Phosphorus-Functionalized Graphene for Lithium-Ion Capacitors with Improved Power and Cyclability

Abstract

Herein, we report an easy approach for the preparation of graphene-based materials suitable as electrodes for lithium-ion capacitors (LICs). To the best of our knowledge, this is the first time that phosphorus-functionalized graphene oxide (rGO800-P) is used as negative (battery-type) electrode in LICs technology. An activated carbon derived from the pyrolysis of graphene-carbon composite served as positive (capacitor-type) electrode. While phosphorus functionalization on the negative electrode enables fast Li+ kinetics during insertion/extraction processes, the flat-shaped morphology, large surface area and proper pore size distribution of the positive electrode enhance the double-layer formation. Full LICs optimization, oversizing the negative electrode allows operating in the extended voltage window of 1.5–4.5 V delivering high energy and power values (91 Wh kg−1AM at 145 W kg−1AM and 33 Wh kg−1AM at 26,000 W kg−1AM) without compromising the cycling performance (76 % capacitance retention after 10,000 cycles).