Carbonized cotton fabric in-situ electrodeposition polypyrrole as high-performance flexible electrode for wearable supercapacitor

A polypyrrole/carbonized cotton fabric (PPy/CCF) flexible bind-free electrode was firstly created by simple carbonization and in-situ electrodeposition method for supercapacitors. The PPy/CCF-1:2 not only exhibits a high specific capacitance of 3596 mF cm⁻² at a current density of 2 mA cm⁻², which is almost 9 times higher than the pristine CCF (420 mF cm⁻²), but also shows good rate capability and high stability with 96.5% capacitance retention after 4000 cycles. The excellent electrochemical properties can be attributed to CCF substrate with a hierarchical 3D porous structure, which can provide conductive pathways for fast electron transfer and large accessible area for PPy loading. Meanwhile, PPy with hornlike microstructure can shorten ion diffusion paths, and ensure adequate contact area between the electrode and the electrolyte, leading to an dramatical increase in the specific capacitance and fast charge/discharge capability of the hybrid electrodes. In addition, the assembled flexible supercapacitor possesses a high volumetric energy density of 1.18 mWh cm⁻³ at power density of 17 mW cm⁻³, expressing no any decline in the capacitance under different bending situations. This device can be easily sewn into a garment for powering an electronic watch, with the low-cost, lightweight and easy fabrication features, which will be considerate as a promising candidate for wearable energy storage device. © 2018 Elsevier Ltd