Efficient Aluminum Chloride Natural Graphite Battery

The quest for low-cost and large-scale stationary storage of electricity has led to a surge of reports on novel batteries comprising exclusively highly abundant chemical elements. Aluminum-based systems, inter alia, are appealing because of the safety and affordability of aluminum anodes. In this work, we examined the recently proposed aluminum-ionic liquid-graphite architecture. Using Al-27 nuclear magnetic resonance, we confirmed that AlCl4- acts as an intercalating species. Although previous studies have focused on graphitic cathodes, we analyzed the practicality of achievable energy densities and found that the AlCl3-based ionic liquid is a capacity-limiting anode material. By focusing on both the graphitic cathode and the AlCl3-based anode, we improved the overall energy density. First, high cathodic capacities of <= 150 mAh g(-1) and energy efficiencies of 90% at high electrode loadings of at least 10 mg cm(-2) were obtained with natural, highly crystalline graphite flakes, which were subjected to minimal mechanical processing. Second, the AlCl3 content in the ionic liquid was increased to its maximal value, which essentially doubled the energy density of the battery, resulting in a cell-level energy density of <= 62 Wh kg(-1). The resulting batteries were also characterized by high power densities of at least 489 W kg(-1).