Ad. Robertson et al., M3-MODIFIED LIMN2O4 SPINEL INTERCALATION CATHODES .2. ELECTROCHEMICALSTABILIZATION BY CR3+(), Journal of the Electrochemical Society, 144(10), 1997, pp. 3505-3512
The 4 V rechargeable capacity of the spinel LiMn2O4 was stabilized by
substituting less than 1 mole percent (m/o) Mn3+ with Cr3+. The optimu
m composition was determined as LiCr0.012Mn1.988O4, which had a discha
rge capacity exceeding 110 mAh/g even after 100 cycles, although impro
ved stabilities were attained for all Cr-modified compositions studied
(0.1 to 7.0 m/o Cr3+ substitution): The effects of varying electrolyt
e salt, temperature, and current density were also investigated. Capac
ity losses in 4 V LiMn2O4-based spinel systems were attributed to Mn d
issolution into the electrolyte causing structural degradation of the
cathode and an increase in cell polarization from deposited Mn interfe
ring with Li+ transport through the anodic solid-electrolyte interphas
e. Substitution of even a small amount of Mn3+ by trivalent Cr3+ minim
ized this dissolution and resulted in enhanced cathodic electrochemica
l stability.