title: Electron bottleneck in the charge/discharge mechanism of lithium titanates for batteries.
abstract: The semi-solid flow battery (SSFB) is a promising storage energy technology featured by employing semi-solid fluid electrodes containing conductive additive and active Li-ion battery materials. The state of art anode material for SSFB is Li4 Ti5 O12 (LTO). This work shows that LTO improves drastically the performance in fluid electrode via hydrogen annealing manifesting the importance of the electrical conductivity of the active material in SSFBs. On the other hand, the properties of fluid electrodes allow the contributions of ionic and electrical resistance to be separated in operando. The asymmetric overpotential observed in Li4 Ti5 O12 and TiO2 is proposed to originate from the so-called electron bottleneck mechanism based on the transformation from electrically insulator to conductor upon (de-)lithiation, or vice versa, which should be considered when modelling, evaluating or designing advanced materials based on Li4 Ti5 O12 , TiO2 or others with insulating-conducting behavior materials.
authors.affiliation: Department of Advanced Materials for Energy, Catalonia Institute for Energy Research, Jardins de les Dones de Negre, 1, 08930 Sant Adria de Besos (Spain). edgar.ventosa@rub.de.
authors.forename: Edgar
authors.initials: E
authors.lastname: Ventosa
authors.affiliation: Department of Advanced Materials for Energy, Catalonia Institute for Energy Research, Jardins de les Dones de Negre, 1, 08930 Sant Adria de Besos (Spain).
authors.forename: Marcel
authors.initials: M
authors.lastname: Skoumal
authors.affiliation: Department of Advanced Materials for Energy, Catalonia Institute for Energy Research, Jardins de les Dones de Negre, 1, 08930 Sant Adria de Besos (Spain).
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Vazquez
authors.affiliation: Department of Advanced Materials for Energy, Catalonia Institute for Energy Research, Jardins de les Dones de Negre, 1, 08930 Sant Adria de Besos (Spain).
authors.forename: Cristina
authors.initials: C
authors.lastname: Flox
authors.affiliation: ICREA and Institut Català de Nanociència i Nanotecnologia (ICN2), Campus UAB, 08193 Bellaterra, CAT (Spain).
authors.forename: Jordi
authors.initials: J
authors.lastname: Arbiol
authors.affiliation: Department of Advanced Materials for Energy, Catalonia Institute for Energy Research, Jardins de les Dones de Negre, 1, 08930 Sant Adria de Besos (Spain).|Departament d'Electronica, Universitat de Barcelona, C. de Martí i Franquès, 1, 08028 Barcelona (Spain).
authors.forename: Joan Ramon
authors.initials: JR
authors.lastname: Morante
mesh_terms: D058266:Dielectric Spectroscopy; D004553:Electric Conductivity; D011211:Electric Power Supplies; D004583:Electrons; D008094:Lithium / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D008094:Lithium; D014025:Titanium
keywords: batteries; conductivity; metal oxides; oxidation; reduction