Low cost ionic liquid electrolytes for rechargeable aluminum/graphite batteries

Abstract

Rechargeable aluminum batteries are promising large-scale energy storage candidates due to the high natural earth abundance and high theoretical volumetric capacity of Al metal. However, they face many problems, including a limited lifetime, rate performance, and high electrolyte cost. Herein, we have designed a high-performance Al rechargeable battery using a graphite cathode and an economical AlCl3/Et3NHCl ionic liquid electrolyte. Based on the high conductivity of the AlCl3/Et3NHCl electrolyte, the battery achieved a reversible capacity of 96 mAh g−1 at 100 mA g−1, which is even higher than that of the battery using an AlCl3/urea electrolyte (89 mAh g−1). Furthermore, almost no capacity attenuation was observed, with AlCl3/Et3NHCl electrolyte having a capacity of 64 mAh g−1 after 1000 cycles, at 1000 mA g−1, while the AlCl3/urea electrolyte had a capacity of only 24 mAh g−1. Therefore, the aluminum/ graphite battery using AlCl3/Et3NHCl ionic liquid electrolyte with a high specific capacity and good long-term cycling stability is a promising candidate for future high-performance, large-scale energy storage devices.