Résumé
A hierarchical nanosheet-constructed yolk-shell TiO<inf>2</inf> (NYTiO<inf>2</inf>) porous microsphere is synthesized through a well-designed, one-pot, template-free solvothermal alcoholysis process using tetraethylenepentamine (TEPA) as the structure directing reagent. Such a yolk-shell structure with a highly porous shell and dense mesoporous core is quite advantageous as an anode material for lithium ion batteries (LIBs). The outer, 2D nanosheet-based porous (15 nm) shell and the nanocrystal-based inner mesoporous (3 nm) core provide a stable, porous framework, effective grain boundaries and a short diffusion pathway for Li<sup>+</sup> and electron transport, facilitating lithium insertion/extraction. The voids between the core and the shell can not only store the electrolyte due to capillary and facilitate charge transfer across the electrode/electrolyte interface but also buffer the volume change during the Li<sup>+</sup> insertion/extraction. As a result, NYTiO<inf>2</inf> demonstrates excellent Li<sup>+</sup> capacity with outstanding cycle performance and superior rate capability at different rates for >700 cycles, retaining a 225 mA h g<sup>-1</sup> reversible capacity after 100 cycles at 1 C. In particular, the reversible capacity can still be maintained at 113 mA h g<sup>-1</sup> after 100 cycles at 10 C. We also observe the formation of homogeneously distributed 5-10 nm Li<inf>2</inf>Ti<inf>2</inf>O<inf>4</inf> nanocrystallites on the surface of the nanosheets during the discharge-charge process. The synergy of the yolk-shell structure with dual mesopores in the shell and core and the Li<inf>2</inf>Ti<inf>2</inf>O<inf>4</inf> nanocrystallites endow the hierarchical NYTiO<inf>2</inf> with high reversible capacity, excellent rate capability and outstanding cycle performance.
langue originale | Anglais |
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Pages (de - à) | 12979-12989 |
Nombre de pages | 11 |
journal | Nanoscale |
Volume | 7 |
Numéro de publication | 30 |
Les DOIs | |
Etat de la publication | Publié - 14 août 2015 |
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Physico-chimie et caractérisation (PC2)
Johan Wouters (!!Manager) & Carmela Aprile (!!Manager)
Plateforme technologique Caracterisation physico-chimiquesEquipement/installations: Plateforme technolgique