Superior Performance of LiFePO₄Aqueous Dispersions via Corona Treatment and Surface Energy Optimization

Abstract

In lithium-ion battery electrode processing, obtaining good wetting and adhesion of the electrode dispersion to the current collector foil is essential for achieving high capacity and good long-term performance. The surface tension of LiFePO4 aqueous dispersions is much higher than the surface energy of untreated Al foil due to the high surface tension of water (72.8 mN/m), which causes inferior wetting during the coating step. In this work it has been shown that the surface energy of Al foil is significantly increased by corona plasma treatment. Consequently, the wetting and adhesion of the LiFePO4 aqueous dispersion to the Al foil are dramatically improved, as evidenced by contact angle measurements, adhesion energy calculations and interfacial tension calculations. The LiFePO4 cathodes with corona treated Al foil exhibited superior capacity (∼20 mAh/g improvement) with no increase in capacity fade at 0.5C/−0.5C cycling compared to an identical electrode without treatment.