Ash‐Free Porous Carbon as the Negative Additive of Lead‐Acid Batteries and Supercapacitors

Herein, a simple method to prepare porous carbon that inhibits hydrogen evolution is used, which has enormous advantages for both capacitors and lead‐acid batteries. The quantitative filter paper spongy porous carbon (SQFPC) is successfully synthesized by the two‐step method. SQFPC displays a porous, spongy structure with a large specific surface area (1847 m 2 g −1 ). In electrochemical tests, SQFPC exhibits high specific capacitance (244 F g −1 at 1 A g −1 ) and a capacitance retention rate of 72.5% at 40 A g −1 . In addition, the capacity of the battery with 0.5 wt% SQFPC is improved by 57.6% at a discharge rate of 0.1C, and the cycle life under the high‐rate partial state of charge is 9.3 times that of the blank battery. The enhanced battery performance is related to the unique structure and surface functional groups of carbon, which speed up ion movement inside the battery and provide active sites for lead deposition.