Unlocking the full energy densities of carbon-based supercapacitors

Carbon-based supercapacitors (SCs) have limited energy density due to sluggish mass diffusion and restricted charge accumulation. To increase the energy density of carbon-based SCs, attention must be paid to the factors of specific capacitance and electrochemical stability window. This review summarizes recent signs of progress in carbon-based materials, including specific surface area, pore structure regulation, heteroatom doped, and carbon composites. In addition, we discuss aqueous, organic, and ionic liquid electrolytes that affect the electrochemical stability window of SCs. Finally, the possibilities for achieving synergy in electrode/electrolytes are summarized via enhancing the pseudocapacitance contribution and developing high-voltage window electrolytes.