Nickel-rich　layered　lithium　transition　metal　oxides,　LiNixCoyMn1-x-yO2,　are　key　cathode　materials　for　high-energy　lithium-ion　batteries　owing　to　their　high　specific　capacity.　However,　the　commercial　deployment　of　nickel-rich　oxides　is　hampered　by　their　parasitic　reactions　and　the　associated　safety　issues　at　high　voltages.　Developing　a　stable　cathode-electrolyte　interphase　(CEI)　is　a　promising　strategy　to　overcome　this　problem.　Herein,　we　report　a　novel　approach,　based　on　the　in　situ　polymerization　reaction,　to　build　a　protective　polymer　skin　on　LiNi0.6Co0.2Mn0.6O2　(NCM622)　cathode　materials.　The　artificial　CEI　skin　was　found　to　drastically　improve　the　intrinsic　thermal　stability,　mitigate　the　evolution　of　phase　transition,　and　effectively　inhibit　the　associated　parasitic　reactions　between　cathodes　and　the　electrolyte　in　the　high-charge　states.　This　coating　approach　leads　to　enhanced　capacity　retention　and　battery　safety　under　high-voltage　operations.　The　CEI　design　concept　offers　a　promising　strategy　for　develop　advanced　nickel-rich　cathodes　for　batteries.