Regulating oxygen redox activity for exploiting Li & Mn rich cathodes as a cost-effective option

초록

Li-and Mn-rich cathodes (LMRs) have emerged as cost-effective alternatives to conventional Ni-and Co-rich cathodes, such as LiNi0.6Mn0.2Co0.2O2 (NMC622), due to their high Mn content and reduced reliance on expensive elements. However, their commercial viability is hindered by performance degradation issues, including voltage fading and capacity decline, largely driven by unstable oxygen redox activity. In this study, we demonstrate a strategy to regulate oxygen redox activity, enabling LMRs to serve as stable, cost-effective cathodes with competitive energy density. By fine-tuning the chemical composition-particularly Mn content and excess Li-and optimizing the upper cutoff voltage, we effectively regulated the balance between oxygen redox and transition metal redox, mitigating key degradation issues. Additionally, minor Mo doping was introduced to further shift the balance toward transition metal redox while reducing oxygen redox reactions, enhancing cycling stability and energy retention, particularly in high-Mn LMR compositions. Our results reveal that oxygen-redoxregulated LMRs can deliver desirable electrochemical stability and practical energy density, making it a viable alternative to conventional mid-Ni cathodes such as NMC622. These findings provide critical design principles for developing next-generation oxygen-redox-regulated LMRs as practical and sustainable cathode materials for lithium-ion batteries.

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