AlCl3-Saturated Ionic Liquid Anolyte with an Excess of AlCl3 for Al-Graphite Dual-Ion Batteries

摘要

Al-graphite dual-ion batteries (AGDIBs) represent a compelling battery concept for large-scale stationary storage of electricity in view of their safety, low cost, long cycling life, and high energy efficiency (80-90 %). However, at present, the deployment of AGDIBs is intrinsically limited by their low cell-level energy density as a result of the non-rocking-chair operation principle and, consequently, the need for large quantities of acidic chloroaluminate ionic liquid (IL) anolytes as a reservoir of Al2Cl7- ions required for AGDIB operation. Thus far, AGDIBs have commonly employed IL anolytes with moderate acidity (AlCl3/Lewis base molar ratio of 1.3), which corresponds to charge-storage anolyte capacity of ca. 19 mAh g(-1), eventually resulting in low cell-level energy densities of 20-30 Wh kg(-1). In this work, we present an AGDIB utilizing an AlCl3-saturated IL anolyte, containing an excess of AlCl3 powder for maintaining constant acidity during operation, leading to a theoretical capacity of 52 mAh g(-1). The resultant AGDIB possesses an energy density of 59.1 Wh kg(-1), along with a high energy efficiency of 85 % and an average discharge voltage of 1.71 V.