Assessment of ecologically prepared carbon-nano-spheres for fabrication of flexible and durable supercell devices

We report the production parameters of single-stage, ecologically fabricated, flexible Carbon-Nano-Spheres (CNS) supercells. These supercells can deliver a total energy, ED, of 100.0 W h kg−1 and power density, PD, of 50.0 W kg−1@38.4 V and 20 mA for a payload of 15 g (5.0 × 2.5 cm2). According to the material analysis, CNS consists of a spherically (40.0 to 50.0 nm) coagulated, interconnected, 3D network of hetero-structured sp2/sp3 carbon with a low crystalline length, La, of ∼3.0 nm and containing a native O-moiety (12.0 at%). They have an appreciably high specific surface area, SA, of ∼790.0 m2 g−1 and an average pore size of ∼3.42 nm combined with multi-channel pore size distribution. Upon integration in electrodes, CNS provided excellent electrochemical performance without any material modification. CNS showed a nearly rectangular cyclic voltammetry (CV) response in 1 M HCl for both two- and three-electrode systems, yielding superior specific capacitances, CSP, of ∼1080.0 and 570.0 F g−1, respectively (@10 mV s−1). They maintained a high cyclic stability of ∼86.0% (@20 000 cycles), with no material degradation according to post-investigations at a molecular level. The electrode showed hybrid battery/electric double layer capacitor (EDLC) behavior, as revealed by Ragone studies. In Nyquist studies, a shift in the Knee frequency with cycling indicated mitigation of the charge transfer process. In Bode studies, the ionic phase shift decreased insignificantly from ∼80 ° to ∼77 ° after 1000 cycles. The performance characteristics of CNS from laboratory scale measurements to supercell-level device development are discussed.