Siying Li

Compared to single-layer graphene (SLG), multilayer graphene (MLG) and graphite films (GF) offer superior mechanical stability, tunable electrical conductivity, and lower manufacturing costs. However, during their preparation and transfer processes, defects such as vacancies, grain boundaries, wrinkles, and stacking disorder are inevitably introduced, and these defects have a critical impact on material performance. The defects such as vacancies, dopant atoms, and edges can enhance gas adsorption, catalytic activity, and ion storage capacity, while the defects such as grain boundaries and dislocations reduce electrical conductivity, strength, and thermal transport properties. Therefore, defect engineering mainly focuses on precisely controlling the type, density, and distribution of defects through methods such as ion implantation, plasma treatment, laser irradiation, and strain engineering, and on repairing them via high-temperature annealing or chemical methods. For applications requiring extremely high carrier mobility or thermal conductivity, nearly defect-free single-crystal MLG/GF can also be prepared, and applications of defect-engineered MLG or GF in corrosion protection, thermal management, energy storage, sensors, electronics, and quantum physics are discussed.

ZnFe₂O₄ is a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, but its practical use is limited by poor conductivity and large volume changes during cycling. To address these issues, a ZnFe₂O₄-reduced graphene oxide (Z-F-rGO) composite was fabricated via solvothermal synthesis and calcination, with Z-F nanoparticles in situ anchored on rGO sheets. Characterizations (XRD, Raman, XPS, SEM, TEM) confirm the formation of highly crystalline spinel Z-F with good interfacial contact with rGO. The Z-F-rGO electrode shows excellent electrochemical performance, maintaining a reversible capacity of 985.4 mA h g⁻¹ after 100 cycles at 0.5 A g⁻¹, significantly higher than the 498.2 mA h g⁻¹ of the Z-F. At 1.0 A g⁻¹, the Z-F-rGO electrode retains 959.4 mA h g⁻¹ after 300 cycles, while the Z-F electrode shows a capacity of 441.3 mA h g⁻¹. CV analysis indicates good reversibility, while EIS and GITT reveal reduced charge-transfer resistance and enhanced Li⁺ diffusion. This work provides an efficient strategy for scalable Z-F-rGO composites, offering a promising approach for high-performance LIB anodes.

Sodium-ion batteries (SIBs) have gained attention for their low cost and abundant sodium resources. However, at low temperature (LT), their electrolytes suffer from reduced conductivity, higher viscosity, poor interfacial stability, and sluggish ion transport, leading to capacity loss and shortened cycle life. These problems significantly restrict the practical application of SIBs in harsh or LT environments, where performance degradation, capacity fading, or even complete failure can occur. Therefore, enhancing the LT performance of SIB electrolytes has become a key research focus. Improvements in electrolyte formulation-including solvent selection, sodium salt optimization, and functional additive engineering-play a vital role in addressing issues such as ion transport limitations and unstable electrode-electrolyte interfaces at LT. This review provides a comprehensive summary of the strategies developed to optimize various types of SIB electrolytes under LT conditions, including organic solvent systems, ionic liquids, solid-state electrolytes, and co-solvents. In addition, it discusses the latest research progress, highlights representative studies, and outlines potential directions for future development, with the aim of guiding the design of high-performance SIBs for LT.

As the core of modern energy technology, lithium-ion batteries (LIBs) have been widely integrated into many key areas, especially in the automotive industry, particularly represented by electric vehicles (EVs). The spread of LIBs has contributed to the sustainable development of societies, especially in the promotion of green transportation. However, the high demand for battery performance and safety in these fields has made the high viscosity, volatility, and potential leakage inherent in traditional organic liquid electrolytes a constraint on their further expansion. Especially at low temperature, the increased viscosity of the electrolyte, reduced solubility of lithium salts, crystallization or solidification of the electrolyte, increased resistance to charge transfer due to interfacial by-products, and short-circuiting due to the growth of anode lithium dendrites all affect the performance and safety of LIBs. Therefore, improving the safety performance of LIBs under low-temperature environments has become a focus of current research. This paper primarily reviews the progress made in utilizing different types of electrolytes in LIBs to enhance safety and optimize low temperature performance and discusses the current research progress as well as the future development direction of the field.

