In this work, both advantages of sodium-ion batteries and dual-ion batteries have been combined in an innovated sodium-ion-based dual-ion battery (SDI) system using a Na metal film as anode and a freestanding meso-carbon microbead film (FS-MCMB) as cathode. FS-MCMB in SDI battery exhibited a superior working performance with the specific capacity of 83.6 mAh/g and a remarkable long-term stability over 300 cycles. The SDI battery with FS-MCMB exhibited an advantage of high mass density loading in the range of 2−7.5 mg cm −2 , which was equal to a comparable capacity of 78−83 mAh/g. The electrochemical impedance analysis indicated that FS-MCMB provided a superior permeability, resulting in facilitating electrolyte infiltration into MCMB structure. In-situ XRD and ex-situ Raman spectroscopy were utilized to characterize the intercalating/deintercalating process of PF 6 − anions into/out of MCMB during charging/discharging processes. Finally, theoretical calculations further confirmed the structural arrangement of PF 6 − anions in the graphite layers.

A battery with high energy density, large capacity, long cyclability, safety, and flexibility is desired to not only power small electronic devices but also provide solutions to large-scale energy storage management. In this work, a hybrid battery of Zn–Ag and Zn–air (Zn–Ag/air) has been successfully fabricated in which Ag acted as an active material at the charging state and as an oxygen reduction reaction catalyst at the discharging state. In traditional zinc air batteries, Ag was used as a catalytic material only. In this work, sufficient amounts of Ag nanoparticles were covered onto stainless steel wire screen via a facile electrodeposition procedure as not only catalytic materials but also active redox materials. The rigid hybrid battery delivered two discharging plateaus at 1.5 and 1.1 V in which the higher one was attributed to reduction of Ag2O to Ag and the lower one resulted from Ag-assisted oxygen reduction reaction. The cyclability test showed that the Coulombic efficiency retained higher than 85% after 1700 cycles. Furthermore, the Zn–Ag/air hybrid battery was also able to be packed in a pouch cell and demonstrated high flexibility and rechargeable capability. Overall results indicate that the hybrid battery possesses both advantages of Zn–Ag and Zn–air batteries with improved discharging potential and enhanced storage capacity.

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Zinc ion batteries have been extensively studied with an aqueous electrolyte system. However, the batteries suffer from a limited potential window, gas evolution, cathode dissolution, and dendrite formation on the anode. Considering these limitations, we developed an alternative electrolyte system based on deep eutectic solvents (DESs) because of their low cost, high stability, biodegradability, and non-flammability, making them optimal candidates for sustainable batteries. The DES electrolyte enables reversible Zn plating/stripping and effectively suppresses zinc dendrite formation. Furthermore, in-depth characterizations reveal that the energy storage mechanism can be attributed to [ZnCl] + ion intercalation and the intermediate complex ion plays a pivotal role in electrochemical reactions, which deliver a high reversible capacity of 310 mAh g −1 at 0.1 A g −1 and long-term stability (167 mAh g −1 at a current density of 0.3 A g −1 after 300 cycles, Coulombic efficiency: ∼98%). Overall, this work represents our new finding in rechargeable batteries with the DES electrolyte.