Method for the Preparation of Gamma-Liv2O5

Abstract

The invention relates to the preparation of an optionally carbonaceous γ-LiV 2 O 5 material. The process consists in preparing a composition formed of carbon and of precursors of Li and of V and in subjecting it to a heat treatment. The composition is prepared by bringing carbon, α-V 2 O 5 and a Li precursor into contact in amounts such that the ratio of the [V 2 O 5 ]/[Li] concentrations is between 0.95 and 1.05 and the carbon is in excess of at least 25% with respect to the stoichiometry. The heat treatment is carried out in two stages: a first stage at a temperature between 90° C. and 150° C. for a time of 1 to 12 hours and a second stage at a temperature between 420° C. and 500° C. for a time of between 10 min and 1 hour, under a nitrogen or argon atmosphere or under vacuum.

1 . A material composed of pure γ-LiV 2 O 5  or of γ-LiV 2 O 5  as an intimate mixture with carbon prepared by a process comprising preparing a composition formed of carbon and of precursors of Li and of V and subjecting said composition to a heat treatment, wherein:
 the composition is prepared by bringing carbon, α-V 2 O 5  and a Li precursor into contact in amounts such that the molar ratio of the [α-V 2 O 5 ]/[Li] is between 0.95 and 1.05 and the carbon is in excess of at least 25% with respect to the stoichiometry; and 
 the heat treatment is carried out in two stages: a first stage at a temperature of between 90° C. and 150° C. for a time of 1 to 12 hours and a second stage under a nitrogen or argon atmosphere or under vacuum at a temperature of between 420° C. and 500° C. for a time of between 10 min and 1 hour. 
 
     
     
         2 . A composite positive electrode for a lithium battery, comprising a composite material which comprises the material composed of pure γ-LiV 2 O 5  or of γ-LiV 2 O 5  as an intimate mixture with carbon as claimed in  claim 1 . 
     
     
         3 . The composite positive electrode as claimed in  claim 2 , wherein the composite material additionally comprises:
 a binder conferring mechanical strength,   a compound conferring electron conduction, and   optionally a compound conferring ionic conduction.   
     
     
         4 . The composite positive electrode as claimed in  claim 2 , wherein:
 the content of the material composed of pure γ-LiV 2 O 5  or of γ-LiV 2 O 5  as an intimate mixture with carbon is between 90 and 100% by weight;   the content of binder is less than 10% by weight;   the content of compound conferring electron conduction is less than or equal to 5% by weight; and   the content of compound conferring ionic conduction is less than 5% by weight.   
     
     
         5 . The electrode as claimed in  claim 3 , wherein the binder comprises a solvating polymer. 
     
     
         6 . The electrode as claimed in  claim 3 , wherein the binder is a mixture of solvating polymer and of nonsolvating polymer. 
     
     
         7 . The electrode as claimed in  claim 3 , wherein the binder additionally comprises a polar aprotic compound. 
     
     
         8 . The electrode as claimed in  claim 3 , the compound conferring ionic conduction is a lithium salt selected from the group consisting of LiClO 4 , LiPF 6 , LiAsF 6 , LiBF 4 , LiR F SO 3 , LiCH 3 SO 3 , lithium bisperfluoroalkylsulfonimides and lithium bis- and trisperfluorosulfonylmethides. 
     
     
         9 . A battery comprising of a negative electrode and a positive electrode separated by an electrolyte comprising a lithium salt in solution in a solvent, wherein the positive electrode is an electrode as claimed in  claim 2 .