Synergically enhancing lithium-ion storage performance of silicon anode by designing shelled structure with reduced graphene oxide and ZrO2

In this work, the Si@reduced graphene oxide/ZrO₂ (Si@rGO/ZrO₂) with the shelled structures is prepared for the high-capacity and stable lithium-ion batteries. The shelled structure not only significantly improves the electrical conductivity of the whole electrode, but also protects the inner Si nanoparticles (Si NPs) from rupturing and being damaged by undesired side reactions with the electrolyte. As a result, the Si@rGO/ZrO₂ anode delivers high initial discharge capacity of 3046 mAh·g⁻¹ at 1.0 A·g⁻¹. After 100 cycles, it can be maintained at 613 mAh·g⁻¹, which is much higher than that of either the pure Si NPs (31 mAh·g⁻¹) or the Si@rGO (261 mAh·g⁻¹). Even at 2 A·g⁻¹, it still provides superior specific capacity of 834 mAh·g⁻¹, while the pure Si anode merely possesses the capacity of 41 mAh·g⁻¹. Moreover, the density functional theory calculations point out that ZrO₂ layer can effectively enhance the adsorption energy of Li⁺ and optimize the migration paths of Li⁺, ensuring the electrochemical performance of Si@rGO/ZrO₂ composite anode. Furthermore, the Li⁺ storage mechanism and low volume expansion of Si@rGO/ZrO₂ anode is investigated by ex-situ X-ray photoelectron spectroscopy and morphological evolution upon cycling, respectively.

Graphical abstract