Hydrogen storage capacity of selected activated carbon electrodes made from brown coal Amandeep Singh Oberoi a,b,* , John Andrews b , Alan L. Chaffee c , Lachlan Ciddor c a Chitkara University Research and Innovation Network (CURIN), Chitkara University, Punjab, 140401, India b School of Aerospace, Mechanical and Manufacturing Engineering, RMIT University, Victoria, 3083, Australia c School of Chemistry, Monash University, Melbourne, Victoria, 3800, Australia article info Article history: Received 7 March 2016 Received in revised form 30 September 2016 Accepted 19 October 2016 Available online xxx Keywords: Hydrogen storage Activated carbon Proton flow battery Double-layer capacitance Proton conductivity abstract Electrochemical storage of hydrogen in activated carbon (aC) electrodes as part of a reversible fuel cell offers a potentially attractive option for storing surplus electrical energy from inherently variable solar and wind energy resources. Such a system e which we have called a proton flow battery e promises to have a roundtrip energy efficiency comparable to lithium ion batteries, while having higher gravimetric and volumetric energy densities. Activated carbons with high internal surface area, high pore volume, light weight and easy availability have attracted considerable research interest as a solid-state hydrogen storage medium. This paper compares the physical characteristics and hydrogen storage capacities of four activated carbon (aC) electrodes made from brown coal. The fabrication methods for these samples are explained. Their proton conductivity was measured using electro- chemical impedance spectroscopy and their hydrogen storage capacity by galvanostatic charging and discharging in a three-electrode electrolytic cell with 1 mol sulphuric acid as electrolyte at atmospheric pressure and room temperature. The highest hydrogen storage capacity obtained was 1.29 wt%, which compares favourably with metal hydrides used in commercially available solid-state hydrogen storages. Finally, the relation between the hydrogen storage capacity of the samples and their Dubinin-Radushkevich surface area (calculated by the CO 2 adsorption method) was investigated. The results point the way towards selecting high-performing electrodes for proton flow batteries and signal the po- tential competitiveness of this energy storage technology. © 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction Pollution leading to climate change has been the main reason for renewable energy technology development for many de- cades. It remains a major technical challenge to achieve reli- able and continuous supply from inherently variable renewable energy sources such as solar and wind. Storing surplus renewable energy as hydrogen is one energy storage option, particularly when longer-term, season-to-season storage is required [1]. Developing a safe and efficient hydrogen storage system with acceptable figures of gravi- metric and volumetric energy densities is still a challenge for researchers to address [2e4]. Hydrogen storage is possible in gaseous form, liquid form, and as a chemical compound (also called electrochemical * Corresponding author. Chitkara University Research and Innovation Network (CURIN), Chitkara University, Punjab, 140401, India E-mail address: amandeep.oberoi@chitkara.edu.in (A.S. Oberoi). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2016) 1 e10 http://dx.doi.org/10.1016/j.ijhydene.2016.10.112 0360-3199/© 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Oberoi AS, et al., Hydrogen storage capacity of selected activated carbon electrodes made from brown coal, International Journal of Hydrogen Energy (2016), http://dx.doi.org/10.1016/j.ijhydene.2016.10.112