Effects of polyvinyl alcohol on the electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathode material

Abstract

In view of the close relationship between the morphology of LiNi0.8Co0.15Al0.05O2 (NCA) and its electrochemical performance, polyvinyl alcohol (PVA) was added to control the NCA morphology. And thus a new NCA cathode material modified by PVA (NCA-PVA) was prepared. The morphology and structure of the obtained samples were characterized by X-ray diffraction, scanning electron microscopy, and laser diffraction. The electrochemical performance was characterized with electrochemical workstation and cell tester by assembling into CR2032 coin-type half-cell. The results show that the obtained NCA-PVA has a better layer structure and smaller cation mixing degree, smaller particle size, and more uniform particle size distribution than the pristine NCA without adding PVA. The electrochemical performance is also improved: the initial discharge capacity increases from 143.36 to 184.84 mAh g−1. And the charge-discharge efficiency increases from 78.25 to 86.42%. The specific discharge capacities of NCA-PVA are all higher than that of the NCA (about 50 mAh g−1) at all testing rates (0.1, 0.2, 0.5, 1.0, 2.0, and 5.0 C).