Enhanced stability of aqueous aluminum metal batteries via CeCl3-mediated water shielding and interfacial modification

Abstract

The stability and safety of aqueous aluminum metal batteries (AAMBs) have garnered an enormous amount of attention. However, severe corrosion during cycling and inefficient deposition behavior at the Al anode hinder their application. In this paper, CeCl₃ was selected as a water inhibition additive to achieve active water confinement, which dramatically improved the corrosion behavior and prolonged the cycle life of the Al electrode. A combination of spectroscopic characterization and computational analysis showed that Cl⁻ breaks hydrogen bonds in the electrolyte and has higher adsorption energy on Al, thus inhibiting water-induced corrosion. Meanwhile, Ce³⁺ has a stronger affinity for Al than H₂O, thus promoting the formation of the surface protective layer. Cl⁻ in the modified electrolyte results in less hydration around Al³⁺. Due to the excellent water inhibition effect of CeCl₃, the corrosion phenomenon of Al electrodes was significantly improved, and the dominant growth of the Al (1 1 1) crystal plane was achieved. Al//Prussian blue analogue (PBA) full cells with CeCl₃ exhibit significantly improved voltage polarization (0.342 V), cycle life (550 cycles), discharge specific capacity (112 mAh g⁻¹), and self-discharge behavior (87.97%). The Ce³⁺ in the additive is also able to be co-intercalated into the PBA with Al³⁺, improving the stability of the PBA. However, the conductivity reduction of this strategy at higher concentrations needs to be further addressed. Compared with organic electrolyte and molten salt systems, the cycle life of the aqueous electrolyte in this work still falls short. This modification method paves the way for further development of efficient AAMBs.