Optimization of electrolyte with enhanced energy density and durability in battery system is highly demanded yet challenging owing to the high ion transport resistance and complex by-reactions in electrolyte. In this work, we tailored the solid-liquid phase transport interface by adding covalent organic frameworks quantum dots (COFs QDs) into electrolyte. COFs QDs with abundant lipophilic ether-oxygen groups and similar to 12 nm nano-size can serve as myriad ion-transport nano-engines for constantly replenishing the interface with Li+ to achieve near-frictionless ion transport (t(Li)(+) = 0.98) and exceptional stability (>400 days). Lithium-sulfur battery based on COFs QDs shows high discharge specific capacity of 1063.7 mAh g(-1) after 100 cycles at 0.2 C and maintains a low overpotential (similar to 16 mV) over 4000 h at 1 mA cm(-2) with 1 mAh cm(-2) in Li//Li symmetric battery. A Li-S pouch battery has also been successfully assembled to validate the practicality. Our results may promote the development of COFs QDs in energy storage field.

The symmetric all-organic batteries (SAOBs) based on the same organic electrode materials for both cathode and anode are promising in achieving an efficient battery system with excellent electrode compatibility, compensable volume change, full discharge ability, low preparation cost, and simple operation procedure, etc. Herein, for the first time, we have designed a kind of anhydride-based three-motif molecular junction COFs (i.e., TAT-AZO-COF) through a melt polymerization method that can serve as dual-electrode active materials for SAOBs. The prepared TAT-AZO-COF with three-motif molecular junction units, resulting from the integration of a cathode-active carbonyl group, an anode-active azo group, and a changeably bipolar-active triazin group, could provide a tunable voltage inductive effect to simultaneously meet the requirements of SAOBs. Thus-assembled SAOBs display excellent rate performance, high energy density (125 Wh kg −1 ) at 1 A g −1 and superior long-cycle property (90 mAh g −1 over 10 000 cycles) at 10 A g −1 , which is represented to be the best high-current density performance among all the organic electrode materials in dual-electrode available SAOBs. The Li + storage mechanisms of three-motif molecular junction COFs are thoroughly scrutinized by experimental and theoretical identification, and the feasibility in practical application has been validated by a successfully assembled pouch cell.

Abstract Since its initial discovery by Dahn et al. in 2002, Li 2 S has emerged as a highly promising cathode material, circumventing the employment of Li metal in battery construction. However, its practical application has been significantly constrained by several challenges, including weak interfacial interactions between electrode components, the high activation potential of Li 2 S, and the absence of suitable binders capable of effectively managing internal stress during repeated charge–discharge cycles. In this study, an anthraquinone‐based covalent organic framework (OH‐AAn‐COF) with a hollow rectangular prism morphology is introduced as a novel nano‐mediator for Li 2 S cathodes. The porous structure of the COF, enriched with functional groups, facilitates enhanced interfacial binding between electrode components, establishing robust interfacial bridges between Li 2 S/Li 2 S and Li 2 S/electrolyte. This results in more cohesive interfacial interactions, thereby reducing the activation potential of Li 2 S, promoting the adsorption and redox conversion of polysulfides, and enabling faster electrochemical reactivity and improved cycling stability compared to conventional PVDF binders. Notably, the Li 2 S@C‐OH‐AAn‐COF//graphite full cell, which operates without lithium metal, demonstrates exceptional cycling performance, achieving over 1000 cycles at 0.5C, surpassing the performances of most reported Li–S battery systems.

