LiMn6　hexatomic-rings　act　as　functional　units　in　Li-rich　layered　oxides　(LLOs),　which　determine　the　capacity,　voltage,　and　structural　stability　of　LLOs.　However,　the　symmetry　of　the　LiMn6　hexatomic-ring　is　always　broken,　especially　in　the　grain　surface　of　LLOs,　which　will　greatly　affect　its　electrochemical　per-formance.　Herein,　the　symmetry-breaking　of　LiMn6　hexatomic-ring　in　the　grain　surface　of　Li2MnO3　was　studied,　and　their　effect　on　charge　compensation　mechanism　and　structure　evolution　behavior　was　thor-oughly　investigated.　The　results　show　that　the　electrochemical　activity　of　the　symmetry-broken　LiMn6　hexatomic-ring　is　higher　than　that　of　the　unbroken　LiMn6,　and　the　former　is　more　favorable　for　spinel-ization　on　the　grain　surface.　Furthermore,　the　exposure　proportion　of　crystallographic　planes　with　differ-ent　symmetry-broken　LiMn6　hexatomic-ring　has　also　been　discussed,　which　can　be　adjusted　by　changing　the　partial　pressure　of　oxygen.　The　in-depth　understanding　of　the　symmetry-breaking　of　LiMn6　hexatomic-ring　will　provide　more　targeted　strategies　for　designing　high-performance　LLOs　cathodes　for　lithium-ion　batteries.(c)　2023　Science　Press　and　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　ELSEVIER　B.V.　and　Science　Press.　All　rights　reserved.