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⁻¹_AM at 145 W kg⁻¹_AM and 33 Wh kg⁻¹_AM at 26,000 W kg⁻¹_AM) without compromising the cycling performance (76 % capacitance retention after 10,000 cycles).