Hybrid Aqueous Energy Storage Cells Using Activated Carbon and Lithium-Intercalated Compounds

A hybrid aqueous electrochemical supercapacitor technology is presented in which activated carbon was used as a negative electrode and a lithium-ion intercalated compound as a positive electrode in a neutral aqueous electrolyte. The charge/discharge process is associated with the transfer of a Li ion between two electrodes. It is quite different from the electrolyte behavior in conventional electrochemical double-layer supercapacitors and other reported hybrid supercapacitors, where the cations and anions separate and the electrolyte is consumed. By optimization of the positive/negative electrode mass load ratio, operating voltage window, and pH of the electrolyte solution, the cell exhibits a sloping voltage profile from and delivers an estimated specific energy of ca. based on the total weight of the active electrode materials. The cell exhibits excellent cycling performance with less than 5% capacity loss over at charge/discharge rate.