Toward the Aqueous Processing of Li4Ti5O12: A Comparative Study with LiFePO4

The aqueous processing of carbon coated LiFePO4-based electrodes being proved; this study focuses on the feasibility to use this environmental friendly route for the preparation of Li4Ti5O12-based electrodes. The chemical stability of the active material in water and the physical stability of aqueous electrode slurries are investigated. As for the LiFePO4-C, taking care of some classical processing parameters (active material (AM) concentration, water exposure duration, slurry pH) guarantees the non-degradation of the active material performance and the aqueous route is thus shown to be an appropriate alternative to the organic one. However the electrodes made in aqueous media can not reach the high level of rate performance achieved with electrodes made in organic solvent because of the critical physical instability of the Li4Ti5O12 aqueous slurries. Rheological measurements and electrodes imaging highlight the role played by the different polymers additives in these Li4Ti5O12 aqueous slurries and enable to get keys to optimize their formulation. Moreover, the good rate performance shown by the Li4Ti5O12-based composite electrode with a poor carbon black distribution or even with no conductive additive show that the presumably low electronic conductivity of this active material is not limiting, at least when the AM particles are submicronic (aggregates (empty set 200-800 nm) of crystallites (empty set 20-40 nm)). (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.075207jes] All rights reserved.