Electrochemical Properties of LiNi1-yMyO2(M=Zn2+, Al3+, and Ti4+) Synthesized by Milling and Solid-State Reaction Method

By calcining at 750 C for 30 h in 02 stream after milling, LiNi1-yMyO2 (M = Zn2+, Al3+, and Ti4+, y = 0.005, 0.01, 0.025, 0.05, and 0.1) were synthesized and their electrochemical properties were investigated. All the samples had R3m structure. LiNi1-yZnyO2 (y = 0.025, 0.05, and 0.1) contained ZnO and/or Li2ZnO2 as impurities. Among the samples substituted with the same element, the samples with relatively large value of I-003/I-004 and the smallest R-factor had the largest first discharge capacity and good cycling performance. LiNi0.975Al0.025O2 had the largest first discharge capacity (172.5 mAh/g) and good cycling performance (about 89.4% of the first discharge capacity at the 20th cycle). This sample had the largest value of I-003/I-104 and the smallest R-factor among all the samples. In addition, the particles of this sample were finer and their size was more homogeneous than the other samples. LiNi0.95Al0.05O2 had relatively large first. discharge capacity 150.4 mAh/g and good cycling performance.