Operando interlayer expansion of multiscale curved graphene for volumetrically-efficient supercapacitors
Petar Jovanović, Meysam Sharifzadeh Mirshekarloo, Phillip Aitchison, Mahdokht Shaibani, Mainak Majumder
Abstract
Supercapacitors deliver high power but are limited in compact applications by low volumetric energy and power densities. Two-dimensional materials like graphene, despite their high packing density, are hindered by poor ion transport kinetics. A rapid thermal annealing step generates unusually curved turbostratic graphene crystallites, integrated and interwoven within disordered domains in micron-size particles to yield multiscale graphene. Ion insertion into the interlayers enables precise pore-ion matching and partial charge transfer, enabling a high Brunauer-Emmett-Teller surface area-normalized capacitance of 85 µF/cm2. Here, we show that multiscale graphene exhibits rapid ion transport dynamics within the curved crystallites and disordered domains. When the thin electrodes are assembled into symmetric pouch cell devices, they deliver a stack-level volumetric energy density of 99.5 Wh/L in ionic liquid electrolytes and 49.2 Wh/L in organic electrolyte with a high power density of 69.2 kW/L at 9.6 Wh/L. Supercapacitors are high-power energy storage devices that suffer from poor volumetric performance. Here, the authors demonstrate that unusually curved graphene crystallites exhibit rapid ion transport dynamics and enable the fabrication of thin electrodes for compact energy and power delivery.