ConspectusRechargeable aqueous zinc-ion batteries (AZIBs) have emerged as promising energy storage systems owing to their high energy density, environmental benignity, and low cost. Nevertheless, the rough surface of the Zn metal anode can easily induce uncontrolled dendrite growth and parasitic reactions, which will limit the large-scale commercial applications of AZIBs. Owing to the diverse active sites and porous channels of covalent-organic frameworks (COFs), the exploration of COFs in this field affords a novel perspective in tackling the bottlenecks encountered through the anode of AZIBs. Based on reported works, this review summarizes the functions of COFs as nanoengines to manipulate the Zn2+ flux, hydrogen evolution, dendrite growth, and the electric field at electrode/electrolyte interface when applied as functional coatings. It also concludes the construction strategies of functional COFs coating and delves into strategies for protecting the Zn anode, with an emphasis on modulating Zn deposition dynamics and minimizing side reactions at the electrode/electrolyte interface. It further provides an evaluation of the current challenges and future expectations of AZIB, aiming to enhance their viability for grid-scale energy storage solutions.

Aqueous zinc–iodine (Zn–I 2 ) batteries are promising for large-scale energy storage. However, their practical use is hindered by challenges such as Zn dendrite growth, hydrogen evolution reaction (HER), corrosion, and polyiodide shuttle effect. In this study, valerolactam (VL) is employed as an organic pH buffer to address these issues. Theoretical and experimental results demonstrate that VL can regulate the electrolyte local pH while in situ polymerizing on the electrode surface to form a mechanically stable solid electrolyte interphase (SEI) protection layer, effectively suppressing HER, corrosion, and dendrite growth. Furthermore, the introduction of VL significantly regulates the solvation structure of Zn 2+ , and disrupts the inherent hydrogen bonding network, which enhances the electrochemical performance. As a result, a symmetric cell with VL-based electrolyte achieves impressive longevity under ultra-high current density (4000 cycles at 40 mA cm −2 and 1 mAh cm −2 ), 4.3 times higher than the counterpart in the conventional ZnSO 4 electrolytes. Moreover, VL effectively suppresses polyiodide shuttle effect and improves electrochemical stability. Consequently, Zn–I 2 full battery exhibits exceptional cycling stability, sustaining 26 500 cycles with a high-capacity retention of 86.4%. Therefore, organic pH buffering engineering has been proved to be a promising strategy for achieving dendrite-free, shuttle-free Zn–I 2 batteries.

Since its initial discovery by Dahn et al. in 2002, Li2S has emerged as a highly promising cathode material, circumventing the employment of Li metal in battery construction. However, its practical application has been significantly constrained by several challenges, including weak interfacial interactions between electrode components, the high activation potential of Li2S, and the absence of suitable binders capable of effectively managing internal stress during repeated charge-discharge cycles. In this study, an anthraquinone-based covalent organic framework (OH-AAn-COF) with a hollow rectangular prism morphology is introduced as a novel nano-mediator for Li2S cathodes. The porous structure of the COF, enriched with functional groups, facilitates enhanced interfacial binding between electrode components, establishing robust interfacial bridges between Li2S/Li2S and Li2S/electrolyte. This results in more cohesive interfacial interactions, thereby reducing the activation potential of Li2S, promoting the adsorption and redox conversion of polysulfides, and enabling faster electrochemical reactivity and improved cycling stability compared to conventional PVDF binders. Notably, the Li2S@C-OH-AAn-COF//graphite full cell, which operates without lithium metal, demonstrates exceptional cycling performance, achieving over 1000 cycles at 0.5C, surpassing the performances of most reported Li-S battery systems.

High-rate lithium-metal batteries call for unique interfacial structures of anode with interfacial compatibility, facilitated lithium insertion/extraction and dendrite suppression properties to meet the growing high-rate demand. Here, we develop an interweaved porous coating based on a kind of covalent organic framework (ODH─Cu 3 ─COF) based helical nanofibers through the assembly of non-linear oxalyldihydrazide unit and rigid Cu 3 unit. The interweaved helical nanofibers network with well-arranged polar groups (i.e., C═N, ─CO─NH─, and pyrazole groups) could serve as nuclei sites to achieve fast Li + insertion/extraction and dendrite suppression in high-rate conditions. Benefiting from the advantages of interface design, the resultant ODH─Cu 3 ─COF modified anode improves the Coulombic efficiency (97.5%, 120 cycles at 5 mA cm −2 ) and showcases a stable lifespan (1000 h at 2 mA cm −2 and 2 mAh cm −2 ) in symmetric cell. Moreover, the high-rate property of ODH─Cu 3 ─COF@Li||LFP full cell presents an excellent cycling stability (900 cycles at 5 C) in commercial carbonate electrolyte. Theoretical calculations reveal that lithiophilic ODH─Cu 3 ─COF has high Li affinity to reduce the nucleation barrier and achieve fast desolvation process in an interface to promote the lifespan of high-rate lithium-metal batteries.

