Yang Hai, Chen Lin-Wei, He Fuxiang, Zhang Jiaqing, Feng Yuezhan, Zhao Lukang, Wang Bin, He Lixin, Zhang Qiaobao, Yu Yan
Hefei National Laboratory for Physical Sciences at the Microscale, Department of Materials Science and Engineering , University of Science and Technology of China, Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences (CAS) , Hefei , Anhui 230026 , China.
Key Laboratory of Quantum Information , University of Science and Technology of China , Hefei , Anhui 230026 , China.
Nano Lett. 2020 Jan 8;20(1):758-767. doi: 10.1021/acs.nanolett.9b04829. Epub 2019 Dec 26.
Bismuth (Bi) has been demonstrated as a promising anode for Na-ion batteries (NIBs) because it has high gravimetry (386 mA h g) and volumetric capacity (3800 mA h cm). However, Bi suffers from large volume expansion during sodiation, leading to poor electrochemical performance. The construction of a nanostructure with sufficient void space to accommodate the volume change has been proven effective for achieving prolonged cycling stability. However the excessive void space will definitely decrease the volumetric energy density of the battery. Herein, we design optimized Bi@Void@C nanospheres (Bi@Void@C-2) with yolk-shell structure that exhibit the best cycling performance and enhanced volumetric energy density. The optimized void space not only could buffer the volume change of the Bi nanosphere but also could keep the high volumetric energy density of the battery. The Bi@Void@C-2 shows an excellent rate capacity of 173 mA h g at ultrahigh current density of 100 A g and long-cycle life (198 mA h g at 20 A g over 10 000 cycles). The origin of the superior performance is achieved through in-depth fundamental studies during battery operation using X-ray diffraction (XRD) and transmission electron microscope (TEM), complemented by theoretical calculations and TEM observation. Our rational design provides insights for anode materials with large volume variation, especially for conversion type and alloying type mechanism materials for batteries (i.e., Li-ion batteries, Na-ion batteries).
铋（Bi）已被证明是一种很有前景的钠离子电池（NIBs）负极材料，因为它具有较高的重量比容量（386 mA h g）和体积比容量（3800 mA h cm）。然而，铋在 sodiation 过程中会发生较大的体积膨胀，导致电化学性能较差。构建具有足够空隙空间以适应体积变化的纳米结构已被证明对实现长期循环稳定性有效。然而，过多的空隙空间肯定会降低电池的体积能量密度。在此，我们设计了具有蛋黄壳结构的优化Bi@Void@C纳米球（Bi@Void@C-2），其表现出最佳的循环性能和提高的体积能量密度。优化后的空隙空间不仅可以缓冲铋纳米球的体积变化，还可以保持电池的高体积能量密度。Bi@Void@C-2在100 A g的超高电流密度下表现出173 mA h g的优异倍率性能和长循环寿命（在20 A g下循环10000次后为198 mA h g）。通过在电池运行过程中使用X射线衍射（XRD）和透射电子显微镜（TEM）进行深入的基础研究，并辅以理论计算和TEM观察，实现了优异性能的起源。我们的合理设计为具有大体积变化的负极材料提供了见解，特别是对于电池（即锂离子电池、钠离子电池）的转换型和合金化型机理材料。
