[en] Yibin Nuclear Fuel Element Plant (YFP) began to make large grain pellet for gaining experience since 1999. Two ways to promote grain growth were studied. One is to add U₃O₈ from grinding sludge, the other is to add other additives. In this paper, the production data with addition of U₃O₈ from grinding sludge are reviewed. It is proved by experience that addition of U₃O₈ from grinding sludge is a useful way to promote grain size. The affect of addition of Al₂O₃ and SiO₂ powder on the grain size of UO₂ pellets was studied in detail. It is confirmed that doping with a small amount of Al₂O₃ and SiO₂ powders can promote grain growth during sintering process and the properties of UO₂ pellets satisfied the technical specification completely. And other additives we also studied, such as Cr₂O₃. (author)

[en] Graphical abstract: Cycle stability and coulombic efficiency curves of the Li/CPE/LiCoO₂ cell with 10% Si/Ti molecular sieve at different C-rates, where the insert shows the constructional diagrams of the assembled Li/CPE/LiCoO₂ cell. - Abstract: The mesoporous Si/Ti molecular sieve was successfully synthesized from tetrabutyl titanate, tetraethoxysilane and EO₂₀PO₇₀EO₂₀ by sol-gel combined with following pyrolysis processes and confirmed by XRD and TEM. The poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))-based composite polymer electrolyte (CPE) membranes doped with Si/Ti molecular sieve were fabricated by phase inversion method and the desirable CPEs were obtained after being activated in liquid electrolytes, which are investigated by SEM, XRD, TG, LSV and EIS measurements. The results show that the CPE doped with 10% Si/Ti molecular sieve (vs P(VDF-HFP) in weight) presents the most uniform surface with abundant interconnected micro-pores and possesses excellent mechanical tensile strength with high decomposition temperature about 400 °C and wide electrochemical working window about 4.7 V; adding Si/Ti molecular sieve into the system can significantly decrease the crystallinity and improve the ionic conductivity of the as-prepared CPEs, in which the ionic conductivity and lithium ion transference number at room temperature are up to 3.263 mS cm⁻¹ and 0.4292, respectively, and the reciprocal temperature dependence of ionic conductivity follows Vogel-Tamman-Fulcher relation. Furthermore, the anti-shrinkage rate of the as-prepared CPE membrane distinctly outperforms the commercial polyolefin membrane at 120 °C about 2 h. The interfacial resistance of the assembled Li/CPE/Li simulated cell can rapidly increase to a steady value about 548 Ω from the initial value about 362 Ω at 30 °C during 5 days storage, and the assembled Li/CPE/LiCoO₂ coin cell with the electrolyte also show excellent rate and cycle performance, which indicates that this kind of CPE is an exciting potential candidate as polymer electrolyte for the lithium ion battery.

[en] Highlights:• The mesoporous carbons with Fe-Nx and C–S–C active sites (Fe/S–N/Cs) were successfully synthesized via a facile strategy.• The Fe/S–N/C catalysts exhibit large specific surface areas (980.9 m² g⁻¹) and high pore volumes (0.556 cm³ g⁻¹).• MFC devices with the Fe/S–N/Cs catalysts exhibit higher maximum power density (1436.42 mW m⁻²) than that of commercial Pt/C. -- Abstract: An efficient catalyst (Fe/S–N/C) possessing abundant ordered mesoporous was synthesized via a facile strategy, in which the active Fe-N_x and C–S–C species exhibited atomic dispersion. Attributing to its well-developed porosity, the total pore volume and specific surface area of Fe/S–N/C catalyst reach 0.556 cm³ g⁻¹ and 980.9 m² g⁻¹ respectively. Electron microscopy results reveal the uniform dispersion of atomic Fe-N_x and C–S–C in this catalyst, which has inherited a polyhedral morphology derived from ZIF-8. X-ray spectroscopy measurements further validate that the Fe/S–N/C composite can provide abundant and highly efficient active sites for ORR. The atomic ratio of nitrogen is 4.28%, with high relative concentrations of the active pyridinic N and Fe-N_x. Furthermore, the Fe/S–N/C catalysts demonstrate significant ORR activity in the practical application of MFC devices. Based on a high open circuit potential (0.674 V) and maximum power density (1436.42 mW m⁻²) of the MFC device which uses the Fe/S–N/C as air-cathode catalyst, the Fe/S–N/C displays better catalytic activity than commercial 20% Pt/C catalyst. This investigation provides a new strategy to design an effective, low-cost ORR catalyst for MFC devices.

