Effect of calcining oxygen pressure gradient on properties of LiNi0.8Co0.15Al0.05O2 cathode materials for lithium ion batteries

To understand the effects of the calcining pressure gradient on the structure, morphology, and electrochemical properties of LiNi0.8Co0.15Al0.05O2 (NCA), LiNi0.8Co0.15Al0.05 (OH)(2) precursors prepared using a coprecipitation method are calcined under gradually increasing oxygen pressures to fabricate different cathode materials. The results of characterization using X-ray diffraction and scanning electron microscopy suggest that the material (NCA-0.6) possesses the best comprehensive properties when the calcining oxygen pressure is 0.6 MPa, at which the values of I(003)/I(104) and D-50 are appropriately 1.727 and 11.06 mu m, respectively. A cell assembled with NCA-0.6 delivers a discharge specific capacity of 143.3 mAh g(-1) with a capacity retention ratio of 80.3% after 100 cycles at 1.0 C. Moreover, it presents a lower resistance of 327.5 Omega and redox peak difference of 0.11 V compared to the values of 1953.2 Omega and 0.26 V for NCA-0.1. These results suggest that appropriately enhancing the calcining oxygen pressure is an effective way to improve the cycle stability of NCA materials without any modified method. (C) 2020 Elsevier Ltd. All rights reserved.