LiFePO 4 is presently the most studied electrode material for battery applications. It can be prepared via solution, although it requires well-controlled pH conditions to master the iron valence state in the newly created material. Here we report its synthesis via the use of "latent bases" capable of releasing a nitrogen base upon heating. This way of controlling the reaction pH enables, in the absence of excess Li, the preparation of Fe +3 -free LiFePO 4 powders having various morphologies and showing good electrochemical performance. This approach is shown to offer great opportunities for the low-temperature synthesis of various electrode materials.Rechargeable Li-ion cells, which are powering most of today's portable electronics, are strongly considered for automotive transportation. Yet, safety and cost issues remain to be solved, prior to seeing this environmentally much-needed market extend globally. 1 The cost is mainly determined by the material abundance, thus 3d metal redox elements, such as in LiFePO 4 , 2 are receiving increased attention, while Co-or Ni-based electrodes are electronic market niches. The carbon nanopainting techniques, applied to insulating LiFePO 4 , yield high-rate yet safe batteries. 3 The environmental attractiveness of LiFePO 4 prevails over an energy density penalty due to low packing density, even more so in the presence of carbon. LiFePO 4 is the main contender for electric vehicle automakers, but natural sources of triphylite are scarce. Synthetic triphylite has to be made with directly processable grain sizes while looking for the most expeditious and energy-saving carbon coating.Precipitation from aqueous medium, under normal pressure 4 or in autoclave, 5,6 is often preferred to ceramic methods; the latter require high temperatures to ensure the diffusion of the reactants and the growth of the grains; they therefore demand high energy while leading to highly polydispersed powders. Precipitation methods in liquid media ͑e.g., solvothermal synthesis͒ 7 require little energy, and if nucleation and growth phenomena are controlled, the size distribution is much narrower.Basically, a solvothermal synthesis reaction consists in reacting metal/nonmetal-based soluble salts with a base, and increasing the temperature to promote the growth of the desired phase via Ostwald ripening. Inherent drawbacks are formation of hydroxides from the metals used, without any control over the nucleation step and possible oxidation by air oxygen. This is particularly worrisome in the case of Fe II and cobalt II .Hydrothermal synthesis of lithium iron phosphate, according to the reaction H 3 PO 4 + FeSO 4 + 3LiOH ⇒ LiFePO 4 + Li 2 SO 4 + 3H 2 O, has been demonstrated, 8 though some Fe ͑III͒ impurities remain in the final product. More recently, Delacourt et al. 4 succeeded in preparing at low temperature ͑ca. 108°C͒ electrochemically active LiFePO 4 nanoparticles having a few percent of Fe +3 9,10 via a precipitation process in a pH range close to neutrality using a waterdimethyl sulfoxide acidic mix...
