An innovative strategy for constructing multicore yolk-shell Si/C anodes for lithium-ion batteries

Abstract

The yolk-shell architecture offers a promising solution to the challenges of silicon (Si) anodes in lithium-ion batteries (LIBs), particularly in addressing the significant volume changes that occur during charge and discharge cycles. However, traditional construction methods often rely on sacrificial templates and acid or alkali etching, which limits industrial applicability. In this work, we successfully constructed a silicon/carbon (Si/C) composite with a multicore yolk-shell structure using scalable spray drying technology and in-situ growth of metal–organic frameworks (MOFs) at room temperature. By controlling the spray drying parameters and the size of the MOF, we achieved a controllable adjustment of cavity size and shell integrity without the need for sacrificial templates, facilitating large-scale preparation. Electrochemical characterization shows that the composites exhibit impressive performance, achieving a reversible specific capacity of 1,054.5 mAh g⁻¹ after 100 cycles at 0.5 A g⁻¹, and retaining 734.8 mAh g⁻¹ after 400 cycles at 1 A g⁻¹. Moreover, finite element analysis (FEA) revealed another reason why the yolk-shell structure improves the performance of Si anodes: the presence of cavities promotes ion diffusion processes. This study provides a new synthetic paradigm for preparing Si-C composite materials with yolk shell structure and offers new insights into the improvement mechanism of this structure.