Highly compressible supercapacitor based on carbon nanotubes-reinforced sponge electrode

Developing flexible and deformable supercapacitors electrodes based on porous materials is of high interest in energy related fields. We propose a novel approach called "soaking-squeezing-calcining" to fabricate a unique carbon nanotubes melamine sponge electrode, and demonstrate its application as a highly compressible supercapacitor electrode with high performance. Our supercapacitor electrode consists of three-dimensional melamine sponge as flexible skeleton and conductive skeleton, the carbon nanotubes filled in the sponge skeleton by physical adsorption and calcination process to enhance the overall conductivity and mechanical properties. After adding carbon nanotubes, the volume specific capacity of the supercapacitors increases by 3 times and the mass specific capacity is basically unchanged. Furthermore, it is found that its capacity retention rate could still reach 91% after the device is compressed by 50% for 1000 cycles of charging and discharging and 88% in the original uncompressed state for 5000 cycles of charging and discharging, respectively, which deeply proves that the carbon nanotubes reinforced sponge electrode has excellent electrochemical stability. Most importantly, the mechanical strength of the electrode increases by 5 times compared with that without carbon nanotubes. The results indicate that this electrode has the potential to fabricate deformable, robust supercapacitors with stable performance and many other energy devices. (C) 2019 Elsevier B.V. All rights reserved.