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

It 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-E f  = 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.