Recent researchs in the field of lithium batteries and their performance improvement involve nanoscaled electrode materials [1]. Among them many oxides have been proved to present better behavior upon Li reaction in terms of rate capabilities [2] and reversibility [2, 3] when divided at the nanoscale. Manganese oxide nanomaterials are of particular interest from a fundamental point of view to investigate structure and size effects on the electrochemical behavior owing to their numerous phases. However, tailoring the properties of such electrodes remains a challenge since it is closely related to the control of the structure and texture. Our group thus develops the synthesis of oxide nanoparticles by precipitation in aqueous medium at low temperature [4].

This contribution addresses a low temperature one-step aqueous route for precipitation of manganese oxides by two different methods: reduction of Mn^VII and Mn^VII/Mn^II reaction. Pure Mn₃O₄ nanoparticles or γ-MnOOH manganite nanowires are synthesized by the first route. The second method leads to morphology control of MnO₂ type oxides. On one hand the morphology of the lamellar oxide birnessite K_0.19MnO₂.(H₂O)_0.75 can be modified. On the other hand, the growth of microporous cryptomelane K_0.11MnO_1.85.(H₂O)_0.75 nanowires is proved to proceed by coarsening or oriented attachment depending on the growth direction, providing new means to control morphology via the growth conditions. Finally, well defined nanoparticles are used to investigate structure and size effects on the electrochemical behavior versus lithium.

[1] Poizot, P.; Laruelle, S.; Grugeon, S.; Dupont, L.; Tarascon, J.-M. Nature, 407, 2000, 496.

[2] Sudant, G.; Baudrin, E.; Larcher, D.; Dunn, B.; Tarascon, J.-M. J. Electrochem. Soc., 151, 2004, A666.

[3] Baudrin, E.; Cassaignon, S.; Koelsch, M.; Jolivet, J.-P.; Dupont, L.; Tarascon, J.-M. Electrochem. Comm., 9, 2007, 337.

[4] Jolivet, J.-P.; Chaneac, C.; Tronc, E. Chem. Commun., 2004, 481.

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