Binder-Free Hybrid Titanium-Niobium Oxide/Carbon Nanofiber Mats for Lithium-Ion Battery Electrodes

Free-standing, binder-free, titanium-niobium oxide/carbon hybrid nanofibers are prepared for Li-ion battery applications. A one-pot synthesis offers a significant reduction of processing steps and avoids the use of environmentally unfriendly binder materials, making the approach highly sustainable. Tetragonal Nb₂ O₅ /C and monoclinic Ti₂ Nb₁₀ O₂₉ /C hybrid nanofibers synthesized at 1000 °C displayed the highest electrochemical performance, with capacity values of 243 and 267 mAh g^-1 , respectively, normalized to the electrode mass. At 5 A g^-1 , the Nb₂ O₅ /C and Ti₂ Nb₁₀ O₂₉ /C hybrid fibers maintained 78 % and 53 % of the initial capacity, respectively. The higher rate performance and stability of tetragonal Nb₂ O₅ compared to that of monoclinic Ti₂ Nb₁₀ O₂₉ is related to the low energy barriers for Li⁺ transport in its crystal structure, with no phase transformation. The improved rate performance resulted from the excellent charge propagation in the continuous nanofiber network.