TiO 2 -coated Fe 2 O 3 composites exhibiting high electrochemical stability with oxygen defects were synthesized as the anode materials of Li-ion batteries using an easy sol−gel method. The industrial submicron-sized Fe 2 O 3 with no special shape and commercial tetrabutyl titanate were adopted as raw materials. The phase structures, morphologies, and elements distribution on the surface were characterized by X-ray diffraction analysis, electron paramagnetic resonance, scanning electron microscopy, X-ray photoelectron spectroscopy, and so forth. Results indicated that TiO 2 was well coated on the surface of raw Fe 2 O 3 with an average thickness of 5.5 nm, and the oxygen defects were successfully introduced into the composites with the reduction treatment. Electrochemical characterization indicated that TiO 2 coating was beneficial to the cycle performance of Fe 2 O 3 . The coating layer significantly improved the electronic conductivity and cycling stability of the Fe 2 O 3 anode material, as theoretically supported by the density functional theory calculation. Moreover, the introduction of oxygen defects in samples resulted in more excellent cycling stability compared to that in samples without reduction. The reduced Fe 2 O 3 @0.2TiO 2 sample exhibited a specific discharge capacity of 405.6 mA h•g −1 after 150 cycles, which effectively improved the intrinsic cycling performance of Fe 2 O 3 , and a corresponding discharge capacity of 50 mA h•g −1 after 30 cycles.
Hereinafter, we report
onion-like carbon (OLC) and fullerene-like
carbon (FLC) materials synthesized via 2,4,6-trinitrotoluene (TNT)
and 1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive, RDX)
detonation technique and acetylene gas explosion process, respectively.
Abundant micropores, mesopores, and different spatial structures exist
inside the two carbon materials. They demonstrate good conductivity
and sulfur storage capacity, and various rich pore structures, inhibiting
the shuttle effect of the solved lithium polysulfide in the charge–discharge
process. The pore size distribution, pore volume, specific surface
area, electronic conductivity, composite structure, interaction between
sulfur and carbon, and cell performance are researched. The Li–S
battery furnished with the two carbon–sulfur hybrid materials
as the cathode host material delivers a well reversible rate cycling
performance, and a low decay rate of 0.037% and 0.056% per cycle during
1000 cycles at 1C for FLC and OLC, respectively, with a sulfur load
of about 2.2 mg/cm2. The excellent electrochemical performance
of the two carbon materials obtained by detonation method makes them
ideal substitute products of the commercial Super P carbon material,
especially the FLC material.
To understand the influence of the length–diameter ratio (L/D) of explosively formed projectiles (EFPs) on the energy spatial distribution of behind-armor debris (BAD), three EFPs with different L/Ds were designed in this study. The scattering characteristics of the BAD formed by the EFP penetrating a steel target were investigated. High-speed photography was used to observe the shape of the BAD cloud. Fiber and foam plates were sequentially stacked to recover the fragments. The three-dimensional damaged area by the BAD was obtained based on the spatial position information of a large amount of BAD. Finally, the energy spatial distribution characteristics of the EFP and target material fragments were analyzed. The results showed that a large EFP L/D increased the total energy of the BAD, and the proportion of the energy of projectile fragments increased. The difference in the energy spatial distribution between EFPs with varying L/Ds was mainly in the scattering angle range of 3–17°. The total energy of fragments within 17° of scattering angle accounted for 85% of the total energy of all fragments. The BAD energy of the EFP with a large L/D (L/D = 3.86) was concentrated in a small scattering angle range in which the residual projectile was located. The average projectile fragment energy of the EFP with a moderate L/D (L/D = 2.4) was evenly distributed in the scattering angle range of 5–20°. As a result, the energy distribution of the BAD from EFP (L/D = 2.4) shifted towards the large scattering angle, thus leading to a uniform radial distribution of the striking area within the range of 500–1100 mm behind the target. However, with the increase in the distance behind the target, the radial direction of the striking area of the other two EFPs was gradually reduced. The reason was explained according to the force analysis of the fragments resulting from the bulge fracture of target. The spatial energy distribution of BAD is closely related to the damage ability of EFP in relation to the armored target. Thus, it is necessary to design EFPs with appropriate L/Ds in order to maximize the damaging effect behind the armor.
In this work, binder-free Co3O4 films with in-situ oxygen vacancies are deposited in a one-step process by solution precursor plasma spraying (SPPS). It is believed to the first time Co3O4 layers composed of hexagonal flakes were synthesized through the SPPS route. Specific capacitances up to 1700 F/g were obtained at a scan rate of 5 mV/sec, almost 97% of which was retained after 13,000 cycles at 20 mV/sec. This supercapacitor-like performance is attributed to the synergistic effects of a binder-free composition with in-situ oxygen vacancies and porous nanostructures.
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