The　rapidly　growing　electric　vehicle　market　as　well　as　large-scale　electric　grid　application　harshly　enforces　the　progress　of　high-energy　Li-ion　batteries　(LIBs),　and　arouses　the　urgent　renovation　of　high-capacity　cathode　materials.　To　this　end,　oxygen　anionic　redox　(OAR),　the　electrochemical　conversions　between　different　oxygen　states　in　oxides　to　compensate　charges　during　the　extraction/insertion　process　of　alkali　metal　ions,　has　served　as　a　new　design　paradigm　to　produce　＂extra＂　capacities　for　cathodes.　By　balancing　the　metal　cationic　redox　(MCR)　and　OAR,　a　variety　of　high-energy　cathodes,　especially　Li-rich　layered　oxides　(LLOs),　have　been　developed　and　extensively　studied　on　issues　such　as　material　design,　reaction　mechanism,　and　performance　enhancement,　making　LLOs　one　of　the　most　appealing　candidates　for　practical　high-energy　LIBs　in　the　near　future.　On　the　other　hand,　the　employment　of　pure　OAR　triggers　the　emerging　lithia-based　sealed　batteries　with　great　long-term　potentials,　although　diverse　fundamental　issues　require　urgent　elucidation.　This　review　paper　provides　an　overview　of　OAR　and　OAR-activated　cathodes　ranging　from　transition　metal　oxides　to　lithia-based　composites,　followed　by　a　personnel　perspective　with　a　hope　to　promote　the　development　of　high-energy　cathodes　for　more　advanced　batteries.　(C)　2021　Elsevier　B.V.　All　rights　reserved.