Polymer interphase on Zn anodes obviates dendrite growth and significant side reactions including corrosion and hydrogen evolution in aqueous zinc ion batteries (AZIBs), however has drawbacks of slow kinetics and large overpotential for Zn plating/stripping that prevent practical application especially under high-rate conditions. Here, a multifunctional polymer interphase with fast kineticsis reported, using poly(phenazine-alt-pyromellitic anhydride) (PPPA) as an electrolyte additive. PPPA, with linear π-conjugated structure and enriched polar pyridine (conjugated cyclic −C=N−) and carbonyl (C=O) groups, preferentially adsorbs on the Zn anode to form a stable solid-electrolyte interphase (SEI) layer in situ. The PPPA SEI is efficient to block direct contact between water molecules and Zn anode, and regulate the interfacial solvation structure and Zn depostion. Importantly, the expanding π-conjugated structure of PPPA is shown to provide abundant 2D open channels for rapid Zn 2+ transport, and the delocalized π electrons form a space electrostatic field to facilitate de-solvation and diffusion of Zn 2+ . As a result, the Zn metal anode with PPPA/ZnSO 4 electrolyte exhibits high Coulombic efficiency of 98.3 % at current density of 20 mA  cm −2 , and excellent cycle lifespan for over 2000 cycles (400 h) at current density 50 mA cm −2 and plating/stripping capacity of 5 mAh cm −2 . The Zn||MnO 2 full battery exhibited a discharge capacity of 74.4 mAh g −1 after 5000 cycles at the current density of 2000 mA g −1 , demonstrating practical feasibility. It is concluded that judicious engineering of polymer additives and interphase will benefit the development of commercial AZIBs with fast kinetics for high-rate applications.

Biomacromolecules with complex structures, are important components of living things. Due to the sensitivity of biomacromolecules to various influencing factors like temperature, acid/alkali, or organic solvent, they would be easily deactivated under various related conditions during the applications. It is necessary to exploit immobilization materials for biomacromolecules to achieve low deactivation rate, high stability and advanced functions. Covalent organic frameworks (COFs) exhibit high porosity, tunable function and biocompatibility, making them to be excellent host materials for immobilizing biomacromolecules. Up to date, the related works about the immobilization of biomacromolecules by COFs have been reported continuously and some reviews have also separately summarized the loading of biomacromolecules like enzyme or nucleic acid into COFs. However, the systematic reviews about the fixation of various biomacromolecules (e.g., enzymes, proteins, peptides, and nucleic acids) in COFs to discuss their differences are still rare. A comprehensive review would be demanded to summarize their varied properties like sizes, types, or functions of biomacromolecules in interaction with COFs, as well as their synergistically integrated effects on various applications. In this review, we will systematically summarize the recent research progress about different biomacromolecule@COFs and their related applications. We will also discuss the challenges or bottlenecks faced by biomacromolecule@COFs and give perspectives of COFs in this field. We hope this review could provide new insights for scientists in this field.

