Self-Supported Single Crystalline H₂Ti₈O₁₇ Nanoarrays as Integrated Three-Dimensional Anodes for Lithium-Ion Microbatteries

Well-ordered, one-dimensional H2Ti2O5, H2Ti8O17, TiO2-B, and anatase TiO2/TiO2-B nanowire arrays were innovatively designed and directly grown on current collectors as high performance three dimensional (3D) anodes for binder and carbon free lithium ion batteries (LIBs). The prepared thin nanowires exhibited a single crystalline phase with highly uniform morphologies, diameters ranging from 70-80 nm, and lengths of around 15 μm. Specifically, reversible Li insertion and extraction reactions around 1.6-1.8 V with initial intercalation capacities of 326 and 271 mA h g(-1) at a cycling rate of 0.1 C (where 1 C = 335 mA g(-1)) were observed for H2Ti8O17 and TiO2-B nanowire arrays, respectively. Among the four compounds investigated, the H2Ti8O17 nanowire electrode demonstrated optimal cycling stability, delivering a high specific discharge capacity of 157.8 mA h g(-1) with a coulombic efficiency of 100%, even after the 500th cycle at a current rate of 1 C. Furthermore, the H2Ti8O17 nanowire electrode displayed superior rate performance with rechargeable discharge capacities of 127.2, 111.4, 87.2, and 73.5 mA h g(-1) at 5 C, 10 C, 20 C, and 30 C, respectively. These results present the potential opportunity for the development of high-performance LIBs based on nanostructured Ti-based anode materials in terms of high stability and high rate capability.