Boosting the cell performance of the SiO<sub><i>x</i></sub>@C anode material via rational design of a Si‐valence gradient
Jianming Tao, Zerui Yan, Jiangshao Yang, Jiaxin Li, Yingbin Lin, Zhigao Huang
Abstract
Abstract Relieving the stress or strain associated with volume change is highly desirable for high‐performance SiO x anodes in terms of stable solid electrolyte interphase (SEI)‐film growth. Herein, a Si‐valence gradient is optimized in SiO x composites to circumvent the large volume strain accompanied by lithium insertion/extraction. SiO x @C annealed at 850°C has a gentle Si‐valence gradient along the radial direction and excellent electrochemical performances, delivering a high capacity of 506.9 mAh g −1 at 1.0 A g −1 with a high Coulombic efficiency of ~99.8% over 400 cycles. Combined with the theoretical prediction, the obtained results indicate that the gentle Si‐valence gradient in SiO x @C is useful for suppressing plastic deformation and maintaining the inner connection integrity within the SiO x @C particle. Moreover, a gentle Si‐valence gradient is expected to form a stress gradient and affect the distribution of dangling bonds, resulting in local stress relief during the lithiation/delithiation process and enhanced Li‐ion kinetic diffusion. Furthermore, the lowest interfacial stress variation ensures a stable SEI film at the interface and consequently increases cycling stability. Therefore, rational design of a Si‐valence gradient in SiO x can provide further insights into achieving high‐performance SiO x anodes with large‐scale production.