Surfaces,　interfaces　and　grain　boundaries　are　classically　known　to　be　sinks　of　defects　generated　within　the　bulk　lattice.　Here,　we　report　an　inverse　case　by　which　the　defects　generated　at　the　particle　surface　are　continuously　pumped　into　the　bulk　lattice.　We　show　that,　during　operation　of　a　rechargeable　battery,　oxygen　vacancies　produced　at　the　surfaces　of　lithium-rich　layered　cathode　particles　migrate　towards　the　inside　lattice.　This　process　is　associated　with　a　high　cutoff　voltage　at　which　an　anionic　redox　process　is　activated.　First-principle　calculations　reveal　that　triggering　of　this　redox　process　leads　to　a　sharp　decrease　of　both　the　formation　energy　of　oxygen　vacancies　and　the　migration　barrier　of　oxidized　oxide　ions,　therefore　enabling　the　migration　of　oxygen　vacancies　into　the　bulk　lattice　of　the　cathode.　This　work　unveils　a　coupled　redox　dynamic　that　needs　to　be　taken　into　account　when　designing　high-capacity　layered　cathode　materials　for　high-voltage　lithium-ion　batteries.