Dilution of the Electron Density in the π‐Conjugated Skeleton of Organic Cathode Materials Improves the Discharge Voltage

Abstract

Organic compounds are promising candidates as battery materials because they can be sourced from sustainable resources, have tunable structures, and are cheap. However, the working voltage of battery cells containing organic compounds as positive electrodes is relatively lower than that of those containing an inorganic counterpart. In this work, a strategy was developed to increase the discharge voltage of battery cells by diluting the electron density of N‐based redox centers in conjugated organic materials. In electron‐rich heterocyclic compounds that utilize N as the redox center, pentatomic rings such as carbazole derivatives exhibited a higher atomic‐dipole‐moment‐corrected Hirshfeld charge population compared with hexatomic rings, which led to a significant increase in the oxidation potential. As a result, polymeric indolocarbazole derivatives showed a high discharge voltage of 3.7–4.3 V vs. Li+/Li and good cycling performance. Such a strategy can be used to design high‐voltage organic electrode materials containing other redox centers.

Machine Learning-Assisted Discovery of High-Voltage Organic Materials for Rechargeable Batteries

“…Totally, we generate 47 structures, but not all of them are novel. Among these structures, three of them were reported previously in our work, which are (1) DPPZ, 21 (2) PhPT, 31 and (3) DPICZ, 32 which strengthened the availability of our work, as shown in Figure 1b. These examples denoted that the generation on high-potential structures preferred benzene rings and some specific functional groups by joining rings and a nitrogen atom.…”

High-performance all-organic aqueous batteries based on a poly(imide) anode and poly(catechol) cathode

“…1b and Table 1). It is worth mentioning here that chemical manipulation, [55][56][57] p-conjugation adaptivity 58,59 and spectator cation substitution in the host structure 60 approaches are most oen used to tune the redox potentials of the organic core. Negatively, such strategies also add deadweight to the active materials, which might penalize the specic capacity as well.…”

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

“…[ 4–6 ] Considering that the p‐type organic cathodes are anion‐hosting electrodes, the battery employing a p‐type organic cathode is also a dual‐ion battery (DIB), since both the anions and cations are the charge carriers in this battery. [ 7,8 ] Many small organic molecules and polymers have been developed as p‐type cathodes for DIBs, which mainly include conductive polymers, [ 9–11 ] radical polymers, [ 12–14 ] and polycyclic aromatic hydrocarbons. [ 15–18 ] Despite these p‐type cathodes displayed the advantage of high working voltage, most of them exhibited low charge‐storage capacity, which restricts to achieve high energy density for DIBs.…”