Functional cathodes with immobilized TEMPO(2,2,6,6-tetramethylpiperidinyloxyl) for Li–O2 batteries

IF 5.4 Q2 CHEMISTRY, PHYSICAL
Takuya Naruse , Norihiro Togasaki , Tetsuya Osaka , Toshiyuki Momma
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Abstract

Non-aqueous Li–O2 batteries offer an extremely high energy density, but suffer from high overvoltage on charge and poor cycle characteristics. In the past decade, soluble redox mediators (RMs) have been utilized to reduce the charge overvoltage. However, the use of RMs inhibits the effective decomposition of Li2O2 due to the shuttling of RMs between the cathode and anode. In this study, 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO), which was previously proposed as an RM, was immobilized on the electrode surface by immersing carbon paper in a solution of the synthesized 4-(N-(3-triethoxysilyl-propyl) carbamoyloxy)-2,2,6,6-tetramethyl-1-piperidinoxyl (TESPCP), followed by a heat treatment. Charge–discharge testing of Li–O2 batteries using the TEMPO-immobilized cathode with a Li anode exhibited a charge plateau of about 3.7 V, indicating that the immobilized TEMPO could react electrochemically as a redox mediator. No overcharge behavior was observed in the cell, suggesting the RM shuttling effect was suppressed. Furthermore, SEM and XPS analyses of the cathode surface confirmed that no Li2O2 residues remained on the cathode after charging, unlike the control sample that utilized soluble RMs. These results indicate that a TEMPO-immobilized cathode can successfully mitigate RM shuttling while maintaining the benefits of RMs, allowing effective decomposition of Li2O2, during charging without leading to overcharging.

固定化TEMPO(2,2,6,6-四甲基胡椒酰氧基)的锂氧电池功能阴极
非水性Li–O2电池具有极高的能量密度,但充电时过电压高,循环特性差。在过去的十年中,可溶性氧化还原介质(RM)已被用于降低电荷过电压。然而,由于RM在阴极和阳极之间的穿梭,RM的使用抑制了Li2O2的有效分解。在本研究中,通过将碳纸浸入合成的4-(N-(3-三乙氧基甲硅烷基丙基)氨基甲酰氧基)-2,2,6,6-四甲基-1-哌啶氧基(TESPCP)溶液中,然后进行热处理,将先前提出的RM 2,2,6,6-四甲基哌啶基氧基(TEMPO)固定在电极表面。使用TEMPO固定化阴极和Li阳极对Li–O2电池进行的充放电测试显示出约3.7V的充电平台,表明固定化TEMPO可以作为氧化还原介质进行电化学反应。在细胞中没有观察到过充电行为,表明RM穿梭效应被抑制。此外,阴极表面的SEM和XPS分析证实,与使用可溶性RM的对照样品不同,充电后没有Li2O2残留物残留在阴极上。这些结果表明,TEMPO固定化阴极可以成功地减轻RM的穿梭,同时保持RM的优点,允许在充电过程中有效分解Li2O2,而不会导致过度充电。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
9.10
自引率
0.00%
发文量
18
审稿时长
64 days
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