Carbonaceous materials that possess reversible anions storage capacity and can worked as the cathode for Ni/NiCl2-Graphite battery. However, differences in storage capacity of carbonaceous cathodes and factors affecting anions storage capacity have not been thoroughly investigated. Here, we systematically evaluated the electrochemical properties and intercalation reaction mechanism of carbonaceous materials cathodes firstly. Expanded graphite and graphite paper cathodes display the highest specific capacity of 72 mAh/g and diffusion-controlled capacity ratios (∼98 %). X-ray powder diffraction and Raman spectroscopy analysis on the graphite intermetallic compounds confirmed the presence of stage-5 intercalation/de-intercalation reactions. Density functional theory calculation and ionic diffusion model analysis showed that the intercalation and diffusion process of AlCl4- in graphite interlayers play a crucial role in anions storage reaction. Rich-in-edged outer graphite-layers are more conducive to form intercalation reaction active sites and store anions effectively. The expanded graphite electrode exhibits the highest intercalation reaction ratio (φR-GP = 1.40), confirming sufficient intercalation reaction active sites in each unit mass. And the multiple wrinkles and curled graphite sheets in expanded graphite provide adequate ionic transport/diffusion channels during electrochemical intercalation/de-intercalation reactions. Our findings provide significant support for understanding anions storage behaviors and designing cathodes with high anions storage capacity in the Ni/NiCl2-Graphite battery.

Link：Stabilizing dual-cation liquid metal battery for large-scale energy storage: A comprehensive hybrid design approach - ScienceDirect