Freezing of Gelled Suspensions: a Facile Route toward Mesoporous TiO2 Particles for High-Capacity Lithium-Ion Electrodes

Electrodes for metal-ion batteries should combine high specific capacity with fast cycling-rate capability. Although the use of mesoporous particles is an attractive approach to reconciling these contradicting performance parameters, synthetic protocols to create such particles are typically time-consuming, require environmentally unfriendly chemistries, and are limited to small batches. We present a simple and scalable processing route to synthesizing mesoporous TiO2 particles through freezing, drying, and grinding of gelled aqueous suspensions of 5-nm-sized TiO2 nanoparticles. Freezing enables partial densification of the nanoparticle network present in the initial gel, thus leading to mesoporous particles combining high density with easily accessible specific surface area for metal-ion insertion. The resulting mesoporous particles can be assembled into hierarchical porous anodes that exhibit superior volumetric capacity in comparison to xerogel and aerogel reference compositions. The aqueous-based nature and simplicity of the freezing process makes this synthetic approach a promising route for the fabrication of architectured electrodes for the next generation of metal-ion batteries.