A covalent organic framework as a dual-active-center cathode for a high-performance aqueous zinc-ion battery.

Organic electrode materials have shown significant potential for aqueous Zn ion batteries (AZIBs) due to their flexible structure designability and cost advantage. However, sluggish ionic diffusion, high solubility, and low capacities limit their practical application. Here, we designed a covalent organic framework (TA-PTO-COF) generated by covalently bonding tris(4-formylbiphenyl)amine (TA) and 2,7-diaminopyrene-4,5,9,10-tetraone (PTO-NH2). The highly conjugated skeleton inside enhances its electron delocalization and intermolecular interaction, leading to high electronic conductivity and limited solubility. The open channel within the TA-PTO-COF provides ionic diffusion pathways for fast reaction kinetics. In addition, the abundant active sites (C[double bond, length as m-dash]N and C[double bond, length as m-dash]O) endow the TA-PTO-COF with a large reversible capacity. As a result, the well-designed TA-PTO-COF cathode delivers exceptional capacity (255 mA h g-1 at 0.1 A g-1), excellent cycling stability, and a superior rate capacity of 186 mA h g-1 at 10 A g-1. Additionally, the co-insertion mechanism of Zn2+/H+ within the TA-PTO-COF cathode is revealed in depth by ex situ spectroscopy. This study presents an effective strategy for developing high-performance organic cathodes for advanced AZIBs.

Rational Design of Multinary Metal Chalcogenide Bi0.4Sb1.6Te3 Nanocrystals for Efficient Potassium Storage.

Multinary metal chalcogenides hold considerable promise for high-energy potassium storage due to their numerous redox reactions. However, challenges arise from issues such as volume expansion and sluggish kinetics. Here, a design featuring a layered ternary Bi0.4Sb1.6Te3 anchored on graphene layers as a composite anode, where Bi atoms act as a lattice softening agent on Sb, is presented. Benefiting from the lattice arrangement in Bi0.4Sb1.6Te3 and structure, Bi0.4Sb1.6Te3/graphene exhibits a mitigated expansion of 28% during the potassiation/depotassiation process and demonstrates facile K+ ion transfer kinetics, enabling long-term durability of 500 cycles at various high rates. Operando synchrotron diffraction patterns and spectroscopies including in situ Raman, ex situ adsorption, and X-ray photoelectron reveal multiple conversion and alloying/dealloying reactions for potassium storage at the atomic level. In addition, both theoretical calculations and electrochemical examinations elucidate the K+ migration pathways and indicate a reduction in energy barriers within Bi0.4Sb1.6Te3/graphene, thereby suggesting enhanced diffusion kinetics for K+. These findings provide insight in the design of durable high-energy multinary tellurides for potassium storage.

Electropolymerized Bipolar Poly(2,3-diaminophenazine) Cathode for High-Performance Aqueous Al-Ion Batteries with An Extended Temperature Range of -20 to 45 °C.

Achieving reversible insertion/extraction in most cathodes for aqueous aluminum ion batteries (AAIBs) is a significant challenge due to the high charge density of Al3+ and strong electrostatic interactions. Organic materials facilitate the hosting of multivalent carriers and rapid ions diffusion through the rearrangement of chemical bonds. Here, a bipolar conjugated poly(2,3-diaminophenazine) (PDAP) on carbon substrates prepared via a straightforward electropolymerization method is introduced as cathode for AAIBs. The integration of n-type and p-type active units endow PDAP with an increased number of sites for ions interaction. The long-range conjugated skeleton enhances electron delocalization and collaborates with carbon to ensure high conductivity. Moreover, the strong intermolecular interactions including π-π interaction and hydrogen bonding significantly enhance its stability. Consequently, the Al//PDAP battery exhibits a large capacity of 338 mAh g-1 with long lifespan and high-rate capability. It consistently demonstrates exceptional electrochemical performances even under extreme conditions with capacities of 155 and 348 mAh g-1 at -20 and 45 °C, respectively. In/ex situ spectroscopy comprehensively elucidates its cation/anion (Al3+ /H3 O+ and ClO4 - ) storage with 3-electron transfer in dual electroactive centers (C═N and -NH-). This study presents a promising strategy for constructing high-performance organic cathode for AAIBs over a wide temperature range.

Design of a bipolar organic small-molecule cathode with mesoporous nanospheres structure for long lifespan and high-rate Li-storage performance.

