Kim Young-Hoon, An Jae-Hyun, Kim Sung-Yeob, Li Xiangmei, Song Eun-Ji, Park Jae-Ho, Chung Kyung Yoon, Choi Yong-Seok, Scanlon David O, Ahn Hyo-Jun, Lee Jae-Chul
Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea.
Department of Materials Engineering and Convergence Technology, Gyeongsang National University, Jinju, 52828, South Korea.
Adv Mater. 2022 Jul;34(27):e2201446. doi: 10.1002/adma.202201446. Epub 2022 Jun 2.
It is challenging to develop alloying anodes with ultrafast charging and large energy storage using bulk anode materials because of the difficulty of carrier-ion diffusion and fragmentation of the active electrode material. Herein, a rational strategy is reported to design bulk Bi anodes for Na-ion batteries that feature ultrafast charging, long cyclability, and large energy storage without using expensive nanomaterials and surface modifications. It is found that bulk Bi particles gradually transform into a porous nanostructure during cycling in a glyme-based electrolyte, whereas the resultant structure stores Na ions by forming phases with high Na diffusivity. These features allow the anodes to exhibit unprecedented electrochemical properties; the developed Na-Bi half-cell delivers 379 mA h g (97% of that measured at 1C) at 7.7 A g (20C) during 3500 cycles. It also retained 94% and 93% of the capacity measured at 1C even at extremely fast-charging rates of 80C and 100C, respectively. The structural origins of the measured properties are verified by experiments and first-principles calculations. The findings of this study not only broaden understanding of the underlying mechanisms of fast-charging anodes, but also provide basic guidelines for searching battery anodes that simultaneously exhibit high capacities, fast kinetics, and long cycling stabilities.
由于载流子离子扩散困难以及活性电极材料破碎，使用块状阳极材料开发具有超快充电和大储能能力的合金化阳极具有挑战性。在此，我们报道了一种合理的策略，用于设计钠离子电池的块状铋阳极，该阳极具有超快充电、长循环寿命和大储能能力，且无需使用昂贵的纳米材料和表面改性。研究发现，在基于甘醇二甲醚的电解质中循环时，块状铋颗粒逐渐转变为多孔纳米结构，而所得结构通过形成具有高钠扩散率的相来存储钠离子。这些特性使阳极表现出前所未有的电化学性能；所开发的钠-铋半电池在3500次循环中，在7.7 A g（20C）下的放电容量为379 mA h g（为1C下测量值的97%）。即使在80C和100C的极快充率下，它分别保持了1C下测量容量的94%和93%。通过实验和第一性原理计算验证了所测性能的结构起源。这项研究的结果不仅拓宽了对快充阳极潜在机制的理解，还为寻找同时具有高容量、快速动力学和长循环稳定性的电池阳极提供了基本指导。
