An all-cotton-derived, arbitrarily foldable, high-rate, electrochemical supercapacitor.

The pure natural cotton provides a low-cost material platform for the facile assembly of all-cotton-derived electrochemical supercapacitors (allC-ECs) with a remarkable character of arbitrary foldability and high response rate, which can be bent, rolled-up, and fully folded without loss of high-rate (<50 ms) capacitive performance.