[Zn(Salen)] metal complex-derived ZnO-implanted carbon slabs as anode material for lithium-ion and sodium-ion batteries

Abstract

Zinc oxide-implanted carbon slabs (ZnO@CS) were prepared by conventional pyrolysis of a [Zn(salen)] complex. The formed ZnO@CS was characterized in detail through material characterization, which confirmed the formation of ZnO nanoparticles implanted into the two dimensional carbon slabs. Then, the ZnO@CS was explored as an anode material for lithium-ion and sodium-ion batteries in the form of CR-2032-type coin cells. The lithium-ion half cell (ZnO@CS|LiPF₆|Li) resulted in a high discharge capacity of 500 mA h g⁻¹ at 0.4C-rate, while the sodium-ion half cell (ZnO@CS|NaClO₄|Na) delivered a stabilized discharge capacity of 60 mA h g⁻¹ at 0.2C-rate with excellent cycling stability as well as coulombic efficiency in both cases. The superior lithium-ion/sodium-ion storage performances of the ZnO@CS anode are attributed to the simultaneous occurrence of the conversion/re-conversion and the alloying/de-alloying reactions that occurred on the ZnO anode. The carbon slab seemed to act as a conductive matrix as well as cushion to withstand the volume stress induced during the lithiation/sodiation, contributing to the cycling stability. Subsequently, the CR-2032-full-cell fabricated using the ZnO@CS as the anode and the commercial LiCoO₂ as the cathode delivered a stable discharge capacity as high as 400 mA h g⁻¹ at 0.1C-rate with excellent rate capability and cycling stability. The CR-2032 type laboratory proto-type full cell was demonstrated to power a commercial (3.0 V) LED bulb for more than 5 h continuously on a single charge.