The Ni6035WC/WC-10Co-4Cr wear- and scour-resistant composite coating was fabricated using supersonic flame spraying technology. To further enhance the wear and scour resistance of the HVAF-sprayed Ni6035WC/WC-10Co-4Cr composite coatings, a post-treatment was conducted via vacuum remelting. This involved placing the coatings in a vacuum sintering process at 1120 °C for 10 min. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and hardness testing were employed to characterize the structure and morphology of the Ni6035WC/WC-10Co-4Cr coating, as well as to assess its wear and scour resistance. The results indicate that vacuum sintering significantly enhances the wear and scour resistance of the coating, while also improving its hardness, density, and bonding strength. The hardness of each coating after vacuum sintering, 1019 HV, 920 HV, and 897 HV, was improved by 6% compared to 966 HV, 906 HV, and 845 HV before sintering. The average wear rate of each coating after sintering was 13% lower than before vacuum sintering. Furthermore, the impact of varying WC-10Co-4Cr content on the coating’s properties was examined under identical test conditions. It was found that the optimal overall performance was achieved with a WC-10Co-4Cr content of 20%, resulting in an average wear rate that was 19% lower than that of other coatings.

Calcium sulfate and calcium sulfate-based biomaterials have been widely used in non-load-bearing bone defects for hundreds of years due to their superior biocompatibility, biodegradability, and non-toxicity. However, lower compressive strength and rapid degradation rate are the main limitations in clinical applications. Excessive absorption causes a sharp increase in sulfate ion and calcium ion concentrations around the bone defect site, resulting in delayed wound healing and hypercalcemia. In addition, the space between calcium sulfate and the host bone, resulting from excessively rapid absorption, has adverse effects on bone healing or fusion techniques. This issue has been recognized and addressed. The lack of sufficient mechanical strength makes it challenging to use calcium sulfate and calcium sulfate-based biomaterials in load-bearing areas. To overcome these defects, the introduction of various inorganic additives, such as calcium carbonate, calcium phosphate, and calcium silicate, into calcium sulfate is an effective measure. Inorganic materials with different physical and chemical properties can greatly improve the properties of calcium sulfate composites. For example, the hydrolysis products of calcium carbonate are alkaline substances that can buffer the acidic environment caused by the degradation of calcium sulfate; calcium phosphate has poor degradation, which can effectively avoid the excessive absorption of calcium sulfate; and calcium silicate can promote the compressive strength and stimulate new bone formation. The purpose of this review is to review the poor properties of calcium sulfate and its complications in clinical application and to explore the effect of various inorganic additives on the physicochemical properties and biological properties of calcium sulfate.

Solid-state lithium sulfur batteries are becoming a breakthrough technology for energy storage systems due to their low cost of sulfur, high energy density and high level of safety. However, its commercial application has been limited by the poor ionic conductivity and sulfur shuttle effect. In this paper, a nitrogen-doped porous carbon fiber (NPCNF) active material was prepared by template method as a sulfur-host of the positive sulfur electrode. The morphology was nano fiber-like and enabled high sulfur content (62.9 wt%). A solid electrolyte membrane (PVDF/LiClO₄/LATP) containing polyvinylidene fluoride (PVDF) and lithium aluminum titanium phosphate (Li₁.₃Al₀.₃Ti₁.₇(PO₄)₃) was prepared by pouring and the thermosetting method. The ionic conductivity of PVDF/LiClO4/LATP was 8.07 × 10⁻⁵ S cm⁻¹ at 25 °C. The assembled battery showed good electrochemical performance. At 25 °C and 0.5 C, the first discharge specific capacity was 620.52 mAh g⁻¹. After 500 cycles, the capacity decay rate of each cycle was only 0.139%. The synergistic effect between the composite solid electrolyte and the nitrogen-doped porous carbon fiber composite sulfur anode studied in this paper may reveal new approaches for improving the cycling performance of a solid-state lithium-sulfur battery.