Ceramic foam with excellent mechanical performance, high thermal conductivity and high surface area-to-volume ratio is thought to have great potential in heat exchanger application. In this study, silicon nitride (Si 3 N 4 ) foams with ultrathin cell walls were prepared by using a protein foaming method via increasing the air fraction of foamed slurry. Cell thickness of these Si 3 N 4 foams was only 2–3 µm and the pores in the Si 3 N 4 foams fabricated here exhibited polyhedral shapes. Thermal conductivities of these Si 3 N 4 foams ranged from 2.427 W m −1 K −1 to 3.154 W m −1 K −1 , whereas compressive strengths of these Si 3 N 4 foams are in the range from 12.85 MPa to 19.99 MPa. Moreover, compressive load–displacement curves of the Si 3 N 4 foams generally exhibit cellular behavior.
Sodium-ion batteries (SIBs) with high energy/power density have been in urgent demand for various power applications. Upgrading the electrochemical dynamics of electrode materials is crucial to achieve this goal. Herein, we exhibit delicately synthesized cellular carbon-wrapped FeSe2 nanocavities (h-FeSe2@PC) with sub-5 nm ultrathin walls and multiple rooms for ultrafast sodium storage. Unlike with the conventional interphase Kirkendall effect, the multi-room FeSe2 nanocavities were formed via an exotic stress-induced cracking–hollowing reassembly mechanism. Benefiting from their unique multi-hierarchy, more than 93% pseudocapacitive capacity contribution was recognized in an h-FeSe2@PC anode, featuring ultrafast dynamics. As a result, h-FeSe2@PC displayed an extremely low-decay (9.5%) rate capability, ultrastable cyclability (over 2000 loops with 98.5% capacity retention), and high energy/power densities (670.7 W h kg−1/35.3 kW kg−1 at 20 A g−1). The results of multiple analyses and comparisons showed that the dynamics-promoted superior performance was correlated almost completely to the applied FeSe2 in h-FeSe2@PC by shortening the Na+-diffusion length to near the accessible limit (<10 nm) and to the fast electron transfer ensured by the cellular carbon. The exhibited dynamics-oriented materials design could open up an avenue to aid the further development of high-performance electrodes.
Due to the special nature of weather conditions at sea, the tricky status quo of heat loss in readiness or operational clothing, there is an urgent need for special insulated clothing materials to withstand harsh environments, maintain body temperature, and increase comfort for naval personnel who have been at sea for a long period of time in preparation for battle or combat. Paraffin is a special kind of phase change energy storage material, And the preparation of paraffin microcapsules is an effective way to solve the above problems, in which the ultra-thin-walled energy storage paraffin capsules have the advantages of large volume, accommodating more paraffin phase change materials, good energy storage effect and low cost. In this study, three kinds of paraffin microcapsules with core-shell structure were prepared by encapsulating a membrane with stable performance on the surface of paraffin particles using microencapsulation and layer-by-layer self-assembly techniques. We characterized their thermal storage capacity, composition and morphology by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier infrared spectroscopy, and optical microscopy, and compared their performances. The results show that the paraffin microcapsules prepared by layer-by-layer (LBL) self-assembly technique in this study have good thermal storage performance and stability, and their thickness increases with the increase of the number of layers, and the materials used in the experiment wrapped the liquid paraffin layer by layer, which is expected to be practically applied in the field of naval energy storage materials.
危险品化学品经营许可证（带存储）