Song Shugui, Li Jingcang, Zheng Anqi, Yang Yongqiang, Yin Kuibo
SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China.
National Graphene Products Quality Supervision and Inspection Center (Jiangsu), Jiangsu Province Special Equipment Safety Supervision Inspection Institute, Wuxi 214174, China.
Molecules. 2021 May 27;26(11):3211. doi: 10.3390/molecules26113211.
To address the challenge of the huge volume expansion of silicon anode, carbon-coated silicon has been developed as an effective design strategy due to the improved conductivity and stable electrochemical interface. However, although carbon-coated silicon anodes exhibit improved cycling stability, the complex synthesis methods and uncontrollable structure adjustment still make the carbon-coated silicon anodes hard to popularize in practical application. Herein, we propose a facile method to fabricate sponge-like porous nano carbon-coated silicon (sCCSi) with a tunable pore structure. Through the strategy of adding water into precursor solution combined with a slow heating rate of pre-oxidation, a sponge-like porous structure can be formed. Furthermore, the porous structure can be controlled through stirring temperature and oscillation methods. Owing to the inherent material properties and the sponge-like porous structure, sCCSi shows high conductivity, high specific surface area, and stable chemical bonding. As a result, the sCCSi with normal and excessive silicon-to-carbon ratios all exhibit excellent cycling stability, with 70.6% and 70.2% capacity retentions after 300 cycles at 500 mA g, respectively. Furthermore, the enhanced buffering effect on pressure between silicon nanoparticles and carbon material due to the sponge-like porous structure in sCCSi is further revealed through mechanical simulation. Considering the facile synthesis method, flexible regulation of porous structure, and high cycling stability, the design of the sCCSi paves a way for the synthesis of high-stability carbon-coated silicon anodes.
为应对硅阳极巨大的体积膨胀挑战，碳包覆硅作为一种有效的设计策略得以开发，这归因于其导电性的改善和稳定的电化学界面。然而，尽管碳包覆硅阳极展现出了提高的循环稳定性，但复杂的合成方法和不可控的结构调整仍使得碳包覆硅阳极难以在实际应用中推广。在此，我们提出一种简便的方法来制备具有可调孔结构的海绵状多孔纳米碳包覆硅（sCCSi）。通过将水加入前驱体溶液并结合预氧化的缓慢加热速率的策略，可以形成海绵状多孔结构。此外，多孔结构可通过搅拌温度和振荡方法进行控制。由于其固有的材料特性和海绵状多孔结构，sCCSi具有高导电性、高比表面积和稳定的化学键合。结果，具有正常和过量硅碳比的sCCSi均表现出优异的循环稳定性，在500 mA g下循环300次后容量保持率分别为70.6%和70.2%。此外，通过力学模拟进一步揭示了sCCSi中海绵状多孔结构对硅纳米颗粒与碳材料之间压力的增强缓冲作用。考虑到简便的合成方法、多孔结构的灵活调控以及高循环稳定性，sCCSi的设计为高稳定性碳包覆硅阳极的合成铺平了道路。
