CNTs embedded in layered Zn-doped Co3O4 nano-architectures as an efficient hybrid anode material for SIBs
Advantageous utilization of sodium-ion batteries (SIBs) requires superior performance, enriched with cost-effective anode materials, having excellent storage capability, high conductivity, and structural stability. Hybrid structures based on inorganic metal oxides and organic nano-carbons are evolving as satisfactory electrode materials for the next-generation SIBs owing to their exceptional properties. In this study, Co2.98Zn0.02O4/CNTs hybrid is synthesized using a facile hydrothermal followed by a solvothermal route. As prepared hybrid has been utilized as an anode in a Na half cell and the results are compared with Co2.98Zn0.02O4 and bare Co3O4 anodes. Galvanostatic charge-discharge profiles revealed a high reversible capacity of 721？mAh？g？1 for the electrode containing carbon nanotubes (CNTs) i.e. Co2.98Zn0.02O4/CNTs exhibiting remarkable coulombic efficiency of 99% as compared to the other two electrodes. The hybrid anode showed improved capacity retention (289？mAh？g？1) after 100 cycles as computed from the cyclic test which is much higher than bare Co3O4. The rate capability test of Co2.98Zn0.02O4/CNTs showed that specific capacity retained as high as 138？mAh？g？1@10？C which is an outstanding rate performance, whereas bare Co3O4 couldn’t perform even after 0.5？C. Sodium insertion/extraction is also improved for Co2.98Zn0.02O4/CNTs, as revealed by electrochemical impedance and diffusion coefficient. From these findings, it is inferred that carbon-based Zn-doped Co3O4 hybrid electrode materials can be a superior combination for high-performance and fast charging future SIBs.