In-depth structural characterization of the influence of Li + excess on spherical, Co-free layered LiMn 0.5 Ni 0.5 O 2 cathode material using correlative Raman–SEM microscopy

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-03, Vol.11 (10), p.5135-5147
• Main Authors: Klein, Florian, Pfeifer, Claudia, Scheitenberger, Philipp, Pfeiffer, Lukas, Zimmer, Dominik, Wohlfahrt-Mehrens, Margret, Lindén, Mika, Axmann, Peter
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D2TA05957F

A series of different spherical Co-free Li 1+ x (Mn 0.5 Ni 0.5 ) 1− x O 2 powders with 0 ≤ x ≤ 0.16 was synthesized to investigate the effect of excess Li + on the host structure of LiMn 0.5 Ni 0.5 O 2 . Structural investigation with XRD shows less Li + /Ni 2+ disordering and strong broadening of the pattern indicating phase separation with increasing x . A deeper understanding of the structural changes was gained from a combined approach of SEM, EDX and Raman microscopy. A phase separation into Ni-rich and Li-/Mn-rich layered oxide domains could be proven. In the investigated series, the best electrochemical performance was obtained for Li 1.07 (Mn 0.5 Ni 0.5 ) 0.93 O 2 with a stable specific discharge capacity of 173 mAh g −1 (658 Wh kg −1 , 12 mA g −1 ) after 40 cycles. The presented results strongly highlight the strength of correlating chemical (EDX), structural (Raman) and morphological (SEM) information with sub-micrometer lateral resolution for the development and understanding of future battery materials.