Lithium-storage and cycleability of nano-CdSnO₃ as an anode material for lithium-ion batteries

Abstract

Nano-CdSnO₃ is prepared by thermal decomposition of the precursor, CdSn(OH)₆ at 600 °C for 6 h in air. The material is characterized physically by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM) and selected-area electron diffraction (SAED) techniques. Nano-CdSnO₃ exhibits a reversible and stable capacity of 475(±5) mAh g⁻¹ (~ 5 mol of cycleable Li per mole of CdSnO₃) for at least 40 cycles between 0.005 and 1.0 V at a current rate of 0.13 C. Extensive capacity fading is found when cycling in the range 0.005-1.3 V. Cyclic voltammetry studies complement galvanostatic cycling data and reveal average discharge and charge potentials of 0.2 and 0.4 V, respectively. The proposed reaction mechanism is supported by ex situ XRD, TEM and SAED studies. The electrochemical impedance spectra taken during 1st and 10th cycle are fitted with an equivalent circuit to evaluate impedance parameters and the apparent chemical diffusion coefficient (D_Li+) of Li. The bulk impedance, R_b, dominates at low voltages (≤0.25 V), whereas the combined surface film and charge-transfer impedance (R_(sf+ct)) and the Warburg impedance dominate at higher voltages, ≥0.25 V. The D_Li+ is in the range of (0.5-0.9) × 10⁻¹³ cm² s⁻¹ at V = 0.5-1.0 V during the 10th cycle.