Electrochemical Performance of TiNb2O7 Nanofibers for Lithium-Ion Battery Anodes Using Flame-Retardant Electrolytes

This study demonstrates an electrode–electrolyte co-design strategy to address the long-standing performance–safety trade-off in lithium-ion batteries by integrating electrospun TiNb2O7 (TNO) nanofiber anodes with fluorinated flame-retardant electrolytes. The electrochemical compatibility of TNO was systematically evaluated over a wide voltage window (0.01–3.0 V) using a conventional carbonate electrolyte and two fluorinated systems (TFMAF and NOMAF). At low current densities, the fluorinated electrolytes deliver capacities comparable to those of the carbonate electrolyte, whereas the carbonate system exhibits superior rate capability at high current densities. Among the flame-retardant electrolytes, TFMAF shows slightly improved electrochemical performance, particularly in terms of rate capability and cycling stability. Elevated temperatures enhance ionic conductivity and reduce polarization across all systems, while low-temperature EIS/DRT analysis reveals distinct, electrolyte-dependent differences in interfacial resistance and charge-transfer behavior. Accelerating rate calorimetry confirms that the fluorinated electrolytes significantly improve thermal safety. Notably, NOMAF exhibits superior thermal stability and emerges as a more practical electrolyte candidate due to its enhanced safety and lower cost.