Exfoliation of Covalent Organic Frameworks into Few-Layer Redox-Active Nanosheets as Cathode Materials for Lithium-Ion Batteries

Abstract

Covalent organic frameworks (COFs) have attracted growing interest by virtue of their structural diversity and tunability. Herein, we present a novel approach for the development of organic rechargeable battery cathodes in which three distinct redox-active COFs were successfully prepared and delaminated into 2D few-layer nanosheets. Compared with the pristine COFs, the exfoliated COFs with shorter Li diffusion pathways allow a significant higher utilization efficiency of redox sites and faster kinetics for lithium storage. Unlike diffusion-controlled manners in the bulk COFs, the redox reactions in ECOFs are mainly dominated by charge transfer process. The capacity and potential are further engineered by reticular design of COFs without altering the underlying topology. Specifically, DAAQ-ECOF exhibits excellent rechargeability (98% capacity retention after 1800 cycles) and fast charge-discharge ability (74% retention at 500 mA g as compared to at 20 mA g). DABQ-ECOF shows a specific capacity of 210 mA h g and a voltage plateau of 2.8 V.

New Anthraquinone‐Based Conjugated Microporous Polymer Cathode with Ultrahigh Specific Surface Area for High‐Performance Lithium‐Ion Batteries

“…These unique structural properties are not available in other porous materials, which are typically not π-conjugated, or conventional conjugated polymers, which are nonporous. [35][36][37][38][39] Enhancement in the following electrochemical properties over common RAPs are anticipated: i) fast charge transport in the preorganized pathways including both eclipsed stacked π columns and π-conjugated intralayer skeletons, ii) the porous structure of the RCMPs serving as electrolyte reservoir iii) open channels at the nanoscale providing facile, rapid, and short diffusion paths for ion mobility, and iv) the shape-persistent polymeric nature of RCMPs guaranteeing high (electro)chemical stabilities and inhibiting the potential dissolution of the electrode materials. [34] Due to their appealing properties, the application of redoxactive COFs and redox-active conjugated microporous polymers (RCMPs), which are synthesized by incorporation of redox-active building blocks, in electrochemical energy storage is becoming a fast growing field, although still in its infancy compared to conventional linear RAPs.…”

Recent Advances in Covalent Organic Frameworks for Catalysis

“…[51][52][53][54] Besides, the versatile and controllable networks can be functionalizedt oi ntroduce catalytic sites for furtheru se as catalytic materials. [51][52][53][54] Besides, the versatile and controllable networks can be functionalizedt oi ntroduce catalytic sites for furtheru se as catalytic materials.…”

Kovalente organische Netzwerke und Käfigverbindungen: Design und Anwendungen von polymeren und diskreten organischen Gerüsten

“…[354] Durch postsynthetische Modifikation erhielten Xu et al zwei [TEMPO] x -NiP-COFs mit x = 50 und 100 %B eladung durch redoxaktive 2,2,6,6-Te tramethylpiperidinyloxyl(TEMPO)-Einheiten sowie Kapazitäten von bis zu 150 Fg À1 . [356] Ionische COFs zeigten effizienten Li + -Tr ansport, [89] und konjugierte COFs wurden sowohl als Ka-thoden- [357] wie auch als Anodenmaterial [358] in Li + -Batterien eingesetzt. [356] Ionische COFs zeigten effizienten Li + -Tr ansport, [89] und konjugierte COFs wurden sowohl als Ka-thoden- [357] wie auch als Anodenmaterial [358] in Li + -Batterien eingesetzt.…”