[en] Highlights: • Novel Si–SiO₂@Fe/NC anodes are successfully prepared from industrial AlSiFe powders. • The polyporous SiO₂ frameworks can accommodate volume expansion of Si particles. • Nitrogen doped carbon layers distinctly boost electronic conductivity of electrodes. • The cells with the Si–SiO₂@Fe/NC anode deliver excellent cycle and rate performance. -- Abstract: Industrial waste AlSiFe powders are employed to provide polyporous SiO₂ frameworks by alkali etching and Si nanoparticles are embedded in the gaps of the porous SiO₂ frameworks via ultrasonic stirring. The nitrogen doped carbon layers are generated on the surface of the porous frameworks to yield the Si–SiO₂@Fe/NC composite by polymerization of dopamine and subsequent carbonization process, in which the polyporous SiO₂ frameworks can not only relieve huge volume changes of the active Si particles, but also can provide abundant charge transfer channels for electrons and lithium ions. Moreover, the nitrogen doped carbon layers significantly promote the electronic conductivity of the composite. Benefitting from these coordinating effects, the Si–SiO₂@Fe/NC anodes demonstrate outstanding cycle performance with a charge specific capacity of 1394.7 mAh g⁻¹ and up to 100% capacity retention rate after 100 cycles under test current of 200 mA g⁻¹, excellent rate performance with a charge specific capacity of 653.1 mAh g⁻¹ under test current of 3000 mA g⁻¹ and enhanced lithium ion diffusion rate of 4.161 E−13 cm² s⁻¹ in the 100th cycle. As a consequence, the comprehensive fabrication of the Si–SiO₂@Fe/NC composite from industrial wastes could provide a promising idea to develop novel anodes for lithium ion batteries.

[en] Highlights: • The Si@TiO₂/NC composite are prepared by sol-gel and in situ N-doped carbon coating processes. • The TiO₂ shell and N-doped carbon coating ensure the stable electrochemical properties. • The cell assembled with Si@TiO₂/NC composite demonstrates excellent rate and cycle performance. • The composite display high Li⁺ diffusion coefficient and stable microstructure after 100 cycles. -- Abstract: The core-shell structural N-doped carbon encapsulating Si@TiO₂ composite (Si@TiO₂/NC) are prepared by facile sol-gel, polymerization of dopamine hydrochloride and the following heat treatment processes, which are confirmed by the scanning electron microscopy, X-ray diffractometer, transmission electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric analyses. The as-prepared Si@TiO₂/NC composite present favorable spherical shape with about 150 nm in diameter and uniform element distribution, and demonstrate the enhanced electrochemical properties compared to the pure silicon, Si@TiO₂ and Si/NC materials when the composite materials are used as anodes for lithium-ion batteries, in which the Si@TiO₂/NC composite anodes display the favorable initial coulombic efficiency of 75.9%, remarkable charge specific capacity of 1070.9 mAh g⁻¹ with the coulombic efficiency approaching 100% after 100 cycles under the test current of 200 mA g⁻¹, extraordinary rate and cycle capability with the charge specific capacity of 696.2 mAh g⁻¹ under the test current of 3000 mA g⁻¹ and increased lithium ion diffusion coefficient from 8.179 E-12 cm² s⁻¹ to 8.995 E-12 cm² s⁻¹ after 100 cycles. Those excellent electrochemical properties can be attributed to the synergistic effect of the robust TiO₂ skeleton and the elastic conductive N-doped carbon network, indicating the as-prepared Si@TiO₂/NC composite could be a promising anode for lithium-ion batteries.

[en] Highlights: • Organic-inorganic hybrid particles PMMA-ZrO₂ are synthesized via in situ polymerization. • The ionic conductivity and tensile strength of the CPE-5 is up to 3.595 mS cm⁻¹ and 26.18 Mpa, respectively. • The CPE-5 membranes show the minimum deformation after being exposed at 160 °C for 1 h. • The assembled cells show good rate and cycle performance. Poly(vinylidene fluoride-hexafluoroprolene) (P(VDF-HFP))-based composite polymer electrolyte (CPE) membranes doped with organic-inorganic hybrid particles poly(methyl methacrylate)ZrO₂ (PMMA-ZrO₂) are fabricated by phase inversion, in which PMMA is firstly successfully grafted onto the surface of the homemade nano-ZrO₂ particles via in situ polymerization confirmed by FT-IR. XRD and DSC patterns show that adding PMMA-ZrO₂ into the polymer matrix can decrease the crystallinity of the CPE membranes and TG curves indicate the CPE membranes possess desirable thermal stability. It can be found that the CPE membrane presents a uniform surface with abundant interconnected micro-pores when the added amount of PMMA-ZrO₂ increases to 5 wt % vs. polymer matrix, in which the ionic conductivity at room temperature and tensile strength can be up to 3.595 mS cm⁻¹ and 26.18 MPa, respectively. In particular, the CPE membrane shows the minimum deformation of about 8% after being exposed at 160 °C for 1 h, and the electrochemical working window of the assembled Li/CPE/SS cell can be stable at 5.1 V (vs Li/Li⁺) at room temperature. Moreover, the LiCoO₂/CPE/Li coin cell can deliver a specific capacity of 114.5 mAh g⁻¹ with 79.13% capacity retention at 2.0 C after 110 cycles. The results suggest that the as-fabricated P(VDF-HFP)-based CPE doped with 5 wt % organic-inorganic hybrid particles PMMA-ZrO₂ can be a promising polymer electrolyte for lithium ion batteries.

