Wu Pengfei, Guo Changqing, Han Jiangtao, Yu Kairui, Dong Xichao, Yue Guanghui, Yue Huijuan, Guan Yan, Liu Anhua
College of Materials, Key Laboratory of High Performance Ceramic Fibers, Xiamen University Xiamen 361005 China
College of Materials, Fujian Key Laboratory of Advanced Materials, Xiamen University Xiamen 361005 China.
RSC Adv. 2018 Mar 1;8(17):9094-9102. doi: 10.1039/c7ra13606d. eCollection 2018 Feb 28.
Yolk-shell structure is considered to be a well-designed structure of silicon-based anode. However, there is only one point (point-to-point contact) in the contact region between the silicon core and the shell in this structure, which severely limits the ion transport ability of the electrode. In order to solve this problem, it is important that the core and shell of the core-shell structure are closely linked (face-to-face contact), which ensures good ion diffusion ability. Herein, a double core-shell nanostructure (Si@C@SiO) was designed for the first time to improve the cycling performance of the electrode by utilising the unique advantages of the SiO layer and the closely contacted carbon layer. The improved cycling performance was evidenced by comparing the cycling properties of similar yolk-shell structures (Si@void@SiO) with equal size of the intermediate shell. Based on the comparison and analysis of the experimental data, Si@C@SiO had more stable cycling performance and exceeded that of Si@void@SiO after the 276 cycle. More interestingly, the electron/ion transport ability of electrode was further improved by combination of Si@C@SiO with reduced graphene oxide (RGO). Clearly, at a current density of 500 mA g, the reversible capacity was 753.8 mA h g after 500 cycles, which was 91% of the specific capacity of the first cycle at this current density.
蛋黄壳结构被认为是硅基负极的一种精心设计的结构。然而，在这种结构中，硅核与壳层的接触区域仅存在一个点（点对点接触），这严重限制了电极的离子传输能力。为了解决这个问题，核壳结构的核与壳紧密连接（面对面接触）很重要，这确保了良好的离子扩散能力。在此，首次设计了一种双核壳纳米结构（Si@C@SiO），通过利用SiO层和紧密接触的碳层的独特优势来提高电极的循环性能。通过比较具有相同尺寸中间壳的类似蛋黄壳结构（Si@void@SiO）的循环性能，证明了循环性能得到了改善。基于对实验数据的比较和分析，Si@C@SiO具有更稳定的循环性能，在第276次循环后超过了Si@void@SiO。更有趣的是，通过将Si@C@SiO与还原氧化石墨烯（RGO）结合，电极的电子/离子传输能力进一步提高。显然，在500 mA g的电流密度下，500次循环后的可逆容量为753.8 mA h g，这是该电流密度下第一循环比容量的91%。
