Sodium-ion batteries are regarded as one of the potential candidates to substitute lithium ion batteries in large-scale electric energy storage applications in the near future. Several forms of sodium titanates including Na₂Ti₃O₇, Na₂Ti₆O₁₃ and Na₄Ti₅O₁₂ have recently been applied as anode in sodium ion batteries. Here, we present an energy-efficient solid-state synthesis, via the addition of carbon, to mass-produce a series of uniform and single-crystalline Na₂Ti₃O₇/Na₂Ti₆O₁₃ nanorods with tunable composition as anode materials for sodium-ion batteries.¹ Due to the extra local heat generation and CO₂/CO release from carbon oxidation, the carbon added in the synthesis provides an alternative low-temperature route for the Na₂Ti₃O₇ formation at 450 °C, a reaction temperature much lower than that of conventional solid-state methods (750–1000 °C), and Na₂CO₃ is regenerated to be recycled in the synthesis. The high theoretical capacity of Na₂Ti₃O₇ and low volume expansion of Na₂Ti₆O₁₃ upon charge–discharge are synergistically exploited to achieve high electrochemical performance and stability.

References

1. Ho, C.-K.; Li, C.-Y. V.; Chan, K.-Y., Scalable Template-Free Synthesis of Na₂Ti₃O₇/Na₂Ti₆O₁₃ Nanorods with Composition Tunable for Synergistic Performance in Sodium-Ion Batteries. Industrial & Engineering Chemistry Research 2016, 55 (38), 10065-10072.

Acknowledgements

This project is financially supported by Research Grants Council of Hong Kong (GRF 17300014), HKU Small Project Funding (201409176115), HKU Strategic Research Theme on Clean Energy, and University Development Fund for Initiative for Clean Energy and Environment.