In this work, we aimed to address the challenges of using Co₃O₄ as an anode material for sodium-ion batteries (SIBs), particularly its poor electrical conductivity, severe volume expansion during cycling, and significant irreversible capacity loss.
To overcome the above challenges, we developed a hierarchical Co₃O₄ nanostructure using a two-step heating process (low-temperature preheating followed by high-temperature calcination) which resulted in an interconnected, porous network that significantly improved charge transport and buffered volume fluctuations and optimized the crystallinity of the material via enhancing the Co³⁺ states to improvise the electrochemical activity.
The engineered electrode demonstrated a high reversible capacity (70% of the theoretical limit at 25 mA/g), excellent rate performance (123 mAh/g at 1 A/g), and stable cycling with 82% capacity retention after 250 cycles at 1 A/g. Further, the electrochemical impedance spectroscopy (EIS) has been performed, confirmed a significant reduction in charge transfer resistance (Rct), which facilitated better Na-ion kinetics.
Further to understand the storage mechanism, in-situ Raman spectroscopy has employed, revealed a conversion-type Na-ion storage process. The ex-situ ToF-SIMS and TEM analysis has also performed that confirmed homogeneous Na-ion storage and structural integrity of the electrode after extensive cycling.
In summary, by combining morphology engineering, crystallinity optimization, and detailed mechanistic studies, we have successfully developed a scalable and cost-effective Co₃O₄ anode with significantly improved electrochemical performance, making it a promising candidate for next-generation sodium-ion batteries.
(2024-11-01)
