Mechanistic Origin of Low Polarization in Aprotic Na-O2 Batteries
Mechanistic Origin of Low Polarization in Aprotic Na-O2 Batteries
复制标题
非质子Na-O2电池低极化的机制起源
DOI：
10.1039/c7cp01928a
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发表时间：
2017
影响因子：
3.3
通讯作者：
Zhangquan Peng
中科院分区：
文献类型：
--
作者：
Shunchao Ma;William C. McKee;Jiawei Wang;Limin Guo;Martin Jansen;Ye Xu;Zhangquan Peng
非质子钠-空气（Na-O 2）电池的研究兴趣正在增长，因为它们具有相当高的理论比能和潜在的比锂-空气（Li-O 2）电池更好的可逆性。虽然Li 2 O2已被明确确定为含有相对稳定电解质的Li-O2电池中的主要放电产物，但Na-O2电池中已报道了大量放电产物，包括NaO 2、Na 2 O2和Na 2 O2·2 H2O，并且相应的阴极电化学仍然不完全了解。在这里，我们提供了分子水平的见解之间的关键机制的差异Na-O2和Li-O2电池的基础上，金电极在严格干燥，非质子二甲基亚砜电解质通过结合原位光谱电化学和密度泛函理论为基础的建模。虽然像Li-O2电池一样，氧还原产物（即，两个因素导致Na-O2电化学更好的可逆性，因此对可行的可再充电金属-空气电池设计非常有益：（i）在放电期间，只有O2-和NaO 2，而没有Na 2 O2，形成低至1.5V（相对于Na/Na+）;（ii）固态NaO 2的溶解性很强，其形成和氧化可以分别通过微可逆EC（电子转移后产物的化学反应）和CE（电子转移前的化学反应）过程进行，O2−是关键中间体。
Research interest in aprotic sodium–air (Na–O2) batteries is growing because of their considerably high theoretical specific energy and potentially better reversibility than lithium–air (Li–O2) batteries. While Li2O2 has been unequivocally identified as the major discharge product in Li–O2 batteries containing relatively stable electrolytes, a multitude of discharge products, including NaO2, Na2O2 and Na2O2·2H2O, have been reported for Na–O2 batteries and the corresponding cathodic electrochemistry remains incompletely understood. Herein, we provide molecular-level insights into the key mechanistic differences between Na–O2 and Li–O2 batteries based on gold electrodes in strictly dry, aprotic dimethyl sulfoxide electrolytes through a combination of in situ spectroelectrochemistry and density functional theory based modeling. While like Li–O2 batteries, the formation of oxygen reduction products (i.e., O2−, NaO2 and Na2O2) in Na–O2 batteries depends critically on the electrode potential, two factors lead to a better reversibility of Na–O2 electrochemistry, and are therefore highly beneficial to a viable rechargeable metal–air battery design: (i) only O2− and NaO2, and no Na2O2, form down to as low as ∼1.5 V vs. Na/Na+ during discharge; (ii) solid NaO2 is quite soluble and its formation and oxidation can proceed through micro-reversible EC (a chemical reaction of the product after the electron transfer) and CE (a chemical reaction preceding the electron transfer) processes, respectively, with O2− as the key intermediate.