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oai:figshare.com:article/34018417 2026-09-28T20:13:42Z category_1 category_4 category_7 category_12 category_14 category_16 category_24 category_873 category_39 category_45 category_61 category_64 category_135 portal_63 item_type_6 month_year_09_2026

Multi-Step Oxygen Redox Mechanism in the Polyanionic Lithium-Rich Cathode Li₂FeSiO₄ Patrick J. Taylor (9682222) Kit McColl (5908817) M. Saiful Islam (366233) Benjamin J. Morgan (1278948) Biophysics Biochemistry Medicine Cell Biology Molecular Biology Physiology Evolutionary Biology Chemical Sciences not elsewhere classified Ecology Sociology Developmental Biology Cancer Computational Biology poor cycling stability irreversible structural change decomposition occurs spontaneously conventional cathode materials 4 − framework rich silicates provide rich cathode li store charge beyond reduction alongside molecular metal redox limit 4 </ sub 2 </ sub v </ sup iv </ sup iii </ sup fully delithiated fesio oxygen redox rich oxides rich chemistry rich cathodes thermodynamically unstable polyanionic frameworks oxide ions metal migration inherently prevent form molecular findings demonstrate covalently bonded computational study compound process charge behavior bulk material Lithium-rich cathode materials offer significantly higher energy densities than conventional cathode materials, due to their ability to store charge beyond the formal transition-metal redox limit, via so-called “oxygen redox”. In lithium-rich oxides, oxygen redox is accompanied by molecular O₂ formation and transition-metal migration, associated with irreversible structural change and poor cycling stability. Lithium-rich silicates provide an alternative lithium-rich chemistry, and have been proposed to be resilient to O₂ formation at the top of charge, due to their covalently bonded [SiO4]4− framework. We report a computational study of the top-of-charge behavior of the prototypical silicate cathode Li₂FeSiO₄. Using density functional theory, we predict that fully delithiated FeSiO₄ is thermodynamically unstable with respect to oxidation of oxide ions to form molecular O₂ within the bulk material. Ab initio molecular dynamics shows this decomposition occurs spontaneously, via a multistep mechanism involving Fe^IV migration and disproportionation to Fe^III and Fe^V, and subsequent Fe^V reduction alongside molecular O₂ formation. Our findings demonstrate that polyanionic frameworks do not inherently prevent O₂ formation in lithium-rich cathodes, and illustrate how different previously proposed oxygen redox mechanisms can function as steps within a compound process. 2026-09-28T00:00:00Z Text Journal contribution 10.1021/jacs.6c02850.s001 https://figshare.com/articles/journal_contribution/Multi-Step_Oxygen_Redox_Mechanism_in_the_Polyanionic_Lithium-Rich_Cathode_Li_sub_2_sub_FeSiO_sub_4_sub_/34018417 CC BY-NC 4.0