Skip to Main content Skip to Navigation
Theses

Étude des propriétés électrochimiques de nouveaux matériaux nanostructurés à base de fer préparés par chimie douce et utilisables comme électrodes positives d'accumulateurs au lithium

Abstract : In the search for new positive electrode materials for lithium batteries, iron compounds are interesting due to their low cost and toxicity. For this purpose, b-FeOOH, g-FeOOH and LiFePO4 were studied.
For oxyhydroxides, direct addition of acetylene black or carbon nanotubes (for the improvement of the electronic conductivity) was developed, which leads to non-uniform deposition and isolation of the grains, unfavorable for lithium insertion. A partial substitution of iron by cobalt was performed (improvement of the ionic conductivity). A stabilization of the exchangeable quantity of lithium is obtained with an optimum.
For LiFePO4, several synthesis modes were performed (hydrothermal, mechanical activation, coprecipitation) to obtain different particles sizes. The electronic conductivity is enhanced by generation of a carbon layer onto the particles from thermal degradation of a carbohydrate. It appears that the finest the particles are, the best the insertion is. Crystallographic structural defects (observed by magnetic measurements) are favorable. The effect of carbon coating was studied with different carbon sources (starch, cellulose, carbon nanotubes, polyacrilonitril). The best compromise is achieved with cellulose: sp2 form (conductive carbon), covering (good electron percolation) and homogeneous (non rough surface).
Document type :
Theses
Complete list of metadatas

Cited literature [48 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00257269
Contributor : Charlotte Benoit <>
Submitted on : Monday, February 18, 2008 - 8:40:18 PM
Last modification on : Wednesday, October 14, 2020 - 3:56:42 AM
Long-term archiving on: : Thursday, May 20, 2010 - 10:46:24 PM

Identifiers

  • HAL Id : tel-00257269, version 1

Collections

Citation

Charlotte Benoit. Étude des propriétés électrochimiques de nouveaux matériaux nanostructurés à base de fer préparés par chimie douce et utilisables comme électrodes positives d'accumulateurs au lithium. Matériaux. Université Paris Sud - Paris XI, 2007. Français. ⟨tel-00257269⟩

Share

Metrics

Record views

708

Files downloads

4592