Metal-free organic electrode materials have attracted vast research attention owing to their designable structures and tunable electrochemical properties. Although n-type cathode materials could be used in various metal-ion batteries, p-type ones with high potential can deliver high energy density. Herein, we report a new p-type polymeric cathode material, poly(2vinyl-5,10-dimethyl-dihydrophenazine) (PVDMP), with a theoretical capacity of 227 mAh g À 1 . PVDMP featuring two-step redox reaction will be doped by two anions to maintain electroneutrality during oxidation, which resulted in an anion-dependent electrochemical behavior of PVDMP-based cathode. The suitable dopant anion for PVDMP was selected and the doping mechanism was confirmed. Under the optimized condition, PVDMP cathode can deliver a high initial capacity of 220 mAh g À 1 at 5 C and even remains 150 mAh g À 1 after 3900 cycles. This work not only provides a new kind of p-type organic cathode materials but also deepens the understanding of its anion-dependent redox chemistry.
Redox-active ionic polymers show low solubility in organic electrolytes and high ionic/electronic conductivity, but most of them coupling with non-active counter ions present low specific capacity. Herein, we design polyviologens...
Covalent organic frameworks (COFs) have emerged as a new class of cathode materials for energy storage in recent years. However, they are limited to two‐dimensional (2D) or three‐dimensional (3D) framework structures. Herein, this work reports designed synthesis of a redox‐active one‐dimensional (1D) COF and its composites with 1D carbon nanotubes (CNTs) via in situ growth. Used as cathode materials for Li‐ion batteries, the 1D COF@CNT composites with unique dendritic core–shell structure can provide abundant and easily accessible redox‐active sites, which contribute to improve diffusion rate of lithium ions and the corresponding specific capacity. This synergistic structural design enables excellent electrochemical performance of the cathodes, giving rise to 95% utilization of redox‐active sites, high rate capability (81% capacity retention at 10 C), and long cycling stability (86% retention after 600 cycles at 5 C). As the first example to explore the application of 1D COFs in the field of energy storage, this study demonstrates the great potential of this novel type of linear crystalline porous polymers in battery technologies.
Metal‐free organic electrode materials have attracted vast research attention owing to their designable structures and tunable electrochemical properties. Although n‐type cathode materials could be used in various metal‐ion batteries, p‐type ones with high potential can deliver high energy density. Herein, we report a new p‐type polymeric cathode material, poly(2‐vinyl‐5,10‐dimethyl‐dihydrophenazine) (PVDMP), with a theoretical capacity of 227 mAh g−1. PVDMP featuring two‐step redox reaction will be doped by two anions to maintain electroneutrality during oxidation, which resulted in an anion‐dependent electrochemical behavior of PVDMP‐based cathode. The suitable dopant anion for PVDMP was selected and the doping mechanism was confirmed. Under the optimized condition, PVDMP cathode can deliver a high initial capacity of 220 mAh g−1 at 5 C and even remains 150 mAh g−1 after 3900 cycles. This work not only provides a new kind of p‐type organic cathode materials but also deepens the understanding of its anion‐dependent redox chemistry.
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