Umicore

Centre National De La Recherche Scientifique

Le Centre National De La Rocherche Scientifique

Le Centre National De La Recherche Scientifique

Sylvain Gwizdala

Christian Masquelier

Mathieu Morcrette

Calin Wurm

Albane Audemer

The invention provides a new route for the synthesis of carbon-coated powders having the olivine or NASICON structure, which form promising classes of active products for the manufacture of rechargeable lithium batteries. Carbon-coating of the powder particles is necessary to achieve good performances because of the rather poor electronic conductivity of said structures. For the preparation of coated LiFePO, sources of Li, Fe and phosphate are dissolved in an aqueous solution together with a polycarboxylic acid and a polyhydric alcohol. Upon water evaporation, polyesterification occurs while a mixed precipitate is formed containing Li, Fe and phosphate. The resin-encapsulated mixture is then heat treated at 700&#xb0; C. in a reducing atmosphere. This results in the production of a fine powder consisting of an olivine LiFePO, phase, coated with conductive carbon. When this powder is used as active material in a lithium insertion-type electrode, fast charge and discharge rates are obtained at room temperature and an excellent capacity retention is observed.

Carbon-coated Li-containing powders and process for production thereof

The invention provides a new route for the synthesis of carbon-coated powders having the olivine or NASICON structure, which form promising classes of active products for the manufacture of rechargeable lithium batteries. Carbon-coating of the powder particles is necessary to achieve good performances because of the rather poor electronic conductivity of said structures. For the preparation of coated LiFePO, sources of Li, Fe and phosphate are dissolved in an aqueous solution together with a polycarboxylic acid and a polyhydric alcohol. Upon water evaporation, polyesterification occurs while a mixed precipitate is formed containing Li, Fe and phosphate. The resin-encapsulated mixture is then heat treated at 700&#xb0; C. in a reducing atmosphere. This results in the production of a fine powder consisting of an olivine LiFePOphase, coated with conductive carbon. When this powder is used as active material in a lithium insertion-type electrode, fast charge and discharge rates are obtained at room temperature and an excellent capacity retention is observed.

Methods of manufacture and use of phosphates of transition metals are described as positive electrodes for secondary lithium batteries, including a process for the production of LiMPOwith controlled size and morphology, M being FeCoNiMn, where 0&#x2266;x&#x2266;1, 0&#x2266;y&#x2266;1, 0&#x2266;w&#x2266;1, and x+y+z+w=1. According to an exemplary embodiment, a process is described for the manufacture of LiFePOincluding the steps of providing an equimolar aqueous solution of Li, Feand PO, evaporating water from the solution to produce a solid mixture, decomposing the solid mixture at a temperature of below 500&#xb0; C. to form a pure homogeneous Li and Fe phosphate precursor, and annealing the precursor at a temperature of less than 800&#xb0; C. in a reducing atmosphere to produce the LiFePOpowder. The obtained powders can have a particle size of less than 1 &#x3bc;m, and can provide superior electrochemical performance when mixed for an appropriate time with an electrically conductive powder.

Process for making lithium transition metal phosphate powder for battery electrode

Methods of manufacture and use of phosphates of transition metals are described as positive electrodes for secondary lithium batteries, including a process for the production of LiMPOwith controlled size and morphology, M being FeCoNiMn, where 0&#x2266;x&#x2266;1,0&#x2266;y&#x2266;1, 0&#x2266;w&#x2266;1, and x+y+z+w=1. According to an exemplary embodiment, a process is described for the manufacture of LiFePOincluding the steps of providing an equimolar aqueous solution of Li, Feand PO, evaporating water from the solution to produce a solid mixture, decomposing the solid mixture at a temperature of below 500&#xb0; C. to form a pure homogeneous Li and Fe phosphate precursor, and annealing the precursor at a temperature of less than 800&#xb0; C. in a reducing atmosphere to produce the LiFePOpowder. The obtained powders can have a particle size of less than 1 &#x3bc;m, and can provide superior electrochemical performance when mixed for an appropriate time with an electrically conductive powder.

Growing community of inventors

Brienon sur Armancon, France

Sylvain Gwizdala