After uncovering the importance of the (001) facets using boththeoretical and experimental methods, the next step was to attemptto further increase the percentage of the exposed (001) facets bydecreasing the thickness along the [001] direction while increasing thelateral size of the NSs. A facile solvothermal method was developed toprepare anatase TiO2 hierarchical spheres assembled from NSs (NSHSs)(Fig. 7a and b)54. It is clear from the figure that the as-prepared samplehas a very uniform size distribution, and NS constituents measuringonly a few nanometers thick can be easily identified under highermagnification. Selected area electron diffraction (SAED) pattern andhigh-resolution transmission electron microscope (HRTEM) imagesconfirmed that the top and bottom surfaces of these NSs were the(001) facets. It is thus possible to estimate that the percentage ofthe exposed (001) facets is close to 100 %. When used as the anodematerial for LIBs, the as-prepared TiO2 NSHSs show excellent cyclingperformance at current rates of 1 C, 5 C, and 10 C (Fig. 7c). This could beattributed to the ultrathin TiO2 NSs with exposed (001) facets allowingfast and efficient lithium diffusion, and the hierarchical structure
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