Revisiting and enhancing electrochemical properties of SnO 2 as anode for sodium-ion batteries

The tin oxide (SnO2) thin films have been prepared by the pulsed laser deposition (PLD) at deposition temperatures (Td) ranging from 300 to 500 °C with different morphologies and studied as anode for sodium-ion battery. The microstructural evolutions of the thin films are investigated by various techniques which reveal a pure SnO2 phase. The crystallinity of the thin film deposited at 300 °C shows partial amorphous characteristics. Among all the samples, SnO2 thin film deposited at 300 °C exhibits superior electrochemical performance. The films at 300 °C display a high specific capacity of 488 mAh g−1 (at 20 mA g−1) after 50 cycles and a coulombic efficiency of 96% after 200 cycles at 130 mA g−1 (voltage window of 0.01 V to 2.0 V). The achieved high specific capacity can be credited to sodium (Na) storage mechanisms of SnO2, which are both (1) conversion of SnO2 to Sn nanocrystals and followed by (2) alloying of Na and Sn.