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

Abstract

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.

Design of SiO x /TiO2@C hierarchical structure for efficient lithium storage

“…As a result, the volume change brought on by nano-silicon and Li + alloy/dealloying can be reduced from the inside of the material. Additionally, it works in tandem with the carbon layer to strengthen the stability of the electrode material structure; in addition, the lithium titanate created when Li + and TiO 2 react possesses a fairly large ion diffusion coefficient (2 × 10 −8 cm −2 s −1 ), and that may efficiently speed up the rate at which ions diffuse through the composite, shorten the ion transport radius [55], and deepen the depth of the reaction with Li + . The rate performance of the SiO x , SiO x @C, and SiO x /TiO 2 @C electrode materials is examined in figure 7(c).…”

Rational design of SiOx based anode materials for next generation lithium-ion batteries

“…After 550 cycles, there is an initial reversible specific capacity of 1093 mA h g −1 at 0.2 A g −1 . Similarly, Gong et al 107 reported a unique SiO x @TiO 2 @C negative electrode material. Tetrabutyl titanate was hydrolysed to coat TiO 2 on the surface of SiO x by the sol–gel method, and phenolic resin was formed on the surface of SiO x by the reaction between resorcinol and formaldehyde, and a carbon shell was formed after calcination.…”

Influence of carbon sources on silicon oxides for lithium-ion batteries: a review

“…Resorcinol–formaldehyde (RF) resin is commonly used as a carbon source for preparation of SiO x /C composites due to its low cost and simple synthesis. 44,86–96 Recently, Li's group reported the synthesis of hollow-structured high-capacity SiO x nanocubes (NC@SiO x @m-C) as a LIB anode using a sequential coating strategy in conjunction with a self-sacrificial template method (Fig. 5a).…”