Zhanjun Liu

This review highlights the formation mechanism, structural regulation and applications of HCPs by external cross-linking methods.

Coal tar pitch (CTP) has become an ideal choice in the preparation of anode precursors for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because of its abundant carbon content, competitive pricing and adjustable structure properties. In this paper, sulfurized pitch-based carbon (SPC-800) was obtained by allowing CTP to react with sulfur at 350 °C and subsequently achieve carbonization at 800 °C. SPC-800 was more disordered and had a larger layer spacing than carbonized CTP (PC-800). Upon utilization as an anode for LIBs, SPC-800 possessed a higher reversible specific capacity (478.1 mAh g⁻¹ at 0.1 A g⁻¹), while utilization in SIBs displayed a capacity of 220.9 mAh g⁻¹ at 20 mA g⁻¹. This work is an important guide to the design of high-performance anodes suitable for use with both LIBs and SIBs.

Non-impregnated small-pore graphite (NSPG), which has a compact microstructure and is used in molten salt reactors (MSRs), was prepared by a novel process. The pore diameter of NSPG was reduced to ~800 nm. The irradiation evaluation of NSPG was carried out by 7 MeV Xe²⁶⁺ ion irradiation. The microstructural changes of NSPG were investigated with IG-110 as a comparison. The graphitization degree of NSPG was higher than that of IG-110, though it was not subjected to an impregnation process. Under low-dose ion irradiation (<2.5 dpa), the microscopic morphology of the NSPG changes in a small magnitude, and the lamellar structure of graphite remains within the scale of more than a dozen nanometers, which exhibits a better resistance to irradiation. With the increase in irradiation dose, the accumulation of defects leads the graphite toward amorphization, which shows consistency with IG-110. This study provides an efficient and low-cost method for the preparation of graphite for MSR, and investigates the damage behavior of graphite, which is of great significance in accumulating data for the development of MSR nuclear graphite and the optimal design of graphite materials.

Non-impregnated small pore graphite (NSPG) with the compact microstructure for using in molten salt reactors (MSR) was prepared by the novel process, and the pore diameter of the obtained graphite was reduced to ~800 nm. The irradiation evaluation of the prepared graphite was carried out by 7 MeV Xe26+ ion irradiation and the microstructural changes of the graphite were investigated with IG-110 as a comparison. The graphitization degree of NSPG was higher than that of IG-110, though it was not subjected to an impregnation process. Under low-dose ion irradiation (

The economics and safety of reactors can be affected by the diffusion of fission products into graphite. Xenon (Xe) fission products diffusing into graphite is the most critical neutron absorber and poison that can slow down or stop the chain reaction. The transport parameters for inhibiting the xenon diffusion in graphite are therefore an important scientific problem. Self-sintered nanopore-isotropic (~40 nm) graphite (SSNG) derived from green pitch coke can decrease Xe diffusion into graphite. In this study, the surface morphology and microstructural evolution in graphite before and after irradiation, as well as after annealing, were studied with different characterization methods. A method for the measurement of diffusion coefficients of fission products’ diffusion in graphite using Rutherford backscattering spectrometry (RBS) was also reported. The SSNG substrates were implanted with Xe at a dose of 4.8 × 10¹⁵ ions/cm² and energy of 7 MeV. The RT-implanted samples were annealed in a vacuum at 650 °C for 9 h. The implanted and annealed samples were characterized using RBS. The diffusion coefficient D (Xe, 650 °C) was 6.49 × 10⁻²⁰ m²/s. The results indicate SSNG’s excellent ability to inhibit Xe diffusion and are significant for designing and evaluating the safety of nuclear reactors.

The economics and safety of reactors can be affected by the diffusion of fission products into graphite. Xenon (Xe) fission products diffusing into the graphite is the most critical neutron absorber and poison that can slow down or stop the chain reaction. The transport parameters for inhibiting the xenon diffusion in graphite are therefore the utmost scientific problem. Self-sintered nanopore-isotropic (~ 40nm) graphite (SSNG) derived from green pitch coke can decrease Xe diffusion into the graphite. In this study, a method for measurement of diffusion coefficients of fission products diffusion in graphite by Rutherford backscattering spectrometry (RBS) was reported. The SSNG substrates were implanted with Xe at a dose of 4.8×1015 ions/cm2 and energy of 7 MeV. The RT-implanted samples were annealed in a vacuum at 650°C for 9 h. The implanted and annealed samples were characterized by RBS. The diffusion coefficient D(Xe,650°C) is 6.49×10-20 m2/s. The results indicate the excellent ability to inhibit Xe diffusion of the SSNG and present significance in designing and evaluating the safety of nuclear reactors.

In this work, a series of high-performance graphite foams (GFs) were synthesized using a melamine foam (MF) template-assisted strategy, which employed AR mesophase pitch (AR MP) as the carbon precursor and airflow was applied to achieve orientation and solidification in the MF network combined with carbonization and graphitization. The results show that the thermal conductivity, compressive strength, and graphitization degree of GFs increase with an increase in AR MP slurry concentration. In contrast, the electromagnetic interference shielding effectiveness (EMI SE) and porosity exhibit an opposite trend. When the concentration was 70 wt%, GF-70 displays isotropic thermal conductivity reaching up to 74.29 W m⁻¹ K⁻¹ in-plane and 76.27 W m⁻¹ K⁻¹ through-plane. Meanwhile, it also shows an EMI SE of 35 dB in the X-band. However, when the concentration drops to 40 wt%, the EMI SE of GF-40 reaches 71 dB, and thermal conductivities of 32.13 W m⁻¹ K⁻¹ and 31.46 W m⁻¹ K⁻¹ in two planes have been achieved in GF-40. The isotropic performance of GFs is related to the structure of the template. At the same time, the superior thermal conductivity of GFs is attributed to the ligaments of a parallel arrangement. The outstanding electromagnetic shielding effectiveness (EMI SE) is ascribed to the porous structure's multiple reflections and repeated scattering. This strategy of the adjustable combination of thermal conductivity and EMI SE paves the way for dual-function thermal management materials.