Structural confinement of ZnTe/CoTe2 heterostructures anchored on carbon nanotubes for ultralong Na-ion storage

Owing to the high theoretical capacity, multi-electron reactions and semimetallic characteristics, metal tellurides present promising potential for sodium-ion storage. Yet structural collapse and capacity degradation remain inevitable. In this work, a structural confinement strategy was employed to fabricate zinc-telluride/cobalt-telluride heterostructures (ZnTe/CoTe 2 @NC) that is constrained by nitrogen-doped carbon (NC) derived from a metal-organic framework (MOF) and reinforced by carbon nanotubes (CNTs), via template self-assembly followed by in-situ tellurization. The CNTs crosslink with the MOF precursor to yield a dual-restricted architecture that suppresses nanoparticles agglomeration and enhances cycling stability. In-situ and ex-situ techniques elucidate the “alloy-conversion” reaction mechanism and pseudocapacitive sodium storage behavior of the ZnTe/CoTe 2 @NC anodes. While the density functional theory (DFT) calculations reveal the electronic structure modulation underlying their enhanced conductivity. These favorable electrochemical features arise from the synergistic effects of the Zn-Co heterointerface, the highly conductive carbon network, and the abundant defect sites introduced by nitrogen doping, which mitigate sluggish ion transport and structural degradation. As a result, the ZnTe/CoTe 2 @NC anode delivers a high-rate capacity of 82.1 mAh·g −1 at 20.0 A g −1 and retains 106.1 mAh·g −1 at 1.0 A g −1 after 5000 cycles. This study offers a rational confinement strategy and provides insight into designing electrochemically durable telluride heterostructure anodes.