Study on the Effect of Calcination Temperature of LiNiO2 on Its Cycle Stability during Lithium Ion Battery Operation

Abstract

In battery industry, the research direction of cathode materials is focused on the achievement of high capacity and stability. The most widely studied cathode materials are layered structure LiMO2 (M = Ni, Co, Mn, Al), where Ni is utilized for high capacity and other elements such as Co, Mn and Al are incorporated for the sake of improving stability and rate capability. In general, stability is lowered at the expense of capacity and capacity is compromised when improving stability. This tradeoff found in LiNiO2 that has received great attention for a high capacity cathode material was investigated in this thesis study. It reveals that calcination temperatures have a significant effect on the grain size and primary particle size of LiNiO2, which is closely related to the capacity and stability of battery cells. As the calcination temperature increases (550, 575, 600, 625, 650, and 700 °C), the grain size and primary particle size increase. Among the samples explored, LiNiO2 synthesized at 625 °C stands out with more than 60% capacity retention of an initial capacity (200 mAhg-1) after 300 cycles. It has been observed that the grain size and the primary particle size should not be large or small, there is an optimal temperature for LiNiO2 in order to achieve both high capacity and stability. This study suggests that a subtle control over the structural characteristics is essential for high-performance cathode material in lithium-ion batteries.