High Power Energy Storage via Electrochemically Expanded and Hydrated Manganese-Rich Oxides

Abstract

Understanding the materials design features that lead to high power electrochemical energy storage is important for applications from electric vehicles to smart grids. Electrochemical capacitors offer a highly attractive solution for these applications, with energy and power densities between those of batteries and dielectric capacitors. To date, the most common approach to increase the capacitance of electrochemical capacitor materials is to increase their surface area by nanostructuring. However, nanostructured materials have several drawbacks including lower volumetric capacitance. In this work, we present a scalable "top-down" strategy for the synthesis of EC electrode materials by electrochemically expanding micron-scale high temperature-derived layered sodium manganese-rich oxides. We hypothesize that the electrochemical expansion induces two changes to the oxide that result in a promising electrochemical capacitor material: (1) interlayer hydration, which improves the interlayer diffusion kinetics and buffers intercalation-induced structural changes, and (2) particle expansion, which significantly improves electrode integrity and volumetric capacitance. When compared with a commercially available activated carbon for electrochemical capacitors, the expanded materials have higher volumetric capacitance at charge/discharge timescales of up to 40 s. This shows that expanded and hydrated manganese-rich oxide powders are viable candidates for electrochemical capacitor electrodes.

Improving the intrinsic conductivity of δ-MnO2 by indium doping for high-performance neutral aqueous sodium-ion supercapacitors with commercial-level mass-loading

“…62 The water within the interlayer can improve cation transfer from the bulk electrolyte to the particles. 64 The band gap was tested by recording the absorption spectra of the solid materials. No obvious differences can be observed in Fig.…”

Manganese Oxide Nanoparticles: An Insight into Structure, Synthesis and Applications

“…Extensive efforts have been put forward to enhance the specific surface area of electrochemical capacitor materials using nanostructuring in order to increase their capacitance. Still, lower volumetric capacitance is one of the major downsides of nanostructured materials [86]. Amorphous MnO 2 compounds were surveyed as plausible materials for serving as electrodes for electrochemical capacitors in 0.1 M K 2 SO 4 electrolyte by Brousse et al and they found a large capacitance value.…”

“…Extensive efforts have been put forward to enhance the specific surface area of electrochemical capacitor materials using nano‐structuring in order to increase their capacitance. Still, lower volumetric capacitance is one of the major downsides of nanostructured materials 86.…”

Manufacturing Shape-Controllable Flexible PEDOT/rGO Composite Electrodes for Planar Micro-Supercapacitors

“…The electrode materials for pseudocapacitors mainly include metal oxides and conductive polymers [13,14]. Pseudocapacitors store energy through reversible reactions on the surface of the electrode, demonstrating a mechanism that is more intricate than that of EDLCs [15][16][17][18].…”