A facile one-step hydrothermal strategy has been developed to prepare 3D porous Co 3 O 4 /graphene aerogel (Co 3 O 4 / GA). Due to the combination of a highly interconnected 3D network of GA and porous Co 3 O 4 nanospheres, the resulting Co 3 O 4 /GA electrode exhibits exceptional electrical conductivity and pseudocapacitance, making it an excellent material for energy-storage devices. The Co 3 O 4 /GA composites possess a high specific surface area of 127 m 2 g -1 and a broad pore-size distribution of 1-110 nm. The presence of porous Co 3 O 4 is found to be remarkably effective in enhancing the specific capacitance of the composite aerogel, up to 1512.7 F g -1 at 1 A g -1 . Furthermore, the combination of the two aerogel electrodes with a [a] LiOH/PVA-gel electrolyte endows our all-solid-state asymmetric supercapacitor (SASC) of Co 3 O 4 /GA//GA with a stable cycling performance in the high-voltage region of 0-1.6 V (capacitance retention of 81.5 % after 5000 continuous charge/discharge cycles), and superior electrochemical performance, with an energy density of 68.1 W h kg -1 at a power density of 982.9 W kg -1 , which is even higher than the maximum energy density of 58.7 W h kg -1 at a power density of 1209.4 W kg -1 of this ASC in a liquid-state electrolyte. These results indicate that Co 3 O 4 /GA could be a potential candidate in the field of supercapacitors.ionic conductivity, toxicity, and easy leakage, which limits their large-scale application. To solve this problem, the all-solid-state ASC has been extensively explored, due to its portability, environmental friendliness, and stability.The key to achieving high energy and power densities in allsolid-state ASCs is to choose electrode materials with excellent electrochemical properties. Intensive efforts have been devoted to ASCs with higher energy and power density by exploring various redox-active materials, such as Co 3 O 4 @Ni(OH) 2 //graphene, CNT/MnO 2 /GR//CNT/PANI, graphene/Ni(OH) 2 //AC, Ni@rGO/ Co 3 S 4 //Ni@rGO/Ni 3 S 2 , and so on. [7][8][9][10] Nevertheless, a simple synthesis method for the development of porous three-dimensional (3D) metal oxides is still a challenge. Porous metal oxides usually show different physical properties than bulk materials. [11,12] A porous 3D structure is beneficial for improving electrochemical properties, because the short ion-diffusion path and the high surface area provide more efficient contact between the electrolyte ions and active materials for faradic energy storage. [13] So, it is essential to develop a new energystorage material with abundantly porous, nanostructured, large surface-area characteristics.Among the many metal oxides, Co 3 O 4 is one of the most promising materials for low-cost and environment-friendly ASC devices with high specific capacitance. [14,15] The usual methods for the synthesis of porous Co 3 O 4 , through the calcination process, easily cause the collapse of the material structure, resulting in limited practical applications. Moreover, the intrinsic nature of transition-metal...