Aqueous zinc-ion batteries (ZIBs) have garnered widespread interest owing to their merits of high safety and low cost. Nevertheless, the commercial application of ZIBs is hindered by uncontrollable dendrite growth and adverse side reactions. Herein, a potential spontaneous reducing and assembling strategy has been tailored to generate a uniform and ultra-thin layer of sulfonate modified Mxene (SM-MXene) layer on the Zn surface to regulate electrochemical behavior. Compared with the bare Zn foil, the optimizing SM-MXene layer has an advantageous charge redistribution effect, resulting in a uniform electric field and a lower Zn nucleation energy barrier. The SM-MXene layer can also block the entry of H2O and inhibit the severe side reactions. The zincophilic SM-MXene layer, possessing abundant sulfonic acid groups (- SO3H), can remarkably reduce the surface energy of the Zn (002) crystal plane and induce the preferential growth of (002) horizontally orientation during the electrodeposition process, resulting in highly reversible process between Zn plating and stripping with dendrite-free and corrosion-free behaviors. Accordingly, the symmetric battery, using SM-MXene/ZnSO4 as electrolyte, exhibits ultra-high Coulombic efficiency (99.48 %) and ultra-long cycle life (over 5000 cycles), subsequently enabling the Zn||MnO2 full cell highly rechargeable.

Visible-light sensitive and bi-functionally favored CO2 reduction (CRR)/evolution (CER) photocathode catalysts that can get rid of the utilization of ultraviolet light and improve sluggish kinetics is demanded to conquer the current technique-barrier of traditional Li-CO2 battery. Here, a kind of redox molecular junction sp2c metal-covalent organic framework (i.e. Cu3-BTDE-COF) has been prepared through the connection between Cu3 and BTDE and can serve as efficient photocathode catalyst in light-assisted Li-CO2 battery. Cu3-BTDE-COF with redox-ability, visible-light-adsorption region, electron-hole separation ability and endows the photocathode with excellent round-trip efficiency (95.2 %) and an ultralow voltage hysteresis (0.18 V), outperforming the Schiff base COFs (i.e. Cu3-BTDA-COF and Cu3-DT-COF) and majority of the reported photocathode catalysts. Combined theoretical calculations with characterizations, Cu3-BTDE-COF with the integration of Cu3 centers, thiazole and cyano groups possess strong CO2 adsorption/activation and Li+ interaction/diffusion ability to boost the CRR/CER kinetics and related battery property.

Adverse side reactions and uncontrolled Zn dendrites growth are the dominant factors that have restricted the application of Zn ion batteries. Herein, a 3D self-supporting porous carbon fibers (denoted as PCFs) host is developed with "trap" effect to adjust the Zn deposition. The unique open structural design of N-doped carbon can act as the zincophilic sites to induce uniform deposition and inhibit adverse side reactions. More importantly, the porous hollow PCFs host with "trap" effect can induce Zn deposition in the fiber by adjusting the local electric field and current density, thereby increasing the specific energy density of the battery and inhibiting dendrite growth. In addition, the 3D open frameworks can regulate Zn2+ flux to enable outstanding cycling performance at ultra-high current densities. As expected, the PCFs framework guarantees the uniform Zn plating and stripping with an outstanding stability over 6000 cycles at the current density of 40 mA cm(-2). And the Zn@PCFs||MnO2 full battery shows an excellent lifespan over 1300 cycles at 2000 mA g(-1).

Photocatalytic hydrogen production is one of the most valuable technologies in the future energy system. Here, we designed a metal-covalent organic frameworks (MCOFs) with both small-sized metal clusters and nitrogen-rich ligands, named COF-Cu 3 TG. Based on our design, small-sized metal clusters were selected to increase the density of active sites and shorten the distance of electron transport to active sites. While another building block containing nitrogen-rich organic ligands acted as a node that could in situ anchor metal atoms during photocatalysis and form interlayer single-atom electron bridges (SAEB) to accelerate electron transport. Together, they promoted photocatalytic performance. This represented the further utilization of Ru atoms and was an additional application of the photosensitizer. N 2 -Ru-N 2 electron bridge (Ru-SAEB) was created in situ between the layers, resulting in a considerable enhancement in the hydrogen production rate of the photocatalyst to 10.47 mmol g −1  h −1 . Through theoretical calculation and EXAFS, the existence position and action mechanism of Ru-SAEB were reasonably inferred, further confirming the rationality of the Ru-SAEB configuration. A sufficiently proximity between the small-sized Cu 3 cluster and the Ru-SAEB was found to expedite electron transfer. This work demonstrated the synergistic impact of small molecular clusters with Ru-SAEB for efficient photocatalytic hydrogen production.

