Enhancing Rate Capability and Cycle Life of TiNb2O7 Anodes: The Synergistic Role of Compositing with Carbon Nanofibers and SDS Morphological Tuning

TiNb 2 O 7 (TNO) has attracted considerable attention as a promising anode candidate for lithium-ion batteries (LIBs) due to its favorable properties, including high theoretical capacity, moderate operating voltage, and multi-electron redox capability, but its poor intrinsic electronic and ionic conductivity limits its practical use. This study presents a dual-modification strategy that combines carbon nanofiber (CNF) compositing with sodium dodecyl sulfate (SDS)-assisted morphological regulation through a one-pot solvothermal synthesis. In addition, the influence of SDS concentration on the morphology of TNO/CNF composites is systematically investigated to identify the optimum composite architecture. Varying SDS concentrations (2×, 10×, and 20× the CNF amount) revealed the 10× ratio as optimal, yielding a well-connected CNF scaffold uniformly decorated with fine TNO nanoparticles, minimizing agglomeration and facilitating electron/ion transport. This composite delivered an initial discharge capacity of 290 mAh/g at 1C, retaining 61% after 200 cycles—outperforming pristine TNO (225 mAh/g) and SDS-free TNO-CNF (272 mAh/g). It also maintained ∼85 mAh/g at 20C, attributed to the synergistic CNF network and SDS-mediation effects. Finally, ternary composites incorporating reduced graphene oxide (rGO) were synthesized using the same procedure. SDS significantly improved morphological homogeneity, creating well-integrated TNO/CNF/rGO networks with uniform nanoparticles distribution across the conductive scaffold. These ternary SDS-modified nanocomposites showed superior high-rate performance at 10–20C. However, they exhibited reduced low-rate capacities and cycling stability (from 255 to 141 mAh/g at 1C over 200 cycles) due to rGO's tortuous pathways that impede bulk Li⁺ diffusion.