State Key Laboratory of Silicon Materials, Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province and School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China.
Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) , Nankai University , Tianjin 300071 , China.
ACS Appl Mater Interfaces. 2018 Jun 20;10(24):20591-20598. doi: 10.1021/acsami.8b05609. Epub 2018 Jun 7.
In this work, we report a novel reaction-ball-milling surface coating strategy to suppress the pulverization of microparticle Si anodes upon lithiation/delithiation. By energetically milling the partially prelithiated microparticle Si in a CO atmosphere, a multicomponent amorphous layer composed of SiO , C, SiC, and LiSiO is successfully coated on the surface of Si microparticles. The coating level strongly depends on the milling reaction duration, and the 12 h milled prelithiated Si microparticles (BM12h) under a pressure of 3 bar of CO exhibit a good conformal coating with 1.006 g cm of tap density. The presence of SiC remarkably enhances the mechanical properties of the SiO /C coating matrix with an approximately 4-fold increase in the elastic modulus and the hardness values, which effectively alleviates the global volume expansion of the Si microparticles upon lithiation. Simultaneously, the existence of LiSiO insures the Li-ion conductivity of the coating layer. Moreover, the SEI film formed on the electrode surface maintains relatively stable upon cycling due to the remarkably suppressed crack and pulverization of particles. These processes work together to allow the BM12h sample to offer much better cycling stability, as its reversible capacity remains at 1439 mAh g at 100 mA g after 100 cycles, which is nearly 4 times that of the pristine Si microparticles (381 mAh g). This work opens up new opportunities for the practical applications of micrometer-scale Si anodes.
在这项工作中，我们报告了一种新颖的反应球磨表面涂层策略，以抑制微颗粒硅负极在锂化/脱锂过程中的粉碎。通过在 CO 气氛中对部分预锂化的微颗粒 Si 进行高能球磨，成功地在 Si 微颗粒表面涂覆了由 SiO、C、SiC 和 LiSiO 组成的多相非晶层。涂层水平强烈依赖于研磨反应持续时间，在 3 巴 CO 压力下研磨 12 小时的预锂化 Si 微颗粒（BM12h）表现出良好的保形涂层，堆积密度为 1.006 g cm。SiC 的存在显著提高了 SiO/C 涂层基质的力学性能，弹性模量和硬度值约增加了 4 倍，有效缓解了 Si 微颗粒在锂化过程中的整体体积膨胀。同时，LiSiO 的存在确保了涂层层的锂离子电导率。此外，由于颗粒的裂纹和粉碎得到了显著抑制，电极表面形成的 SEI 膜在循环过程中保持相对稳定。这些过程共同作用，使 BM12h 样品具有更好的循环稳定性，其在 100 mA g 下 100 次循环后的可逆容量保持在 1439 mAh g，几乎是原始 Si 微颗粒（381 mAh g）的 4 倍。这项工作为实用化的微米级硅负极开辟了新的机会。
