“The most crucial result of this work is the correlation between form and function in supercapacitor materials,” states first author Dina Ibrahim Abouelamaiem. She elaborates that “our research is driven by the need for a greener future and improved energy systems”, which is why their Sustainable Energy Fuels paper focuses on understanding how the 3D structure affects the supercapacitor properties of biocarbon-based materials derived from plant cellulose. These materials could provide an environmentally-friendly alternative to precious metals and toxic chemicals currently used in top-performing supercapacitors.

Powering the future

Supercapacitors are devices full of potential, often quite literally, as they are charged to exhibit high power densities and long lifetimes. Due to these properties, supercapacitors are able to bridge the gap in device performance between batteries and fuel cells. Understanding the nanostructure in depth and over multiple length scales is paramount to optimize performance and design better devices. By combining an extensive set of complementary techniques, Ibrahim and her colleagues have shed light on the complex synergy between structure and performance, and show what electrode materials really need a hierarchical porous network to function most effectively.

In their study, biocarbon electrodes activated using potassium hydroxide act as a model system, and the findings are also tested against commercial materials to demonstrate wider applicability. To form a complete picture of the materials the researchers exploited a range of characterization methodologies, such as SEM (scanning electron microscopy), BET (Brunauer-Emmett-Teller theory for nitrogen adsorption), XPS (X-ray photoelectron spectroscopy), and X-ray CT (X-ray computed tomography). This long list of techniques (and associated large number of acronyms) covers a wide range of length scales, which means the researchers were able to analyse nano-, micro-, meso- and macro-pores altogether.