In　the　past　several　decades,　the　research　communities　have　witnessed　the　explosive　development　of　lithium-ion　batteries,　largely　based　on　the　diverse　landmark　cathode　materials,　among　which　the　application　of　manganese　has　been　intensively　considered　due　to　the　economic　rationale　and　impressive　properties.　Lithium-manganese-based　layered　oxides　(LMLOs)　are　one　of　the　most　promising　cathode　material　families　based　on　an　overall　theoretical　evaluation　covering　the　energy　density,　cost,　eco-friendship,　etc.　Unfortunately,　the　Mn3+　cation　introduces　severe　Jahn–Teller　(J–T)　effect,　which　profoundly　distorts　the　localized　lattice　structure　and　reduces　the　electrochemical　stability.　This　perspective　presents　the　principal　comprehensions　of　the　J–T　effect　in　LMLOs　and　offers　an　outline　picture　of　material　design　to　suppress　it.　We　outline　the　history　of　material　design　and　further　assess　available　approaches　to　address　the　J–T　effect.　Finally,　we　tentatively　propose　promising　design　trends　with　eliminated　J–T　effect　to　revive　this　important　cathode　material　family　toward　practical　applications.　©　2021　Elsevier　Inc.