Search for: All records

Abstract New acceptor‐type graphite intercalation compounds (GICs) offer candidates of cathode materials for dual‐ion batteries (DIBs), where superhalides represent the emerging anion charge carriers for such batteries. Here, the reversible insertion of [LiCl₂]⁻into graphite from an aqueous deep eutectic solvent electrolyte of 20mLiCl+20mcholine chloride is reported. [LiCl₂]⁻is the primary anion species in this electrolyte as revealed by the femtosecond stimulated Raman spectroscopy results, particularly through the rarely observed H–O–H bending mode. The insertion of Li–Cl anionic species is suggested by⁷Li magic angle spinning nuclear magnetic resonance results that describe a unique chemical environment of Li⁺ions with electron donors around.²H nuclear magnetic resonance results suggest that water molecules are co‐inserted into graphite. Density functional theory calculations reveal that the anionic insertion of hydrated [LiCl₂]⁻takes place at a lower potential, being more favorable. X‐ray diffraction and the Raman results show that the insertion of [LiCl₂]⁻creates turbostratic structure in graphite instead of forming long‐range ordered GICs. The storage of [LiCl₂]⁻in graphite as a cathode for DIBs offers a capacity of 114 mAh g⁻¹that is stable over 440 cycles. 

Abstract Oxidative anion insertion into graphite in an aqueous environment represents a significant challenge in the construction of aqueous dual‐ion batteries. In dilute aqueous electrolytes, the oxygen evolution reaction (OER) dominates the anodic current before anions can be inserted into the graphite gallery. Herein, we report that the reversible insertion of Mg‐Cl superhalides in graphite delivers a record‐high reversible capacity of 150 mAh g⁻¹from an aqueous deep eutectic solvent comprising magnesium chloride and choline chloride. The insertion of Mg‐Cl superhalides in graphite does not form staged graphite intercalation compounds; instead, the insertion of Mg‐Cl superhalides makes the graphite partially turbostratic.