Ultra‐Long Lifespan Ni Based Porphyrin Complex Cathode for Organic Alkali Metal Batteries.

The high solubility and low intrinsic electronic conductivity are the key challenges for application of organic materials in electrochemical energy storage. Herein, a functionalized porphyrin complex of [5,15‐Bis(ethynyl)‐10,20‐diphenylporphinato]nickel(II) (NiDEPP) is proposed as new cathode material for alkali metal ion batteries. Owing to the in‐situ electropolymerization, NiDEPP became extremely stable after initial cycling. Therefore, the NiDEPP electrode delivers remarkable reversible capacity of 153 mAh g−1 at 1 A g−1, a high specific energy density of 459 Wh kg−1 and extremely stable cyclability for 4000 cycles with negligible capacity decay in organic lithium batteries. It can further be cycled upto 10000 cycles. Due to the bipolar capability of porphyrin ring, this cathode can also be extended in both sodium and potassium based organic cells. Similar charge storage mechanism enables highly reversible capacity and long‐term cycling stability. This study would open a pathway toward new organic electrodes with long cycling life and high energy densities for renewable charge storage devices. [ABSTRACT FROM AUTHOR]