Factors Influencing the Electrochemical Properties of High-Voltage Spinel Cathodes: Relative Impact of Morphology and Cation Ordering

Abstract

In order to achieve consistent electrochemical properties essential for the commercialization of the high-voltage spinel cathode LiMn1.5Ni0.5O4, a deeper fundamental understanding of the factors contributing to capacity fade is required. Specifically, the relationship between cation ordering, impurity phases present, and particle morphology must be elucidated. We present here a comparison of stoichiometric LiMn1.5Ni0.5O4 cathodes with a 3:1 Mn/Ni ratio prepared by different methods with varying morphologies and degrees of cation ordering. Careful structural, chemical, and electrochemical characterizations illuminate the relative influence of the various factors on the electrochemical cycling stability and high-rate performance. It is found that although an increase in the degree of cation ordering decreases the rate capability, the crystallographic planes in contact with the electrolyte have a dominant effect on the electrochemical properties.