Adopting　ultra-thin　copper　foil　as　the　current　collector　is　one　of　the　most　important　strategies　for　improving　the　gravimetric　energy　density　of　lithium-ion　batteries　(LIBs),　however,　stumbled　by　the　quality-control　of　physicochemical　properties　for　ultra-thin　foils.　Herein,　by　utilizing　combinative　additives,　the　＜=　4.5　mu　m　ultra-thin　electrolytic　copper　foil　with　appealing　physicochemical　properties　is　prepared,　presenting　very　low　Rz　(surface　roughness)　of　1.74　mu　m　and　extraordinarily　high　tensile　strength　of　435.65　MPa.　When　being　used　as　the　current　collector　in　LIBs,　a　high　gravimetric　energy　density　of　323.19　Wh/kg　was　achieved,　outperforming　both　the　commercial　9　mu　m　candidate　(205.81　Wh/kg)　and　the　purchased　4.5　mu　m　counterpart　(310.48　Wh/kg).　Also,　decreasing　the　thickness　of　commercial　copper　foil　(9　mu　m)　to　4.5　mu　m　demonstrates　superiorities　in　both　resources　saving　and　environmental　benignity,　contributing　to　similar　to　32　million　tons　copper　savings　in　2030　and　40.6　%　elimination　in　carbon　footprint　for　copper　foil　preparation.　The　results　herein　can　provide　guidance　for　quality-controlled　preparation　of　ultra-thin　copper　foil　as　well　as　new　insights　for　resource　savings　and　environmentally　friendly　manufacturing.