金属锂因具有高理论容量和低化学电位被认为是电化学储能系统的"圣杯",但无规则的锂枝晶生长和与电解液的高反应活性导致其安全性能差和库伦效率低,这严重阻碍了锂金属负极的大规模应用。电解液添加剂具有用量小、效果显著等特点,是改善电池性能的有效手段之一。本研究首次报道一种植物多酚—丹宁酸(TA)用作电解液添加剂改善锂金属负极的电化学性能。通过在基础电解液1 mol·L^-1 LiPF_6-EC/DMC/EMC (1:1:1,质量比)中添加质量分数0.15%TA,Li|Li对称电池在电流密度为1 m A·cm^-2和容量为1 m Ah·cm^-2的条件下能稳定循环270 h (以0.1 V为截止电压),而没有TA添加剂的Li|Li电池在相同条件下只能循环170 h。电化学阻抗、扫描电镜、傅里叶红外、循环伏安和X射线能谱分析测试结果表明,丹宁酸能在锂金属表面参与形成了一层稳定且致密的固态电解质界面层。推测其可能的机理为多羟基酚有助于LiPF_6的水解反应并形成LiF,多羟基酚的锂盐能与碳酸二甲酯发生酯交换反应而形成交联聚合物,从而形成了稳定且均匀的有机/无机复合SEI膜、显著提高了锂金属负极的电化学性能。
Effects of meta-substituent of 3,4＇/4,3＇/3,3＇-substituted benzylideneanilines （XBAYs） on the electrochemical reduction potentials （E（Red）） were investigated, in which 49 samples of target compounds were synth...
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Effects of meta-substituent of 3,4＇/4,3＇/3,3＇-substituted benzylideneanilines （XBAYs） on the electrochemical reduction potentials （E（Red）） were investigated, in which 49 samples of target compounds were synthesized, and their reduction potentials were measured by cyclic voltammetry. The substituent effects on the E（Red） of target compounds were analyzed and an optimality equation with four parameters （Hammett constant a of X, Hammett constant a of Y, excited-state substituent constant σexCC of X, and the substituent specific cross-interaction effect △σexCC2 between X and Y） was obtained. The results show that the factors affecting the E（Red） of 3,4＇/4,31/3,3P-substituted XBAYs are different from those of 4,4＇-substituted XBAYs. For 3,4＇/4,3＇/3,3＇-substituted XBAYs, σ（X） and σ（Y） must be employed, and the contribution of △σexCC2 is important and not negligible. Compared with 4,4＇-substituted XBAYs, X group contributes less to 3,4＇/4,3＇/3,3＇-substituted XBAYs, while Y group contributes more to them. Additionally, it was observed that either para-substituted XBAYs or meta-substituted XBAYs, the substituent effects of X are larger than those of Y on the E（Red） of substituted XBAYs.
Fifty-three samples of multi-substituted benzylideneanilines XArCH=NArYs （abbreviated XBAYs） were synthesized and their NMR spectra were determined. An extensional study of substituent effects on the 1H NMR chemical...
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Fifty-three samples of multi-substituted benzylideneanilines XArCH=NArYs （abbreviated XBAYs） were synthesized and their NMR spectra were determined. An extensional study of substituent effects on the 1H NMR chemical shifts （δH（CH=N）） and 13C NMR chemical shifts （δc（CH=N）） of the CH=N bridging group from di-substituted to multi-substituted XBAYs was made based on a total of 182 samples of XBAYs, together with the NMR data of other 129 samples of di-substituted XBAYs quoted from literatures. The results show thatthe substituent specific cross-interaction effect parameter （△（∑σ）2） plays an important role in quantifying the δc（CH=N） values of XBAYs, but it is negligible for quantifying the δH （CH=N） values; the other substituent parameters also present different influences on the δc （CH=N） and （δH （CH=N）. On the whole, the contributions of X and Y to the δc （CH=N） of XBAYs are balanced, but the δH（CH=N） values of XBAYs mainly rely on the contributions of X.
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