Computational Design of High-Performance Li- and Mn-Rich Layered Cathodes via Dual-Doping Strategies

Abstract

The Lithium- and Manganese-rich (LMR) layered oxides are being highlighted as the next-generation cathode materials due to the high energy density (≈ 300 mAh g-1) and low cost. However, their practical application is limited by oxygen release, structural instability, voltage decay, and limited cycle life. Cathodic doping is effective but limited by a fundamental misunderstanding of multi-dopant interactions, which prevents the systematic optimization of cathode compositions. Herein, we investigate the effects of five single dopants and four dual-dopant combinations on the electronic structure of LMR cathodes using first-principles density functional theory (DFT) calculations combined with ligand field theory. A Hamiltonian-based cluster expansion approach is employed to model the intricate delithiated configurations in doped systems. We compute phase stability, capacity, voltage, volume, oxygen stability, and cost depending on the type of doping. Based on this, we reveal the physical (e.g., atomic size) and chemical effects (e.g., charge transfer) of dopants on the electrochemical performance of LMR layered cathodes. Specifically, we identify a linear correlation between dopant-intrinsic electronic descriptors and the formation energy, demonstrating their direct influece on dopant-induced thermodynamic stability. In terms of electrochemical performance, we identify a clear synergy between d⁰ elements and redox-active dopants. In particular, combining d⁰ elements with redox active elements enhances the redox activity of the redox-active dopants themselves, which effectively stabilizes the anionic redox process. This dual dopant strategy also enables modulation of the operating voltage and suppresses lattice volume changes upon delithiation. We further uncover a pronounced trade-off between volume variation and oxygen vacancy formation. Based on this trade-off, the investigated dopant combinations can be classified into three distinct groups, allowing a systematic assessment of their cyclability. This study will provide predictive insights into dopant selection for designing novel LMR layered cathode materials.