Pseudocapacitive materials hold great promise to achieve battery-level energy density integrated with power-related preponderance of electrostatic capacitors. However, it still remains a large challenge in finding proper capacitive material pairs to provide high operation voltage and high-level capacitance with good rate capability. Here, a three-dimensional hierarchical porous N-rich graphitic carbon (HNGC) material was prepared to construct novel symmetric aqueous carbonaceous supercapacitors (ACSCs). With ultrathin slice units, highly graphitic texture, and copious heteroatom functionalities, HNGC significantly promoted the faradic pseudo-capacitors, demonstrating extremely high single-electrode capacitance of over 710 F g-1 in 1 M H2SO4 aqueous solution. First-principles computations revealed that copious N-induced defects tremendously boost the electrochemical performance of HNGC in acidic electrolytes by accommodating more protons, facilitating ion mobility and interfacial charge transport. Simultaneously integrated electrical double-layer capacitance and pseudo-capacitance, the novel symmetric ACSCs with both structural and elemental advantages provide high operation voltage and further high-level energy density of over 75 W h kg-1 electrodes at a large power density of 1500 W kg-1, achieving battery-level energy density while retaining the capacitor-level power delivery ability (30 kW kg-1) and cyclic stability (ultra-long 8000 cycles). The proof-of-concept design of ACSCs outclasses the generally-known high-voltage asymmetric counterparts under the same power and represents an advance towards battery-level energy density in supercapacitors.