Tunable Synthesis of Hierarchical Yolk/Double‐Shelled SiOx@TiO2@C Nanospheres for High‐Performance Lithium‐Ion Batteries

Abstract This work reports the preparation of unique hierarchical yolk/double‐shelled SiO x @TiO 2 @C nanospheres with different voids by a facile sol‐gel method combined with carbon coating. In the preparation process, SiO x nanosphere is used as a hard template. Etch time of SiO x yolk affects the morphology and electrochemical performance of SiO x @TiO 2 @C. With the increase in etch time, the yolk/double‐shelled SiO x @TiO 2 @C with 15 and 30 nm voids and the TiO 2 @C hollow nanospheres are obtained. The yolk/double‐shelled SiO x @TiO 2 @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 SiO x 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 SiO x @TiO 2 @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.