Friendly Environmental Strategies to Recycle Zinc-Carbon Batteries for Excellent Gel Polymer Electrolyte (PVA-ZnSO 4 -H 2 SO 4 ) and Carbon Materials for Symmetrical Solid-State Supercapacitors.

In this report, we introduce a novel idea to prepare a redox additive in a gel polymer electrolyte system of PVA-ZnSO 4 -H 2 SO 4 based on zinc-carbon battery recycling. Here, zinc cans from spent zinc-carbon batteries are dissolved completely in 1 M H 2 SO 4 to obtain a redox additive in an aqueous electrolyte of ZnSO 4 -H 2 SO 4 . Moreover, carbon nanoparticles and graphene nanosheets were synthesized from carbon rod and carbon powder from spent zinc-carbon batteries by only one step of washing and electrochemical exfoliation, respectively, which have good electrochemical capability. The three-electrode system using a ZnSO 4 -H 2 SO 4 electrolyte with carbon nanoparticles and graphene nanosheets as working electrodes shows high electrochemical adaptability, which points out its promising application in supercapacitor devices. Thus, the symmetrical solid-state supercapacitor devices based on the sandwich structure of graphene nanosheets/PVA-ZnSO 4 -H 2 SO 4 /graphene nanosheets illustrated the highest energy density of 39.17 W h kg -1 at a power density of 1700 W kg -1 . While symmetrical devices based on carbon nanoparticles/PVA-ZnSO 4 -H 2 SO 4 /carbon nanoparticles exhibited a maximum energy density of 35.65 W h kg -1 at a power density of 1700 W kg -1 . Moreover, these devices illustrate strong durability after 5000 cycles, with approximately 90.2% and 73.1% remaining, respectively. These results provide a promising strategy for almost completely recycling zinc-carbon batteries, one of the most popular dry batteries.