Amorphous Carbon-Derived Nanosheet-Bricked Porous Graphite as High-Performance Cathode for Aluminum-Ion Batteries

Graphite is an attractive cathode material for energy storage because it allows reversible intercalation/deintercalation of many compound anions at high potentials. However, because the sizes of the compound anions are greatly larger than the lamellar spacing of graphite, common graphite used as cathode may suffer from slow kinetics and large volume expansion. Here, it is demonstrated that graphite with high crystallinity and nanosheet-bricked porous structure can be an excellent cathode for aluminum-ion batteries. This porous graphite is derived from carbon black via a simple electrochemical graphitization in molten CaCl2, and the high crystallinity and thin layer characters facilitate the high capacity and high rate storage of aluminum tetrachloride ions. Moreover, the bricked porous structure endows the fabricated cathode with a providential porosity to perfectly match the huge volume expansion of graphite (650% against a charging capacity of 100 mA h g–1), thus this electrochemical graphite exhibits integrated high gravimetric and volumetric capacities as well as high structural stability during cycling.