A Hydrocarbon Cathode for Dual-Ion Batteries

We have demonstrated, for the first time, a polycyclic aromatic hydrocarbon (PAH), crystalline and readily available coronene, exhibits highly reversible anion-storage properties. Conventional graphite anion-insertion electrodes operate at potentials >4.5 V vs Li+/Li, requiring electrolyte additives or the use of ionic liquids as electrolytes. The coronene electrode shows flat plateaus at 4.2 V (charge) and 4.0 V (discharge) in a standard alkyl carbonate electrolyte and delivers a reversible discharge capacity of ∼40 mA h g–1. Ex situ characterization reveals that coronene retains its crystalline structure and chemical bonding upon initial PF6– incorporation. Coronene–PF6 electrodes show impressive cycling stability: 92% capacity retention after 960 cycles. The discovery of the reversible anion-storage properties of coronene may open new avenues toward dual-ion batteries based on PAHs as electrodes.