Correlating the initial gas evolution and structural changes to cycling performance of Co-free Li-rich layered oxide cathode

• Published in: Journal of power sources 2022-04, Vol.527, p.231181, Article 231181
• Main Authors: Pham, Hieu Quang, Kondracki, Łukasz, Tarik, Mohamed, Trabesinger, Sigita
• Format: Article
• Language: English
• Subjects: Co-free cathode; Fe-based cathode; Li-rich layered oxides; Operando/post-mortem; Oxygen redox; Voltage fade
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2022.231181

Alternatives to Lithium-rich layered oxides xLi2MnO3∙(1−x)LiNi1−y−zCoyMnzO2 (LR-NCMs) are needed, despite them being promising high-capacity cathode materials for next generation of high-energy batteries, because these materials contain toxic Co in their structure and their practical applications are restricted by prominent capacity and voltage fade, caused by structural transformation upon long-term cycling. To address these issues, a search for a low-cost, Co-free Li-rich cathode materials with a better surface structural stability than LR-NCMs is ongoing. One of such compounds is Li1.16Ni0.19Fe0.18Mn0.46O2 (LNFM). Our as-synthesized LNFM cathode not only delivers a high specific capacity of 229 mAh g−1 with the capacity retention of 83% in half-cell and 81% in a full-cells but also a stable average discharge voltage, even when cycled at C/5 rate to upper cutoff potential of 4.8 V vs Li+/Li in additive-free electrolyte. Both operando and post mortem characterization was used to understand the structural changes, gas evolution and oxygen redox processes of LNFM material, as well as to understand cathode−electrolyte interfacial reactions and their correlation to the improved electrochemical performance. The gained understanding will help designing new high-capacity Co-free cathode materials, meeting the performance requirements for future high-energy density batteries. [Display omitted] •High-quality Co-free Li-rich Li1.16Ni0.19Fe0.18Mn0.46O2 obtained by co-precipitation.•Both voltage fade and layered-to-spinel structural transformation are weak.•LNFM delivers 229 mAh g−1 in voltage window of 2–4.8 V vs Li+/Li.•Excellent full-cell performance, 81% capacity retention after 100 cycles.•Viable competitor material for Co-free high energy density Li-ion battery.