This research employed the powder-in-tube (PIT) method to facilitate the introduction of the non-metallic element iodine (I) into the preparation of Nb 3 Al superconducting wires. After heating in a tube furnace, a rapid heating, quenching, and transformation (RHQT) treatment was conducted. It was observed that as the quantity of iodine introduced increased, the extent of the Nb/Al reaction also rose, indicating that a certain amount of iodine can be introduced to facilitate the Nb/Al reaction, thereby enabling Nb to react more fully with Al in the subsequent process and generating a Nb 3 Al superconducting phase that is closer to the stoichiometric ratio. Wires with iodine contents of 1.0 wt%, 1.5 wt%, and 2.0 wt% exhibited a diffusion layer at the Nb/Al interface after heating in a tube furnace at 1000 °C for 30 min. The primary component of the diffusion layer was Nb 2 Al. No diffusion layer was observed in the pure sample or in the group with 0.5 wt% I. However, a eutectic phase was present at the edge of Nb and Al. The wires with 1.0 wt% and 1.5 wt% I exhibited higher critical temperatures ( T c ) of 18.236 K and 17.421 K, respectively, than the pure sample. Additionally, they demonstrated superior critical current density ( J c ) properties compared to the pure sample.
Fangfang Dong,Shengrui Cui,Chengliang Lin,Xin Wan,Ning Wang,Xiang Huang,Wei Liu,Yongcheng Jin
The insufficient structural stability of high-voltage spinel cobalt-free LiNi 0.5 Mn 1.5 O 4 (LNMO) throughout the cycling process hinders its widespread application. To address these issues, we incorporate elemental iodine into LNMO during the precursor preparation process using an ethanol-assisted hydrothermal method and successfully modify the bulk and interface coating structure of LNMO-3% I 2 . The incorporation of iodine not only induces the formation of a cavity and fast lithium-ion transfer pathway within the particles but also facilitates the development of a thin LiI coating layer on the surface of cathode materials. Compared with bared LNMO, LNMO-3% I 2 exhibits a capacity retention of 90.31% following 500 cycles at 1C and a capacity retention of 88.74% even following 450cycles at a high-rate of 50C. Furthermore, the cells with LNMO-3% I 2 demonstrate an excellent electrochemical performance under both high temperatures of 40 ℃ and low temperatures of −15 ℃. This study offers valuable insights into the simultaneous optimization of internal and external structures in cathode materials, thereby enhancing the long-term cycling performance of high-voltage lithium-ion batteries.
Because of its high density, a carbon microsphere is a good candidate for ultrahigh volumetric capacity electrode materials. We find that the synergistic effects of nitrogen and iodine element can tremendously improve the carbon electrode capacity. Here, we present a high volumetric capacity anode consisting of iodine and nitrogen codoping carbon microspheres synthesized by a low-temperature solvothermal route. A reversible capacity of 1418 mAh cm–3, which is much larger than that of commercial graphitic carbon anode, is achieved at a current density of 0.05 mA cm–2 by using these carbon microspheres as anode material. After 100 charge–discharge cycles at 0.1 mA cm–2 and 500 charge–discharge cycles at 1 mA cm–2, carbon microspheres retained volumetric capacities of 1335 and 1090 mAh cm–3, respectively
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