3D hierarchical CoO@MnO 2 core–shell nanohybrid for high-energy solid state asymmetric supercapacitors

The 3D CoO@MnO 2 core-shell nanohybrid based asymmetric supercapacitors deliver an excellent energy density (~85.9 Wh kg −1 ), an ultra-high power density (~16769 W kg −1 at 51.7 Wh kg −1 ), and remarkable cycle stability (86.8% capacitance retention after 10 000 cycles).