Anode engineering using a hybrid AlCl3/PTHF coating for enhanced electrochemical stability of Mg–O2 batteries

Abstract

Anode modification is vital for enhancing the performance and lifespan of Mg–O₂ batteries. This study presents an AlCl₃/PTHF coating process to improve the stability of magnesium anodes. The coating, which is formed by treating the Mg metal with an AlCl₃ and tetrahydrofuran (THF) solution, creates a gradient hybrid layer with a PTHF-rich top for facilitating Mg-ion transport and a magnesiophilic Al–Mg mixed ionic conductive surface for uniform Mg plating and stripping. The AlCl₃/PTHF-coated anode achieved remarkable stability, cycling for over 300 h in symmetric Mg–Mg cells with markedly reduced overpotential compared with bare Mg anodes. Integrated with electrospun-quasi-solid-state electrolytes (EQSSEs) and Ru/CNT cathodes in Mg–O₂ cells, the modified anode demonstrated excellent compatibility, delivering stable performance for over 50 cycles under controlled discharge conditions. These findings indicate the synergistic benefits of the AlCl₃/PTHF-coated Mg anode, EQSSE, and Ru/CNT cathode, paving the way for sustainable high-performance Mg–O₂ battery systems.