Effects of mechanical compression on the performance of carbon-based supercapacitors

We have fabricated activated carbon spheres from xylose via the combination of hydrothermal carbonization, carbonization at 500 ℃ and chemical activation at 800 ℃ under nitrogen environment. Using the activated carbon spheres as electrode material, we assemble electrical-double-layer capacitors (EDLCs). The electrochemical performance of the prepared EDLCs under compression is studied. The experimental results show that the capacity and IR drop of the EDLCs increase with the increase of the compressive loading. We develop a simple relationship between the capacity and mechanical loading, which is qualitatively in accord with the experimental results. From the electrochemical impedance analysis, we calculate the diffusivity of ions in the EDLCs. The numerical results reveal that the diffusion of ions is stress-dependent. This work is supported by the NSF.