Electrochemical energy storage devices with a high energy density are an important technology in modern society, especially for electric vehicles. The most effective approach to improve the energy ...density of batteries is to search for high‐capacity electrode materials. According to the concept of energy quality, a high‐voltage battery delivers a highly useful energy, thus providing a new insight to improve energy density. Based on this concept, a novel and successful strategy to increase the energy density and energy quality by increasing the discharge voltage of cathode materials and preserving high capacity is proposed. The proposal is realized in high‐capacity Li‐rich cathode materials. The average discharge voltage is increased from 3.5 to 3.8 V by increasing the nickel content and applying a simple after‐treatment, and the specific energy is improved from 912 to 1033 Wh kg−1. The current work provides an insightful universal principle for developing, designing, and screening electrode materials for high energy density and energy quality.
Li‐ion batteries with high energy quality require a high capacity coupled with high operating voltage. This requires the electrode materials to not only have a high specific capacity but also a high discharge voltage for cathode materials and low charge voltage for anode materials.
Forced obedience: Layer‐structured montmorillonite (MMT) was used as a nanoreactor for the generation of planar pyridinic and pyrrolic N sites in nitrogen‐doped graphene (NG; see picture). The ...selectivity for the formation of planar N sites was inversely proportional to the interspace width (δ) of the MMT and reached a maximum of 90.27 %. The NG catalyst exhibited low electrical resistance, high electrocatalytic activity, and good stability.
Two‐dimensional (2D) nanomaterials, such as graphene and transition metal chalcogenides, show many interesting dimension‐related materials properties. Inspired by the development of 2D inorganic ...nanomaterials, single‐layered covalent organic frameworks (sCOFs), featuring atom‐thick sheets and crystalline extended organic structures with covalently bonded building blocks, have attracted great attention in recent years. With their unique graphene‐like topological structure and the merit of structural diversity, sCOFs promise to possess novel and designable properties. However, the synthesis of sCOFs with well‐defined structures remains a great challenge. Herein, the recent development of the bottom‐up synthesis methods of 2D sCOFs, such as thermodynamic equilibrium control methods, growth‐kinetics control methods, and surface‐assisted covalent polymerization methods, are reviewed. Finally, some of the critical properties and application prospects of these materials are outlined.
Single‐layered covalent organic frameworks (sCOFs), mimicking the topology of graphene, but incorporating chemical functionality into their backbones, are pursued as potential candidates in nanoelectronics. Several representative synthesis strategies for the synthesis of high‐quality graphene‐like sCOFs with extended order are reviewed and the application prospects of sCOFs are outlined.
The confined synthesis of two-dimensional covalent organic framework (2D COF) thin films was developed by using thin superspreading water on the hydrogel immersed under oil as reactor. Through ...loading two monomers into oil and hydrogel, respectively, COF thin films are synthesized at the oil/water/hydrogel interface. This strategy provides a new way for synthesis of freestanding 2D COF thin films. Detailed characterizations of the COF thin films reveal homogeneous topography, large area, controllable thickness from 4 to 150 nm, and crystallinity with certain orientation. Young’s modulus of COF film is measured by AFM indentation as 25.9 ± 0.6 GPa, showing good mechanical properties. On the basis of the freestanding COF films, a nanofilter membrane and photoelectrochemical sensors for Ru3+ were successfully developed. Moreover, the strategy was extended to the synthesis of crystalline zeolitic imidazolate framework-8 thin film, which exhibited high application potential.
A Kagome structure covalent organic framework (COF) film with three‐state NIR electrochromic properties was designed and synthesized. The COFTPDA‐PDA film is composed of hexagonal nanosheets with ...high crystallinity and has three reversible color states at different applied potentials. It has high absorption spectra changes in the NIR region, ascribed to the strong intervalence charge transfer (IVCT) interaction of the Class III mixed‐valence systems of the conjugated triphenylamine species. The film showed sub‐second response time (1.3 s for coloring and 0.7 s for bleaching at 1050 nm) and long retention time in the NIR region. COFTPDA‐PDA film shows superior NIR electrochromic properties in term of response time and stability, attributed to the highly ordered porous structure and the π–π stacking structure of the COFTPDA‐PDA architecture. The COFTPDA‐PDA film was applied in mimicking a flip‐flop logic gate with optical memory function.
A Kagome structure covalent organic framework (COF) film was synthesized and exhibited three‐state electrochromic properties with sub‐second response time and long retention time in the near‐infrared region. Taking potential and absorbance as input and output signal, respectively, a mimicking logic gate with optical memory functions was demonstrated based on the COFTPDA‐PDA film.
