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A breakthrough in advancing power density and stability of carbon-based supercapacitors is trapped by ineff?cient pore structures of electrode materials. Herein, an ultra-microporous carbon with ultrahigh integrated capacitance fabricated via one-step carbonization/activation of dense bacte?rial cellulose (BC) precursor followed by nitrogen/sulfur dual doping is reported. The microporous carbon possesses highly concentrated micropores (~?2 nm) and a considerable amount of sub-micropores (1 nm). The unique porous structure provides high specific surface area (1554 m2 g?1) and packing density (1.18 g cm?3). The synergistic effects from the particular porous structure and optimal doping effectively enhance ion storage and ion/electron transport. As a result, the remarkable specific capacitances, including ultrahigh gravimetric and volumetric capacitances (430 F g?1 and 507 F cm?3 at 0.5 A g?1), and excellent cycling and rate stability even at a high current density of 10 A g?1 (327 F g?1 and 385 F cm?3) are realized. Via compositing the porous carbon and BC skeleton, a robust all-solid-state cellulose-based supercapacitor presents super high areal energy density (~?0.77 mWh cm?2), volumetric energy density (~?17.8 W L?1), and excellent cyclic stability.