Lithium-rich　materials　(LRMs)　are　among　the　most　promising　cathode　materials　toward　next-generation　Li-ion　batteries　due　to　their　extraordinary　specific　capacity　of　over　250　mAh　g(-1)　and　high　energy　density　of　over　1　000　Wh　kg(-1).　The　superior　capacity　of　LRMs　originates　from　the　activation　process　of　the　key　active　component　Li2MnO3.　This　process　can　trigger　reversible　oxygen　redox,　providing　extra　charge　for　more　Li-ion　extraction.　However,　such　an　activation　process　is　kinetically　slow　with　complex　phase　transformations.　To　address　these　issues,　tremendous　effort　has　been　made　to　explore　the　mechanism　and　origin　of　activation,　yet　there　are　still　many　controversies.　Despite　considerable　strategies　that　have　been　proposed　to　improve　the　performance　of　LRMs,　in-depth　understanding　of　the　relationship　between　the　LRMs＇　preparation　and　their　activation　process　is　limited.　To　inspire　further　research　on　LRMs,　this　article　firstly　systematically　reviews　the　progress　in　mechanism　studies　and　performance　improving　attempts.　Then,　guidelines　for　activation　controlling　strategies,　including　composition　adjustment,　elemental　substitution　and　chemical　treatment,　are　provided　for　the　future　design　of　Li-rich　cathode　materials.　Based　on　these　investigations,　recommendations　on　Li-rich　materials　with　precisely　controlled　Mn/Ni/Co　composition,　multi-elemental　substitution　and　oxygen　vacancy　engineering　are　proposed　for　designing　high-performance　Li-rich　cathode　materials　with　fast　and　stable　activation　processes.