Space-Confined MoS2 in Gradient-Structured Carbon Spheres for Ultra-Stable Sodium-Ion Storage

Abstract

Rational design of electrode architectures that simultaneously facilitate rapid ion diffusion and ensure structural stability remains a critical challenge for sodium ion batteries (SIBs). To address this, a novel gradient pore-directed confinement strategy to construct MoS₂ nanosheets within a 3D ordered mesoporous carbon matrix (MoS₂@MC) is developed. This unique architecture guides the uniform growth of MoS₂, establishing continuous conductive networks for efficient electron transfer, creating graded ion-diffusion channels for reduced energy barriers, and providing robust mechanical buffers to mitigate volume expansion. As a result, the optimized MoS₂@MC-3-II delivers outstanding cycling stability (290.4 mAh g⁻¹ after 2500 cycles at 5 A g⁻¹) and high-rate capability. The in-situ X-ray diffraction (XRD), ex-situ X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron microscopy (HRTEM) analyses reveal a reversible conversion mechanism of MoS₂@MC. Furthermore, Na₃V₂(PO₄)₃//MoS₂@MC-3-II coin-type full cells show stable cycling performance, demonstrating the practical viability of this strategy for advanced SIBs.