Enhanced Long-Term Stability of Organic Electrode Materials by a Trap Filler Strategy

Abstract

The sensitivity of organic electrode materials to water and oxygen has long been the bottleneck of their further development. The residual and penetrative water and oxygen in electrochemical cells form electron traps that trigger irreversible side reactions, which is detrimental to their long-term stability. A trap filler strategy by introducing molecules with low ionization energy in a cell, bis­(pentamethylcyclopentadienyl)­cobalt­(II) (DMC) as an example, is demonstrated to deactivate traps spontaneously by donating electrons to traps without causing undesirable reactions with electrode materials. The electrode materials BthCz and AQCz, with lowest unoccupied molecular orbital levels above or near the electron traps (−3.6 to −3.8 eV), exhibit conspicuous stability increment of 68.6 and 26.3%, respectively, with the optimized DMC concentration of 5 × 10–4 M in acetonitrile electrolyte.

Organic Supercapacitors as the Next Generation Energy Storage Device: Emergence, Opportunity, and Challenges

“…The residual and penetrative water and oxygen in electrochemical cells form electron traps which trigger irreversible side reactions. [216] This becomes a detrimental fact for such supercapacitors electrode for long-term stability. Zhao et al utilized a trap-filling strategy for organic electrode material to have long-term stability.…”

“…Two electrode materials BthCz and AQCz, with the lowest unoccupied molecular orbital levels above or near the electron traps (À 3.6 to À 3.8 eV) exhibit conspicuous stability increments of 68.6 and 26.3 %, respectively, with the optimized DMC concentration of 5 × 10 À 4 M in acetonitrile electrolyte. [216] If the material is photoactive, sometime light-induced degradation of the material can also be seen. Small molecular organic electrode materials enjoy favourable high capacity and low cost, but these materials suffer from poor cycling stability and low Coulombic efficiency due to the unavoidable dissolution in aprotic electrolytes which showed the stability of electrodes is a necessity to have industrial applications.…”

“…Over the years water and oxygen have been the bottleneck of their further development. The residual and penetrative water and oxygen in electrochemical cells form electron traps which trigger irreversible side reactions [216] . This becomes a detrimental fact for such supercapacitors electrode for long‐term stability.…”

“…utilized a trap‐filling strategy for organic electrode material to have long‐term stability. Two electrode materials BthCz and AQCz, with the lowest unoccupied molecular orbital levels above or near the electron traps (−3.6 to −3.8 eV) exhibit conspicuous stability increments of 68.6 and 26.3 %, respectively, with the optimized DMC concentration of 5×10 −4 M in acetonitrile electrolyte [216] . If the material is photoactive, sometime light‐induced degradation of the material can also be seen.…”