Improvement in hydrophobicity of olivine lithium manganese iron phosphate cathodes by SiF4 treatment for lithium-ion batteries

In this report, we successfully demonstrate a novel SiF4 treatment on lithium manganese iron phosphate cathode (LMFP) that can significantly improve its hydrophobic property. The effect of SiF4 treatment on the structure and hydrophobicity of LMFP powder was studied by X-ray diffraction, Fourier transform infra-red spectroscopy, scanning transmission electron microscopy-energy dispersive X-ray spectroscopy, Karl Fisher titration, and thermo-microbalance gravimetric studies. The SiF4 treated LMFP cathode shows a substantial decrease in moisture adsorption by up to half of the untreated LMFP under ambient conditions. The SiF4-treated LMFP also shows excellent cycle life when cycled in lithium-ion full cells, even after exposing the electrodes to ambient conditions for one day, while the untreated LMFP showed a decrease in cycle life after the same exposure.