Electrochemical storage behavior of NiCo2O4 nanoparticles anode with structural and morphological evolution in lithium-ion and sodium-ion batteries

Abstract

NiCo2O4 nanoparticles (5-10 nm) were prepared by a simple sol-gel method and evaluated in the Li/Na-cell as an anode. The anode exhibited excellent lithium storage capacity (1050 and 860 mAh g(-1) at specific currents of 0.1 and 0.5 A g(-1), respectively) and outstanding cycling performance of over 200 cycles. However, it showed a moderate sodium storage capacity with poor cycle retention. A clear comparison of the structural stability of the electrode determined via the cross-sectional scanning electron microscopy (SEM) micrographs indicates swelling and extensive volume expansion in the Na cell. The investigations conducted using in situ X-ray diffraction (XRD) and ex situ X-ray absorption spectroscopy (XAS) reveal the limited reduction of Co and Ni oxidation states and a minimal degree of conversion during Na uptake. This study highlights the ability of NiCo2O4 nanoparticles to withstand high mechanical stress during the conversion reaction with Li, thus providing excellent performance. Conversely, the NiCo2O4 anode with Na could not be overcome massive volume expansion and irreversibility by reducing the size of particles in nano-dimension.