context: The Zn symmetric and Zn–Ti asymmetric cells were assembled as CR2030 coin cells to measure the electrochemical performances. Glass fiber and a 3 M Zn(CF3SO3)2 aqueous solution were used as the separator and the electrolyte, respectively. Before cell fabrication, Ti foil, bare Zn foil and PAM/PVP-coated Zn were cut into disk-shaped electrodes. The symmetric cells consist of two bare Zn foils (or PAM/PVP-coated Zn foils) separated by a glass fiber separator. The cells underwent galvanostatic charge and discharge cycling at a current density of 0.2–10 mA cm−2 on a Neware battery testing instrument. These experiments were performed to evaluate the stripping/plating behavior and cycling stability of the bare Zn and PAM/PVP-coated Zn anodes. Furthermore, Zn–Ti asymmetric cells were fabricated to investigate the coulombic efficiency of Zn stripping/plating. The asymmetric cell was initially discharged for 10 min, and then to 2.0 V at various current densities from 0.2–20 mA cm−2. To obtain the corrosion potential (Ecorr) and corrosion current density (Icorr), Tafel plots of the Zn symmetric cells were recorded on an electrochemical workstation (CHI660E, China) at a scan rate of 10 mV s−1. Chronoamperograms (CAs) of the bare Zn and the PAM/PVP-coated Zn symmetric cells were recorded under a −200 mV overpotential. The Zn–AC hybrid supercapacitors were fabricated with AC as the cathode, bare Zn or PAM/PVP-coated Zn foil as the anode, and 3 M Zn(CF3SO3)2 aqueous solution as the electrolyte. The cathode slurry was fabricated by mixing the cathode active materials, Super P, and PTFE at a mass ratio of 80:10:10. The resulting slurry was rolled into a thin film with a thickness of about 120 μm. Finally, the film was cut into discs with a diameter of 10 mm, pressed into a Ti mesh (15 mm in diameter) and dried in a vacuum oven at 100 °C for 6 h. The electrochemical performance was evaluated by cyclic voltammetry on an electrochemical workstation. The galvanostatic charge–discharge processes of the Zn–AC hybrid supercapacitor were recorded on a Neware battery testing system.
answer:  3 M Zn(CF3SO3)2 aqueous solution