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.
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