Anodic behaviour and X-ray photoelectron spectroscopy of ternary tin oxides

The compounds SrSnO3, BaSnO3 and Ca2SnO4 have been synthesized by solid-state and/or sol–gel methods, characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) and their electrochemical properties studied as cathodes versus Li metal in the range 0.005–1.0 V. ASnO3 (A = Sr, Ba), adopt the perovskite structure whereas Ca2SnO4 has the Sr2PbO4 structure. The discharge capacities (mAh g−1) (moles of equivalent Li) on the 20th cycle at a current rate of 30 mA g−1 are: SrSnO3 (solid-state) (144 (1.4)), SrSnO3 (sol–gel) (222 (2.1)), BaSnO3 (solid-state) (190 (2.2)), BaSnO3 (sol–gel) (156 (1.8)) and Ca2SnO4 (247 (2.4)). The SrSnO3 (sol–gel) with nano-particle morphology displays better galvanostatic cycling performance than SrSnO3 (solid-state). The cycling behaviour of SrSnO3 and BaSnO3 is inferior to that of Ca2SnO4 and CaSnO3, which demonstrates that ‘Ca’ is superior as a matrix element than Sr or Ba. The inferior electrochemical performance of Ca2SnO4 in comparison to CaSnO3 reveals that the higher Ca:Sn ratio in the former is not advantageous and the perovskite structure is preferable to that of Sr2PbO4 structure. The coulombic efficiencies are >98% in all cases. Cyclic voltammetry (CV) compliments the observed cycling behaviour.