具奈米氧化鎂預添加陰極之鎂氧氣電池

Abstract

隨環保意識提升，全球電動汽機車產業逐漸興起，鋰離子電池已臨近其應用之極限，找尋更合適之高效電力來源成為熱門議題。金屬空氣電池(metal–air battery)之陰極活性物質於生活中隨處可見，且其能量密度約為傳統鋰離子電池十倍以上，使其同時具備質輕、高效率、低成本等優勢，為新一代能源儲備優選。本研究聚焦於鎂氧氣電池(magnesium–oxygen battery)之電化學性能，旨於探討其作為新一代高能量密度儲能系統之可能性，藉預添加氧化鎂陰極減緩鎂氧氣電池於放電過程因初始成核活化能致使之成核過電位(nucleation overpotential)，以延長循環過程之放電電壓穩定性與循環壽命。 本研究以燃燒法(combustion method)合成奈米級結晶氧化鎂(magnesium oxide; MgO)，並藉定性分析技術鑑定樣品晶相與純度，以電子顯微鏡觀察樣品大小與均一性。接著將奈米氧化鎂與奈米碳管以球磨(ball milling)方式共同製作為陰極漿料，並將其應用於鎂氧氣電池系統，於定電流條件下以鈕扣型電池測試添加不同比例氧化鎂陰極之長循環壽命，並藉多項儀器監測奈米氧化鎂於電化學測試前後之含量變化與放電產物種類之消長。 本研究之新穎性為將預添加奈米級放電產物之陰極應用於鎂氧氣電池系統，並成功藉預添加奈米氧化鎂陰極降低電池循環過程所需之成核過電位，使其可於0.1C電流與截止電容量700 mAh g−1條件下循環15次，顯著提升電池之長循環穩定性。本研究亦進一步將預添加奈米氧化鎂陰極之鎂氧氣電池組裝為軟包型電池，串聯後可成功點亮紅光發光二極體(light-emitting diode; LED)長達72小時，揭示其未來之商業應用價值。此外，本研究亦應用國家同步輻射(National Synchrotron Radiation Research Center; NSRRC)之原位X光繞射(in situ X-ray diffraction)技術，揭示預添加之晶相氧化鎂於充電與放電過程之含量消長。

With the growing demand for sustainable energy and the limitations of lithium-ion batteries, metal–air batteries have emerged as promising alternatives due to their high energy density, low cost, and utilization of ambient oxygen as the cathodic reactant. The magnesium–oxygen battery (Mg–O2 battery) offers advantages such as high theoretical capacity, natural abundance, and safety. However, challenges such as high nucleation overpotential during the initial discharge hinder its cycling stability. This study investigates the electrochemical performance of Mg–O2 batteries through the use of a cathode pre-added with nanoscale magnesium oxide (MgO). The MgO was synthesized via a combustion method, characterized using X-ray diffraction and electron microscopy, and then combined with carbon nanotubes (CNTs) via ball milling to form a composite cathode. Coin-type Mg–O2 batteries were assembled and tested under constant current conditions. The pre-filled MgO significantly reduced nucleation overpotential and improved long-term discharge voltage stability. The optimized cell sustained 15 cycles at 0.1C with a cutoff capacity of 700 mAh g⁻¹. A pouch-type Mg–O2 battery incorporating the same cathode configuration successfully powered a red light-emitting diode (LED) for over 72 hours, demonstrating its practical applicability. Additionally, in situ X-ray diffraction conducted at the National Synchrotron Radiation Research Center (NSRRC) confirmed the reversible phase behavior of MgO during cycling. These results highlight the effectiveness of MgO pre-filled in enhancing the cycling performance of Mg–O2 batteries, suggesting a viable pathway toward practical, high-energy metal–air energy storage systems.