Thermal annealing-mediated fine-tuning of SnO₂ nanoparticles for advanced lithium-ion battery anodes

In this study, tin dioxide (SnO₂) nanoparticle samples are synthesized using a wet chemical method, where SnCl₄ is used as a precursor and NH₄OH as the precipitate, followed by calcination at 400 (SnO₂_400), 500 (SnO₂_500) and 600 °C (SnO₂_600) in Ar gas. Given their nanostructure, these samples exhibit impressive specific capacity and cycling stability when utilized as anodes for lithium-ion batteries. The specific charge-discharge capacity at the first cycles of the SnO₂_400, SnO₂_500, and SnO₂_600 electrodes are 1035/611, 1756/1074, and 1903/1257 mAh g^-1, respectively, and the coulombic efficiency remained above 93% after the second cycle. Further, after 100 cycles, the specific capacity of the SnO₂_500 electrode is around 1247 mAh g^-1, which is about 154% and 377% higher than those of the SnO₂_400 and SnO₂_600 electrodes, respectively. Moreover, the rate capacity test reveals that the remarkable rate capability reaches 585.8, 891.7, 767.8 mAh g^-1 for the SnO₂_400, SnO₂_500, and SnO₂_600 electrodes at a current density of 3 A g^-1, respectively. Electrochemical impedance spectroscopy results revealed that the SnO₂_500 electrode exhibits a significantly lower total resistance than those of the other two electrodes. The SnO₂_500 electrode is more effective than those of the SnO₂_400 and SnO₂_600 electrodes in terms of energy storage capacity because of its highest pseudocapacitance mechanism, which indicates that the SnO₂_500 electrode can realize high-speed charging. Given the high capacity, long-term cycling durability, good high-rate performance, and high pseudocapacitance, SnO₂_500 material can become an anode material for lithium-ion batteries in the future.