Covalent organic frameworks and their composites for rechargeable batteries

Covalent organic frameworks (COFs), characterized by well-ordered pores, large specific surface area, good stability, high precision, and flexible design, are a promising material for batteries and have received extensive attention from researchers in recent years. Compared with inorganic materials, COFs can construct elastic frameworks with better structural stability, and their chemical compositions and structures can be precisely adjusted and functionalized at the molecular level, providing an open pathway for the convenient transfer of ions. In this review, the energy storage mechanism and unique superiority of COFs and COF composites as electrodes, separators and electrolytes for rechargeable batteries are discussed in detail. Special emphasis is placed on the relationship between the establishment of COF structures and their electrochemical performance in different batteries. Finally, this review summarizes the challenges and prospects of COFs and COF composites in battery equipment.

Organosulfur Materials for Rechargeable Batteries: Structure, Mechanism, and Application

Lithium-ion batteries have received significant attention over the last decades due to the wide application of portable electronics and increasing deployment of electric vehicles. In order to further enhance the performance of the batteries and overcome the capacity limitations of inorganic electrode materials, it is imperative to explore new cathode and functional materials for rechargeable lithium batteries. Organosulfur materials containing sulfur-sulfur bonds as a kind of promising organic electrode materials have the advantages of high capacities, abundant resources, tunable structures, and environmental benignity. In addition, organosulfur materials have been widely used in almost every aspect of rechargeable batteries because of their multiple functionalities. This review aims to provide a comprehensive overview on the development of organosulfur materials including the synthesis and application as cathode materials, electrolyte additives, electrolytes, binders, active materials in lithium redox flow batteries, and other metal battery systems. We also give an in-depth analysis of structure-property-performance relationship of organosulfur materials, and guidance for the future development of organosulfur materials for next generation rechargeable lithium batteries and beyond.

Recent Advancements in Selenium-Based Cathode Materials for Lithium Batteries: A Mini-Review

Selenium (Se)-based cathode materials have garnered considerable interest for lithium-ion batteries due to their numerous advantages, including low cost, high volumetric capacity (3268 mAh cm−3), high density (4.82 g cm−3), ability to be cycled to high voltage (4.2 V) without failure, and environmental friendliness. However, they have low electrical conductivity, low coulombic efficiency, and polyselenide solubility in electrolytes (shuttle effect). These factors have an adverse effect on the electrochemical performance of Li-Se batteries, rendering them unsuitable for real-world use. In this study, we briefly examined numerous approaches to overcoming these obstacles, including selecting an adequate electrolyte, the composition of Se with carbonaceous materials, and the usage of metal selenide base electrodes. Furthermore, we examined the effect of introducing interlayers between the cathode and the separator. Finally, the remaining hurdles and potential study prospects in this expanding field are proposed to inspire further insightful work.

Novel SeS2-loaded Co MOF with Au@PANI comprised electroanalytical molecularly imprinted polymer-based disposable sensor for patulin mycotoxin

An SeS₂-loaded Co MOF and Au@PANI nanocomposite comprising the base matrix of the electrode was developed with electropolymerized molecularly imprinted polymer (MIP) consisting of p-aminobenzoic acid (PABA) and patulin (PT) to detect PT molecules based on the PT imprinted cavities. SeS₂@Co MOF and Au@PANI were synthesized using hydrothermal synthesis and interfacial polymerization strategies, respectively. A suitable functional monomer to fabricate the MIP platform was selected using the density functional theory (DFT/M06-2X method). Higher electrochemical active surface area (0.985 cm² which is 6.99 times higher than the bare SPE) and a lower charge transfer resistance (R_ct = 27.8 Ω) at the MIP/Au@PANI/SeS₂@Co MOF electrode was achieved based on the higher number of adsorptive sites and enhanced conductivity (electron transfer rate constant (k_s = 3.24 × 10^-3 s^-1) of the sensing platform. The fabricated MIP sensor performance was studied in 10 mM PBS (pH = 6.4), where an improved detection limit (0.66 pM) for PT and a broad logarithmic linear dynamic range (0.001-100 nM) were both observed. The sensor possessed higher selectivity (Imprinting factor = 15.4 for PT), excellent reusability (%RSD of 10 cycles = 2.49%), high storage stability (6.7% lost after 35 days), and robust reproducibility (%RSD = 3.22%) The as-prepared MIP-based PT sensor was applied to detect PT in a real-time apple juice sample (10% diluted with PBS) with a recovery % ranging from 94.5 to 106.4%. The proposed sensor possesses great advantages in terms of cost-effectiveness, providing a simple detection strategy for long-term storage stability, and reversible cycle measurements.

State-Of-The-Art and Future Challenges in High Energy Lithium-Selenium Batteries

Li-chalcogen batteries, especially the Li-S batteries (LSBs), have received paramount interests as next generation energy storage techniques because of their high theoretical energy densities. However, the associated challenges need to be overcome prior to their commercialization. Elemental selenium, another chalcogen member, would be an attractive alternative to sulfur owing to its higher electronic conductivity, comparable capacity density, and moreover, excellent compatibility with carbonate electrolytes. Unlike LSBs, the research and development of Li-Se batteries (LSeBs) have garnered burgeoning attention but are still in their infant stage, where a comprehensive yet in-depth overview is highly imperative to guide future research. Herein, a critical review of LSeBs, in terms of the underlying mechanisms, cathode design, blocking layer engineering, and emerging solid-state electrolytes is provided. First, the electrolyte-dependent electrochemistry of LSeBs is discussed. Second, the advances in Se-based cathodes are comprehensively summarized, especially highlighting the state-of-the-art Se_x S_y cathodes, and mainly focusing on their structures, compositions, and synthetic strategies. Third, the versatile separators/interlayers optimization and interface regulation are outlined, with a particular focus on the emerging solid-state electrolytes for advanced LSeBs. Last, the remaining challenges and research orientations in this booming field are proposed, which are expected to motivate more insightful works.

Covalent organic frameworks: an ideal platform for designing ordered materials and advanced applications

Covalent organic frameworks offer a molecular platform for integrating organic units into periodically ordered yet extended 2D and 3D polymers to create topologically well-defined polygonal lattices and built-in discrete micropores and/or mesopores.

Microwave-Assisted Solvothermal Synthesis of Covalent Organic Frameworks (COFs) with Stable Superhydrophobicity for Oil/Water Separation

COFs were synthesized by a microwave-assisted solvothermal route, with the building blocks containing 1,3,5-tris(4-aminophenyl) benzene and 2,3,5,6-tetra-fluoroterephthalaldehyde (or 1,4-phthalaldehyde). The -F groups introduced into the benzene ring promoted hydrophobicity and stability of the COFs. The universality and long effectiveness of oil adsorption can be realized when applying COFs as adsorbent. The powder also exhibited excellent water-in-oil emulsions separation performance, with the separation efficiency no lower than 99.5%. In this work, the use of microwave solvothermal synthesis of superhydrophobic COFs is potential to replace the conventional synthesis process and more suitable for industrial scale-up production. Furthermore, the findings provide a new strategy for solving the problem of oil spill treatment and industrial water-in-oil emulsions separation by using the emerging 2D COFs.

Bulk COFs and COF nanosheets for electrochemical energy storage and conversion

The current advances, structure-property relationship and future perspectives in covalent organic frameworks (COFs) and their nanosheets for electrochemical energy storage (EES) and conversion (EEC) are summarized.