Boosted Lithium Storage on a Small Organic Molecule Cathode with Ether and Hydroxyl Modification

Organic cathode materials have become a research hotspot as cathodes for lithium-ion batteries (LIBs) originating from their diverse structures with adjustable properties. However, the fabrication of organic cathode materials with enhanced cyclability, reversible capacity, and energy density is still a big challenge. To address these issues, we synthesize an organic polyphenylene ether-based small molecule DHBD, 3,13-dihydroxybenzo-1,2,4′,5′-bis(1,4-benzodioxane) via the Williamson reaction. The small molecule realizes intermolecular hydrogen bonding through the introduction of hydroxyl functional groups, and combined with its π–π conjugated structure, effectively enhanced stability and conductivity of the small molecule material in the organic electrolyte can be achieved. Using DHBD as a cathode for LIBs, its initial capacity can reach to 132.4 mA h·g–1 at 0.1 A·g–1, while after 100 cycles, its capacity retention can keep at 84.8%. In addition, the mechanism of lithium ions reacting with ether bonds and hydroxyl units in the structure of DHBD has also been studied by ex-situ experimental characterization supplemented by theoretical calculations. This work reports the modification of ether bonds and hydroxyl units for promoted energy storage, and it would further extend the applications of organic molecules with electrochemically active groups.