Intensive Study on the Catalytical Behavior of N-Methylphenothiazine as a Soluble Mediator to Oxidize the Li2O2 Cathode of the Li-O2 Battery
Intensive Study on the Catalytical Behavior of N-Methylphenothiazine as a Soluble Mediator to Oxidize the Li2O2 Cathode of the Li-O2 Battery
复制标题
N-甲基吩噻嗪作为可溶性介体氧化Li-O-2电池Li2O2正极催化行为的深入研究
DOI：
10.1021/acsami.6b14889
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发表时间：
2017-02-01
影响因子：
9.5
通讯作者：
Zhou, Haoshen
中科院分区：
文献类型：
--
作者：
Feng, Ningning;Mu, Xiaowei;Zhou, Haoshen
非质子Li-O-2电池因其理论能量密度高而受到广泛关注。然而，实际的Li-O-2电池仍然遭受高充电过电位和低能量效率，这是由于在电化学氧化绝缘过氧化锂（Li 2 O2）中的缓慢动力学造成的。最近，溶解在电解质中的氧化还原介体已经使得能够在液-固界面处有效地催化氧化Li 2 O2。在这里，我们报告说，纳入N-甲基吩噻嗪（MPT），作为一个氧化还原梭在锂-O-2电池，提供了一个显着降低充电过电位为0.67 V和改善的往返效率接近76%。此外，通过各种表征进一步研究MPT在Li-O-2电池中的功效。充电时，MPT+阳离子首先在阴极表面电化学生成，随后通过化学反应氧化固体放电产物Li 2 O2。此外，MPT的存在已被证明可以改善电池的循环稳定性并抑制在高电位下由碳和电解质引起的副反应。
Aprotic Li-O-2 batteries have attracted worldwide interest owing to their ultrahigh theoretical energy density. However, the practical Li-O-2 batteries still suffer from high charge overpotential and low energy efficiency resulting from the sluggish kinetics in electrochemically oxidizing the insulating lithium peroxide (Li2O2). Recently, dissolved redox mediators in the electrolyte have enabled the effective catalytic oxidation of Li2O2 at the liquid-solid interface. Here, we report that the incorporation of N-methylphenothiazine (MPT), as a redox shuttle in Li-O-2 batteries, provides a dramatic reduction in charge overpotential to 0.67 V and an improved round-trip efficiency close to 76%. Moreover, the efficacy of MPT in Li-O-2 cells was further investigated by various characterizations. On charging, MPT+ cations are first generated electrochemically at the cathode surface and subsequently oxidize the solid discharge products Li2O2 through a chemical reaction. Furthermore, the presence of MPT has been demonstrated to improve the cycling stability of the cells and suppress side reactions arising from carbon and electrolytes at high potentials.