Tuning the Chemistry of Organonitrogen Compounds for Promoting All‐Organic Anionic Rechargeable Batteries

Ion Co-storage in Porous Organic Frameworks through On-site Coulomb Interactions for High Energy and Power Density Batteries

Fast and continuous ion insertion is blocked in the common electrodes operating with widely accepted single-ion storage mechanism, primarily due to Coulomb repulsion between the same ions. It results in an irreconcilable conflict between capacity and rate performance. Herein, we designed a porous organic framework with novel multiple-ion co-storage modes, including PF₆ ^- /Li⁺ , OTF^- /Mg²⁺ , and OTF^- /Zn²⁺ co-storage. The Coulomb interactions between cationic and anionic carriers in the framework can significantly promote electrode kinetics, by rejuvenating fast ion carrier migration toward framework interior. Consequently, the framework via PF₆ ^- /Li⁺ co-storage mode shows a high energy density of 878 Wh kg^-1 cycled more than 20 000 cycles, with an excellent power density of 28 kW kg^-1 that is already comparable to commercial supercapacitors. The both greatly improved energy and power densities via the co-storage mode may pave a way for exploring new electrodes that are not available from common single-ion electrodes.

Conjugated and Non-conjugated Polymers Containing Two-Electron Redox Dihydrophenazines for Lithium-Organic Batteries

Organic p-type cathode materials have recently attracted increasing attention due to their higher redox potentials and rate capabilities in comparison to n-type cathodes. However, most of the p-type cathodes based on one-electron redox still suffer from limited stability and low specific capacity (<150 mAh g^-1 ). Herein, two polymers, conjugated poly(diethyldihydrophenazine vinylene) (CPP) and non-conjugated poly(diethyldihydrophenazine ethylidene) (NCPP) containing two-electron redox dihydrophenazine, have been developed as p-type cathode materials. It is experimentally and theoretically found that the conjugated linkage among the redox centers in polymer CPP is more favorable for the effective charge delocalization on the conjugated polymer backbone and the sufficient oxidation in the higher potential region (3.3-4.2 V vs. Li/Li⁺ ). Consequently, the CPP cathode displays a higher reversible specific capacity of 184 mAh g^-1 with excellent cycling stability.

Dual Electroactivity in a Covalent Organic Network with Mechanically Interlocked Pillar[5]arenes

The synthesis and characterization of a polyrotaxanated covalent organic network (CON) based on the association between the viologen and pillar[5]arene (P[5]OH) units are reported. The mechanical bond allows for the irreversible insertion of n-type redox centers (P[5]OH macrocycles) within a pristine structure based on p-type viologen redox centers. Both redox units are active on a narrow potential range and, in water, the presence of P[5]OH greatly increases the electroactivity of the material.

Reversible Anion Insertion in Molecular Phenothiazine-Based Redox-Active Positive Material for Organic Ion Batteries

The increasing demand for rechargeable batteries induces the development of greener and better devices. Significant advances have been made in the last decade together with a renewed interest in organic electrode materials. Thus, stable electron-donating organic materials are candidates for "greener" molecular batteries (metal-free). Herein, we report the design of a monomeric p-type N-substituted phenothiazine salt as an efficient anionic host structure working reversibly in a dual-ion cell configuration using lithium as the negative electrode. Investigation of different electrolyte salts, LiClO₄ , LiPF₆ , and LiTFSI in PC (propylene carbonate), reveals that lithium 4-(10H-phenothiazin-10-yl) benzoate (LiPHB) exhibits a high operating potential (≈3.7 vs. Li⁺ /Li) corresponding to a one-electron process with a reversible specific capacity of 86 mAh g^-1 in a LiClO₄ -based electrolyte, exhibiting an extraordinary cycling stability over 500 cycles at 0.2 C. Such impressive results are rendering LiPHB a promising scaffold for developing next-generation molecular organic batteries.

Pairing Cross-Linked Polyviologen with Aromatic Amine Host Structure for Anion Shuttle Rechargeable Batteries

Electroactive organic compounds could bring new chemical opportunities to further improve existing electrochemical energy-storage technologies as they can be prepared from less-limited resources and potentially at low environmental footprint. Among the current explored research fields, the anion-ion cell configuration appears poorly investigated although quite promising to promote the fabrication of molecular (metal-free) rechargeable batteries. Herein, we report the synthesis and the electrochemical behavior of both Mg/Li salts of 2,5-(dianilino)terephthalate (MgDAnT and Li₂ DAnT) and cross-linked polyviologen (c-PV²⁺ ) that can reversibly uptake/extract anions at different working potentials, enabling the assembly of full anionic organic batteries. The reversible anion ingress in MgDAnT is however accompanied by solvent co-insertion from the electrolyte that provokes an overpotential effect during the first charge. Full anionic batteries pairing Li₂ DAnT with c-PV²⁺ were assembled giving rise to 0.7 V as output voltage with a specific capacity of 50 mAh per gram of Li₂ DAnT.