DDQ/graphite dual-ion hybrid positive electrode in new AMC/AlCl3 electrolyte for advanced aluminum-organic battery

Rechargeable aluminum battery is a promising energy storage system for large-scale application due to abundant aluminum resources and high safety. Organic small molecules with active carbonyl group as positive electrode materials are expected to provide high voltage and large capacity. High solubility in acidic ionic liquid electrolyte and low conductivity are the key challenges. Here, novel multi-group (2),3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)/graphite dual-ion hybrid positive electrode and 1-allyl-3-methylimidazolium chloride/AlCl3 (AMC/AlCl3) electrolyte are proposed. DDQ exhibit low solubility in AMC/AlCl3 electrolyte and high conductivity based on electron structure engineering by heterogeneous electron-withdrawing groups (i.e. Cl and C≡N), which brings about large capacity, high and stable discharge voltage (1.75 V). DDQ/graphite dual-ion hybrid positive electrode delivers high discharge capacity (224 mAh/g) based on reversible coordination/dissociation of AlCl2+ cations with carbonyl groups and intercalation/de-intercalation of AlCl4- anions in graphite. Excellent stability is exhibited and a large capacity of 185 mAh/g remains after 1000 cycles. The hybrid positive electrode and AMC/AlCl3 electrolyte create a promising strategy to advance aluminum batteries.