Wu Feng, Dong Yu, Su Yuefeng, Wei Chenxi, Chen Tongren, Yan Wengang, Ma Siyuan, Ma Liang, Wang Bin, Chen Lai, Huang Qing, Cao Duanyun, Lu Yun, Wang Meng, Wang Lian, Tan Guoqiang, Wang Jionghui, Li Ning
Beijing Key Laboratory of Environmental Science and Engineering, School of Material Science and Engineering, Beijing Institute of Technology, Beijing, 100081, China.
Beijing Institute of Technology Chongqing Innovation Center, Chongqing, 401120, China.
Small. 2023 Oct;19(42):e2301301. doi: 10.1002/smll.202301301. Epub 2023 Jun 20.
High-capacity silicon has been regarded as one of the most promising anodes for high-energy lithium-ion batteries. However, it suffers from severe volume expansion, particle pulverization, and repeated solid electrolyte interphase (SEI) growth, which leads to rapid electrochemical failure, while the particle size also plays key role here and its effects remain elusive. In this paper, through multiple-physical, chemical, and synchrotron-based characterizations, the evolutions of the composition, structure, morphology, and surface chemistry of silicon anodes with the particle size ranging from 50 to 5 µm upon cycling are benchmarked, which greatly link to their electrochemical failure discrepancies. It is found that the nano- and micro-silicon anodes undergo similar crystal to amorphous phase transition, but quite different composition transition upon de-/lithiation; at the same time, the nano- and 1 µm-silicon samples present obviously different mechanochemical behaviors from the 5 µm-silicon sample, such as electrode crack, particle pulverization/crack as well as volume expansion; in addition, the micro-silicon samples possess much thinner SEI layer than the nano-silicon samples upon cycling, and also differences in SEI compositions. It is hoped this comprehensive study and understanding should offer critical insights into the exclusive and customized modification strategies to diverse silicon anodes ranging from nano to microscale.
高容量硅被认为是高能锂离子电池最有前景的负极材料之一。然而，它存在严重的体积膨胀、颗粒粉碎以及固态电解质界面（SEI）的反复生长问题，这会导致快速的电化学失效，而颗粒尺寸在此也起着关键作用，但其影响仍不明确。在本文中，通过多种物理、化学以及基于同步加速器的表征方法，对粒径在50至5微米范围内的硅负极在循环过程中其组成、结构、形态和表面化学的演变进行了基准测试，这与它们的电化学失效差异密切相关。研究发现，纳米硅和微米硅负极经历了相似的从晶相到非晶相的转变，但在脱锂/锂化过程中的组成转变却大不相同；同时，纳米硅和1微米硅样品与5微米硅样品呈现出明显不同的机械化学行为，如电极开裂、颗粒粉碎/破裂以及体积膨胀；此外，在循环过程中，微米硅样品的SEI层比纳米硅样品薄得多，并且SEI组成也存在差异。希望这项全面的研究和理解能够为从纳米到微米尺度的各种硅负极的专属定制改性策略提供关键见解。
