Electrochemical performance and computational analysis of an Al-based battery system using a cathode of graphene obtained from processed expandable graphite

The electrochemical storage of aluminum in graphitic electrodes is a topic of much interest in the search for alternative battery systems. Here, we show that an Al-based battery can be realized using a cathode assembled with graphene flakes obtained from processed expandable graphite. When compared to pristine graphite (in this work, with 45 mAh/g at a current density of 214 mA/g), the capacity and cycle life performance are notably increased by the use of the graphene flakes (172 mAh/g, at 214 mA/g, after 100 cycles). The location and persistence of the charged choloraluminate species in the carbon materials was experimentally analyzed and complemented with computational modelling. Accordingly, and besides intercalation, grafting of the Al-species onto the graphene layers was identified as a possible mechanism that enhanced the performance of the processed expandable graphite cathodes. Such a phenomena would make the electrode more conductive and introduce a path for charge storage on its surface (akin to faradaic supercapacitors).