembly approach,in which the GO and Fe_(3)O_(4) nanoparticles(NPs)realize the efficient selfassembly owing to the electrostatic and van der Waals interactions,as well as the sufficient reduction of GO during the preparation process.The resultant fiber-shaped architecture shows boosted charge-transfer kinetics,high flexibility and structural integrity.Such Fe_(3)O_(4)@GF linear electrode exhibits excellent electrochemical behaviors including a large volumetric specific capacitance(~250.75 F cm^(−3)),remarkable rate capability and favorable electrochemical kinetics in aqueous electrolyte,superior than previously reported GF-based linear electrodes.For real application,a high-performance wire-shaped SC with excellent flexibility and weavability is fabricated based on such Fe_(3)O_(4)@GF linear electrode and gel electrolyte,demonstrating ultrahigh volumetric energy density(18.8 mWh cm^(−3)),power density(4000 mW cm^(−3))and strong durability(~93.5%retention after 10000 cycles).Prospectively,the fabricated wire-shaped SC can maintain reliable electrochemical behaviors in various deformation states,showing its potentials in future portable and wearable devices.