ゼオライトを用いたリチウムイオン二次電池の正極材料の開発

抄録

Lithium-ion rechargeable batteries are the high-performance batteries in use today. However, there are three problems with the cathode material lithium cobaltate. First, they generate heat during charging. Second, they tend to change their structure during charging, resulting in a decrease in capacity. Third, the cobalt used for the material is expensive and scarce. In order to produce a battery that can compensate for these three points, this study focused on zeolite, which has a strong three-dimensional structure and can store lithium ions within its structure. The incorporation of valence-changeable transition metals into the zeolite's framework structure enables the transfer of lithium ions. Among transition metals, when an element with a large valence change when becoming an ion, such as Mn, is incorporated into the three-dimensional structure of a zeolite and synthesised, the number of lithium ions entering and leaving a single pore increases, making it possible to increase battery capacity. As the crystal structure of the zeolite does not change before and after charging, there is no decrease in capacity, and the higher porosity reduces the amount of heat generated. And the material is cheaper than lithium cobaltate because no rare metals are used. The aim of this research is to develop a new cathode material for lithium-ion batteries that incorporates manganese within the zeolite framework and has a higher capacity and longer life than conventional materials. In this study, Si-Mn-based NaP1 zeolites were synthesised by a melting method. The crystal structure and elemental analysis of the composite using XRD showed that NaP1 zeolite may be formed.