Molecular-spin batteries using degenerate molecular orbitals: performance improvement by MO-engineering and controlling intermolecular interactions in the solid state

Abstract

Organic cathode-active materials have drawn much attention in quest of new high-performance secondary batteries. We have proposed a new approach to high-capacity batteries by utilizing organic molecules with multi-stage redox ability for cathode-active materials in 2002. On the basis of the idea, we have implemented the batteries using stable organic open-shell molecules with degenerate frontier-molecular orbitals (MOs), termed "Molecular Crystalline Secondary Batteries". In order to elevate the output voltage and cycle performance of the batteries, we have designed and synthesized novel organic molecules as cathode-active materials in terms of MO-engineering and controlling intermolecular interactions in the solid state. We have fabricated the coin-type cells using these molecules, demonstrating the elevation of the output voltages and improvement of the cycle performance, as expected.