Ethynyl and Furyl Functionalized Porphyrin Complexes as New Organic Cathodes Enabling High Power Density and Long-Term Cycling Stability

Abstract

Organic cathode materials have recently attracted abundant attention due to their flexible structural tunability and recyclability. However, the low intrinsic electrical conductivity and high solubility in electrolytes of organic electrode materials have significantly limited their practical application. Herein, we present [5,15-bis(ethynyl)-10,20-difurylporphinato] copper(II) (Cu-DEOP) as a new cathode for rechargeable organic lithium batteries (ROLBs). The combination of both ethynyl and furyl groups of the CuDEOP cathode with a nanorod structure renders it with enhanced structural stability and an extended delocalized πelectron system to deliver excellent cycling stability (capacity retention of 76% after 6000 cycles) and a high power density (16 kW kg −1 ). The furyl electroactive groups participate in charge storage contribution to achieve a reversible six-electron-transfer redox reaction in a specific voltage range. The mechanism characterizations indicate that the nitrogen atoms on the porphyrin ring act as active sites to alternatively store both PF 6 − anions and Li + cations, and the charge storage process is a pseudocapacitive-dominated reaction. This observation will offer a new avenue for designing functionalized molecules for electrochemical energy-storage (EES) systems.

A π‐Conjugated Porphyrin Complex as Cathode Material Allows Fast and Stable Energy Storage in Calcium Batteries

“…A comparative CV measurement (Figure S20) suggests that an additional redox peak, which occurs at 2.7 V in the anodic scan and reverses at 2.5 V in the cathodic scan, could be attributed to the copper atom in the porphyrin core structure. Previous research also reported on partial Cu(II) to Cu(I) redox reaction in Cu−porphyrins [25a,29,41a,42] . However, in this study, we observe the reaction to be more reversible and complete than previous studies have suggested.…”

A bipolar pyridine-functionalized porphyrin with hybrid charge-storage for dual-ion batteries

“…[18][19][20][21][22][23][24] Moreover, the formation of p-conjugated aromatic compounds by introducing heteroatoms (S, O, and N) with a lone pair of electrons to organic materials might lead to multiple redox centers. [25][26][27] Compared with other organic electrode materials, the porphyrin compounds have high stability due to their rigid and extended frameworks. Cui and coworkers synthesized tetrakis(4-carboxyphenyl)porphyrin as an anode, where superior electrochemical performance (548.4 mA h g À1 and 43000 cycles) was achieved due to the large p-conjugated system.…”

Ferrocene Appended Porphyrin‐Based Bipolar Electrode Material for High‐Performance Energy Storage

“…During the first anodic sweep (Figure 2a), two anodic peaks appeared that might be ascribed to the oxidation of CuDEFcP into cationic species [CuDEFcP] 4+ and the peak located at 3.51 V is mostly associated with the oxidation of ferrocene units into ferrocenium [16d,21] . The observed irreversible process is a common feature for this class of compounds and will be discussed further later [14a,15a,22] . In the reverse scan, four cathodic peaks were observed.…”