# Revealing the Mg-Ion Storage Mechanism within a Covalent Organic Framework Electrode

## TL;DR

This paper explores a new COF-based electrode for magnesium batteries, revealing how Mg ions are stored and how structural limitations affect performance.

## Contribution

The study introduces a COF composite electrode and provides insights into the Mg-ion storage mechanism through in situ Raman spectroscopy.

## Key findings

- The COF composite delivers 70 mAh g–1 at 200 mA g–1 with a 1.3 V operating voltage.
- In situ Raman confirms carbonyl-centered redox reactions driven by Mg2+.
- Steric and electrostatic constraints limit carbonyl utilization compared to Li+.

## Abstract

Magnesium batteries offer a promising alternative to
lithium-ion
systems, but suitable electrodes remain limited. Covalent organic
frameworks (COFs) are attractive candidates due to their structural
tunability and open channels for ion transport. We report a pyrene-
4,5,9,10-tetraone COF composite with carbon nanotubes as a Mg electrode,
delivering 70 mAh g–1 at 200 mA g–1 and operating at 1.3 V. In situ Raman spectroscopy
confirms carbonyl-centered redox on pyrene tetraone, supporting a
Mg2+-driven carbonyl reduction. Compared with Li+, only partial carbonyl utilization occurs, attributed to steric
and electrostatic constraints of divalent Mg2+. This incomplete
conversion to magnesium-enolate inspires future work toward structural
optimization.