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38. Enhancing the Lithium Storage Performance of the Nb2O5Anode via Synergistic Engineering of Phase and Cu Doping

Author

Dong, Hao, Yao, Tianhao, Ji, Xin, Zhang, Qingmiao, Lin, Xiongfeng, Zhang, Binglin, Ma, Chuansheng, Meng, Lingjie, Chen, Yu, and Wang, Hongkang

Abstract

Nb2O5has been viewed as a promising anode material for lithium-ion batteries by virtue of its appropriate redox potential and high theoretical capacity. However, it suffers from poor electric conductivity and low ion diffusivity. Herein, we demonstrate the controllable fabrication of Cu-doped Nb2O5with orthorhombic (T–Nb2O5) and monoclinic (H–Nb2O5) phases through annealing the solvothermally presynthesized Nb2O5precursor under different temperatures in air, and the Cu doping amount can be readily controlled by the concentration of the precursor solution, whose effect on the lithium storage behaviors of the Cu-doped Nb2O5is thoroughly investigated. H–Nb2O5shows obvious redox peaks (Nb5+/Nb4+and Nb4+/Nb3+) with much higher capacity and better cycling stability than those for the widely investigated T–Nb2O5. When introducing appropriate Cu doping, the optimized H–Cu0.1–Nb2O5electrode shows greatly enhanced conductivity and lower diffusion barrier as revealed by the theoretical calculations and electrochemical characterizations, delivering a high reversible capacity of 203.6 mAh g–1and a high capacity retention of 140.8 mAh g–1after 5000 cycles at 1 A g–1, with a high initial Coulombic efficiency of 91% and a high rate capacity of 144.2 mAh g–1at 4 A g–1. As a demonstration for full-cell application, the H–Cu0.1–Nb2O5||LiFePO4cell displays good cycling performance, exhibiting a reversible capacity of 135 mAh g–1after 200 cycles at 0.2 A g–1. More importantly, this work offers a new synthesis protocol of the monoclinic Nb2O5phase with high capacity retention and improved reaction kinetics.

Published
2024
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41. Combustion Synthesis of Porous NiCuZn Spinel Ferrite Hierarchies and Their Magnetic Properties.

Author

Chen, Chuan, Qian, Sen, Zhang, Qiang, Zhang, Ximin, and Yao, Tianhao

Subjects
NICKEL ferrite, COPPER ferrite, SELF-propagating high-temperature synthesis, MAGNETIC properties, SPINEL, FERRITES, ELECTRICAL harmonics
Abstract

Nickel‐copper‐zinc (NiCuZn) spinel ferrites have attracted intensive research owing to their unique magnetic properties and low co‐fire temperature. Combustion synthesis has been viewed as a promising protocol for the large‐scale fabrication of NiCuZn spinel ferrites. However, the spinel ferrites prepared by this method usually suffer from limited saturation magnetization and high coercivity due to their large size, which will impose detrimental harmonics on electrical equipment (e. g. transformer, motor, etc.). To address these issues, highly porous NiCuZn spinel ferrite hierarchies were prepared within several hours through a modified solution combustion method, using glucose and ammonium nitrate as the fuel and combustion enhancer, respectively. The as‐obtained NiCuZn spinel ferrite hierarchies show excellent magnetic properties with a high saturation magnetization up to 62.61 emu/g and a low coercivity of 9.6 Oe thanks to the rational distribution of cations and grain size. More importantly, this method also allows various modifications (heteroatom doping) and large‐scale applications, which may be promising for the fabrication of high‐performance soft magnets for electrical equipment. [ABSTRACT FROM AUTHOR]

Published
2023
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