Two-dimensional Covalent Organic Frameworks with Enhanced Aluminum Storage Properties.

: Aluminum ion batteries (AIBs) are regarded as one of the most promising energy storage devices considering the safety, natural abundance and predominant electrochemical properties. However, the rate capabilities of AIBs are limited due to the sluggish kinetics of chloroaluminate anions. Herein, a covalent organic framework (COF) is adopted as cathode material of AIBs. Theoretical and experimental results suggest that the COFs allow fast anion diffusion and intercalation without structure collapse owing to the hierarchical pores with a large specific surface area of 1794 m 2 g -1 and robust frameworks. Therefore, the resultant AIB exhibits remarkable long-term stability with a reversible discharge capacity of 150 mA h g -1 after 13000 cycles at 2 A g -1 and an excellent rate capability (113 mA h g -1 at 5 A g -1 ). This work fully demonstrates the potential of COFs in the storage of chloroaluminate anions and other large-sized ions.