Organic small-molecule compounds have become promising cathode materials for high-performance lithium-ion batteries (LIBs) due to their high theoretical capacity, efficient utilization of active sites, low cost, and sustainability. However, severe dissolution and poor electronic conductivity limit their further practical applications. Herein, we have synthesized an insoluble organic small molecule, ferrocenyl-3-(λ1-azazyl) pyrazinyl [2,3-f] [1,10] phenanthrolino-2-amine (FCPD), by grafting ferrocene onto pyrazino[2,3-f] [1,10] phenanthroline-2,3-diamine (PPD). The combination of ferrocene (p-type Fe2+ moiety) and PPD (n-type C[double bond, length as m-dash]N groups) in a bipolar manner endows the target FCPD cathode with an increased theoretical capacity and a wide voltage window. The highly conjugated π-π aromatic skeleton inside enhances FCPD's electron delocalization and promotes strong interaction between FCPD units. Additionally, the mesoporous structure within the FCPD can provide numerous electroactive sites, contact area, and ion diffusion channels. Benefiting from the bipolar feature, aromatic, and mesoporous structure, the FCPD cathode demonstrates a large capacity of 250 mA h g-1 at 0.1 A g-1, a long lifespan of 1000 cycles and a high-rate capability of 151 mA h g-1 at 5 A g-1 along with a wide voltage window (1.2-3.8 V). Additionally, in situ synchrotron FT-IR and ex situ XPS reveal its dual ion storage mechanism in depth. Our findings provide essential insights into exploring the molecular design of advanced organic small molecules.

A liquid metal-fluoropolymer artificial protective film enables robust lithium metal batteries at sub-zero temperatures.

Batteries that are both high-energy-density and durable at sub-zero temperatures are highly desirable for deep space and subsea exploration and military defense applications. Our design incorporates a casting membrane technology to prepare a gallium indium liquid metal (LM)/fluoropolymer hybrid protective film on a lithium metal anode. The LM not only spontaneously forms a passivation alloy layer with lithium but also reduces the nucleation potential barrier and homogenizes the Li+ flux on the surface of the lithium anode. The fluoropolymer's polar functional groups (-C-F-) effectively induce targeted dispersion of gallium indium seeds, and the unique pit structure on the surface provides oriented sites for lithium plating. By implementing these strategies optimally, the protected lithium metal anode remains in operation at a current density of 20 mA cm-2 with an over-potential of about 50.4 mV after 500 h, and the full cells have a high capacity retention rate of up to 98.5% at a current density of 0.5 C after 100 cycles. Furthermore, the battery shows improved low temperature performance at -30 °C, validating the potential of the protective film to enable battery operation at sub-zero temperatures.

Two-dimensional polymer nanosheets as a high-performance organic anode for sodium-ion batteries.

Organic compounds have become a potentially important choice for a new generation of energy-storage electrode materials due to their designability, flexibility, green sustainability, and abundance. However, the applications of organic electrode materials are still limited because of their dissolution in electrolytes and low electrical conductivity, which in turn cause poor cycling stability. Here, for the first time, we report 2-amino-4-thiazole-acetic acid (ATA) and its sodium salt, sodium 2-amino-4-thiazol-derived polymer (PATANa), as an anode. The PATANa showed a two-dimensional (2D) nanosheet structure, offering a larger contact area with the electrolyte and a shorter ion-migration path, which improved the ion-diffusion kinetics. The polymer showed excellent cycling stability and outstanding rate capability when tested as an anode for sodium-ion batteries (SIBs). It could deliver a high reversible specific capacity of 303 mA h g-1 at 100 mA g-1 for 100 cycles and maintain a high discharge capacity of 190 mA h g-1 after 1000 long cycle numbers even at a high current density of 1000 mA g-1. This approach of salinizing the polymer opens a new way to develop anode materials for sodium-ion batteries.

Enhanced cycling stability and rate capability of a graphene-supported commercialized Vat Blue 4 anode for advanced Li-ion batteries.

Commercialized Vat Blue 4 (VB4) has attracted more attention as a promising anode for large-scale applications in Li-ion batteries (LIBs) due to its high electrochemical activity, low price, and large-scale production. However, its moderate solubility results in severe capacity decay and low utilization of active components. Herein, we present a graphene-supported VB4 composite (VB4/rGO) prepared by a facile sonication and hydrothermal process for long cycling stability and high-rate capability. This design can significantly enhance the Li-storage properties, including high capacity (1045 mA h g-1 at 0.1 A g-1), long cycling stability (537 mA h g-1 even over 1000 cycles at 1 A g-1), and rate capability (315 mA h g-1 at 5 A g-1). Strong π-π interaction derived from the aromatic rings within the π-conjugated system (graphene and VB4) and spatial confinement in-between graphene sheets both can suppress the high solubility of VB4 for superior capacity retention. Moreover, conductive graphene and channels in-between nanosheets can simultaneously facilitate the electron and Li+ transfer. This work demonstrates a simple and effective method to improve the electrochemical performance of commercialized Vat dyes and provides a low-cost and large-scale strategy to develop their practical application in the energy storage field.

