Kneading and dispersion of positive electrode materials in a lithium ion secondary battery for high-density film

Focusing on the manufacturing process of the positive electrode of the lithium ion secondary battery, this research set out to investigate the kneading and dispersion that is required to distribute positive electrode particles of a high density within the film, and to investigate methods for evaluating the state of dispersion of the positive electrodes. We demonstrated that the dispersion of the positive electrode particles of the lithium ion secondary battery can be quantitatively evaluated by measuring the particle size distribution of positive electrode particles in the paste, the volume resistivity of the film, the film thickness, the film density and the glossiness, and by organically analyzing these measured values. Moreover, we revealed that, in order to manufacture high-density film, it is better to adopt the method of adding the binder in divided stages. In other words, we pointed out that in order to make positive electrode particles fill the film (plate) of a high density and to create good battery characteristics, the kneading and dispersion processes are extremely important. Furthermore, we were able to obtain a good correlation between volume resistivity and film density. In short, to produce a film that excels in battery properties, it is essential to increase the film density.