Defect engineering unveiled: Enhancing potassium storage in expanded graphite anode.

Expanded graphite (EG) stands out as a promising material for the negative electrode in potassium-ion batteries. However, its full potential is hindered by the limited diffusion pathway and storage sites for potassium ions, restricting the improvement of its electrochemical performance. To overcome this challenge, defect engineering emerges as a highly effective strategy to enhance the adsorption and reaction kinetics of potassium ions on electrode materials. This study delves into the specific effectiveness of defects in facilitating potassium storage, exploring the impact of defect-rich structures on dynamic processes. Employing ball milling, we introduce surface defects in EG, uncovering unique effects on its electrochemical behavior. These defects exhibit a remarkable ability to adsorb a significant quantity of potassium ions, facilitating the subsequent intercalation of potassium ions into the graphite structure. Consequently, this process leads to a higher potassium voltage. Furthermore, the generation of a diluted stage compound is more pronounced under high voltage conditions, promoting the progression of multiple stage reactions. Consequently, the EG sample post-ball milling demonstrates a notable capacity of 286.2 mAh g-1 at a current density of 25 mA g-1, showcasing an outstanding rate capability that surpasses that of pristine EG. This research not only highlights the efficacy of defect engineering in carbon materials but also provides unique insights into the specific manifestations of defects on dynamic processes, contributing to the advancement of potassium-ion battery technology.

Supramolecular assemblies of Cu(II) with a tetraphenylethene-imidazole ligand for tuning photocatalytic CO2 reduction.

Cu(II) supramolecular assemblies [Cu2(tipe)2(H2O)2](NO3)4·2.5H2O (CuN4) and [Cu2Cl4(tipe)(CH3CN)]·H2O (CuN2Cl2) (tipe = 1,1,2,2-tetrakis(4-(imidazole-1-yl)phenyl)ethene) were synthesized and utilized for photocatalytic CO2 reduction. CuN4 exhibits CO production of up to 891 µmol gcat-1 with a selectivity of 79.9%, while CuN2Cl2 gives low CO production of 206 µmol gcat-1 but with a high selectivity of >99.9% in 5 h. The experimental and DFT calculation results indicate that the coordination environment and non-covalent interactions within the assemblies have a great impact on the photocatalytic CO2 reduction behavior. This work provides useful insights on Cu(II) assembly catalyzed CO2 photoreduction.

Janus Binder Chemistry for Synchronous Enhancement of Iodine Species Adsorption and Redox Kinetics toward Sustainable Aqueous Zn-I2 Batteries.

Currently, the desired research focus in energy storage technique innovation has been gradually shifted to next-generation aqueous batteries holding both high performance and sustainability. However, aqueous Zn-I2 batteries have been deemed to have great sustainable potential, owing to the merits of cost-effective and eco-friendly nature. However, their commercial application is hindered by the serious shuttle effect of polyiodides during reversible operations. In this work, a Janus functional binder based on chitosan (CTS) molecules was designed and prepared; the polar terminational groups impart excellent mechanical robustness to hybrid binders; meanwhile, it can also deliver isochronous enhancement on physical adsorption and redox kinetics toward I2 species. By feat of highly effective remission to shuttle effect, the CTS cell exhibits superb electrochemical storage capacities with long-term robustness, specifically, 144.1 mAh g-1, at a current density of 0.2 mA g-1 after 1500 cycles. Simultaneously, the undesired self-discharging issue could be also well-addressed; the Coulombic efficiency could remain at 98.8 % after resting for 24 h. More importantly, CTS molecules endow good biodegradability and reusable properties; after iodine species were reloaded, the recycled devices could also deliver specific capacities of 73.3 mAh g-1, over 1000 cycles. This Janus binder provides a potential synchronous solution to realize high comprehensive performance with high iodine utilization and further make it possible for sustainable Zn-I2 batteries.

Hybrid Binder Chemistry with Hydrogen-Bond Helix for High-Voltage Cathode of Sodium-Ion Batteries.

Since sodium-ion batteries (SIBs) have become increasingly commercialized in recent years, Na3V2(PO4)2O2F (NVPOF) offers promising economic potential as a cathode for SIBs because of its high operating voltage and energy density. According to reports, NVPOF performs poorly in normal commercial poly(vinylidene fluoride) (PVDF) binder systems and performs best in combination with aqueous binder. Although in line with the concept of green and sustainable development for future electrode preparation, aqueous binders are challenging to achieve high active material loadings at the electrode level, and their relatively high surface tension tends to cause the active material on the electrode sheet to crack or even peel off from the collector. Herein, a cross-linkable and easily commercial hybrid binder constructed by intermolecular hydrogen bonding (named HPP) has been developed and utilized in an NVPOF system, which enables the generation of a stable cathode electrolyte interphase on the surface of active materials. According to theoretical simulations, the HPP binder enhances electronic/ionic conductivity, which greatly lowers the energy barrier for Na+ migration. Additionally, the strong hydrogen-bond interactions between the HPP binder and NVPOF effectively prevent electrolyte corrosion and transition-metal dissolution, lessen the lattice volume effect, and ensure structural stability during cycling. The HPP-based NVPOF offers considerably improved rate capability and cycling performance, benefiting from these benefits. This comprehensive binder can be extended to the development of next-generation energy storage technologies with superior performance.

