Conjugated polymeric molecules have been heralded as promising electrode materials for the next-generation energy-storage technologies owing to their chemical flexibility at the molecular level, environmental benefit, and cost advantage. However, before any practical implementation takes place, the low capacity, poor structural stability, and sluggish ion/electron diffusion kinetics remain the obstacles that have to be overcome. Here, we report the synthesis of a few-layered two-dimensional covalent organic framework trapped by carbon nanotubes as the anode of lithium-ion batteries. Remarkably, upon activation, this organic electrode delivers a large reversible capacity of 1536 mAh g −1 and can sustain 500 cycles at 100 mA g −1 . Aided by theoretical calculations and electrochemical probing of the electrochemical behavior at different stages of cycling, the storage mechanism is revealed to be governed by 14-electron redox chemistry for a covalent organic framework monomer with one lithium ion per C=N group and six lithium ions per benzene ring. This work may pave the way to the development of high-capacity electrodes for organic rechargeable batteries.

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units, SBUs) and coordinated organic ligands via the more flexible coordination bonds, which results in the controllable morphology and pore characteristic. [1f,g] Induced by these structural merits, COF and MOF have been widely applied in gas storage/separation, catalysis, and photoelectric conversion, and even the field of energy storage including Li-ion batteries, supercapacitors, and hydrogen storage. [2] In order to effectively combine the merits of COF and MOF and acquire the maximized performances, there are few recent reports regarding the hybridization of COF and MOF. [3] By introducing the as-prepared MOF into the synthetic process of COF, MOF@COF core-shell [3a,b] or MOF-coated COF [3c] hybrids were obtained. All these hybrids have been demonstrated with excellent photocatalytic performances as the effective photocatalysts/photocatalysis platforms for degradation of rhodamine B, [3a] dehydrogenation of ammonia borane, [3b] and H 2 evolution, [3c] respectively. This kind of approach (introducing the as-prepared MOF into the synthetic process of COF) would result in the comparatively simple combination of COF and MOF with core-shell or coating composite mode (no principal morphology change), and the molecular-level interlinked hybridization between COF and MOF remains unexplored.For the purpose of property optimization, intimate hybridization between two components is highly desirable, which may lead to further morphology adjustment, and consequent performance improvement. Considering the fact that organic groups from COF may also coordinate with metal ions of MOF, we design a COF/Mn-MOF hybrid structure with flower-like morphology, which is different from pristine COF or Mn-MOF. A strong synergistic effect relative to new active sites from MOF and COF for lithium storage is observed in the composite. Hollow or coreshell microspheres of MnS@N/S codoped carbon can also be derived with superior electrochemical properties.The COF/Mn-MOF composite with benchmarked pristine COF or Mn-MOF ( Figure S1a,b, Supporting Information) was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman and 13 C nuclear magnetism measurements in Figure S2a-d (Supporting Information). All characteristic diffraction peaks for Mn-MOF [4] can be detected for COF/ Mn-MOF with clear shift to small angle for its two main peaks (2θ ≈ 10.5° and ≈21.7°), which is probably originated from the Covalent organic frameworks (COF) or metal-organic frameworks have attracted significant attention for various applications due to their intriguing tunable micro/mesopores and composition/functionality control. Herein, a coordination-induced interlinked hybrid of imine-based covalent organic frameworks and Mn-based metal-organic frameworks (COF/Mn-MOF) based on the MnN bond is reported. The effective molecular-level coordinationinduced compositing of COF and MOF endows the hybrid with unique flower-like microsphere morphology and superior lithium-storage performances that originate from activated Mn centers an...

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