Study on high voltage (5V) spinel lithium manganese oxide LiNi0.5Mn1.5O4
by doping niobium
Abstract
The effect of niobium ion with high valence doping on high voltage
LiNi0.5Mn1.5O4 materials was investigated. LiNi0.5Mn1.5-xNbxO4 was
prepared by doping high-valent niobium ion into LiNi0.5Mn1.5O4 material
using the organic assisted combustion method. The experimental samples
were characterized by scanning electron microscopy, transmission
electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy
and electrochemical impedance analysis. The experimental results show
that the doping with high valence niobium ion change the orientation of
the crystal plane growth of spinel particles, and the morphology of
these particles change from the octahedral shape before doping to the
spherical shape after doping. With the increase of doping amount, the
crystal structure changes gradually, resulting in the Li0.96Nb1.01O3
impurity phase. The doping of high valence niobium ion increases the
content of Mn3+ in the material, resulting in the appearance of a 4 V
discharge platform, and the formation of a 4.7 V and 4 V discharge
platform. The doping of Nb can improve the cycling stability of
LiNi0.5Mn1.5O4 material, but the specific capacity of the material is
reduced.