Design and performance of an ultra-flexible solid state supercapacitor based on thermo-crosslinking carbon nanotube paper/Co₃O₄ nanowire electrode

An ultra-flexible carbon nanotube paper (CNP) was achieved by thermo-crosslinking reaction between carbon nanotubes via high temperature annealing to enhance mechanical property, which was indicated from the tensile test, Raman spectra and conductivity measurement. Based on the mechanical enhanced CNP, a sandwich structure binder free, separator free and encapsulation layer free flexible solid state CNP/Co₃O₄ nanowire supercapacitor was proposed that could be executed in various external mechanical conditions. The high specific capacitance of device was 345.8 F g⁻¹, when current density was 0.15 A g⁻¹, and its good cycling stability after 5000 cycles kept about 75.9% of the initial capacitance. For various external mechanical conditions, such as bending, pressing, folding and tearing, the capacitance retention is 74.9%–81.3%. Proof-of-concept of the multi-shape survived supercapacitor presents a strategy for designing a novel electrochemical device that could resist harsh external mechanical conditions in future application fields required the safety of a power supply system. (paper)