Ultramicroporous carbon cloth for flexible energy storage with high areal capacitance

Most advances towards flexible supercapacitors (SCs) have been focused on porous carbon materials. However, the poor flexibility and low areal capacitance impede their industrial application. While carbon cloth is generally regarded as improper electrode material due to its poor electrochemical performance, here, we demonstrate the capacitance of carbon cloth can be boosted to three orders of magnitude higher (2900 mF cm^-2) with a simple high-temperature annealing process. The improvement stems from ultramicropores effects in the range of 0.46–0.64 nm besides superhydrophilicity and high specific surface area. Remarkably, direct implementation for flexible solid-state SCs (SSCs) provides areal capacitance and energy density for the stack of 920 mF cm^-2 and 128 μW h cm^-2, respectively. In addition, these devices are bendable, durable and easy to be any dimensions, hence, holding great promise for large-scale production of flexible electronics.