Hydrazone-linked covalent organic frameworks (COFs) with structural flexibility, heteroatomic sites, post-modification ability and high hydrolytic stability have attracted great attention from scientific community. Hydrazone-linked COFs, as a subclass of Schiff-base COFs, was firstly reported in 2011 by Yaghi's group and later witnessed prosperous development in various aspects. Their adjustable structures, precise pore channels and plentiful heteroatomic sites of hydrazone-linked structures possess much potential in diverse applications, for example, adsorption/separation, chemical sensing, catalysis and energy storage, etc. Up to date, the systematic reviews about the reported hydrazone-linked COFs are still rare. Therefore, in this review, we will summarize their preparation methods, characteristics and related applications, and discuss the opportunity or challenge of hydrazone-linked COFs. We hope this review could provide new insights about hydrazone-linked COFs for exploring more appealing functions or applications.

Precise design and tuning of Zn hopping/transfer sites with deeper understanding of the dendrite-formation mechanism is vital in artificial anode protective coating for aqueous Zn-ion batteries (AZIBs). Here, we probe into the role of anode-coating interfaces by designing a series of anhydride-based covalent organic frameworks (i.e., PI-DP-COF and PI-DT-COF) with specifically designed zigzag hopping sites and zincophilic anhydride groups that can serve as desired platforms to investigate the related Zn 2+ hopping/transfer behaviours as well as the interfacial interaction. Combining theoretical calculations with experiments, the ABC stacking models of these COFs endow the structures with specific zigzag sites along the 1D channel that can accelerate Zn 2+ transfer kinetics, lower surface-energy, homogenize ion-distribution or electric-filed. Attributed to these superiorities, thus-obtained optimal PI-DT-COF cells offer excellent cycling lifespan in both symmetric-cell (2000 cycles at 60 mA cm −2 ) and full-cell (1600 cycles at 2 A g −1 ), outperforming almost all the reported porous crystalline materials.

Lithium–sulfur batteries (LSBs) currently suffer from severe polysulfide shuttling, slow redox kinetics at the sulfur cathode, and irreversible dendrite growth at the lithium anode. To address these issues, a dual interfacial engineering strategy on both the cathode and anode is proposed. For the cathode, iminated polyaniline (iPANI) is used to achieve energetic engineering to induce mid‐energy level to the adsorption of polysulfides, and catalyze the redox conversion of sulfur species, and realize morphological engineering via self‐assembly of iPANI onto a scaffold integrated by reduced graphene oxide (rGO) and carbon nanotubes (CNTs), namely iPANI@rGO‐CNTs. For the anode, the highly conductive and lithiophilic nature and porous nanostructure of the iPANI@rGO‐CNTs composite facilitates the uniform deposition of lithium‐ions, significantly preventing the growth of lithium dendrites. Density functional theory calculations suggest that the iminated functional group at the excited state in iPANI can significantly suppress the shuttling effect, catalyze the conversion of sulfur species, and enhance the conversion of the sulfur species on the sulfur cathode. With the synergic effects of the iPANI@rGO‐CNTs nanoreactors, the as‐prepared LSBs deliver an excellent rate capability and outstanding cycling life. This large‐scale production and application of the iPANI@rGO‐CNTs nanocomposite may lead to the eventual commercialization of LSBs.

