A Lithium-Free Energy-Storage Device Based on an Alkyne-Substituted-Porphyrin Complex.

Porphyrin complexes are well-known for their application in solar-cell systems and as catalysts; however, their use in electrochemical energy-storage applications has scarcely been studied. Here, a tetra-alkenyl-substituted [5,10,15,20-tetra(ethynyl)porphinato]copper(II) (CuTEP) complex was used as anode material in a high-performance lithium-free CuTEP/PP14 TFSI/graphite cell [PP14 TFSI=1-butyl-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide]. Thereby, the influence of size and morphology on the electrochemical performance of the cell was thoroughly investigated. Three different nanocrystal CuTEP morphologies, namely nanobricks, nanosheets, and nanoribbons, were studied as anode material, and the best cyclability and highest rate capability were obtained for the nanoribbon samples. A high specific power density of 14 kW kg-1 (based on active material) and excellent rechargeability were achieved with negligible capacity decay over 1000 cycles at a high current density of 5 A g-1 . These results indicate that the porphyrin complex CuTEP could be a promising electrode material in high-performance lithium-free batteries.