Engineering vacancy-rich van der Waals heterostructures in high-conductivity carbon networks for ultrastable sodium...

Rational design and application of high performance anodes are crucial for advancing sodium-ion batteries (SIBs). In this work, the 3D Mo-ZIF-L is subjected to a directional cross-linking process, followed by g-C₃N₄ incorporation to modify the self-assembled precursor, ultimately yielding a high-conductivity carbon material. Subsequently, bimetallic selenide (ZnSe/MoSe₂) is successfully loaded onto the carbon surface via chemical vapor deposition. This strategy simultaneously created van der Waals (vdW) heterostructures and abundant vacancies while alleviating volume expansion during cycling, endowing the ZnSe/MoSe₂-C@g-C₃N₄ (ZMSCN) with stable sodium storage ability (358.4 mAh g^-1 after 3000 cycles at 5 A g^-1). The remarkable performance originates from enhanced charge transfer at p-type/n-type heterointerfaces, which provides high capacitive contribution and rational Na⁺ adsorption energy. Furthermore, ZMSCN features dynamic heterostructures and vacancies evolution, with in-situ characterizations confirming charge transfer-controlled reaction kinetics and carbon matrix-dominated Na⁺ gradient diffusion, along with stable solid electrolyte interface (SEI) film ionic transport kinetics. Therefore, ZMSCN//NVP delivers an outstanding reversible capacity of 375.6 mAh g^-1 at 0.5 A g^-1 while maintaining 118.6 mAh g^-1 after 700 cycles at 5 A g^-1. This work provides fundamental insights into heterostructures engineering and vacancies modulation, demonstrating a viable pathway for developing practical anodes for SIBs.