Electrochemical stability of aluminum current collector in aqueous rechargeable lithium-ion battery electrolytes

Abstract

Aqueous rechargeable lithium-ion batteries (ARLBs) use aqueous electrolytes, which create conditions where corrosion may occur when aluminum is used as the current collector. The electrochemical stability of AA1085 in 2 M Li2SO4 and 5 M LiNO3 aqueous electrolytes was evaluated over a range of pH conditions by cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. Aluminum presented high corrosion resistance at pHs 5, 7, and 9 within the stability windows of both electrolytes. At the pH 11 condition, 2 M Li2SO4 is capable of inhibiting aluminum from pitting but the inhibiting effect is not sustainable and crystallographic pitting occurs under a continuously applied anodic potential. Aluminum was well passivated against pitting in 5 M LiNO3 electrolyte at pH 11 due to the formation of a thick corrosion product barrier layer. Raman spectra depicted the presence of sulfate and nitrate anions on aluminum surface after cyclic voltammetry at pH 11. Inductively coupled plasma results showed that the amount of dissolved aluminum in electrolyte after cyclic voltammetry increases when pH increases from 5 to 11. The chemical adsorption mechanisms of sulfate and nitrate anions on aluminum were proposed to explain the dependency of electrochemical stability of aluminum on pH, anodic potential, and type of anions. The applicability of aluminum as current collector in ARLB using the 2 M Li2SO4 and 5 M LiNO3 electrolytes is discussed.