Performance optimization and fast rate capabilities of novel polymer cathode materials through balanced electronic and ionic transport

Abstract

Balancing electronic and ionic transport is crucial to developing next-generation high-power organic electrode materials.

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

“…[25,[42][43][44] However, the two Pz-based polymers of BzPz and TzPz have similar surface area, indicating that the difference in rate performance of the two polymer cathodes is dominated by other factors (Figure 2c). Taking into account that the rate performance is also influenced by both the ionic and electron conductivities, [24,45,46] we first estimated the ionic diffusivities in BzPz and TzPz cathodes by galvanostatic intermittent titration technique (GITT; Figure S11, Supporting Information). The results demonstrated that the ionic diffusion efficiency in BzPz is slightly higher than that in TzPz (Figure 3a).…”

“…Very recently, Abruna et al demonstrated that the ionic and electronic conductivities of the crosslinked Pz-based polymer cathodes could be balanced by tuning the length of linear polymer chains between two adjacent knots through statistical copolymerization, the optimized Pz-based polymer cathode delivered a high specific capacity around 195 mAh g −1 at 1 A g −1 with a cycling life of 500 cycles. [24] Herein, we developed a donor-acceptor (D-A) Pz-based conjugated microporous polymer (TzPz) cathode 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. Compared with its counterpart polymer BzPz produced from 1,3,5-triphenylbenzene (Bz) and Pz, the TzPz cathode with D-A molecular structure shows a higher conjugation degree and a narrower band gap, which are beneficial for the electron transportation along the polymer chains in TzPz during the charge/discharge process.…”

“…Recently, the p‐type dihydrophenazine (Pz) unit has attracted intense attention as redox‐active building block for constructing polymer cathodes in DIBs, owing to its high reversible redox reaction and high theoretical charge‐storage capacity. [ 5,20–24 ] The redox centers in Pz are the two nitrogen atoms with lone pair electrons, which endow Pz with a theoretical capacity up to 297 mAh g −1 and high discharge voltage higher than 3 V versus Li + /Li. Park et al for the first‐time reported the methyl‐ and benzene‐substituted Pz derivatives as the cathodes in lithium DIBs, and a high discharge capacity around 191 mAh g −1 was obtained.…”

“…Very recently, Abruna et al demonstrated that the ionic and electronic conductivities of the crosslinked Pz‐based polymer cathodes could be balanced by tuning the length of linear polymer chains between two adjacent knots through statistical copolymerization, the optimized Pz‐based polymer cathode delivered a high specific capacity around 195 mAh g −1 at 1 A g −1 with a cycling life of 500 cycles. [ 24 ]…”

Polymer Electrode Materials for Lithium‐Ion Batteries

“…As a result, the p-DPPZ delivered higher capacity retention of 81.7% after 1000 cycles (Figure 21e). [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.…”