Active role of inactive current collector in aqueous aluminum-ion battery

Abstract

The recent revival of research interest in rechargeable aluminum-ion batteries has opened up avenues to overcome its inherent challenges. While there are fierce attempts to find suitable electrode materials for aluminum-ion batteries, it is very important to carefully evaluate them. We show here that an essential criterion for correct electrochemical evaluation of aqueous aluminum-ion batteries is to appropriately select the current collector. Considering anatase TiO2 as a model electrode material, it is demonstrated that type of current collector could transform an inactive electrode material to an active one. TiO2 could exhibit initial Al3+ ion storage capacity of 256 mAhg−1 at a current density of 4 Ag−1 with graphite current collector, whereas it is only 82 mAhg−1 with titanium current collector at similar current density. Interestingly, no charge/discharge characteristics could be obtained with stainless steel and nickel current collectors at any current densities.