RESUMO
Although covalent organic frameworks (COFs) with a graphene-like structure present unique chemical and physical properties, they are essentially insoluble and infusible crystalline powders with poor processability, hindering their further practical applications. How to improve the processability of COF materials is a major challenge in this field. In this contribution, we proposed a general side-chain engineering strategy to construct a gel-state COF with high processability. This method takes advantages of large and soft branched alkyl side chains as internal plasticizers to achieve the gelation of the COF. We systematically studied the influence of the length of the side chain on the COF gel formation. Benefitting from their machinability and flexibility, this novel COF gel can be easily processed into gel-type electrolytes with specific shape and thickness, which were further applied to assemble lithium-ion batteries that exhibited high cycling stability.
RESUMO
Proton-conducting materials are key components for constructing high-energy-density electronic devices. In this work, by accumulating NH4Br into the nanospace of the classical metal organic framework MIL-101-Cr, a proton conductivity as high as 1.53 × 10-1 S cm-1 was achieved at 363 K and 100% RH. The proton conduction of NH4Br@MIL-101-Cr was also high even at lower relative humidity; for instance, it was â¼10-2 S cm-1 at 75% RH. The activation energy was calculated to be 0.11 eV for NH4Br@MIL-101-Cr, indicative of tight H-bond networks and a low barrier to proton transfer, and confirming the occurrence of pure proton conduction as well.
RESUMO
An anhydrous proton conductor represents a key material for the manufacture of high-energy electrical devices. Incorporation of proton carriers into the vacancies of the porous solid provides an effective method for their preparation, but the weak or even no interactions between the ion carriers and the porous solids causing a serious leaking of ion carriers result in trade-off of long-term conductivity. In this term, we developed a host-guest supramolecular chemistry-induced strategy to assemble hydrogen bond networks along the 1D nanochannels of covalent organic frameworks (COFs) for ultrafast and anhydrous proton transfer (1.33 × 10-2 S cm-1 at 140 °C). Solid-state NMR was applied to explore guest interaction between protic ionic liquids (PILs) and the COFs to investigate the proton transport mechanism. This work presents an excellent example of accumulation of PILs into the nanochannels of COFs for anhydrous proton conduction at high temperature, demonstrating great advantages of COFs to serve as a supramolecular host for holding/transiting ions in the solid state.
RESUMO
Introducing nonvolatile liquid acids into porous solids is a promising solution to construct anhydrous proton-conducting electrolytes, but due to weak coordination or covalent bonds building these solids, they often suffer from structural instability in acidic environments. Herein, we report a series of steady conjugated microporous polymers (CMPs) linked by robust alkynyl bonds and functionalized with perfluoroalkyl groups and incorporate them with phosphoric acid. The resulting composite electrolyte exhibits high anhydrous proton conductivity at 30-120 °C (up to 4.39 × 10-3 S cm-1), and the activation energy is less than 0.4 eV. The excellent proton conductivity is attributed to the hydrophobic pores that provide nanospace for continuous proton transport, and the hydrogen bonding between phosphoric acid and perfluoroalkyl chains of CMPs promotes short-distance proton hopping from one side to the other.
