title: Shape-Controlled TiO2Nanocrystals for Na-Ion Battery Electrodes: The Role of Different Exposed Crystal Facets on the Electrochemical Properties.
abstract: Rechargeable sodium-ion batteries are becoming a viable alternative to lithium-based technology in energy storage strategies, due to the wide abundance of sodium raw material. In the past decade, this has generated a boom of research interest in such systems. Notwithstanding the large number of research papers concerning sodium-ion battery electrodes, the development of a low-cost, well-performing anode material remains the largest obstacle to overcome. Although the well-known anatase, one of the allotropic forms of natural TiO2, was recently proposed for such applications, the material generally suffers from reduced cyclability and limited power, due to kinetic drawbacks and to its poor charge transport properties. A systematic approach in the morphological tuning of the anatase nanocrystals is needed, to optimize its structural features toward the electrochemical properties and to promote the material interaction with the conductive network and the electrolyte. Aiming to face with these issues, we were able to obtain a fine tuning of the nanoparticle morphology and to expose the most favorable nanocrystal facets to the electrolyte and to the conductive wrapping agent (graphene), thus overcoming the intrinsic limits of anatase transport properties. The result is a TiO2-based composite electrode able to deliver an outstandingly stability over cycles (150 mA h g-1for more than 600 cycles in the 1.5-0.1 V potential range) never achieved with such a low content of carbonaceous substrate (5%). Moreover, it has been demonstrated for the first time than these outstanding performances are not simply related to the overall surface area of the different morphologies but have to be directly related to the peculiar surface characteristics of the crystals.
authors.affiliation: Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca , via Cozzi 55, 20125 Milano, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Longoni
authors.affiliation: Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca , via Cozzi 55, 20125 Milano, Italy.
authors.forename: Rosita Lissette
authors.initials: RL
authors.lastname: Pena Cabrera
authors.affiliation: Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari Venezia and Centro di Microscopia Elettronica "G. Stevanato" , Via Torino 155/b, 30172 Venezia-Mestre, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Polizzi
authors.affiliation: Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca , via Cozzi 55, 20125 Milano, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: D'Arienzo
authors.affiliation: Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca , via Cozzi 55, 20125 Milano, Italy.
authors.forename: Claudio Maria
authors.initials: CM
authors.lastname: Mari
authors.affiliation: Materials Science and Engineering Department, Stanford University , 476 Lomita Mall, 94305 Stanford, California, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca , via Cozzi 55, 20125 Milano, Italy.
authors.forename: Riccardo
authors.identifier: 0000-0001-7509-7052
authors.initials: R
authors.lastname: Ruffo
keywords: Sodium ion batteries; TiO2; anatase; energy storage; nanoparticle facets