New molecule fix gives 99.96% efficiency, 600 cycles to zinc batteries

Researchers at Seoul National University have significantly enhanced the performance and stability of aqueous zinc-ion batteries (AZIBs) by modifying a single molecule in the electrolyte. By engineering the electrolyte’s co-solvent, they developed a phosphate-based molecule called diethyl(difluoromethyl)phosphonate (DEDFP), which replaces an ethoxy group in the conventional triethyl phosphate (TEP) with a difluoromethyl group. This modification leads to a weaker interaction with zinc ions, reducing the energy needed for zinc deposition, and increases hydrophobicity, which repels water molecules from the electrode surface. As a result, the batteries achieved an average Coulombic efficiency of 99.96% and maintained stable operation for up to 600 charge-discharge cycles, outperforming TEP-based systems that fail after fewer cycles. A crucial benefit of the DEDFP co-solvent is the formation of a stable solid-electrolyte interphase (SEI) layer composed of