Hierarchical yolk?shell SiOx@TiO2@C nanospheres were prepared via a facile sol?gel method combined with carbon coating. The unique structure possessing a suitable void space between yolk and shell can accommodate the volume expansion of the SiOx core; the lithiation products of STC3 including LimTiO2, LinSi, and LizC6 are reversible, and exhibit excellent electrochemical performance.This work reports the preparation of unique hierarchical yolk/double?shelled SiOx@TiO2@C nanospheres with different voids by a facile sol?gel method combined with carbon coating. In the preparation process, SiOx nanosphere is used as a hard template. Etch time of SiOx yolk affects the morphology and electrochemical performance of SiOx@TiO2@C. With the increase in etch time, the yolk/double?shelled SiOx@TiO2@C with 15 and 30?nm voids and the TiO2@C hollow nanospheres are obtained. The yolk/double?shelled SiOx@TiO2@C nanospheres exhibit remarkable lithium?ion battery performance as anodes, including high lithium storage capacity, outstanding rate capability, good reversibility, and stable long?term cycle life. The unique structure can accommodate the large volume change of the SiOx yolk, provide a unique buffering space for the discharge/charge processes, improve the structural stability of the electrode material during repeated Li+ intercalation/deintercalation processes, and enhance the cycling stability. The SiOx@TiO2@C with 30?nm void space exhibits a high discharge specific capacity of ?1195.4?mA?h?g?1 at the current density of 0.1?A?g?1 after 300?cycles and ?701.1?mA?h?g?1 at 1?A?g?1 for over 800 cycles. These results suggest that the proposed particle architecture is promising and may have potential applications in improving various high performance anode materials.

» Author: Qinghua Gong, Haiqing Wang, Wenhua Song, Bin Sun, Pei Cao, Shaonan Gu, Xuefeng Sun, Guowei Zhou

» Reference: doi:10.1002/chem.202003246

» Publication Date: 03/12/2020

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