Synergies in Blended LiMn₂O₄and Li[Ni_1/3Mn_1/3Co_1/3]O₂Positive Electrodes

The differential capacity and coulombic efficiency of blended Li/LiMn 2 O 4 -Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 half cells were examined using high-precision constant-current chronopoteniometry. The experiments showed that the addition of even modest amounts of Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 to the relatively low energy density LiMn 2 O 4 electrodes produced a significant improvement in capacity retention. Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 was also found to help suppress Mn dissolution from LiMn 2 O 4 , and a correlation between Mn dissolution, capacity retention and coulombic efficiency was found. The retained Mn ions reduce the increase of x in Li 1+x Mn 2-x O 4 at the particle surfaces. If x in Li 1+x Mn 2-x O 4 increases, a more Li rich, lower capacity material results, so by suppressing the increase of x, better capacity retention results.