Recent Advances in Covalent Organic Framework Electrode Materials for Alkali Metal-Ion Batteries

Owing to the shortcomings of traditional electrode materials in alkali metal-ion batteries (AIBs), such as limited reversible specific capacity, low power density, and poor cycling performance, it is particularly important to develop new electrode materials. Covalent organic frameworks (COFs) are crystalline porous polymers that incorporate organic building blocks into their periodic structures through dynamic covalent bonds. COFs are superior to organic materials because of their high designability, regular channels, and stable topology. Since the first report of D_TP-A_NDI-COF as a cathode material for lithium-ion batteries in 2015, research on COF electrode materials has made continuous progress and breakthroughs. This review briefly introduces the characteristics and current challenges associated with COF electrode materials. Furthermore, we summarize the basic reaction types and active sites according to the categories of covalent bonds, including B-O, C=N, C-N, and C=C. Finally, we emphasize the perspectives on basic structure and morphology design, dimension and size design, and conductivity improvement of COFs based on the latest progress in AIBs. We believe that this review provides important guidelines for the development of high-efficiency COF electrode materials and devices for AIBs.