Protecting Al foils for high-voltage lithium-ion chemistries

High concentrations of protons generated by the rapid oxidation of electrolyte solvent at high working potentials always lead to undesired reactions like the corrosion of Al current collectors. This issue is exaggerated with the recent effort in search for high-voltage cathode materials for a further increase on the achievable energy density of lithium-ion batteries. In this study, LiNi0.6Mn0.2Co0.2O2 (NMC 622) was investigated as a model high-voltage cathode to illustrate the potential impact of corrosion on the long-term performance of lithium-ion batteries. Both electrochemical measurements and X-ray photoelectron spectroscopy depth-profile studies confirmed that the AlPO4-coated Al foil was more resistive to corrosion. Meanwhile, an improvement on the capacity retention of NMC 622 was also observed by utilizing an AlPO4-coated Al foil as the current collector. It also implies that the corrosive environment generated at the relatively high working potential needs to be effectively mitigated to unlock the full potential of high-voltage cathodes.