Rechargeable Batteries with 100% Cathode Active Materials─Conductive Vapor-Deposited Films of a Stable Organic Neutral Radical

Organic cathode active materials have been developed as promising alternatives to inorganic materials for rechargeable batteries due to environmental sustainability. However, the electrically insulating feature of organic materials causes the limitation in the capacity of the whole device, where the cathode requires massive conductive carbons. In this paper, we have realized rechargeable batteries with a cathode of 100% organic active material using highly conductive vapor-deposited films of 4,8,12-trioxotriangulene (TOT) neutral radical. These cathodes contained neither a binder nor a conductive additive and showed high capacities close to the theoretical value of the active material. The face-on films had better rate and cycle characteristics in comparison with the edge-on film due to their anisotropic conductivities. The films of ∼3 μm thickness maintained the face-on orientation and high capacities close to the theoretical value. The battery characteristics of highly oriented vapor-deposited films of TOT will provide a new promising strategy for the development of flexible, high-capacity thin-film rechargeable batteries.