Tin-oxide based binder-free light-weight nanostructured anode with high reversible capacity and cyclability for lithium-ion batteries manifesting the interfacial effect

Abstract

The advancement of lithium-ion batteries (LIBs) with higher storage capacity, energy density, and power density is critical to meet the growing power demands of modern technologies. Light-weight, micro-devices are attracting attention due to their growing demand in flexible and portable electronics, such as wearable health monitors, implanted medical devices, smart cards, and IoT sensors emphasizing the need for miniaturization of energy storage. This report describes a high-performance light-weight, binder-free tin-oxide (SnO2) based nanostructured thin-film anode on copper (Cu) current collector for rechargeable LIBs, with lithium foil as counter electrode. Importantly, fabrication process of this binder-free electrode does not involve any kind of binders, conductive agents or any other additional inactive components (unlike the typical electrode preparation method), which results in providing improved energy density by reducing the effective weight of the LIB. Further it eliminates weak interaction and interface issues between binder and electrode material, thus minimizing active materials self-aggregation possibility, besides providing an increased accessibility of the electrolyte to the active material. The fabricated half-cell exhibits a significantly high reversible capacity of 1430 mAh g-1 and about 1200 mAh g-1 after 100 and 500 cycles respectively, at a current density of 0.3 A g-1 (0.2C), excellent cyclability, rate-performance (~800 mAh g-1 at 3 A g-1 at 110 cycles) and stability with a high coulombic efficiency (98-99%), as tested in the 0.02 to 1.8 V window. The activation of the electrode was achieved by controlled post deposition annealing process of optimized SnO2 film on Cu, providing a suitable nanostructured hierarchical morphology and conformation involving SnO2-Cu interface, which facilitates good electrical contact and enhanced electron/ion transport kinetics, yielding a high cyclability, rate performance and stability, preventing pulverization. Moreover, it brings forth an extra interfacial charge storage phenomenon via Cu/Li2O nanocomposites, resembling capacitive characteristics. Stable capacity involving SnO2 dealloying-alloying along with the interface induced extra lithium storage capability contribute to accomplish the observed high specific capacity of the electrode. This study provides an insight in designing of advanced light-weight electrode for next-generation energy-storage devices.