Defect-Engineered La _1.7 Ti ₂ O _7−δ Nanofiber as a High-Rate and High-Stability Anode for Li-Ion Batteries

Layered perovskites have recently garnered considerable attention for their applications in energy storage. Manipulating defects in layered perovskites, such as vacancies and doping, improves ionic conductivity and stability during electrochemical applications. This study examines the potential application of layered perovskite-type La2Ti2O7 nanofibers (NFs) as anodes for lithium-ion batteries. It focuses on the impact of defect engineering and hydrocolloid binders on the performance for lithium storage. The X-ray diffraction (XRD) Rietveld refinement confirmed that the defect-engineered La1.7Ti2O7–δ nanofibers and the defect-free La2Ti2O7 nanofibers crystallize in a monoclinic P21 structure. Raman spectroscopy revealed lattice distortions in the defective La1.7Ti2O7–δ nanofibers attributed to vacancies at the lanthanum and oxygen sites. The elongated nanofiber morphology of La1.7Ti2O7–δ, with a uniform distribution of La, Ti, and O elements, was revealed through morphological analysis. The La1.7Ti2O7–δ NFs exhibit better electrochemical activity, enhanced rate capability, and remarkable cycling stability than the La2Ti2O7 NFs and La1.7Ti2O7−δ bulk samples. The improved performance is attributed to the synergistic effects of La/O vacancies and nanofiber morphology, which collectively enhance electronic conductivity, reduce charge transfer resistance, and provide abundant active sites for Li+ intercalation. The galvanostatic intermittent titration technique (GITT) and bond valence sum energy (BVSE) mapping further reveal that defect engineering significantly reduces Li+ migration barriers and creates interconnected diffusion channels, thereby promoting efficient ion transport. Further, the electrochemical performance of La1.7Ti2O7–δ nanofiber anodes was evaluated using different binders (polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), and sodium alginate). Sodium alginate significantly improved charge storage kinetics, rate capability, and cycling stability compared to conventional binders. These results highlight the combined impact of defect engineering and binder selection in enhancing the performance of perovskite-type titanate nanofibers for high-performance lithium-ion battery anodes.