Aluminium-ion batteries: developments and challenges
The concept of exploring the superior benefits of electropositive metals as anodes in rechargeable metal-batteries has resurfaced in recent times in anticipation of the future societal need for high energy density and affordable batteries. A rechargeable battery based on aluminium chemistry is envisioned to be a low cost energy storage platform, considering that aluminium is the most abundant metal in the Earth's crust. The high volumetric capacity of aluminium, which is four and seven times larger than that of lithium and sodium respectively, unarguably has the potential to boost the energy density of aluminium-batteries on a per unit volume basis. Efforts to develop rechargeable aluminium-batteries can be traced to as early as the 1970s, however this area of research has seen a surge in activity since 2010, when the possibility of achieving an ambient temperature aluminium system was convincingly demonstrated. In recent times, rechargeable aluminium-batteries have been rechristened as aluminium-ion batteries. This review aims to comprehensively illustrate the developments regarding rechargeable non-aqueous aluminium-batteries or aluminium-ion batteries. Additionally, the challenges that impede progress in achieving a practical aluminium-ion battery are also discussed.