Tuning the electrochemical performance of covalent organic framework cathodes for Li- and Mg-based batteries: the influence of electrolyte and binder

abstract

Covalent organic frameworks (COFs) are crystalline porous organic polymers that have recently emerged as promising electrode materials for rechargeable batteries. Herein, we present an approach to improve the electrochemical performance of an anthraquinone-based COF (DAAQ-TFP-COF) cathode material in metal anode (Li, Mg) based batteries through proper selection of the electrolyte and binder. Our results show that the combination of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in tetraethylene glycol dimethyl ether (TEGDME) as electrolyte and poly(tetrafluoroethylene) (PTFE) as binder led to the best electrochemical performance with high utilisation efficiency of the redox sites and specific capacities close to the theoretical value. Using such electrolyte and binder, cyclable symmetric cells consisting of two DAAQ-TFP-COF organic electrodes exemplify 79% capacity retention after 2000 cycles at a high current density of 500 mA h g-1. The high reversibility and stability of the COF electrode material upon cycling were confirmed by ex situ IR spectroscopy. In addition, DAAQ-TFP-COF was explored as a cathode in magnesium cells using two different Mg electrolytes; one based on MgCl2 and one containing weakly coordinating anions. Electrochemical characterisation reveals significant differences in the performance of COF in terms of achievable capacities and voltage profiles, pointing towards hindered transport. Our findings demonstrate that the appropriate choice of electrolyte and binder is crucial to maximise the performance of COF-based materials in different post-lithium-ion metal anode batteries. We present an approach to improve the electrochemical performance of an anthraquinone-based covalent organic framework (COF) cathode material in metal anode (Li, Mg) batteries through proper selection of the electrolyte and binder.

keywords

ENERGY-STORAGE; LITHIUM; POLYMER; NANOSHEETS

subject category

Chemistry; Energy & Fuels; Materials Science

authors

Luzanin, O; Dantas, R; Dominko, R; Bitenc, J; Souto, M

Groups

G3 - Electrochemical Materials, Interfaces and Coatings

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

Redox-active Metal-Organic Frameworks as Electrode Materials for Lithium-Ion Batteries (RedoxMOFs)

acknowledgements

This work has received funding from the European Research Council (ERC) under the European Union's Horizon Europe Framework Programme (ERC-2021-Starting Grant, grant agreement no. 101039748-ELECTROCOFS). This work was developed within the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC). We also thank FCT for funding the PTDC/QUI-ELT/2593/2021 project. The authors would like to acknowledge the financial support from European Union's Horizon 2020 research and innovation program under the Marie Sklodowska Curie framework, grant agreement no. 860403 and Slovenian Research Agency through program P2-0423 and projects N2-0279 and J2-4462.