Na-O2　batteries　are　considered　a　promising　energy　storage　device　for　powering　next-generation　electric　vehicles,　due　to　their　high　theoretical　energy　density,　high　energy　efficiency,　and　low　cost.　Furthermore,　Na-O2　batteries　that　have　sodium　superoxide　as　their　discharge　product　are　highly　attractive　as　they　exhibit　extremely　low　charge　overpotentials.　Though　significant　advances　have　been　made　on　superoxide-based　Na-O2　batteries,　the　practical　application　of　this　technology　is　still　severely　hindered　by　insufficient　achievable　capacities　and　limited　cycling　performance.　This　review　presents　a　comprehensive　summary　of　superoxide-based　Na-O2　batteries,　beginning　with　an　overview　of　their　configuration,　historical　development,　and　technical　challenges,　followed　by　their　discharge/charge　reaction　mechanisms　discussed　in　light　of　recent　findings.　Furthermore,　the　development　of　air　electrodes,　electrolytes,　and　the　Na　anode,　as　well　as　the　detrimental　effect　of　O2/O2-　crossover　are　discussed.　Finally,　a　general　conclusion　and　perspective　on　the　current　limitations　and　recommended　future　research　directions　of　Na-O2　batteries　is　presented.　This　review　aims　at　serving　as　a　guideline　for　the　development　of　superoxide-based　Na-O2　batteries　with　high　energy　density　and　long　cycle　life　for　next-generation　applications　such　as　electric　vehicles.