[en] Highlights: ► Chitosan was used as carbon and nitrogen resource to modify TiO₂ nanostructure. ► Nanocomposites with mesostructure were obtained by one-step solvothermal method. ► Carbon species were modified on the surface of TiO₂. ► Nitrogen was doped into the anatase titania lattice. ► CTS-TiO₂ nanocomposites show superior visible light photocatalytic activity. - Abstract: Visible light-active carbon coated N-doped TiO₂ nanostructures(CTS-TiO₂) were prepared by a facile one-step solvothermal method with chitosan as carbon and nitrogen resource at 180 °C. The as-prepared samples were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), N₂ adsorption–desorption analysis, X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy. The CTS-TiO₂ nanocomposites possess anatase phase of nanocrystalline structure with average particle size of about 5–7 nm. A wormhole mesostructure can be observed in the CTS-TiO₂ nanocomposites due to the constituent agglomerated of nanoparticles. It has been evidenced that the nitrogen was doped into the anatase titania lattice and the carbon species were modified on the surface of TiO₂. The photocatalytic activities of the as-prepared photocatalysts were measured by the degradation of methylene blue (MB) under visible light irradiation at λ ≥ 400 nm. The results show that CTS-TiO₂ nanostructures display a higher visible light photocatalytic activity than pure TiO₂, commercial P25 and C-coated TiO₂ (C-TiO₂) photocatalysts. The higher photocatalytic activity could be attributed to the band-gap narrowed by N-doping and the accelerated separation of the photo-generated electrons and holes by carbon modification.

[en] Highlights: • The electrochemical reconstructed CGP exhibits excellent performance in LIBs. • The CGP could deliver reversible capacity of 1576.5 mAh g⁻¹ after 364 cycles. • The high performance of CGP is attributed to as-formed integrated nanostructure. • The methodology may also be applicable to the design of other TMOs-based anode. Co₃O₄ nanoplates/reduced graphene oxide (CGP) composite was synthesized through a facile hydrothermal method followed by thermal treatment. The obtained CGP composite exhibits a superior electrochemical performance as an anode for lithium ion batteries, especially after 150 discharge/charge cycles. Characterization of the microscopic features suggests that the structure of the Co₃O₄ nanoplates gradually evolves during cycling due to the electrochemical reconstruction process, transforming into an integrated architecture assembled by nanoparticles with thicknesses of tens of nanometers. The as-formed integrated nanostructure can reduce the stress caused by volume variations during cycling, provide short diffusion path lengths for Li ions and electrons, and offer good electrode conductivity to improve the reaction kinetics, which will tremendously enhance the electrochemical performance of the CGP electrode in lithium ion batteries.

[en] Highlights: • The mesoporous La_0.8Sr_0.2MnO₃ nanowires (LSMO-Mes-NW) were successfully prepared. • LSMO-Mes-NW exhibit high specific surface area of 31.03 m² g⁻¹. • The oxygen vacancy concentration and ratio of Mn⁴⁺/Mn³⁺ were precisely regulated. • LSMO-Mes-NW-based Zn-air batteries show high peak power density of 113.86 mW cm⁻². • DFT calculation reveals strengthened electrocatalytic mechanism by Sr dopants. The one-dimensional mesoporous La_0.8Sr_0.2MnO₃ catalysts with excellent electronic conduction were successfully prepared by molten salt template method to accelerate the kinetics of ORR for metal-air batteries. The as-synthesized mesoporous La_0.8Sr_0.2MnO₃ nanowires with relatively high oxygen vacancy concentration and ratio of Mn⁴⁺/Mn³⁺ show high specific surface area of 31.03 m² g⁻¹, higher than the most of reported perovskite oxides. More importantly, more catalytic active sites can be exposed at the three-phase interface of ORR due to high specific surface area. The mesoporous La_0.8Sr_0.2MnO₃ nanowires exhibit high half-wave potential and catalyze near 4 e⁻ ORR process. Besides, the one-dimensional mesoporous La_0.8Sr_0.2MnO₃-based Zn-air batteries show high peak power density of 113.86 mW cm⁻². Simultaneously, density functional theory (DFT) calculation reveals that strengthened electrocatalytic mechanism of La_1-xSr_xMnO₃ catalysts originates from lower formation energy of oxygen vacancy and more positive O 2p band center because of Sr dopants, which is consistent with the experimental results. Consequently, this investigation not only provide a new idea for developing mesoporous perovskite oxides nanowires but also reveals enhanced electrocatalytic mechanism of La_1-xSr_xMnO₃ catalysts.