Two-dimensional　(2D)　membrane-based　ion　separation　technology　has　been　increasingly　explored　to　address　the　problem　of　lithium　resource　shortage,　yet　it　remains　a　sound　challenge　to　design　2D　membranes　of　high　selectivity　and　permeability　for　ion　separation　applications.　Zeolitic　imidazolate　framework　functionalized　modified　layered　double　hydroxide　(ZIF-8@MLDH)　composite　membranes　with　high　lithium-ion　(Li+)　permeability　and　excellent　operational　stability　were　obtained　in　this　work　by　in　situ　depositing　functional　ZIF-8　nanoparticles　into　the　nanopores　acting　as　framework　defects　in　MLDH　membranes.　The　defect-rich　framework　amplified　the　permeability　of　Li+,　and　the　site-selective　growth　of　ZIF-8　in　the　framework　defects　bettered　its　selectivity.　Specifically　speaking,　the　ZIF-8@MLDH　membranes　featured　a　high　permeation　rate　of　Li+　up　to　1.73 mol m−2 h−1　and　a　desirable　selectivity　of　Li+/Mg2+　up　to　31.9.　Simulations　supported　that　the　simultaneously　enhanced　selectivity　and　permeability　of　Li+　are　attributed　to　changes　in　the　type　of　mass　transfer　channels　and　the　difference　in　the　dehydration　capacity　of　hydrated　metal　cations　when　they　pass　through　nanochannels　of　ZIF-8.　This　study　will　inspire　the　ongoing　research　of　high-performance　2D　membranes　through　the　engineering　of　defects.[InlineMediaObject　not　available:　see　fulltext.].　©　2023,　The　Author(s).