Showing papers by "Dominique Larcher published in 2012"

Non-Aqueous Li-Based Redox Flow Batteries

Abstract: Redox flow batteries have gained renewed interest for grid storage applications. This work focuses on the effect of various chemical/physical parameters on the performance of the LiFePO4/LiPF6 EC-DMC/Li redox flow system. A methodical study of the influence of the content of active material and of the flow rate, coupled with electrochemical and hydrodynamic characterizations, have been carried out in order to better understand the various ‘migration’ and ‘diffusion’ limitations, as well as to try to overcome their effects. As a result, power density performances higher than 328 mW.cm−2 at 104 mA.cm−2 were achieved and the feasibility of reaching energy density of 50 Wh.kg−1 demonstrated.

Improving the Li-Electrochemical Properties of Monodisperse Ni2P Nanoparticles by Self-Generated Carbon Coating

Abstract: Carbon coating of electrode materials is nowadays a major tool to improve the electronic percolation of the electrode. In this study, a self-generated carbon coating is described as a new way to deposit a regular thin layer of carbon on the surface of nanoparticles. It relies on the soft decomposition of the nanoparticles surface native ligands, containing alkyl chains, under inert atmosphere at 400 °C, a route particularly suited for oxidation-sensitive nanoparticles. Using 25 nm monodispersed Ni2P nanoparticles as a model phase, we succeeded in forming nonsintered and nonoxidized carbon-coated nanoparticles. The carbon coating is then tuned in thickness by modifying the ligands set. Electrochemical properties of the resulting Ni2P/C nanoparticles vs Li are compared with those of bulk Ni2P. Both materials are shown to undergo a conversion reaction. The capacity of the bulk material collapses after a few cycles while Ni2P/C nanoparticles show much better retention. The self-generated carbon coating is thus found to promote Li uptake by providing a Li-permeable electron-conductive percolating network and by improving the mechanical integrity of the electrode.

Biosynthesis of Co3O4 electrode materials by peptide and phage engineering: comprehension and future

Abstract: Biologically templated electrodes for Li-ion batteries are proposed. However, many questions regarding their practicality and their use on a large scale remain. Herein we revisit the phage-assisted synthesis of Co3O4 nanoparticles so as to identify the bio-chemistry/chemistry involved beyond this engineering phage synthetic approach and weigh its overall benefit. Various synthesis approaches to mimic the role of the phage which consist of using (i) wild or genetically modified phages made by insertions of specific peptides in the capsid protein, (ii) free peptides, and (iii) MWCNTs as the template were tried, and the resulting Co3O4 nanoparticles were checked for their morphology, size, organization, and electrochemical performances. We spotted the importance of a tetra-peptide motif in the Co3O4 nucleation/texturation process, whether this motif is part of the phage capsid or not, suggesting that the structure of the whole phage is not necessary for the production of the nanoparticles. In light of such findings the use of self-organized peptides or engineered bacteria for the templated synthesis of materials on a larger scale is proposed.