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 Er 2 O 3 phase on the Li(Li 0.2 Ni 0.13 Co 0.13 Mn 0.54 )O 2 (LNCMO) cathode material for lithium ion batteries is proposed for the first time. The Er 2 O 3 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 Er 2 O 3 layer is successfully encapsulated onto the entire surface of the LNCMO matrix material. This unique nanoscale Er 2 O 3 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 Er 2 O 3 -coated LNCMO composite exhibits excellent cycling performace and a high initial Coulombic efficiency.