Modified graphite and graphene electrodes for high-performance lithium ion hybrid capacitors

Lithium ion capacitors (LICs) have recently received considerable attention as a new class of energy storage system because they possess the combined advantages of lithium ion batteries and supercapacitors. LICs typically consist of activated carbon cathodes and pre-lithiated graphite anodes. Despite the promising electrochemical performance, most LICs still hold room for further improvement in terms of power density, which is largely related to the limited (de)intercalation kinetics of graphite. In an attempt to address these limited kinetics, we have developed a simple treatment to modify the morphology and surface characteristics of graphite engaging hydrogen peroxide. The treatment increases the exposed edge planes and generates more stable solid-electrolyte-interphase layers, which facilitate substantially improved power and cycling performance of the graphite anodes. Especially when integrated with a urea-reduced graphene cathode, the modified graphite-based LIC exhibits significantly higher energy and power densities compared to those of the pristine graphite-based and other reported counterparts.