The temperature factor is an important factor affecting the intercomponent forces while maintaining the physical stability of solid-liquid mixed fuels. Through self-designed experimental equipment, feedback was provided on the fuel stratification and density distribution uniformity with solid-liquid volume ratios of 1.25:1 and 1:1 under different temperature conditions. As the viscosity of the liquid increased with decreasing temperature, the ability of the fuel to overcome particle deposition was enhanced. Although none of the three fuel ratios with a solid-liquid volume ratio of 1.25:1 showed stratification, the differences in the liquid bridging forces of the components resulted in an increasingly uneven distribution of density with increasing surface tension of the liquid components. By analyzing the imaging results and measuring the liquid bridge force, it was found that the fuel with a nitromethane mass ratio of 40% had the lowest temperature effect on the solid-liquid contact area and the most uniform density distribution. Properly reducing the surface tension of liquid components could effectively resist the influence of the temperature on the liquid bridge force while maintaining the physical stability of the fuel.
The stratification phenomenon resulting from differences in the physical properties of solid‒liquid components seriously affect the final combustion and explosion characteristics of mixed fuel under the action of oscillation. The effects of oscillation on the physical stability of mixed fuel with two solid‒liquid ratios and three liquid component distribution ratios have been investigated using a self-designed experimental system at oscillation frequencies of 60–300 r/min. The explosion characteristics of mixed fuel before and after oscillation are gained from a 20 L spherical explosion container system. When the mass ratio of liquid components is controlled at 66.9%, 64.7%, 62.6% the final explosion characteristics are stable, with a maximum difference of only 0.71%. The volume of liquid fuel precipitation increases with increasing oscillation frequency when the mass ratio of liquid components reaches 71.7%, 69.6%, 67.7%. The fuel explosion overpressure after oscillation decreases with increasing liquid precipitation volume, and the repeatability is poor, with a maximum standard deviation of 82.736, which is much higher than the ratio without stratification. Properly controlling the mass ratio of liquid components of the mixed fuel can effectively combat the impact of oscillation on the physical state and maintain the stability of the final explosion characteristics.
Heterostructures with a rich phase boundary are attractive for surface-mediated microwave absorption (MA) materials. However, understanding the MA mechanisms behind the heterogeneous interface remains a challenge. Herein, a phosphine (PH3) vapor-assisted phase and structure engineering strategy was proposed to construct three-dimensional (3D) porous Ni12P5/Ni2P heterostructures as microwave absorbers and explore the role of the heterointerface in MA performance. The results indicated that the heterogeneous interface between Ni12P5 and Ni2P not only creates sufficient lattice defects for inducing dipolar polarization but also triggers uneven spatial charge distribution for enhancing interface polarization. Furthermore, the porous structure and proper component could provide an abundant heterogeneous interface to strengthen the above polarization relaxation process, thereby greatly optimizing the electromagnetic parameters and improving the MA performance. Profited by 3D porous heterostructure design, P400 could achieve the maximum reflection loss of -50.06 dB and an absorption bandwidth of 3.30 GHz with an ultrathin thickness of 1.20 mm. Furthermore, simulation results confirmed its superior ability (14.97 dB m2 at 90°) to reduce the radar cross section in practical applications. This finding may shed light on the understanding and design of advanced heterogeneous MA materials.
LiPF6-based commercial electrolytes are widely used in lithium-ion batteries (LIBs). However, due to the low ion conductivity that originated from the high freezing point of EC, sluggish desolvation process, and large interface resistance, LIBs with the currently commercial electrolyte based on LiPF6 demonstrate unsatisfactory performance in low-temperature operation. Herein, a LiPF6-based local high-concentration electrolyte with lithium difluorobis(oxalato)phosphate (LiDFBOP) additive is designed to enhance the performance of LIBs at low temperature. Higher-concentration LiPF6 in EC-free solvent improve the overall ionic conductivity of electrolyte. The Li+–solvent–PF6– structure can be obtained to reduce the desolvation energy; meanwhile, LiDFBOP is introduced to construct an effective SEI film with high ionic conductivity and cycle stability. The graphite/Li cells demonstrate good rate performance and low-temperature performance (ca. 240 mAh g–1 at −20 °C (0.1 C)). This work provides a feasible strategy for developing a commercial LiPF6-based electrolyte to improve the operation of LIBs at low temperature.
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