CaH2 热还原 Si 制备多孔 Si/Ca-Si-O 纳米复合储锂材料,Journal of Energy Storage

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CaH2 热还原 Si 制备多孔 Si/Ca-Si-O 纳米复合储锂材料
Journal of Energy Storage ( IF 8.9 ) Pub Date : 2024-04-19 , DOI: 10.1016/j.est.2024.111641
Donghan Youn , Nam Gyu Kim , Ji Young Kim , Seung Tae Kim , Dong Jae Chung , Hansu Kim

一氧化硅 (SiO) 基阳极材料是研究最深入的一类材料，可用作锂离子电池的高容量阳极。然而，由于SiO中的非晶SiO（a-SiO）相发生不可逆电化学反应，导致其初始库仑效率（ICE）较低，限制了SiO基负极材料在锂离子电池中的广泛采用。在电池组装之前预先形成不可逆相，将 a-SiO2 转化为与锂不反应的状态，这对于增强 ICE 引起了广泛关注。然而，该工艺存在不能保证长期循环性能的缺点。在此，提出了不可逆相的预先形成与高能机械铣削（HEMM）工艺相结合，以同时提高ICE和长期循环性能。由此产生的多孔 Si/Ca-Si-O 纳米复合电极的 ICE 高达 86.4%，并在 200 次循环后仍保持 55% 的容量。 ICE 显着改善的关键因素是不可逆的 Ca-Si-O 相，它是由 Si 与 CaH 热热还原形成的。此外，HEMM工艺引起的微观结构变化有效减轻了循环过程中Si的体积膨胀，从而提高了长期循环稳定性。

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Porous Si/Ca-Si-O nanocomposite lithium storage materials by calciothermic reduction of Si with CaH2

Silicon monoxide (SiO)-based anode materials are one of the most intensively investigated class of materials for use as high-capacity anodes in lithium-ion batteries. However, their low initial Coulombic efficiency (ICE), resulting from the irreversible electrochemical reaction of the amorphous SiO (a-SiO) phase in the SiO, restricts the wide-spread adoption of SiO-based anode materials in lithium-ion batteries. Pre-emptive formation of an irreversible phase that converts a-SiO to a non-reactive state with lithium prior to cell assembly has received much attention for enhancing ICE. However, this process has the drawback of not ensuring long-term cycle performance. Herein, the pre-emptive formation of irreversible phase combined with the high-energy mechanical milling (HEMM) process is proposed to simultaneously improve both the ICE and long-term cycle performance. The resulting porous Si/Ca-Si-O nanocomposite electrode exhibits an impressive ICE of 86.4 % and maintains 55 % of its capacity over 200 cycles. The key factor in the significant ICE improvement is the irreversible Ca-Si-O phase, which is formed by the calciothermic reduction of Si with CaH. In addition, the microstructural changes induced by the HEMM process effectively mitigate the volume expansion of Si during cycling, resulting in improved long-term cycle stability.

更新日期：2024-04-19

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