The prognostic role of inflammation index like neutrophil‐to‐lymphocyte ratio (NLR) in colorectal cancer (CRC) remains controversial. We conduct a meta‐analysis to determine the predictable value of ...NLR in the clinical outcome of CRC patients. The analysis was carried out based on the data from 16 studies (19 cohorts) to evaluate the association between NLR and overall survival (OS) and progression‐free survival (PFS) in patients with CRC. In addition, the relationship between NLR and clinicopathological parameters was assessed. Hazard ratio (HR) or odds ratio (OR) with its 95% confidence interval (CI) was used as the effect size estimate. Our analysis results indicated that elevated pretreatment NLR predicted poorer OS (HR: 1.813, 95% CI: 1.499–2.193) and PFS (HR: 2.102, 95% CI: 1.554–2.843) in patients with CRC. Increased NLR is also significantly associated with the poorer differentiation of the tumor (OR: 1.574, 95% CI: 1.226–2.022) and higher carcino‐embryonie antigen (CEA) level (OR: 1.493, 95% CI: 1.308–1.705). By these results, we conclude that NLR gains a prognostic value for patients with CRC. NLR should be monitored in CRC patients for rational stratification of the patients and adjusting the treatment strategy.
What's new?
Although correlated with the severity of disease course, the impact of neutrophil‐to‐lymphocyte ratio (NLR) on survival and tumor characteristics in cancer patients remains unclear. In the meta‐analysis presented here, elevated pre‐treatment NLR was found to predict poor overall survival in patients with colorectal cancer. NLR was also associated with unfavorable biologic behavior in colorectal cancer. The findings suggest that NLR, as an inexpensive and widely available index, should be routinely monitored in colorectal cancer patients.
A hybrid solid/liquid electrolyte with superior security facilitates the implementation of high‐energy‐density storage devices, but it suffers from inferior chemical compatibility with cathodes. ...Herein, an optimal lithium difluoro(oxalato)borate salt was introduced to build in situ an amorphous cathode electrolyte interphase (CEI) between Ni‐rich cathodes and hybrid electrolyte. The CEI preserves the surface structure with high compatibility, leading to enhanced interfacial stability. Meanwhile, the space‐charge layer can be prominently mitigated at the solid/solid interface via harmonized chemical potentials, acquiring promoted interfacial dynamics as revealed by COMSOL simulation. Consequently, the amorphous CEI integrates the bifunctionality to provide an excellent cycling stability, high Coulombic efficiency, and favorable rate capability in high‐voltage Li‐metal batteries, innovating the design philosophy of functional CEI strategy for future high‐energy‐density batteries.
The CEI's advantage: An amorphous cathode electrolyte interphase (CEI) with superior chemical compatibility and plasticity was formed via in situ LiDFOB conversion. It endows high‐voltage hybrid solid/liquid batteries with significantly enhanced interfacial stability, durability, and dynamics.
The electrochromic property and device construction of a triphenylamine-based oriented two-dimensional covalent organic framework (2D COF) film on indium tin oxide (ITO) coated glass was reported. ...The characterization of the 2D COF3PA‑TT film revealed that the film was uniform, with good crystallinity, and oriented with its 2D plane parallel to the substrate. For the first time, the electrochromic properties of 2D COF3PA‑TT film were studied. 2D COF3PA‑TT film on ITO exhibited reversible color transition between deep red and dark brown during redox process. Spectroelectrochemical experiments revealed color changes in the absorption spectra of 2D COF3PA‑TT film in the visible and near-infrared regions and showed the characteristics of intervalence charge transfer. The quasi-solid-state electrochromic device was prepared based on the COF3PA‑TT film, and it exhibited moderate performance and stability in the near-infrared region.
Single‐atom catalysts (SACs) with specific coordination environment are expected to be efficient electrocatalysts for oxygen reduction reaction (ORR). Herein, NiN4C10 coordination site is ...constructed through encapsulating Ni2+ into the cavity of ZIF‐8 as a self‐sacrificing precursor and anchoring it on 3D N‐doped carbon frameworks. The NiN4C10 catalyst shows excellent ORR activity and stability, with a high half‐wave potential (0.938 V vs RHE), which is currently the best performances in Ni‐based SACs. The remarkable performance with high ORR activity in alkaline solution is attributed to the single‐atom nickel active sites with faster electron transport and suitable electronic structure. Moreover, the power density of zinc‐air battery assembled by NiN4C10 as cathode is 47.1% higher than that of the commercial Pt/C. This work not only provides a facile method to prepare extremely active Ni‐based SACs, but also studies the intrinsic mechanism toward the oxygen reduction reaction under alkaline condition.
The NiN4C10 coordination site is constructed through encapsulating Ni2+ into the cavity of ZIF‐8 as a self‐sacrificing precursor and anchoring it on 3D N‐doped carbon frameworks. The NiN4C10 catalyst shows excellent oxygen reduction reaction activity and stability, with a high half‐wave potential (0.938 V vs RHE), which is currently the best performances in Ni‐based single‐atom catalysts.
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