Unified understanding and mitigation of detrimental phase transition in cobalt-free LiNiO2

A methodology to synthesize easily oxidized materials containing Li ions in an inert atmosphere

“…When the Ni 3+ contents are enriched in layered oxides, the oxides are calcined at slightly lower temperatures at higher oxygen partial pressures. 19 The oxides containing transition metal ions, which are easily oxidized during calcination, i.e. (Fe 2+ , V 3+ , Cr 3+ , Mo 3+ , and Mn 3+ ), can be synthesized in an inert atmosphere (N 2 ).…”

Tailoring Primary Particle Size Distribution to Suppress Microcracks in Ni-Rich Cathodes via Controlled Grain Coarsening

“…The degree of cation mixing in the Nb-CS NCA cathode is higher than that in the CS NCA cathode at each calcination temperature. This behavior is attributable to the incorporation of high-oxidation-state Nb 5+ , which induces the partial reduction of Ni 3+ to Ni 2+ to maintain charge neutrality. ,, Regarding the increase of cation mixing by the incorporation of high oxidation state elements, it has been reported that some Ni-rich cathodes with higher cation mixing showed the improved cycling stability because the presence of transition metal ions in the Li layer prevents local collapse of the layered structure and preserves the structural framework even in a highly delithiated state, thus enhancing the reversibility of Li (de)­intercalation. ,− For the Nb-CS NCA cathode, the temperature at which the c/3a ratio is maximized (cation mixing is minimized) is higher, with the highest crystallinity observed at 740 °C. The optimized crystallinity shifting to a higher temperature and the layered crystal structure resisting collapse, even at high calcination temperatures, have also been reported for cathodes doped with other high-valence elements, such as Ta and Mo. , In addition, the crystallite size of the Nb-CS NCA cathode (estimated from the XRD pattern in Figure S3) is smaller than that of the CS NCA cathode at each calcination temperature.…”