Investigation on the charging process of Li2O2-based air electrodes in Li–O2 batteries with organic carbonate electrolytes
Investigation on the charging process of Li2O2-based air electrodes in Li–O2 batteries with organic carbonate electrolytes
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DOI：
10.1016/j.jpowsour.2010.12.065
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发表时间：
2011-04
影响因子：
9.2
通讯作者：
Wu Xu;V. Viswanathan;Deyu Wang;Silas A. Towne;Jie Xiao;Z. Nie;Dehong Hu;Ji‐Guang Zhang
中科院分区：
文献类型：
--
作者：
Wu Xu;V. Viswanathan;Deyu Wang;Silas A. Towne;Jie Xiao;Z. Nie;Dehong Hu;Ji‐Guang Zhang
采用现场气相色谱/质谱（GC/MS）联用技术研究了有机碳酸盐电解质锂氧电池中锂基空气电极的充电过程。使用Li 2 O2/Fe 3 O 4/Super P碳/聚偏二氟乙烯（PVDF）的混合物作为起始空气电极材料，并且使用碳酸盐基溶剂中的1-M双（三氟甲基磺酰基）酰亚胺锂（LiTFSI）作为电解质。我们发现Li_2O_2对制备电极的1-甲基-2-吡咯烷酮和PVDF具有活性反应。在第一次充电期间（高达4.6V），O2是释放气体中的主要成分。通过GC/MS测量的O2的量与通过充电容量测量的在电化学过程中分解的Li 2 O2的量一致，这表明Li 2 O2具有良好的可充电性。然而，电池在O2气氛中放电至2.0V，然后再充电至4.6V后，释放的气体中CO2占主导地位。通过X射线衍射（XRD）和傅里叶变换红外（FTIR）光谱对放电空气电极的进一步分析表明，含锂碳酸盐物质（碳酸烷基锂和/或Li 2CO 3）是主要的放电产物。因此，需要为可充电锂空气电池开发兼容的电解质和电极以及电极制备程序，以供长期运行。
The charging process of Li2O2-based air electrodes in Li–O2batteries with organic carbonate electrolytes was investigated using in situ gas chromatography/mass spectroscopy (GC/MS) to analyze gas evolution. A mixture of Li2O2/Fe3O4/Super P carbon/polyvinylidene fluoride (PVDF) was used as the starting air electrode material, and 1-M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in carbonate-based solvents was used as the electrolyte. We found that Li2O2was actively reactive to 1-methyl-2-pyrrolidinone and PVDF that were used to prepare the electrode. During the first charging (up to 4.6V), O2was the main component in the gases released. The amount of O2measured by GC/MS was consistent with the amount of Li2O2that decomposed during the electrochemical process as measured by the charge capacity, which is indicative of the good chargeability of Li2O2. However, after the cell was discharged to 2.0V in an O2atmosphere and then recharged to ∼4.6V, CO2was dominant in the released gases. Further analysis of the discharged air electrodes by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy indicated that lithium-containing carbonate species (lithium alkyl carbonates and/or Li2CO3) were the main discharge products. Therefore, compatible electrolytes and electrodes, as well as the electrode-preparation procedures, need to be developed for rechargeable Li-air batteries for long term operation.