High Specific-Capacity Al-Graphite Dual-Ion Batteries

Abstract

Rechargeable Al-graphite dual ion batteries are believed as a promising stationary energy storage system due to its low cost and long cycling life. Through engineering both Al and graphite electrodes using poly(vinylidene fluoride) and poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP) copolymer as both binder and ionic network, Al-graphite batteries with high specific capacities and rate capabilities were demonstrated. We employed high-surface-area acetylene black (AB) as the substrate for Al plating to enhance the rate capability (up to 20 mA cm−2 geo) and stability (>500 h) of Al plating/stripping. The utilization of graphite was increased by anchoring graphite particles in the PVDF-HFP ionic network. With these Al and graphite electrodes, Al-graphite dual ion batteries were shown to have a specific capacity of ∼140 mAh g−1 C at a current density of 186 mA g−1 C and high cycling stability (∼0.07% decay per cycle based on the fully activated capacity at 2.98 A g−1 C). The 3D electrode design (Al negative and carbon positive electrode) with stable structure and high surface area can facilitate the development of the new Al-based battery chemistries (Al-Cl2, Al-Br2, and Al-O2, etc.).