An interwoven carbon nanotube core–shell network supports a Co9S8–Ni3S2 heterojunction for superior aqueous nickel/cobalt–zinc battery kinetics

Abstract

Hollow core–shell nanomaterials offer attractive features for energy storage but often suffer from poor interfacial charge transport due to physical gaps between the core and shell. In this work, we report a coupled Co₉S₈–Ni₃S₂ heterojunction with a CNT-bridged core–shell architecture designed to address this interfacial transport challenge. Using a bimetallic CoNi-BTC precursor, we synthesize a CNT-bridged Co₉S₈–Ni₃S₂ heterostructure (CoNiS/CNT) via pyrolysis and solvothermal sulfidation. The in situ formed CNTs create conductive pathways across the core–shell gap, enabling efficient electron and ion transport. As an electrode, CoNiS/CNT delivers a high capacity of 201.8 mAh g⁻¹ at 1 A g⁻¹. In a Zn//CoNiS/CNT battery, it achieves 343.2 Wh kg⁻¹ at 1.6 kW kg⁻¹ and retains 73% of its capacity after 4000 cycles at 6 A g⁻¹, far exceeding the performance of its non-bridged counterparts. This work provides an effective interface-engineering strategy for constructing durable and kinetically efficient core–shell materials for energy storage.