Abstract:

Na₂Li₂Ti₆O₁₄ as a reliable anode material is becoming a hopeful candidate for Li-ion battery. Nevertheless, the pristine Na₂Li₂Ti₆O₁₄ usually suffer from bad rate performance and poor cycling stability under high current due to limited diffusion kinetics and poor electrical conductivity. Here, the PPy-coated Na₂Li₂Ti₆O₁₄ composites are successfully obtained via the solid-state method and followed by chemical oxidation process in the first time. The results of tests prove that the Na₂Li₂Ti₆O₁₄@PPy composites have better electrochemical performance than the bare Na₂Li₂Ti₆O₁₄ because of the excellent electrical conductivity and the special macromolecular architecture of PPy. In particular, the Na₂Li₂Ti₆O₁₄@PPy (4 wt%) exhibits excellent charge capacities of about 223.2, 218.0, 200.8, 184.3 and 172.6 mAh g^-1 at 50, 100, 200, 300 and 500 mA g^-1, respectively, revealing the best rate capability of all electrode materials. The Na₂Li₂Ti₆O₁₄@PPy(4 wt%) not only has the highest charge capacity under 0.5 mA g^-1, but also has the highest capacity retention of 85.12% among all samples after 100 loops. Hence, the PPy coating is known as a promising way to improve the electrochemical property of Na₂Li₂Ti₆O₁₄. The PPy-coated Na₂Li₂Ti₆O₁₄ demonstrates the great prospect as promising negative materials for Li-ion batteries.

Key words: Li-ion battery, Anode material, Na₂Li₂Ti₆O₁₄, PPy coating, Electrochemical property