The Effect on Electrochemical Properties By the Content of Mn3+ of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode Material for Highly Stable Lithium-Ion Batteries

High voltage spinel LiNi_0.5Mn_1.5O₄ (LNMO) is considered as one of the most promising cathode material for next generation lithium ion batteries, which can greatly meet the rapid increasing demand of power sources applied into portable electronic devices and electric vehicles. The electrochemical performance of LNMO is greatly affected by the morphology and lattice structure. In order to improve the long-term cycling stability, particularly at elevated temperature, one of effective methods is to tune the amount of Mn³⁺ in LNMO for controlling the stability of spinel lattice structure due to complex interactions on the interface of electrode material and the electrolyte on the high operating voltage.

In this work, the influence of different content of Mn3+ in LNMO on electrochemical properties is displayed by truncated octahedral LNMO obtained by controlling synthetic conditions of heating atmosphere and temperature cooling rate. Superior truncated octahedral LNMO materials were synthesized with tuned Mn³⁺ content through heating under oxygen atmosphere and controlling the cooling conditions of natural cooling and a cooling rate of 5 ^oC/min, respectively. The material synthesized under O2 shows the smallest amout of Mn3+, while the one with natural cooling has the highest amount. The LNMO material obtained under O₂ shows the best electrochemical stability with about 96% capacity retention after 500 cycles at 0.5C (1C = 147 mA/g). The material obtained at 5 ^oC/min shows about 90% of capacity retention after 2000 C cycles at 1C, while the one obtained with natural cooling can reach up to 88% of capacity retention after 500 cycles at 0.5C at 60 ^oC. Therefore, the Ni-Mn disordering intrinsically related to the Mn3+ amount has a great effect on the electrochemical performance of LNMO. More experimental details and measurement results will be exhibited later.

Reference:

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2. Chemelewski, K. R.; Lee, E.; Li, W.; Manthiram, A. Chem. Mater. 2013, 25, 2890.