Three‐Dimensional Anionic Cyclodextrin‐Based Covalent Organic Frameworks

Abstract

Three-dimensional covalent organic frameworks (3D COFs) are promising crystalline materials with well-defined structures, high porosity, and low density; however, the limited choice of building blocks and synthetic difficulties have hampered their development. Herein, we used a flexible and aliphatic macrocycle, namely γ-cyclodextrin (γ-CD), as the soft struts for the construction of a polymeric and periodic 3D extended network, with the units joined via tetrakis(spiroborate) tetrahedra with various counterions. The inclusion of pliable moieties in the robust open framework endows these CD-COFs with dynamic features, leading to a prominent Li ion conductivity of up to 2.7 mS cm at 30 °C and excellent long-term Li ion stripping/plating stability. Exchanging the counterions within the pores can effectively modulate the interactions between the CD-COF and CO molecules.

Defective 2D Covalent Organic Frameworks for Postfunctionalization

“…The activation energy ( E a ) of these COF‐based electrolytes were calculated by the linear Arrhenius plots with the values of 1.08, 0.81, 0.67, 0.49, 0.41, and 0.28 eV for TPB‐DHTP‐COF@Li, dCOF‐NH 2 ‐60@Li, dCOF‐ImBr‐60, dCOF‐ImTFSI‐20, dCOF‐ImTFSI‐40@Li, and dCOF‐ImTFSI‐60@Li, respectively (Figure b). The relatively lower E a value of dCOF‐ImTFSI‐60@Li compared with other reported COF‐based solid electrolytes reveals the easier lithium‐ion motion across the channel of dCOF‐ImTFSI‐60 (Table S8, Supporting Information) . To reveal the Li‐ion migration behaviors of dCOF based materials, density functional theory (DFT) calculations were employed to simulate the motion in the local structure of dCOFs (Figure S15, Supporting Information).…”

“…Their tunable structures and pore sizes, high surface area values, and good thermal/chemical stabilities make them good candidates in various applications . Since the first COF was reported by Yaghi's group in 2005, numerous 2D or 3D COFs have been achieved by utilizing different kinds of building blocks via dynamic covalent chemistry principle. As reported, COFs are designed to obtain an ideal crystal as perfect as possible, which are well‐aligned arrangements and structural regularities by connected the building blocks.…”

Recent Progress of Hybrid Solid‐State Electrolytes for Lithium Batteries

“…[69] Such 3D COF with anionic framework could conduct Li + ions after incorporating Li + as the counter ion. [69] Such 3D COF with anionic framework could conduct Li + ions after incorporating Li + as the counter ion.…”

Electrochromic Poly(chalcogenoviologen)s as Anode Materials for High‐Performance Organic Radical Lithium‐Ion Batteries

“…Notably,the poly(Te-BnV) anode was able to intercalate 20 Li ions and showed higher conductivity and insolubility in the electrolyte,t hus contributing to ar eversible capacity of 502 mAh g À1 at 100 mA g À1 when the Coulombic efficiency approached 100 %. [12] As ap romising emerging technology for energy storage, [13] ORBs have shown several advantages as compared to previously reported inorganic [14] and polymeric materials, [15] such as no need for rare metals,r eady tunability of redox properties,g reater safety,a nd design flexibility at the molecular level, but the development of such batteries has still been limited. [5] Owing to their synthetic versatility and the ready tunability of their redox properties, [6] the development of viologen-based energy-storage devices has increased dramatically over the past decades.…”

“…[7] Theexcellent redox properties and unique radical states of viologens make them exceptional electrode candidates for an ew generation of energy-storage devices,s uch as inorganic/organic Li/Na/ Mg ion batteries, [8] aqueous organic redox flow batteries, [9] organic radical batteries, [10] lithium-oxygen batteries, [11] and others. [12] As ap romising emerging technology for energy storage, [13] ORBs have shown several advantages as compared to previously reported inorganic [14] and polymeric materials, [15] such as no need for rare metals,r eady tunability of redox properties,g reater safety,a nd design flexibility at the molecular level, but the development of such batteries has still been limited. [16] Reported ORBs suffered from poor performance,f or example,l ow cell capacity and stability, owing to fewer redox states and low specific energy.T herefore,t he development of novel viologen derivatives with multiple stable redox centers and higher specific energy could dramatically enhance the performance and expand the limits of ORBs.…”