Photothermally Reduced Graphene as High-Power Anodes for Lithium-Ion Batteries

Abstract

Conventional graphitic anodes in lithium-ion batteries cannot provide high-power densities due to slow diffusivity of lithium ions in the bulk electrode material. Here we report photoflash and laser-reduced free-standing graphene paper as high-rate capable anodes for lithium-ion batteries. Photothermal reduction of graphene oxide yields an expanded structure with micrometer-scale pores, cracks, and intersheet voids. This open-pore structure enables access to the underlying sheets of graphene for lithium ions and facilitates efficient intercalation kinetics even at ultrafast charge/discharge rates of >100 C. Importantly, photothermally reduced graphene anodes are structurally robust and display outstanding stability and cycling ability. At charge/discharge rates of ∼40 C, photoreduced graphene anodes delivered a steady capacity of ∼156 mAh/g_anode continuously over 1000 charge/discharge cycles, providing a stable power density of ∼10 kW/kg_anode. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization.