A Naphthalene Diimide Covalent Organic Framework: Comparison of Cathode Performance in Lithium-Ion Batteries with Amorphous Cross-linked and Linear Analogues, and Its Use in Aqueous Lithium-Ion Batteries
Samik Jhulki, Cameron H. Feriante, Roman Mysyk, Austin M. Evans, Alexandre Magasinski, Ashwin Sankara Raman, Kostiantyn Turcheniuk, Stephen Barlow, William R. Dichtel, Gleb Yushin, Seth R. Marder
Abstract
We report a two-dimensional (2D) imine-linked covalent organic framework (COF) containing naphthalene diimide (NDI) redox groups, TAPB-NDI COF. Lithium-ion batteries (LIBs) with TAPB-NDI COF-based electrodes exhibited >95% of their theoretical capacity at a C/20 charge/discharge rate, among the highest faradaic efficiency of a NDI-COF electrode. The pores of TAPB-NDI COF are among the largest reported and presumably facilitate efficient Li+ ion transport. An amorphous cross-linked network (TAPB-NDI Amp) and a linear polymer (PD-NDI Lp) with similar chemical structures demonstrated lower capacities than the COF at C/20 current rate. However, PD-NDI Lp exhibited an overall higher gravimetric capacity and superior specific capacity retention at higher discharge rates compared to the TAPB-NDI COF. The COF is stable in neutral aqueous solutions, allowing its use as an electrode in neutral aqueous LIBs, which exhibited better rate performances than those in coin-cell set ups. Importantly, the cathodes did not suffer from a competitive hydrogen evolution reaction in aqueous LIBs. This opens up opportunities for using NDI moieties in neutral aqueous batteries and other energy-storage devices. Aqueous devices have been largely limited to “quinone–hydroquinone”-based redox couples, which are, however, operable only in acidic media.