jp503584k_si_001.pdf (2.26 MB)
Investigation of the Effect of Extra Lithium Addition and Postannealing on the Electrochemical Performance of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode Material
journal contribution
posted on 2014-07-24, 00:00 authored by Yunxian Qian, Yuanfu Deng, Lina Wan, Hongjie Xu, Xusong Qin, Guohua ChenThe
LiNi0.5Mn1.5O4 (LNMO) spinel
is an attractive cathode candidate for next generation lithium-ion
batteries as it offers high power and energy density. In this paper,
the effects of extra amounts of lithium addition and postannealing
process on the physicochemical and electrochemical properties of the
spherical LNMO material were investigated. The experimental results
show that the amount of lithium and the postannealing process have
significant impacts on the Mn3+ content, phase impurity
(rock-salt phase) and phase structures (Fd3m and P4332) of the spherical
LNMO cathode materials, so as their electrochemical performance. In
particular, the phase transition from Fd3m to P4332 and the Mn3+ content of the LNMO spinels were found to be adjusted by lithium
additions and the postannealing process. With the presence of Mn3+, the absence of the impurity phase (rock-salt phase) and
the cation ordering in the spinels, the electrochemical rate performance
and capacity retention of the products could be significantly improved.
In a half cell test, LNMO cathode material with 5% of lithium excess
(based on theoretical formula calculation) displays a high specific
discharge capacity of 123 mAh g–1 at 2 C rate with
excellent capacity retention of 84% after 500 cycles at 55 °C.
All these findings show the important roles of the synergic effects
of Mn3+ content, phase impurity (rock-salt phase) and phase
structures (Fd3m and P4332) on the electrochemical performance improvement of LNMO-based
cathode materials, which will guide the preparation of LNMO-based
cathode material with excellent electrochemical performance.