Construction of Bimetallic Heterojunction Based on Porous Engineering for High Performance Flexible Asymmetric Supercapacitors

Abstract

AbstractIt remains a great challenge to design and manufacture battery‐type supercapacitors with satisfactory flexibility, appropriate mechanical property, and high energy density under high power density. Herein, a concept of porous engineering is proposed to simply prepare two‐layered bimetallic heterojunction with porous structures. This concept is successfully applied in fabrication of flexible electrode based on CuO‐Co(OH)2 lamella on Cu‐plated carbon cloth (named as CPCC@CuO@Co(OH)2). The unique structure brings the electrode a high specific capacity of 3620 mF cm−2 at 2 mA cm−2 and appropriate mechanical properties with Young's modulus of 302.0 MPa. Density functional theory calculations show that porous heterojunction provides a higher intensity of electron state density near the Fermi level (E–Ef = 0 eV), leading to a highly conductive CPCC@CuO@Co(OH)2 electrode with both efficient charge transport and rapid ion diffusion. Notably, the supercapacitor assembled from CPCC@CuO@Co(OH)2//CC@AC shows high energy density of 127.7 W h kg−1 at 750.0 W kg−1, remarkable cycling performance (95.53% capacity maintaining after 10 000 cycles), and desired mechanical flexibility. The methodology and results in this work will accelerate the transformative developments of flexible energy storage devices in practical applications.