In-situ　polymerization　of　gel　polymer　electrolyte　(GPE)　is　expected　to　be　promising　approach　to　solve　the　safety　and　interfacial　problems　of　lithium　ion　battery,　but　it　is　still　challenging　ways　to　tradeoff　the　high　electrochemical　properties　and　mechanical　toughness.　Here,　30　μm　thickness　of　free-standing　GPEs　with　extremely　high　monomer　conversion　were　obtained　by　in-situ　UV　approach　on　lithium　metal　anode　within　only　few　seconds.　The　coordination　of　amide　and　aliphatic　carbonyl　groups　with　lithium　ion　endows　the　tough　mechanical　properties,　which　tensile　strength　and　elongation　at　break　reach　up　to　∼1.0　MPa　and　∼920　%.　Furthermore,　the　good　degree　of　graphitization　on　the　surface　of　burned　polymer　gel　contribute　to　its　flame　resistance.　The　ionic　conductivity　and　lithium　ion　transferance　number　are　up　to　1.03　mS/cm　and　0.44　at　room　temperature,　respectively.　Finally,　Li/LiFePO4　half　cells　assembled　with　the　optimized　GPEs　exhibit　stable　cycle　performance　at　0.5C　rate,　delivering　77.44　%　of　capacity　retention　after　1000　cycles.　©　2023　Elsevier　B.V.