Phase formation mechanism and electrochemical performance of Na2Ti3O7 prepared by spray-drying method as anode material for Li/Na-ion batteries

Energy production using renewable energy sources is intermittent. Therefore there is a need of the development of new low cost, safe and efficient large-scale energy technologies. While in the last decades, lithium-ion... [ view full abstract ]

Energy production using renewable energy sources is intermittent. Therefore there is a need of the development of new low cost, safe and efficient large-scale energy technologies. While in the last decades, lithium-ion batteries have become the main electrochemical energy storage system for portable devices and electrical vehicles field, sodium-ion batteries are an attractive solution for stationary applications [1,2]. Indeed, for effective batteries, we need to develop new electrode materials using new synthesis methods. Na₂Ti₃O₇ is considered as a promising intercalation anode material for sodium ion batteries thanks to its low insertion potential (0.3 V vs Na⁰/Na⁺) and relatively good theoretical capacity (178 mAh/g) [3,4]. We report here a new spray-drying synthesis of Na₂Ti₃O_7. By contrast to the solid-state synthesis, the advantages of the spray-drying method are a high homogeneity of the precursors and good control of the particle size and morphology (typically spherical particles of 3-30 µm, depending on the injection mode, concentration, pressure, temperature, etc.). Therefore, the heat treatment time is decreased. Moreover, this method is easily up-scalable. In this work, we studied the formation mechanism of Na₂Ti₃O₇ using high temperature X-ray diffraction to identify sequences of intermediate phases, starting from spray-dried TiO₂ and NaOH or Na₂CO₃ precursors. TGA-DSC analysis was in good agreement with XRD results. In order to reduce the particle size a ball-milling process was conducted and then electrochemical measurements (galvanic cycling) at different cycling rates were performed on the material to evaluate its electrochemical performance in half cell.

[1] J. Deng et al., Advanced Energy Materials, 2017, 1701428

[2] J.-Y. Hwang et al., Chemical Society Review, 2017, 46, 3529-3614

[3] J. Nava-Avendaño et al., Journal of Material Chemistry A, 2015, 3, 22280-22286

[4] M. Zarrabeitia et al., Acta Materialia, 2016, 104, 125-130