Three-dimensional (3D) porous carbon materials made of two-dimensional carbon sheets possess great potential as high-performance electrode materials for supercapacitors. In this work, 3D interconnected sheet-like porous carbons (ISPCs) are constructed from cheap coal tar for the first time by a confined ionic liquid soft-template strategy coupled with in-situ KOH activation. The as-made 3D ISPCs are composed of thin carbon nanosheets with abundant short pores, possessing a high specific surface area up to 1593 m(2) g(-1). Due to these synergistic structural characteristics, ISPCs as supercapacitor electrode measured in two-electrode configuration exhibit an outstanding electrochemical performance with a high specific capacitance (314F g(-1) at 0.05 A g(-1)), good rate capability (195F g(-1) at 100 A g(-1)) and superior cycle stability (97.1% capacitance retention after 10,000 cycles at 5 A g(-1)) in KOH electrolyte. This work paves a novel way for the production of high-performance ISPCs from carbon-rich liquid industrial by-products for energy storage devices.