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

Abstract

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 TiO 2 particles through freezing, drying, and grinding of gelled aqueous suspensions of 5-nm-sized TiO 2 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.

Architectured ZnO–Cu particles for facile manufacturing of integrated Li-ion electrodes

“…Similar improvements have been made by casting electrode pastes onto unidirectional sacrificial templates, followed by removal of the template by thermal treatment 13 . Anodes with hierarchical porous structure have also been developed to optimize the porosity of the electrode 14 , 15 . Provided that the transport of Li ions is the main factor limiting the electrochemical performance of the device, these approaches can be used to increase the volumetric charge capacity of the electrodes without compromising the achievable charging rates.…”

Mesoporous TiO2 Spheres as Advanced Anodes for Low-Cost, Safe, and High-Areal-Capacity Lithium-Ion Full Batteries

“…On the one hand, TiO 2 is one of the most promising anode materials and has been attracting more and more attention. − It is an abundant source and works at a high operating voltage range of 1–3 V (vs Li + /Li) with suppression of Li plating, granting it low cost and high security. − In addition, TiO 2 also has other merits that include good availability, environmental friendliness, and stable structure with small lattice change (<4%) during Li insertion/extraction. − On the other hand, mesoporous materials are representatives of advanced materials benefiting from their attractive advantages of abundant pores, various pore shapes, high specific areas, and adjustable nanocrystals. − Thus, mesoporous TiO 2 nanostructures are intensively investigated as advanced anode materials and exhibit impressive electrochemical performances. − For example, Caruso et al have fabricated mesoporous yolk–shell anatase TiO 2 /TiO 2 (B) microspheres with high specific surface area and large pore volume. The mesoporous microspheres exhibited high specific reversible capacity, excellent rate performance, and impressive cyclability.…”

Ultrafast and Stable Lithium Storage Enabled by the Electric Field Effect in Layer-Structured Tablet-Like NH4TiOF3 Mesocrystals

“…Recent studies also show that the formation of oxygen vacancy or the heterogeneous interface cause an imbalanced charge distribution and a local build-in electric field, which accelerates ion and/or electron transportations and promotes charge-transfer behavior. 35−39 Design and synthesis of controlled morphology and microstructure such as nanoparticles, 40 nanotubes, 41 nanowires, 29 nanosheets, 17,26 and mesoporous TiO 2 26,42 are also helpful to decrease the ionic diffusion length and accelerate ionic transportation. It should be mentioned here that the nanostructured electrodes show high surface energy and tend to agglomerate to reduce the total energy, resulting in the loss of particle connectivity and poorer conductive networks.…”

“…Design and synthesis of controlled morphology and microstructure such as nanoparticles, nanotubes, nanowires, nanosheets, , and mesoporous TiO 2 , are also helpful to decrease the ionic diffusion length and accelerate ionic transportation. It should be mentioned here that the nanostructured electrodes show high surface energy and tend to agglomerate to reduce the total energy, resulting in the loss of particle connectivity and poorer conductive networks. , As a solution, the nanoscale electrodes can be assembled into micro/nanostructured hierarchical architectures .…”