利用氧化還原介質提升鎂氧氣電池性能

Abstract

環保意識高漲下，各國提倡藉電能作為汽車之動力來源，故具高能量密度與環保優勢之鎂氧氣(Mg–O2)電池受廣泛注目，然Mg–O2電池之發展受限於高過電位與循環能力不佳之問題，故本研究藉加入3,4,5,6-四氯-1,2-苯醌(3,4,5,6-tetrachloro-1,2-benzoquinone; TCBQ)作為氧化還原介質(redox mediator)以改善Mg–O2電池性能。 本研究首先藉量測吸收光譜與循環伏安法(cyclic voltammetry; CV)確認其反應路徑與催化效能，並比較添加TCBQ與否之Mg–O2電池差異，藉電化學測試結果可得知添加TCBQ使Mg–O2電池起始電壓由1.18 V提升至1.59 V，增幅達35%，而最大放電電容量則由19,722 mAh g–1提升至27,788 mAh g–1，增加約41%，且穩定循環次數由7圈提升至58圈，增長超過8倍，電池過電位自1.7 V降低至0.7 V，減少近60%。 本研究亦藉同步輻射X光繞射(synchrotron X-ray diffraction; S-XRD) 、X光吸收光譜(X-ray absorption spectroscopy; XAS) 、X光光電子能譜(X-ray photoelectron spectroscopy; XPS) 、掃描式電子顯微鏡(scanning electron microscope; SEM) 及穿透式電子顯微鏡(transmission electron microscopy; TEM) 儀器技術分析經放電後之陰極，可得知無論添加TCBQ與否其放電產物皆為MgO，且TCBQ使放電產物更均勻分布於陰極上。 本研究之新穎性為成功藉添加TCBQ作為氧化還原介質催化氧還原反應，解決Mg–O2電池面臨高過電位與循環能力不佳問題，以提升Mg–O2電池性能，為添加於Mg–O2電池之氧化還原介質提供新選擇。

In response to the growing global emphasis on environmental protection, the use of electric energy as a vehicle power source has been increasingly advocated worldwide. Magnesium–oxygen (Mg–O2) batteries, characterized by their high energy density and environmental benefits, have emerged as promising candidates for next-generation energy storage systems. However, their practical application remains limited due to challenges such as high overpotential and poor cycling stability. In this study, 3,4,5,6-tetrachloro-1,2-benzoquinone (TCBQ) was introduced as a redox mediator to address these issues and enhance the overall performance of Mg–O2 batteries. The reaction pathways and catalytic efficiency of TCBQ were investigated through absorption spectroscopy and cyclic voltammetry (CV) measurements. Electrochemical testing revealed that the addition of TCBQ significantly increased the initial discharge voltage from 1.18 V to 1.59 V (a 35% enhancement), elevated the maximum discharge capacity from 19,722 mAh g⁻¹ to 27,788 mAh g⁻¹ (a 41% improvement), extended the stable cycle life from 7 cycles to 58 cycles, and reduced the overpotential from 1.7 V to 0.7 V, representing a nearly 60% reduction. Furthermore, synchrotron X-ray diffraction (S-XRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses indicated that the primary discharge product was magnesium oxide (MgO) regardless of the presence of TCBQ, with a more homogeneous distribution observed when TCBQ was incorporated. These results demonstrate that TCBQ effectively catalyzes the oxygen reduction reaction, thereby mitigating the major limitations of Mg–O2 batteries. This study provides a new strategy for improving the electrochemical performance and cycle life of Mg–O2 batteries through the use of redox mediators.