Flexible Asymmetric Threadlike Supercapacitors Based on NiCo2Se4 Nanosheet and NiCo2O4/Polypyrrole Electrodes

Abstract Flexible threadlike supercapacitors with improved performance are needed for many wearable electronics applications. Here, we report a high performance flexible asymmetric all‐solid‐state threadlike supercapacitor with a NiCo 2 Se 4 positive electrode and a NiCo 2 O 4 @PPy (PPy: polypyrrole) negative electrode. The as‐prepared electrodes display outstanding volume specific capacitance (14.2 F cm −3 ) and excellent cycling performance (94 % retention after 5000 cycles at 0.6 mA) owing to their nanosheet and nanosphere structures. The asymmetric all‐solid‐state threadlike supercapacitor expanded the stability voltage window from 0–1.0 V to 0–1.7 V and exhibits high volume energy density (5.18 mWh cm −3 ) and superior flexibility under different bending conditions. This study provides a scalable method for fabricating high performance flexible supercapacitors from easily available materials for use in wearable and portable electronics.