Mn-rich orthorhombic (o)-LiMn1–x
Ti
x
O2 with
a stable oxygen/cation site occupancy and cycling-dependent phase
transition is explored as a novel Co- and Ni-free cathode material
for Li-ion rechargeable batteries. Typical o-LiMnO2 suffers from oxygen deficiency, cation mixing between Li
and Mn, and monoclinic (m)-Li2MnO3 secondary phase with low conductivity. Together with these
drawbacks, the gradual, irreversible phase transition from layered o-LiMnO2 into spinel-like cubic (c)-LixMnO2 (x ≈ 0.5)
during repeated charge/discharge cycles degrades the cycling performance
of o-LiMnO2 despite the activation of
electroactive c-Li
x
MnO2 (x ≈ 0.5). By contrast, o-LiMn1–x
Ti
x
O2 consists of Ti-doped o-LiMnO2 and c-LiTiO2 as the primary and secondary phases,
respectively. The presence of Ti–O bonds, stronger than the
existing Mn–O bonds, improves the structural stability of Ti-doped o-LiMnO2 by reducing the imperfections of the
oxygen/cation lattices (including Mn octahedral sites associated with
the Jahn–Teller distortion) in Ti-doped o-LiMnO2 during the long-term synthesis under an inert atmosphere.
In addition, the electrochemically inactive (>2 V vs Li+/Li) c-LiTiO2 phase with high conductivity serves as a
pillar that suppresses the severe structural collapse of Ti-doped o-LiMnO2 through an abrupt phase/structural
transition during cycling (2–4.5 V). As a result, o-LiMn1–x
Ti
x
O2 with an optimal Ti content exhibits a higher
maximum discharge capacity and superior cycling performance compared
to the pristine o-LiMnO2.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.