The Electrochemical Stability of Spinel Electrodes Coated with ZrO₂, Al₂O₃, and SiO₂ from Colloidal Suspensions

Stoichiometric LiMn₂O₄ and substituted Li_1.05M_0.05Mn_1.9O₄ (M=Al,Ni) spinel electrodes, coated with ZrO₂, Al₂O₃, and SiO₂ from colloidal suspensions, have been evaluated in lithium cells. ZrO₂-coated Li_1.05Ni_0.05Mn_1.9O₄ electrodes provide the best cycling stability at 50°C. The excellent cycling stability is attributed to a porous network of amphoteric ZrO₂ particles, less than 4 nm in dimension, that protect the spinel surface from acid attack by scavenging HF and H₂O from the electrolyte, while still allowing access of the electrolyte to the active electrode.