Li_1.04(Ni_0.40Mn_0.40Co_0.20−zAl_z)_0.96O₂"(z = 0; 0.05 and 0.10) samples were synthesized using a coprecipitationmethod followed by calcinations at 500°C for 5 h andthen at 950°C for 2 h. Structural and physico-chemical characterizationshave shown that these materials were obtained pure with asmall overlithiation ratio (Li/M = 1.01-1.03) and thus a significant exchange betweenthe divalent nickel ions from the slabs and the lithiumions from the interslab spaces (between 4% for the nonsubstituted material and 8% for the aluminum substituted ones). Aluminumsubstitution induces a decrease of the reversible capacity, but alsoa major improvement of the thermal stability in the deintercalatedstate (corresponding to the charge state of the battery). Theseresults have thus shown that the composition Li_1.01(Ni_0.39Mn_0.40Co_0.15Al_0.06)_0.99O₂ is veryattractive for large scale lithium-ion batteries to be developed forEV and HEV applications.< Leer menos