Yan Qinghui, Yan Linghui, Huang Haoshen, Chen Zhengfei, Liu Zixuan, Zhou Shaodong, He Haiyong
School of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211, China.
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
Molecules. 2024 Apr 28;29(9):2034. doi: 10.3390/molecules29092034.
LiCO is the most tenacious parasitic solid-state product in lithium-air batteries (LABs). Developing suitable redox mediators (RMs) is an efficient way to address the LiCO issue, but only a few RMs have been investigated to date, and their mechanism of action also remains elusive. Herein, we investigate the effects of the central metal ion in binuclear metal phthalocyanines on the catalysis of LiCO decomposition, namely binuclear cobalt phthalocyanine (bi-CoPc) and binuclear cobalt manganese phthalocyanine (bi-CoMnPc). Density functional theory (DFT) calculations indicate that the key intermediate peroxydicarbonate (*CO) is stabilized by bi-CoPc and bi-CoMnPc, which is accountable for their excellent catalytic effects. With one central metal ion substituted by manganese for cobalt, the bi-CoMnPc's second active redox couple shifts from the second Co(II)/Co(III) couple in the central metal ion to the Pc(-2)/Pc(-1) couple in the phthalocyanine ring. In artificial dry air (N-O, 78:22, /), the LAB cell with bi-CoMnPc in electrolyte exhibited 261 cycles under a fixed capacity of 500 mAh g and current density of 100 mA g, significantly better than the RM-free cell (62 cycles) and the cell with bi-CoPc (193 cycles).
碳酸锂是锂空气电池（LABs）中最顽固的寄生固态产物。开发合适的氧化还原介质（RMs）是解决碳酸锂问题的有效方法，但迄今为止，仅有少数几种氧化还原介质得到研究，其作用机制也仍不明确。在此，我们研究了双核金属酞菁中的中心金属离子对碳酸锂分解催化作用的影响，即双核钴酞菁（bi-CoPc）和双核钴锰酞菁（bi-CoMnPc）。密度泛函理论（DFT）计算表明，关键中间体过氧二碳酸根（*CO）被bi-CoPc和bi-CoMnPc稳定，这解释了它们出色的催化效果。随着一个中心金属离子的钴被锰取代，bi-CoMnPc的第二个活性氧化还原对从中心金属离子中的第二个Co(II)/Co(III)对转移到酞菁环中的Pc(-2)/Pc(-1)对。在人工干燥空气（N-O，78:22，/）中，电解质中含有bi-CoMnPc的LAB电池在500 mAh g的固定容量和100 mA g的电流密度下表现出261次循环，明显优于无RM的电池（62次循环）和含有bi-CoPc的电池（193次循环）。
