Under　the　growing　crisis　of　the　coronavirus　disease　2019　pandemic,　the　global　medical　system　is　facing　the　predicament　of　an　acute　shortage　of　medical-grade　oxygen　(O-2,　＞=　99.5%　purity).　Herein,　an　oxygen　generation　device　is　manufactured　that　relies　on　electrochemical　technology.　The　performance　of　the　electrochemical　oxygen　generator　(EOG)　is　remarkably　improved　to　a　practically　applicable　level,　achieving　long-term　(＞200　h),　stable,　and　quick　production　(＞1.5　L　min(-1))　of　high　purity　O-2　(99.9%)　at　high　energy　efficiency　(496　L　kW(-1)　h(-1)),　via　simultaneous　optimization　for　intrinsic　electrochemical　reaction　mechanisms,　electrocatalysts,　and　external　cell　structure.　The　EOG　also　presents　powerful　competitiveness　in　user　experience,　which　finds　expression　in　high　portability　(4.7　kg),　nearly　instant　O-2　production　(＜1　s),　and　a　quiet　working　condition　(＜39　dB).　The　EOG　shows　great　potential　to　substitute　commercial　pressure　swing　adsorption　O-2　generation　devices,　which　may　significantly　impact　the　traditional　oxygen　production　industry.