Two-step synthesis of stannic oxide and its electrochemical properties as lithium-ion battery anode

Abstract

Stannic oxide, also known as tin (IV) oxide (SnO₂), is commonly synthesized from a chemical derivative of a tin compound as an important inorganic compound as an anode material in lithium-ion batteries (LiB). This study developed a two-step synthesis technique, comprising alkaline degradation and thermal oxidation, to produce SnO₂ from pure tin metal as the precursor. The results indicate a morphological change from Sn metal to SnO₂ was observed, highlighted by a cavity structure at 500 °C to an interconnected network of individual SnO₂ particles at 900 °C. These changes concurrently indicate the phase composition change of sodium-based compounds into pure cassiterite SnO₂ at 900 °C. In this current research, the electrochemical properties of SnO₂, with a purity level of 98.6 % and a yield ranging from 90 to 92 wt%, were also investigated. The electrochemical performance of cassiterite SnO₂ deteriorated, evidenced by capacity loss, a negative trend in specific capacity, and irregular reduction and oxidation regions due to cyclic treatment. The initial discharge capacity of 770 mAh g⁻¹ at 0.1C gradually decreases with a capacity loss of 29.9 % and maintains a cycle retention rate of 45 % after 100 cycles. The particle size expansion, high oxygen concentration, and reduced tin content after cyclic treatment are critical contributors to the degradation of electrochemical properties. The relationship among morphological structure, phase composition, and electrochemical properties is extensively investigated.