Interfacial-Confined Isochronous Conversion to Biphasic Selenide Heterostructure with Enhanced Adsorption Behaviors for Robust High-Rate Na-Ion Storage.

Sodium-ion batteries (SIBs) have gradually become one of the most promising energy storage techniques in the current era of post-lithium-ion batteries. For anodes, transitional metal selenides (TMSe) based materials are welcomed choices , owing to relatively higher specific capacities and enriched redox active sites. Nevertheless, current bottlenecks are blamed for their poor intrinsic electronic conductivities, and uncontrollable volume expansion during redox reactions. Given that, an interfacial-confined isochronous conversion strategy is proposed, to prepare orthorhombic/cubic biphasic TMSe heterostructure, namely CuSe/Cu3 VSe4 , through using MXene as the precursor, followed by Cu/Se dual anchorage. As-designed biphasic TMSe heterostructure endows unique hierarchical structure, which contains adequate insertion sites and diffusion spacing for Na ions, besides, the surficial pseudocapacitive storage behaviors can be also proceeded like 2D MXene. By further investigation on electronic structure, the theoretical calculations indicate that biphasic CuSe/Cu3 VSe4 anode exhibits well-enhanced properties, with smaller bandgap and thus greatly improves intrinsic poor conductivities. In addition, the dual redox centers can enhance the electrochemical Na ions storage abilities. As a result, the as-designed biphasic TMSe anode can deliver a reversible specific capacity of 576.8 mAh g-1 at 0.1 A g-1 , favorable Na affinity, and reduced diffusion barriers. This work discloses a synchronous solution toward demerits in conductivities and lifespan, which is inspiring for TMSe-based anode development in SIBs systems.

A Green Environmental Protection Photocatalytic Molecular Reactor for Aerobic Oxidation of Sulfide to Sulfoxide.

The design and synthesis of metal-organic frameworks (MOFs) as photocatalytic molecular reactors for varied reactions have drawn great attention. In this work, we designed a novel photoactive perylenediimides-based (PDI) carboxylate ligand N,N'-di(3',3",5',5"-tetrakis(4-carboxyphenyl))-1,2,6,7-tetrachloroperylene-3,4,9,10-tetracarboxylic acid diimide (Cl-PDI-TA) and use it to successfully synthesize a novel Zr(IV)-based MOF 1 constructed from [Zr6 O8 (H2 O)8 ]8+ clusters bridged by Cl-PDI-TA ligands. Structural analysis revealed that Zr-MOF 1 manifests a 3D framework with (4,8)-connected csq topology and possesses triangular channels of ~17 Šand mesoporous hexagonal channels of ~26 Šalong c-axis. Moreover, the synthesized Zr-MOF 1 exhibits visible-light absorption and efficient photoinduced free radical generation property, making it a promising photocatalytic molecular reactor. When Zr-MOF 1 was used as a photocatalyst for the aerobic oxidation of sulfides under irradiation of visible light, it could afford the corresponding sulfoxides with high yield and selectivity. Experimental results demonstrated that the substrate sulfides could be fixed in the pores of 1 and directly transformed to the products sulfoxides in the solid state. Furthermore, the mechanism for the photocatalytic transformation was also investigated and the results revealed that the singlet oxygen (1 O2 ) and superoxide radical (O2 ⋅- ) generated by the energy transfer and electron transfer from the photoexcited Zr-MOF to oxidants were the main active species for the catalytic reactions. This work offers a perceptive comprehension of the mechanism in PDI-based MOFs for further study on photocatalytic reactions.

Advanced Covalent Organic Frameworks for Multi-Valent Metal Ion Batteries.

Covalent organic frameworks (COFs) have received increased interest in recent years as an advanced class of materials. By virtue of the available monomers, multiple conformations and various linkages, COFs offer a wide range of opportunities for complex structural design and specific functional development of materials, which has facilitated the widespread application in many fields, including multi-valent metal ion batteries (MVMIBs), described as the attractive candidate replacing lithium-ion batteries (LIBs). With their robust skeletons, diverse pores, flexible structures and abundant functional groups, COFs are expected to help realize a high performance MVMIBs. In this review, we present an overview of COFs, describe advances in topology design and synthetic reactions, and study the application of COFs in MVMIBs, as well as discuss challenges and solutions in the preparation of COFs electrodes, in the hope of providing constructive insights into the future direction of COFs.

Advanced Lithium Primary Batteries: Key Materials, Research Progresses and Challenges.

In recent years, with the vigorous development and gradual deployment of new energy vehicles, more attention has been paid to the research on lithium-ion batteries (LIBs). Compared with the booming LIBs, lithium primary batteries (LPBs) own superiority in specific energy and self-discharge rate and are usually applied in special fields such as medical implantation, aerospace, and military. Widespread application in special fields also means more stringent requirements for LPBs in terms of energy density, working temperature range and shelf life. Therefore, how to obtain LPBs with high energy density, wide operational temperature range and long storage life is of great importance in future development. In view of the above, this paper reviews the latest research on LPBs in cathode, anode and electrolyte over the years, and puts forward relevant insights for LPBs, along with the intention to explore avenues for the design of LPBs components in the coming decades and promote further development in this field.