Solvents' Critical Role in Nonaqueous Lithium-Oxygen Battery Electrochemistry
Solvents' Critical Role in Nonaqueous Lithium-Oxygen Battery Electrochemistry
复制标题
DOI：
10.1021/jz200352v
复制
发表时间：
2011-05-19
影响因子：
5.7
通讯作者：
Luntz, A. C.
中科院分区：
文献类型：
--
作者：
McCloskey, B. D.;Bethune, D. S.;Luntz, A. C.
在Li-空气电池的发展所面临的许多重要挑战中，理解电解质在产生适当的可逆电化学中的作用（即，2Li（+）+ O（2）+2 e（-）Li（2）O（2））是临界的。定量差示电化学质谱（DEMS）结合氧气的同位素标记，用于研究Li-O（2）在各种溶剂中的电化学，包括碳酸盐（典型的锂离子电池溶剂）和二甲氧基乙烷（DME）。结合气相DEMS分析，使用非原位分析技术，如X-射线衍射和拉曼光谱，表征了放电过程中在Li-O（2）电池阴极上形成的电沉积物。发现基于碳酸酯的溶剂在电池放电时不可逆地分解。然而，基于DME的电池在放电时主要产生过氧化锂。在电池充电时，过氧化锂在高电位下既分解以放出氧气又氧化DME。我们的研究结果得出两个结论;（1）库仑法必须与定量气体消耗和演变数据相结合，以正确表征锂空气电池的可充电性，以及（2）过氧化锂及其中间体存在下的化学和电化学电解质稳定性对于产生真正可逆的Li-O（2）电化学至关重要。
Among the many important challenges facing the development of Li-air batteries, understanding the electrolyte's role in producing the appropriate reversible electrochemistry (i.e., 2Li(+) + O(2) + 2e(-) Li(2)O(2)) is critical. Quantitative differential electrochemical mass spectrometry (DEMS), coupled with isotopic labeling of oxygen gas, was used to study Li-O(2) electrochemistry in various solvents, including carbonates (typical Li ion battery solvents) and dimethoxyethane (DME). In conjunction with the gas-phase DEMS analysis, electrodeposits formed during discharge on Li-O(2) cell cathodes were characterized using ex situ analytical techniques, such as X-ray diffraction and Raman spectroscopy. Carbonate-based solvents were found to irreversibly decompose upon cell discharge. DME-based cells, however, produced mainly lithium peroxide on discharge. Upon cell charge, the lithium peroxide both decomposed to evolve oxygen and oxidized DME at high potentials. Our results lead to two conclusions; (1) coulometry has to be coupled with quantitative gas consumption and evolution data to properly characterize the rechargeability of Li-air batteries, and (2) chemical and electrochemical electrolyte stability in the presence of lithium peroxide and its intermediates is essential to produce a truly reversible Li-O(2) electrochemistry.