Encapsulation of BiOCl nanoparticles in N-doped carbon nanotubes as a highly efficient anode for potassium ion batteries.

With gradually increasing cost and shrinking crustal abundance for lithium ion batteries (LIBs), it is necessary to develop potassium ion batteries (PIBs) and explore suitable electrode materials for advanced PIBs. In this work, nanoscale BiOCl nanoparticles encapsulated in N-doped carbon nanotubes (BiOCl@N-CNTs) are designed and used as the anode material for K ion storage. The BiOCl@N-CNT composite is composed of BiOCl nanoparticles (≈ 5 nm) and N-doped carbon nanotubes. The ultralsmall BiOCl nanoparticles offer excellent electrochemical activity for K ion storage and short ion diffusion path for rapid reaction kinetics, while the outer layer of N-CNTs can effectively improve the conductivity and provide space to accommodate volume expansion. Due to this synergistic effect of small size and a highly conductive skeleton, the BiOCl@N-CNT composite delivers good rate capability and long-term cycling stability when evaluated as an anode for PIBs. The special structure of embedding ultrasmall active materials with high performance in highly conductive N-CNTs represents an effective way of improving the activity of the electrode material, facilitating ion/charge transfer, and alleviating volume change towards excellent energy storage technology.

Enhanced Structural Stability and Volumetric Capacity of a 3D Pyknotic Graphene Conductive Network via a Pillar Effect of Sn Nanoparticles for Sodium-Ion Batteries.

High volumetric capacity and durability anode materials for sodium ion batteries have been urgently required for practical applications. Herein, we reported a Sn-pillared pyknotic graphene conductive network with high-level N-doping. This densely stacked block offers high volumetric Na-ion storage capacity, rapid electrochemical reaction kinetics, and robust structural stability during cycling owing to the high capacity component (metallic Sn ≈847 mAh g-1), high tap density (≈2.63 g cm-3), high conductivity (N doping ≈5 at. %), and strong spatially confined and pillared structure. Moreover, theoretical simulations have indicated that the charge accumulation around the N-doped region is more pronounced compared to the pristine one, and electrons accumulate around the N atom while loss occurs at the Na atom. These studies also suggest that it might possibly contribute to higher conductivity and stronger electrophilic reactivity, thereby resulting in enhanced Na-ion storage performance. As a result, the as-obtained electrode material exhibits competitive volumetric capacity (1462 mAh cm-3 at 0.1 A g-1), cycling performance (1207 mAh cm-3 after 100 cycles), and promising rate behavior simultaneously.

Conjugated Porous Polydiaminophenylsulfone-Triazine Polymer-A High-Performance Anode for Li-Ion Batteries.

Organic compounds are promising electrode materials because of their resource sustainability, environmental friendliness, and highly tailorable properties. The porous conjugated polymer shows great potential as an electrode material for its tunable redox nature, conjugated skeleton, and porous structure. Herein, a novel conjugated porous polymer, polydiaminophenylsulfone-triazine, was synthesized by a simple nucleophilic substitution reaction. The conjugated structure and triazine ring can improve the conductivity, charge-transfer efficiency, and physicochemical stability. Also, the porous polymeric framework shows a large specific surface area and high porosity, providing a large contact area with electrolytes and reducing diffusion distance. The polymer demonstrates highly stable cycling performance and good rate capability as an anode for lithium-ion batteries, suggesting a promising strategy to design a competitive electrode material.

Novel coumarin-pyrazole carboxamide derivatives as potential topoisomerase II inhibitors: Design, synthesis and antibacterial activity.

The identification of novel Topoisomerase II (Topo II) inhibitors is one of the most attractive directions in the field of bactericide research and development. In our ongoing efforts to pursue the class of inhibitors, six series of 70 novel coumarin-pyrazole carboxamide derivatives were designed and synthesized. As a result of the evaluation against four destructive bacteria, including Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella. Compound 8III-k (MIC = 0.25 mg/L) showed considerable inhibitory activity than ciprofloxacin (MIC = 0.5 mg/L) against Escherichia coli and 8V-c (MIC = 0.05 mg/L) exhibited excellent antibacterial activity than ciprofloxacin (MIC = 0.25 mg/L) against Salmonella. The selected compounds (8III-k, 8V-c and 8V-k) exhibit potent inhibition against Topo II and Topo IV with IC50 values (9.4-25 mg/L). Molecular docking model showed that the compounds 8V-c and 8V-k can bind well to the target by interacting with amino acid residues. It will provide some valuable information for the commercial Topo II inhibiting bactericides.