Frontiers of Materials Science最新文献

This paper describes how to produce a wearable dry electrode at a reasonable cost and how to use it for the monitoring of biopotentials in electrocardiography. Smart textiles in wearable technologies have made a great advancement in the health care management and living standards of humans. Graphene was manufactured using the low-cost single-step process, laser ablation of polyimide, a commercial polymer. Graphene dispersions were made using solvent isopropyl alcohol which has low boiling point, nontoxicity, and environmental friendliness. After successive coating of the graphene dispersion on the cotton fabric to make it conductive, the sheet resistance of the resulting fabric dropped to 3% of its initial value. The laser-induced graphene (LIG) cotton dry electrodes thus manufactured are comparable to Ag/AgCl wet electrodes in terms of the skin-to-electrode impedance, measuring between 78.0 and 7.2 kΩ for the frequency between 40 Hz and 1 kHz. The LIG cotton electrode displayed a signal-to-noise ratio of 20.17 dB. Due to its comfort, simplicity, and good performance over a longer period of time, the textile electrode appears suited for medical applications.

In this work, C@Fe₃O₄ composites were prepared through a typical template method with emulsified asphalt as carbon source, ammonium ferric citrate as transition metal oxide precursor, and NaCl as template. As an anode for lithium-ion batteries, the optimized C@Fe₃O₄-1:2 composite exhibits an excellent reversible capacity of 856.6 mA·h·g⁻¹ after 100 cycles at 0.1 A·g⁻¹ and a high capacity of 531.1 mA·h·g⁻¹ after 300 cycles at 1 A·g⁻¹, much better than those of bulk carbon/Fe₃O₄ prepared without NaCl. Such remarkable cycling performance mainly benefits from its well-designed structure: Fe₃O₄ nanoparticles generated from ammonium ferric citrate during pyrolysis are homogenously encapsulated in graphitized and in-plane porous carbon nanocages derived from petroleum asphalt. The carbon nanocages not only improve the conductivity of Fe₃O₄, but also suppress the volume expansion of Fe₃O₄ effectively during the charge–discharge cycle, thus delivering a robust electrochemical stability. This work realizes the high value-added utilization of low-cost petroleum asphalt, and can be extended to application of other transition-metal oxides-based anodes.

There are still many challenges including low conductivity of cathodes, shuttle effect of polysulfides, and significant volume change of sulfur during cycling to be solved before practical applications of lithium–sulfur (Li–S) batteries. In this work, (FeO)₂FeBO₃ nanoparticles (NPs) anchored on interconnected nitrogen-doped carbon nanosheets (NCNs) were synthesized, serving as sulfur carriers for Li–S batteries to solve such issues. NCNs have the cross-linked network structure, which possess good electrical conductivity, large specific surface area, and abundant micropores and mesopores, enabling the cathode to be well infiltrated and permeated by the electrolyte, ensuring the rapid electron/ion transfer, and alleviating the volume expansion during the electrochemical reaction. In addition, polar (FeO)₂FeBO₃ can enhance the adsorption of polysulfides, effectively alleviating the polysulfide shuttle effect. Under a current density of 1.0 A·g⁻¹, the initial discharging and charging specific capacities of the (FeO)₂FeBO₃@NCNs-2/S electrode were obtained to be 1113.2 and 1098.3 mA·h·g⁻¹, respectively. After 1000 cycles, its capacity maintained at 436.8 mA·h·g⁻¹, displaying a decay rate of 0.08% per cycle. Therefore, combining NCNs with (FeO)₂FeBO₃ NPs is conducive to the performance improvement of Li–S batteries.

