Abstract
Resorcinol – Formaldehyde Carbon Aerogels (CAGs) with different microstructure properties are very interesting materials for energy storage applications [1]. By changing the molar ratio between resorcinol and catalyst, and varying the resorcinol concentration, it is possible to change the density, mesoporosity and microporosity of the aerogels [2]. In this work we synthesize a number of materials with different properties and test their performance in an all Vanadium RFB.
The BET analysis showed a total surface area between 643 to 931 m2 g-1 and a variation of deposition morphology. The best performing material did not have the highest surface area, but instead had a good balance between microporous and external surface area (about 50:50), and on the macroscopic scale had sufficiently large pores to allow efficient electrolyte permeation. In contrast although the poorest electrodes had the highest surface areas, they had poor macroscopic porosity leading to large mass transport loss. The best performing electrode achieved a power density of 706 mW cm-2 at 1 V. This electrode was cycled at two different current densities for 20 cycles, achieving a battery efficiency between 75 to 80 % [3].
References
[1] J. Biener et al., "Advanced carbon aerogels for energy applications," Energy Environ. Sci., vol. 4, no. 3, p. 656, Mar. 2011, doi: 10.1039/c0ee00627k.
[2] A. M. Elkhatat and S. A. Al-Muhtaseb, "Advances in tailoring resorcinol-formaldehyde organic and carbon gels," Adv. Mater., vol. 23, no. 26, pp. 2887–2903, 2011, doi: 10.1002/adma.201100283.
[3] A. Parra-Puerto, J. Rubio-Garcia, M. Markiewicz, Z. Zheng, and A. Kucernak, "Factors Leading to Optimum Carbon Aerogel Based Electrodes for Redox Flow Batteries." In Preparation
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