Optimized Ni-Rich NCMA Cathode for Electric Vehicle Batteries

Abstract

The electrochemical and structural stabilities of a conventional Li[Ni0.90Co0.045Mn0.045Al0.01]O-2 (NCMA90) cathode and a core-shell with concentration gradient cathode (CSG-NCMA90) are evaluated by cycling the cathodes at different depths of discharge (DoDs). The CSG-NCMA90 cathode consists of fine, elongated primary particles that are radially aligned from the center of a spherical secondary particle. This unique microstructure effectively suppresses microcrack formation and propagation in the highly charged state. Moreover, microstructural analysis through transmission electron microscopy reveals that the thin elongated primary particles, largely featuring (001) facets on their lateral sides, are tolerant of electrolyte attack, thus suppressing surface degradation. In a full cell, these microstructural features enable the CSG-NCMA90 cathode to retain 90.7% of its initial capacity after 1000 cycles at 100% DoD. Unlike conventional Ni-rich layered cathodes whose capacity should be restricted to approximate to 60-80% to ensure their long service life, the proposed CSG-NCMA90 cathode can be cycled at full capacity, thus facilitating higher electrochemical performance and realizing the development of economical Li-ion batteries.