Silica/Carbon Composites with Controllable Nanostructure from a Facile One‐Step Method for Lithium‐Ion Batteries Application
Silica/Carbon Composites with Controllable Nanostructure from a Facile One‐Step Method for Lithium‐Ion Batteries Application
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DOI：
10.1002/admi.201801809
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发表时间：
2019-01
影响因子：
5.4
通讯作者：
Xiaoqing Yang;Hong Ma;Guoqing Zhang;Xinxi Li
中科院分区：
文献类型：
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作者：
Xiaoqing Yang;Hong Ma;Guoqing Zhang;Xinxi Li
纳米二氧化硅因其比硅更好的循环稳定性和更低的成本而在锂离子电池中引起了人们的关注。然而，在二氧化硅与碳的偶联过程中，不可控和不均匀的纳米结构出现了重大挑战。本文利用氢氟酸控制正硅酸乙酯凝胶化过程的机理，制备了一系列纳米结构可调的二氧化硅/碳(S/C)复合材料。通过改变HF/TEOS的比例，可以精确地调整复合材料的二氧化硅骨架尺寸、比表面积和孔隙率。结果表明，二氧化硅粒径为≈9 nm，比表面积为208m2 g−1，总孔容为0.24cm3g−1的S/C复合材料具有最佳的储锂性能，其比容量为820mAhg−1，循环性能和高倍率性能较好。这可归因于以下原因：1)合适的≈9 nm的二氧化硅尺寸在保持二氧化硅骨架稳定的同时使Li+的迁移距离最小；2)刚性的连续碳骨架起到导电骨架的作用，限制了二氧化硅的聚集和体积变化；3)多孔结构起到了缓冲体积变化和促进电解质转移的作用。
Nanosized silica is drawing attentions in lithium‐ion batteries because of its better cycling stability and lower cost compared to silicon. However, significant challenges appear at the uncontrollable and inhomogeneous nanostructure while coupling silica with carbon. Herein, a series of silica/carbon (S/C) composites with tunable nanostructure are developed based on the mechanism that hydrofluoric acid (HF) can control the gelating process of tetraethylorthosilicate (TEOS). By changing the HF/TEOS ratio, the size of the silica skeleton, surface area and porosity of the composites can be tailored precisely. As a result, the optimal lithium storage performance is obtained on the S/C composite with a silica size of ≈9 nm, surface area of 208 m2 g−1, and total pore volume of 0.24 cm3 g−1, including a specific capacity of 820 mAh g−1, superior cycling performance, and high‐rate capability. This can be attributed to the following reasons: 1) the suitable silica size of ≈9 nm simultaneously minimizes the Li+ migrating distance while maintaining the stability of the silica skeleton; 2) the rigid continuous carbon framework acts as a conductive skeleton and restricts the aggregation and volume change of the silica; 3) the porous structure plays roles in buffering the volume change and facilitating the electrolyte transfer.