In Situ Encapsulation of the Nanoscale ErO 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 ErO phase on the Li(LiNiCoMn)O (LNCMO) cathode material for lithium ion batteries is proposed for the first time. The ErO 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 ErO layer is successfully encapsulated onto the entire surface of the LNCMO matrix material. This unique nanoscale ErO 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 ErO-coated LNCMO composite exhibits excellent cycling performace and a high initial Coulombic efficiency.