Controlling the oxygen deficiency for improving the insertion performance of the layered LiNi0.6Co0.2Mn0.2O2

Spherical Ni0.6Co0.2Mn0.2(OH)(2) precursor was synthesized by a co-precipitation method, and then uniformly mixed with Li salts and calcined to obtain the layered Ni-rich LiNi0.6Co0.2Mn0.2O2 materials. The obtained layered product was further treated at 600 degrees C for 2 h in four different atmospheres (oxygen, air, argon, argon/hydrogen (95/5)), to explore the effect of oxygen deficiency on the lithium-insertion and storage performance. X-ray diffraction, scanning electron spectroscopy and X-ray photoelectron spectroscopy were used to characterize the phase composition and structure, and the electrochemical performances were evaluated. A well developed layered crystal structure is obtained and the cations arrange more regularly under a high oxygen partial pressure, which leading to the remarkable electrochemical performance of higher discharge specific capacity (176 mAh g(-1) at 0.1 C), excellent rate performance and structural stability (67.17% in capacity retention after 300 cycles at 1.0 C). These results demonstrate the positive effects and the underlying mechanisms of the oxygen deficiency regulated lithium-insertion properties in the layered materials. (C) 2019 Elsevier Ltd. All rights reserved.