In situ carbon-coated Co₃Se₄/CoSe₂ (CO_xSe_y) nanoparticles (NPs) attached on three-dimensional (3D) reduced graphene oxide (rGO) sheets were skillfully developed in this work, which involved the environment-friendly hydrothermal method, freeze drying, and selenide calcination. Within the structure, the glucose-derived carbon layer exhibited significantly homogeneous dispersion under an argon environment. This structure not only has enhanced stability, but also can effectively mitigate the volume swell of Co_xSe_y particles. The resulted Co₃Se₄/CoSe₂@C/rGO (CSe@C/rGO) exhibited a specific surface area (SSA) of 240.9 m²·g⁻¹, offering more electrochemically active sites for the storage of energy related to lithium ions. The rGO matrix held exceptional flexibility and functional structural rigidity, facilitating the swift ion intercalation and ensuring the high conductivity and recyclability of the structure. When applied to anodes designed for lithium-ion batteries (LIBs), this material demonstrated distinguished rate and ultra-high reversible capacity (872.98 mA·h·g⁻¹ at 0.5 A·g⁻¹). Meanwhile, its capacity retention reached 119.5% after 500 cycles at 2 A·g⁻¹, with a coulombic efficiency of 100%. This work potentially paves the way for generating fast and powerful metal selenide anodes and initiating LIBs with good performance.

Electrolyte interface resistance and low ionic conductivity are essential issues for commercializing solid-state lithium metal batteries (SSLMBs). This work details the fabrication of a double-layer solid composite electrolyte (DLSCE) for SSLMBs. The composite comprises poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF–HFP) and poly(methyl methacrylate) (PMMA) combined with 10 wt.% of Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO), synthesized through an ultraviolet curing process. The ionic conductivity of the DLSCE (2.6 × 10⁻⁴ S·cm⁻¹) at room temperature is the high lithium-ion transference number (0.57), and the tensile strength is 17.8 MPa. When this DLSCE was assembled, the resulted LFP/DLSCE/Li battery exhibited excellent rate performance, with the discharge specific capacities of 162.4, 146.9, 93.6, and 64.0 mA·h·g⁻¹ at 0.1, 0.2, 0.5, and 1 C, respectively. Furthermore, the DLSCE demonstrates remarkable stability with lithium metal batteries, facilitating the stable operation of a Li/Li symmetric battery for over 200 h at both 0.1 and 0.2 mA·cm⁻². Notably, the formation of lithium dendrites is also effectively inhibited during cycling. This work provides a novel design strategy and preparation method for solid composite electrolytes.

The solar-to-hydrogen conversion using the photoelectrochemical (PEC) method is a practical approach to producing clean energy. However, it relies on the availability of photocatalyst materials. In this work, a novel photocatalyst comprising molybdenum telluride quantum dots (MoTe₂ QDs)-modified titanium dioxide nanorods (TiO₂ NRs) was prepared for the enhancement of the PEC water splitting performance after combination with a Al₂O₃ layer using the atomic layer deposition (ALD) technique. MoTe₂ QDs were initially prepared, and then they were loaded onto TiO₂ NRs using a warm water bath-based heating method. After a layer of Al₂O₃ was deposited onto resulted TiO₂ NRs/MoTe₂ QDs, the composite TiO₂ NRs/MoTe₂ QDs/Al₂O₃ was finally obtained. Under simulated sunlight (100 mW·cm⁻²), such a composite exhibited a maximum photocurrent density of 2.25 mA·cm⁻² at 1.23 V (versus RHE) and an incident photon-to-electron conversion efficiency of 69.88% at 380 nm, which are 4.33 and 6.66 times those of pure TiO₂ NRs, respectively. Therefore, the composite photocatalyst fabricated in this work may have promising application in the field of PEC water splitting, solar cells and other photocatalytic devices.

Zinc-based flow battery is an energy storage technology with good application prospects because of its advantages of abundant raw materials, low cost, and environmental friendliness. The chemical stability of zinc electrodes exposed to electrolyte is a very important issue for zinc-based batteries. This paper reports on details of chemical stability of the zinc metal exposed to a series of solutions, as well as the relationship between the morphological evolution of zinc electrodes and their properties in an alkaline medium. Chemical corrosion of zinc electrodes by the electrolyte will change their surface morphology. However, we observed that chemical corrosion is not the main contributor to the evolution of zinc electrode surface morphology, but the main contributor is the Zn/Zn²⁺ electrode process. The morphological evolution of zinc electrodes was controlled by using ionic liquids, 1-ethyl-3-methylimidazolium acetate (EMIA), and 1-propylsulfonic-3-methylimidazolium tosylate (PSMIT), and the electrode performance was recorded during the morphological evolution process. It was observed that the reversible change of zinc electrode morphology was accompanied by better electrode performance.