High-Voltage Zero-Strain Mid-Mn Layered Cathode

Abstract

Although Ni-rich cathodes deliver high energy density, their limited cycling stability and safety restrict their practical application. Increasing the cutoff voltage of mid-Ni (60% <= Ni <= 70%) cathodes has received renewed interest; however, their strong reliance on expensive and scarce Ni raises concerns regarding supply security and sustainability. Despite their high Mn contents, Li-/Mn-rich cathodes suffer from structural instability and oxygen release, limiting their suitability for reliable operation. Consequently, zero-strain mid-Mn (40% <= Mn < 60%) materials with quasi-ordered structures have emerged as promising high-energy and safe alternatives. This study investigated the formation mechanism of quasi-ordered structures in mid-Mn cathode materials, identifying the key compositional and morphological factors that influence their development. The electrochemical performances of the cathodes were systematically evaluated across various cutoff voltages to determine their suitability for high-voltage application. Additionally, a critical anisotropy transition point was defined, highlighting the structural influence of cation ordering on performance.