Carbon Nanosponge Cathode Materials and Graphite-Protected Etched Al Foil Anode for Dual-Ion Hybrid Supercapacitor

Abstract

Al-based anode can potentially reduce the dual-ion energy storage device's quality and volume, however, the cycling performance is always insufficient. Herein, we fabricated Al-CNSs hybrid supercapacitors (SCs) using carbon nanosponge materials (CNSs) as cathode materials and graphite-protected etched Al foils as the anodes. The macro-/mesoporous structure in CNSs facilitates the ions (solvated PF6−) transport, resulting in much better SC rate capability compared to the commercial activated carbon. The etched pores in Al foil offer numerous alloying reaction sites to accommodate the volume expansion. In addition, the graphite layer on the Al surface blocks the Li dendrite growth, leading to homogeneous alloying-dealloying reaction. Such Al-CNSs hybrid SC delivered a high maximum specific capacitance of 181 F g−1 at 0.05 A g−1, remained 62 F g−1 at 1 A g−1, and offered a retention value of 83% after 1000 cycles, which was largely improved compared to the pure Al and etched Al without coating. The whole device can offer 75 Wh L−1 due to the thin anode design, which is comparable to the lead acid batteries.