In　this　work,　N-doped　carbon　nanotubes　(NCNTS)　have　been　easily　unzipped　using　a　chemical　oxidation　method　to　obtain　porous　and　multi-defective　partially　unzipped　N-doped　carbon　nanotubes　(PU-NCNTs),　which　are　promising　as　negative　electrode　materials　for　supercapacitors　and　are　also　suitable　substrate　materials　for　the　efficient　loading　of　ultrathin　manganese　dioxide　(MnO2)　nanosheets.　Herein,　the　PU-NCNT/MnO2composite　was　synthesized　through　a　simple　microwave　irradiation　method.　Moreover,　we　have　fabricated　an　asymmetric　supercapacitor　(ASC)　using　PU-NCNT/MnO2composite　as　cathode,　PU-NCNTs　as　anode　and　neutral　aqueous　Na2SO4as　electrolyte.　Because　of　the　synergistic　effects　of　the　PU-NCNTs　electrode　and　the　high　capacitance　as　well　as　good　rate　performance　of　PU-NCNT/MnO2composite,　the　asymmetric　cell　exhibited　good　electrochemical　performance.　The　optimized　ASC　can　be　worked　stably　in　the　voltage　window　of　0–1.8　V　and　exhibited　a　maximum　energy　density　of　14.76　Wh　kg−1at　the　current　density　of　1　A　g−1.　Additionally,　the　PU-NCNT/MnO2//PU-NCNT　ASC　exhibited　long　cycling　stability　with　80.5%　specific　capacitance　retained　after　1000　cycles　at　a　current　density　of　1　A　g−1.　These　encouraging　results　show　that　PU-NCNT/MnO2could　be　promising　materials　for　commercial　use　of　supercapacitors.　©　2017