Lithium-rich　layered　oxides　are　considered　as　promising　cathode　materials　for　Li-ion　batteries　with　high　energy　density　due　to　their　higher　capacity　as　compared　with　the　conventional　LiMO2　(e.g.,　LiCoO2,　LiNiO2,　and　LiNi1/3Co1/3Mn　O-1/3(2))　layered　oxides.　However,　why　lithium-rich　layered　oxides　exhibit　high　capacities　without　undergoing　a　structural　collapse　for　a　certain　number　of　cycles　has　attracted　limited　attention.　Here,　based　on　the　model　of　Li2RuO3,　it　is　uncovered　that　the　mechanism　responsible　for　the　structural　integrity　shown　by　lithium-rich　layered　oxides　is　realized　by　the　fl　exible　local　structure　due　to　the　presence　of　lithium　atoms　in　the　transition　metal　layer,　which　favors　the　formation　of　O-2(2-)-like　species,　with　the　aid　of　in　situ　extended　X-ray　absorption　fi　ne　structure　(EXAFS),　in　situ　energy　loss　spectroscopy　(EELS),　and　density　functional　theory　(DFT)　calculation.　This　fi　nding　will　open　new　scope　for　the　development　of　high-capacity　layered　electrodes.