Method for the preparation of Li1+αV3O8

A positive electrode for a lithium battery comprising a composite material which comprises:

• a binder conferring mechanical strength,
• a compound conferring electron conduction,
• optionally a compound conferring ionic conduction, and
• lithium oxide Li1+αV3O8 (0.1≦α≦0.25) obtained by a process comprising:
• preparing a precursor gel and subjecting said gel to a heat treatment, wherein:
• the precursor gel is prepared by bringing α-V2O5 and a Li precursor into contact in a reaction medium in amounts such that the ratio of the [V2O5]/[Li] concentrations is between 1.15 and 1.5;
• and
• the heat treatment is carried out in two stages:
• a first stage under air at a temperature of between 80° C. and 150° C. for a time of 3 hours to 15 days and a second stage under a nitrogen or argon atmosphere at a temperature of between 250° C. and 350° C. for a time of between 4 min and 1 hour.