Breaking Solvation Dominance of Phosphate via Dipole-Dipole Chemistry in Gel Polymer Electrolyte

A prevalent method to bolster the safety of lithium-ion batteries (LIBs) is through the deployment of phosphate-based electrolytes. Nonetheless, an intrinsic challenge arises from the incompatibility between phosphate components and graphite anodes, a phenomenon known as coinsertion. To tackle this obstacle, we introduce a comprehensive strategy that employs in situ thermal polymerization, leveraging a flame-retardant solvent and a polymer matrix. This approach fosters strong dipole-dipole interactions between phosphate molecules and the polymer matrix, effectively alleviating the adverse impacts on graphite anodes. This significant enhancement is validated through in situ X-ray diffraction, X-ray photoelectron spectroscopy depth profile analysis, and transmission electron microscopy imaging. Our methodology facilitated stable lithium-ion operations within electrolytes comprising 20% phosphate components in assembled NCM811|P-GPE|Gr pouch cells, achieving a low-capacity decay rate of 0.0023% per cycle with good flame-retardant characteristics. We believe this strategy heralds new commercial prospects for incorporating phosphate-based solvents in the creation of exceptionally safe LIBs. © 2024 American Chemical Society.