Towards Ultra Low Cobalt Cathodes: A High Fidelity Computational Phase Search of Layered Li-Ni-Mn-Co Oxides

Abstract

Layered Li(Ni,Mn,Co,)O${}_2$ (NMC) presents an intriguing ternary alloy design space for optimization as a cathode material in Li-ion batteries. Recently, the high cost and resource limitations of Co have added a new design constraint and high Ni-containing NMC alloys have gained enormous attention despite possible performance trade-offs. It is not fully understood if this material space is a disordered solid solution at room temperature and any arbitrary combination can be used or if there exist distinct transition metal orderings to which meta-stable solid solutions will decay during cycling and affect performance. Here, we present a high fidelity computational search of the ternary phase diagram with an emphasis on high-Ni, and thus low Co, containing compositional phases to understand the room temperature stability of the ordered and disordered solid solution phases. This is done through the use of density functional theory training data fed into a reduced order model Hamiltonian that accounts for effective electronic and spin interactions of neighboring transition metal atoms at various lengths in a background of fixed composition and position lithium and oxygen atoms. This model can then be solved to include finite temperature thermodynamics into a convex hull analysis to understand the regions of ordered and disordered solid solution as well the transition metal orderings within the ordered region of the phase diagram. We find that for the majority of transition metal compositions of the layered material, specifically medium to high-Ni content, prefer transition metal ordering and predict the collection of preferred compositions in the ordered region.

arXiv comment30 pages, 8 figures, 7 pages of Supporting Information

References in corpus (10)

• Configurational electronic entropy and the phase diagram of mixed-valence oxides: the case of Li${}_x$FePO${}_4$
• Surface Restructuring of Nickel Sulfide Generates Optimally-Coordinated Active Sites for ORR Catalysis
• Quantifying Confidence in DFT Predicted Surface Pourbaix Diagrams and Associated Reaction Pathways for Chlorine Evolution
• Quantifying Confidence in DFT Predicted Surface Pourbaix Diagrams of Transition Metal Electrode-Electrolyte Interfaces
• Ab-initio modeling of electrolyte molecule Ethylene Carbonate decomposition reaction on Li(Ni,Mn,Co)O2 cathode surface
• Systematic Error Estimation for Chemical Reaction Energies
• Maximal predictability approach for identifying the right descriptors for electrocatalytic reactions
• Probabilistic performance estimators for computational chemistry methods: the empirical cumulative distribution function of absolute errors
• Quantifying Confidence in Density Functional Theory Predicted Magnetic Ground States
• Quantification of uncertainty in first-principles predicted mechanical properties of solids: Application to solid ion conductors