Hierarchically ordered mesoporous TiO2 nanofiber bundles derived from natural collagen fibers for lithium and sodium storage

Abstract

To date, most of reported high performance TiO2 anode materials for both lithium and sodium ion batteries rely on employing tedious, high cost, and complex preparation procedures, which impede its scalable production and practical uses. Here, we demonstrate a facile synthetic strategy to engineer a one-dimensional (1D) hierarchically ordered mesoporous TiO2 nanofiber bundles (TBs) by using low-cost natural collagen fibers as the biotemplate. The as-prepared TBs are mainly constructed by hierarchical organization of ordered nanofibers (∼50–100 nm in diameter) each of which composed of well-crystallized TiO2 nanoparticles with a particle size of ∼10–20 nm, endowing a well-defined mesoporous structrue of the TBs along with a large specific surface area of 100.89 m2 g−1. This 1D hierarchical mesoporous structure is not only able to offer shortened ion diffusion paths, but also to ensure efficient electrolyte penetration for ion access and keep the structure integrity. As a result, the TBs-based anode materials show excellent electrochemical lithium and sodium storage prorperties. When evaluated in a lithium ion cell, TBs delivery a high discharge capacity of 120 mAh g−1 under 5C rate, and exhibits long-term cycling stability with an extremely low capacity decay of 0.03% over 500 cycles. Even for sodium ion cell tests, a remarkable capacity of nearly 130 mAh g−1 is also achieved at a current density of 200 mA g−1, suggesting the reversible sodium storage capability of the TBs. This synthetic approach is promising for developing low cost, high efficient and practical TiO2 anode materials available for lithium and sodium ion batteries.