In Situ Encapsulation of the Nanoscale Er2O3 Phase To Drastically Suppress Voltage Fading and Capacity Degradation of a Li- and Mn-Rich Layered Oxide Cathode for Lithium Ion Batteries.

A novel strategy of in situ precipitation and encapsulation of the Er2O3 phase on the Li(Li0.2Ni0.13Co0.13Mn0.54)O2 (LNCMO) cathode material for lithium ion batteries is proposed for the first time. The Er2O3 phase is precipitated from the bulk of the LNCMO material and encapsulated onto its entire surface during the calcining process. Electrochemicial performance is investigated by a galvanostatic charge and discharge test. The structure and morphology are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The results show that an about 10 nm Er2O3 layer is successfully encapsulated onto the entire surface of the LNCMO matrix material. This unique nanoscale Er2O3 encapsulation can significantly prevent the LNCMO cathode material from being corroded by electrolytes and stabilize the crystal structure of the LNCMO cathode during cycling. Therefore, the prepared Er2O3-coated LNCMO composite exhibits excellent cycling performace and a high initial Coulombic efficiency.