Institution: | 1. Department of Chemistry, University of Houston, 3585 Cullen Blvd., Houston, TX-77204-5003 USA
These authors contributed equally to this work.;2. Department of Chemistry, University of Houston, 3585 Cullen Blvd., Houston, TX-77204-5003 USA;3. Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX-77204-4004 USA
These authors contributed equally to this work.;4. Department of Electrical and Computer Engineering and Materials Science and Engineering Program, University of Houston, Houston, TX-77204 USA
Texas Center for Superconductivity at the University of Houston, University of Houston, Houston, TX-77204 USA;5. Department of Electrical and Computer Engineering and Materials Science and Engineering Program, University of Houston, Houston, TX-77204 USA |
Abstract: | Organic electrode materials could revolutionize batteries because of their high energy densities, the use of Earth-abundant elements, and structural diversity which allows fine-tuning of electrochemical properties. However, small organic molecules and intermediates formed during their redox cycling in lithium-ion batteries (LIBs) have high solubility in organic electrolytes, leading to rapid decay of cycling performance. We report the use of three cyclotetrabenzil octaketone macrocycles as cathode materials for LIBs. The rigid and insoluble naphthalene-based cyclotetrabenzil reversibly accepts eight electrons in a two-step process with a specific capacity of 279 mAh g−1 and a stable cycling performance with ≈65 % capacity retention after 135 cycles. DFT calculations indicate that its reduction increases both ring strain and ring rigidity, as demonstrated by computed high distortion energies, repulsive regions in NCI plots, and close C⋅⋅⋅C] contacts between the naphthalenes. This work highlights the importance of shape-persistency and ring strain in the design of redox-active macrocycles that maintain very low solubility in various redox states. |