A Unique Structure of Highly Stable Interphase and Self-Consistent Stress Distribution Radial-Gradient Porous for Silicon Anode

Stress failure and continued growth of the solid electrolyte interface are the main factors contributing to the failure of lithium-ion batteries with silicon (Si) anode. Conventional porous structures typically result in a reduction in the strength and tap density of Si materials. Due to the high melting point and chemical stability of Si, there are limited methods to prepare its porous structure. Here, a method for preparing core–shell gradient porous Si with a high-strength core and a high-porosity shell is presented. The high-strength core can withstand enormous volume change stress. The rich porous structure of the shell ensures the stable existence of SEI. The Si anode material with a core–shell gradient porous structure delivers a discharge capacity of 2127 mAh g −1 (1488 mAh cm −3 ) after 100 cycles at 1 A g −1 , cycling stability with more than 1059 mAh g −1 even after 500 cycles at 2 A g −1 , and a rate capability of 1916 mAh g −1 at 4 A g −1 . These results suggest that the core–shell gradient porous structure provides a new research strategy to address the stress rupture and continuous SEI growth in Si-based anode materials during charge/discharge.