全固態鈉氧氣與二氧化碳電池反應機制研究

Abstract

近年來電動汽車市場日益蓬勃發展，科學家開始將目光投向發展高能量密度電池。可充電鈉空氣(Na–Air)電池具較高能量密度、低充電電位與鈉地殼含量豐富，已成為替代傳統鋰離子電池最有希望之候選者。 本研究第一部分探討鈉氧氣(Na–O2)電池反應機制，藉鈉超離子導體型(NASICON)固態電解質(Na3Zr2Si2PO12; NZSP)，釕奈米粒子修飾之多壁碳奈米管(Ru/CNT)，塑化晶體丁二腈(succinonitrile; SN)與過氯酸鈉(NaClO4)鈉鹽組成之中間層，組裝全固態Na–O2電池。過氧化鈉(Na2O2)為Na–O2電池最終氧還原反應(oxygen reduction reaction; ORR)產物，其均勻沉積於陰極表面。揭示Na–O2電池反應機制為2Na+ + O2 + 2e- → Na2O2, E° = 2.33 V vs. Na+/Na。 研究第二部分探討鈉二氧化碳(Na–CO2)電池反應機制。常見之Na–CO2電池反應機制以碳與碳酸鈉(Na2CO3)為放電產物(4Na+ + 3CO2 + 4e- → 2Na2CO3 + C, E° = 2.35 V vs. Na+/Na)。於先前研究中鮮見Na–CO2電池放電產物之碳形成證據，故藉原位環境壓力X射線光電子能譜儀(In situ APXPS)研究Na–CO2電池之氧化還原反應，並揭示Na–CO2電池之新反應機制(2Na+ + 2CO2 + 2e- → Na2CO3 + CO, E°= 2.05 V vs. Na+/Na)。 本研究之新穎性為以無機固態電解質取代有機電解質提升電池之安全性，並揭示Na–O2電池與Na–CO2電池反應機制，此將可為未來Na–Air電池之研究奠定重要基礎。

The electric vehicle market has been increasing year by year. However, high-energy-density batteries have become an important research topic. Rechargeable sodium air (Na–Air) battery has become the most promising candidates to replace Li-ion batteries because of their high energy density, which is about 5–10 times compared with Li-ion batteries, and extensive research interest due to their low charging potential and abundant sodium content. The first part of this study explores the reaction mechanism of sodium oxygen (Na–O2) batteries. Using Na superionic conductor (NASICON)-type solid electrolyte Na3Zr2Si2PO12 (NZSP), ruthenium nanoparticle modified multi-wall carbon nanotubes (Ru/CNT), and plastic crystalline succinonitrile (SN) with NaClO4 interlayer to assemble all solid-state Na–O2 battery. Na2O2 is the final oxygen reduction reaction (ORR) product of the Na–O2 battery and evenly covers the cathode surface. The reaction mechanism would be 2Na+ + O2 + 2e- → Na2O2, E° = 2.33 V vs. Na+/Na. The second part of this study explores the reaction mechanism of sodium carbon dioxide (Na–CO2) batteries. Common Na–CO2 battery reaction mechanism uses carbon and Na2CO3 as discharge products (4Na+ + 3CO2 + 4e- → 2Na2CO3 + C, E° = 2.35 V vs. Na+/Na). However, there is seldom evidence of carbon formation in previous studies. We investigate the reduction-oxidation reaction by in situ ambient pressure X-ray photoelectron spectroscopy (In situ APXPS) and propose the new reaction mechanism of Na–CO2 battery (2Na+ + 2CO2 + 2e- → Na2CO3 + CO, E° = 2.05 V vs. Na+/Na). The novelty of this study is using inorganic solid electrolytes to improve the safety of the battery and to reveal the reaction mechanism of the Na–O2 battery and Na–CO2 battery. They also lay an essential foundation for future research on Na–Air batteries.