The inhomogeneous consumption of anions and direct contact between electrolyte and anode during the Zn-deposition process generate Zn-dendrites and side reactions that can aggravate the space-charge effect to hinder the practical implementation of zinc-metal batteries (ZMBs). Herein, electrospray has been applied for the scalable fabrication (>10 000 cm 2 in a batch-experiment) of hetero-metallic cluster covalent-organic-frameworks (MCOF-Ti 6 Cu 3 ) nanosheet-coating (MNC) with integrated micro space electrostatic field for ZMBs anode protection. The MNC@Zn symmetric cell presents ultralow overpotential (≈72.8 mV) over 10 000 cycles at 1 mAh cm −2 with 20 mA cm −2 , which is superior to bare Zn and state-of-the-art porous crystalline materials. Theoretical calculations reveal that MNC with integrated micro space electrostatic field can facilitate the deposition-kinetic and homogenize the electric field of anode to significantly promote the lifespan of ZMBs.

Anisotropically hybridized porous crystalline Li-S battery separators based on porous crystalline materials that can meet the multiple functionalities of both anodic and cathodic sides are much desired for Li-S battery yet still challenging in directional design. Here, an anisotropically hybridized separator (CPM) based on an ionic liquid-modified porphyrin-based covalent-organic framework (COF-366-OH-IL) and catalytically active metal-organic framework (Ni3 (HITP)2 ) that can integrate the lithium-polysulfides (LiPSs) adsorption/catalytic conversion and ion-conduction sites together to directionally meet the requirements of electrodes is reported. Remarkably, the-obtained separator exhibits an exceptional high Li+ transference-number (tLi+ = 0.8), ultralow polarization-voltage (<30 mV), high initial specific-capacity (921.38 mAh g-1 at 1 C), and stable cycling-performance, much superior to polypropylene and monolayer-modified separators. Moreover, theoretical calculations confirm the anisotropic effect of CPM on the anodic side (e.g., Li+ transfer, LiPSs adsorption, and anode-protection) and cathodic side (e.g., LiPSs adsorption/catalysis). This work might provide a new perspective for separator exploration.

A strategy that enables introducing bimetallic active sites is desired for the exploration of light-sensitive covalent organic framework (COF)-based electrocatalysts in light-assisted CO2 electroreduction. Here, salphen-pockets have been implanted into phthalocyanine (Pc)-based COFs through the elaborate design of structural struts; the produced NiPc-DFP-M COFs (M = Ni and Co) possess the advantages of controllable bimetallic centers with different coordination environments, outstanding light sensitivity, and built-in electric-field effects that can be successfully applied in light-assisted CO2 electroreduction. Notably, the optimal heterometallic NiPc-DFP-Co COF presents a similar to 100% Faradic efficiency for CO formation (FECO) in a wide potential range of -0.7 to -1.1 V and similar to 70% energy efficiency (-0.7 V) under light-irradiation, which is superior to mono-and homometallic COFs and under dark conditions. The high performance can be ascribed to the synergistic effect of the NiPc and Co-salphen pockets that can largely reduce the rate-determining energy-barrier and enhance the electron density to boost the light-assisted activity as supported by density functional theory calculations.

The precise tuning of components, spatial orientations, or connection modes for redox units is vital for gaining deep insight into efficient artificial photosynthetic overall reaction, yet it is still hard achieve for heterojunction photocatalysts. Here, we have developed a series of redox molecular junction covalent organic frameworks (COFs) (M-TTCOF-Zn, M = Bi, Tri, and Tetra) for artificial photosynthetic overall reaction. The covalent connection between TAPP-Zn and multidentate TTF endows various connection modes between water photo-oxidation (multidentate TTF) and CO2 photoreduction (TAPP-Zn) centers that can serve as desired platforms to study the possible interactions between redox centers. Notably, Bi-TTCOF-Zn exhibits a high CO production rate of 11.56 μmol g-1 h-1 (selectivity, ∼100%), which is more than 2 and 6 times higher than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn, respectively. As revealed by theoretical calculations, Bi-TTCOF-Zn facilitates a more uniform distribution of energy-level orbitals, faster charge transfer, and stronger *OH adsorption/stabilization ability than those of Tri-TTCOF-Zn and Tetra-TTCOF-Zn.