Towards a high MnO2 loading and gravimetric capacity from proton-coupled Mn4+/Mn2+ reactions using a 3D free-standing conducting scaffold
- 24 December 2020
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of Materials Chemistry A
- Vol. 9 (3), 1500-1506
- https://doi.org/10.1039/d0ta10685b
Abstract
We highlight 3D free-standing electrospun CNF electrodes as superior conductive scaffolds for the highly reversible proton-coupled MnIV (s) ↔ MnII (aq) conversion in a mild aqueous buffered electrolyte (pH 5). An electrochemical quartz crystal microbalance is used to in situ monitor these conversion reactions on the non-transparent CNF electrodes. Free-standing CNFs allow for a remarkably high relative MnO2 loading (63%, equivalent to an m MnO2 /mCNF ratio of 1.7) at a maximal charge of 1.4 mA h cm−2, while keeping the C.E. ≥ 95% over 300 cycles. The gravimetric capacity of the complete cathode is thus as high as 338 mA h g MnO2+CNF −1 (i.e., 534 mA h g MnO2 −1), outperforming the current state-of-the-art cathodes based on conventional graphite/carbon felts as substrates (2 loading, m MnO2 /mCNF ratio and 2+substrate −1) or composite electrodes. Furthermore, the buffered electrolyte allows for remarkably highly constant deposition–dissolution potentials with a low hysteresis (0.16 V). Pairing 3D electrospun CNFs (diameter ≤ 200 nm) and mild aqueous buffered electrolytes is thus a striking approach towards the development of MnO2-based mild aqueous batteries with high energy efficiency.Funding Information
- Agence Nationale de la Recherche
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