Three-dimensional mesoporous rutile TiO2 hollow spheres for high-energy-density pseudocapacitance and rapid lithium storage

Despite the advantages of TiO 2 , such as its low cost, long lifespan, and excellent thermodynamic/kinetic properties, its inherent slow ion diffusion limits its commercial application. Therefore, in this work, a three-dimensional(3D) mesoporous rutile TiO 2 hollow sphere suitable for high-energy-density pseudocapacitance and rapid lithium storage was meticulously designed. The average diameter of the hollow spheres is approximately 1.6 μm, with individual mesoporous-spheres assembled from 50 to 300 nm nanoparticles, and the hollow spheres exhibit a high specific surface area of ~58.57 m 2  g −1 and a large pore size of ~14.18 nm. The results demonstrate that the electrochemical performance of 3D rutile TiO 2 hollow sphere samples is superior to that of conventional microsized particles. Specifically, the MS-TiO 2 –2 sample retained a high capacity of 295 mAh g −1 after 100 cycles at 0.5C. After 1000 cycles at 1C and 5C, the reversible specific capacities of MS-TiO 2 –2 were 254 and 174 mAh g −1 , respectively. Its pseudocapacitive contribution reached as high as 82 % under a fast cyclic voltammetry scan at 10 mV s −1 . These excellent electrochemical properties are attributed to the unique design and regulation of the three-dimensional mesoporous structure. The precise control of porosity is the primary reason for the optimal electrochemical performance of MS-TiO 2 –2. This anode with the 3D mesoporous structure enables rapid Li + transport, which is of great significance for the design of high-energy-density pseudocapacitors and fast Li + batteries.