Extraordinary long-term cycleability of TiO2-B nanorods as anodes in full-cell assembly with electrospun PVdF-HFP membranes

Abstract

One dimensional TiO₂-B nanorods are synthesized by a conventional hydrothermal approach under highly concentrated alkali hydroxide solutions. Various characterization techniques such as X-ray diffraction, Raman studies, BET surface area measurements, scanning electron microscopy and transmission electron microscopy (TEM) are utilized. Electrochemical Li-insertion properties are evaluated by means of half-cell configuration (Li/TiO₂-B) which delivered a discharge capacity of 195 mA h g⁻¹ at a current density of 150 mA g⁻¹ under ambient temperature conditions. The test cell, Li/TiO₂-B, displayed good cycling profiles up to 500 cycles with columbic efficiency over 99.5%. Full-cell, LiMn₂O₄/TiO₂-B, is fabricated and tested both in conventional liquid and PVdF-HFP membranes at a current density of 150 mA g⁻¹ and exhibited an excellent cycleability up to 1000 cycles at an operating potential of ∼2.5 V. The results demonstrate the improved electrochemical performance and durability of one dimensional nanostructures i.e. TiO₂-B nanorods and electrospun membranes during prolonged cycling. In addition, ex-situ TEM analysis revealed the retention of nanorod morphology along with the crystalline structure after 1000 cycles in full-cell assembly, which ensures excellent long-term cycleability of TiO₂-B anodes.