Electrochemistry of sodium titanate nanotubes as a negative electrode for sodium-ion batteries

• Published in: Electrochimica acta Vol. 331; p. 135422
• Main Authors: Leite, Marina M., Martins, Vitor L., Vichi, Flavio M., Torresi, Roberto M.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.01.2020; Elsevier BV
• Subjects: Electrochemical impedance spectroscopy; Electrochemistry; Electrode kinetics; Electrode materials; Electrodes; Hydrothermal treatment; Lithium; Lithium ions; Na-ion batteries; Nanotubes; Rechargeable batteries; Sodium; Sodium trititanate nanotubes; Sodium-ion batteries; Titanium dioxide; Titration; Electrode kinetics; Sodium trititanate nanotubes; Na-ion batteries
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2019.135422

Sodium-ion batteries are a promising alternative to lithium-ion devices, but the development of proper negative electrode materials is still challenging. Here, the properties of a low-voltage sodium titanate material are evaluated. Sodium titanate nanotubes (NTO) were produced by an alkalyne alkaline hydrothermal treatment with TiO2 and consisted of a hydrated Na1.4H0.6Ti3O7 with a surface area of 128 m2 g−1. NTO electrode kinetics were studied by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic intermittent titration techniques. The (de)intercalation of Na+ ions involved two redox pairs at 0.3/0.5 V and 1.0/1.2 V, associated with the present mixture of nanotubes and nanosheets. Surface processes had a 95% coulombic efficiency and a high contribution even at low scan rates, accounting for 47% of the total capacity at 0.5 mV s−1. Upon Na+ removal, the electronic resistance and the semiconductor capacitance increased. Battery tests performed on Na|NTO half-cells showed a reversible capacity of 90 mA h g−1 at 10 mA g−1 and near 100% coulombic efficiency at current rates ranging from 10 mA g−1 to 10 A g−1. Additionally, NTO presented a good capacity retention of 92% after 170 cycles at 100 mA g−1. •Surface process contribution is 47% at 0.5 V s−1 with 95% efficiency.•Finite-space diffusion model to fit EIS data considering particle-size distribution.•(Semi)conductive properties of NTO change with (de)sodiation.•Electrode capacity of 93 mA h g−1 at 10 mA g−1•92% capacity retention after 170 cycles at 100 mA g−1