Electrochemical properties of tin phosphates with various mesopore ratios

Tin phosphates with various mesopore ratios are synthesized with surfactants as templates. The mesopore ratios of the tin phosphates are controlled by adjusting the surfactant: inorganic precursor ratios. As an anode material for Li-ion batteries, the mesoporous and non-mesoporous mixture with a high mesopore ratio exhibits enhanced cycling stability. Compared with the ∼34% (∼135 mAh g−1) capacity retention after 50 cycles of the non-mesoporous tin phosphate (between 2.5 and 0.001 V), the tin-phosphate anodes with mesopore ratios of 42, 82 and 100% show capacity retentions that are enhanced by more than 50%, showing charge capacities of ∼260, ∼290, and ∼325 mAh g−1, respectively (after 50 cycles). The mesoporous structures may alleviate the large volume change of the Sn nanoparticles embedded in the lithium-phosphate matrix during charge–discharge. Cycling tests of the 100% mesoporous tin phosphate between 0.8 and 0.001 V exhibit no capacity decay: ∼325 mAh g−1 remains after 50 cycles. This is probably because re-oxidation of metallic tin with lithium-phosphate matrix does not occur.