Wang Jingbo, Cao Li, Li Songyuan, Xu Jiejie, Xiao Rongshi, Huang Ting
High-Power and Ultrafast Laser Manufacturing Lab, Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
Nanomaterials (Basel). 2023 Sep 11;13(18):2534. doi: 10.3390/nano13182534.
Si is a highly promising anode material due to its superior theoretical capacity of up to 3579 mAh/g. However, it is worth noting that Si anodes experience significant volume expansion (>300%) during charging and discharging. Due to the weak adhesion between the anode coating and the smooth Cu foil current collector, the volume-expanded Si anode easily peels off, thus damaging anode cycling performance. In the present study, a femtosecond laser with a wavelength of 515 nm is used to texture Cu foils with a hierarchical microstructure and nanostructure. The peeling and cracking phenomenon in the Si anode are successfully reduced, demonstrating that volume expansion is effectively mitigated, which is attributed to the high specific surface area of the nanostructure and the protection of the deep-ablated microgrooves. Moreover, the hierarchical structure reduces interfacial resistance to promote electron transfer. The Si anode achieves improved cycling stability and rate capability, and the influence of structural features on the aforementioned performance is studied. The Si anode on the 20 μm-thick Cu current collector with a groove density of 75% and a depth of 15 μm exhibits a capacity of 1182 mAh/g after 300 cycles at 1 C and shows a high-rate capacity of 684 mAh/g at 3 C.
硅是一种极具潜力的负极材料，因其高达3579 mAh/g的卓越理论容量。然而，值得注意的是，硅负极在充放电过程中会经历显著的体积膨胀（>300%）。由于负极涂层与光滑的铜箔集流体之间的附着力较弱，体积膨胀的硅负极容易剥离，从而损害负极的循环性能。在本研究中，使用波长为515 nm的飞秒激光对铜箔进行纹理化处理，使其具有分级微观结构和纳米结构。硅负极中的剥离和开裂现象成功减少，表明体积膨胀得到有效缓解，这归因于纳米结构的高比表面积以及深蚀刻微槽的保护作用。此外，分级结构降低了界面电阻，促进了电子转移。硅负极实现了更好的循环稳定性和倍率性能，并研究了结构特征对上述性能的影响。在20μm厚、沟槽密度为75%、深度为15μm的铜集流体上的硅负极，在1C下循环300次后容量为1182 mAh/g，在3C下显示出684 mAh/g的高倍率容量。
