Green ball dianthus-like Na₂Ti₆O₁₃ as high-rate performance anode for sodium-ion batteries

Benefitting from high abundance and low cost, sodium-ion batteries (NIBs) have been considered as promising energy storage device in large-scale application. However, low cycling stability and poor rate performance originated from the large size and heavy weight of the sodium ions hinder its application. In this work, a green ball dianthus-like sodium titanate (Na₂Ti₆O₁₃) with a tunnel structure and large interlayer space has been synthesized via hydrothermal method and its formation mechanism has been investigated. As NIBs anode materials, Na₂Ti₆O₁₃ exhibits excellent rate performance and superior cyclability. A high reversible capacity over 100 mA h g⁻¹ is delivered at 1000 mA g⁻¹ after 300 cycles. Even after 200 cycles at 500 mA g⁻¹ and 200 cycles at 1000 mA g⁻¹, the electrode can afford a capacity of 66 mA h g⁻¹ at 2000 mA g⁻¹ without apparent decay after 200 cycles. This outstanding performance can attribute to the unique nano-structure and large interlayer space of Na₂Ti₆O₁₃ with a green ball dianthus-like morphology.