Toward High‐Performance Dihydrophenazine‐Based Conjugated Microporous Polymer Cathodes for Dual‐Ion Batteries through Donor–Acceptor Structural Design

Abstract

Recent studies have demonstrated that dihydrophenazine (Pz) with high redox-reversibility and high theoretical capacity is an attractive building block to construct p-type polymer cathodes for dual-ion batteries. However, most reported Pz-based polymer cathodes to date still suffer from low redox activity, slow kinetics, and short cycling life. Herein, a donor-acceptor (D-A) Pz-based conjugated microporous polymer (TzPz) cathode is constructed by integrating the electron-donating Pz unit and the electron-withdrawing 2,4,6-triphenyl-1,3,5-triazine (Tz) unit into a polymer chain. The D-A type structure enhances the polymer conjugation degree and decreases the band gap of TzPz, facilitating electron transportation along the polymer skeletons. Therefore the TzPz cathode for dual-ion battery shows a high reversible capacity of 192 mAh g −1 at 0.2 A g −1 with excellent rate performance (108 mAh g −1 at 30 A g −1 ), which is much higher than that of its counterpart polymer BzPz produced from 1,3,5-triphenylbenzene (Bz) and Pz (148 and 44 mAh g −1 at 0.2 and 10 A g −1 , respectively). More importantly, the TzPz cathode also shows a long and stable cyclability of more than 10 000 cycles. These results demonstrate that the D-A structural design is an efficient strategy for developing high-performance polymer cathodes for dual-ion batteries.

Integrated Covalent Organic Framework/Carbon Nanotube Composite as Li‐Ion Positive Electrode with Ultra‐High Rate Performance

“…Here, 19 mAh g −1 corresponds to 12% utilization of the redox‐active sites and highlights that the lower porosity hinders electrolyte diffusion. [ 41 ]…”

“…Here, 19 mAh g −1 corresponds to 12% utilization of the redoxactive sites and highlights that the lower porosity hinders electrolyte diffusion. [41] Long-term cycling stability is an important criterion to estimate cell performance. Here, the long-term cycling properties of the optimized composite, DAPQ-COF50, were studied by repeated charge/discharge cycling experiments at a current density of 2000 mA g −1 (about 12.7 C) (Figure 3d).…”

Polymer Electrode Materials for Lithium‐Ion Batteries

“…[201][202][203] In addition, the 1-/2-positions of phenazine and phenyl units are usually modified with different functionalities to adjust the redox voltage. The redox plateaus of -OMe substituted polymer decreased by 0.1-0.2 V and that of the -CN substituted polymer increased by 0.2 V. [204] Besides, the triphenylamine, [205] 2,4,6-triphenyl-1,3,5-triazine (Tz), 1,3,5-triphenylbenzene (Bz) [206] were utilized to replace the phenyl in p-DPPZ, forming highly-crosslinked structures. They showed remarkable cycle stability and high rate performance.…”

“…The poly(phenazine-co-Tz) showed an ultra-long cycle life of 10 000 cycles at 5 A g −1 because the donor-acceptor electron structure of phenazine narrowed the bandgap and promoted the electron transfer. [206] From the above discussion, different kinds of PEMs have their unique advantages and disadvantages in electrochemical performance, including theoretical capacity, voltage plateau, specific capacity, rate capability, and cycling performance. In recent years, much progress has been made in the electrochemical performance of various PEMs, as shown in Table 2.…”

Catalyst-free nitro-coupling synthesis of azo-linked conjugated microporous polymers with superior aqueous energy storage capability

“…Thus, carbonyl (C=O), imine (C=N), and triphenylamine groups have been incorporated into polymers to function as electrochemical hosts for various cations (e.g., Li + , Na + , Mg 2+ , H + ) [13][14][15]. Building blocks such as quinones [16][17][18][19], phenazine [20,21], and triphenylamine [5,22] are usually employed as conjugated backbones. Furthermore, new redox functionalities are highly demanding to enrich the family of electrochemical CMPs.…”