调整用于稳定全有机水系氧化还原液流电池的TEMPO阴极电解液的赫希菲尔德电荷
Adjusting Hirshfeld charge of TEMPO catholytes for stable all-organic aqueous redox flow batteries.
作者信息
Tang Gonggen, Wu Wenyi, Liu Yahua, Peng Kang, Zuo Peipei, Yang Zhengjin, Xu Tongwen
机构信息
Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui, China.
School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei, Anhui, China.
出版信息
Nat Commun. 2025 Jan 2;16(1):47. doi: 10.1038/s41467-024-55244-4.
2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives are typical catholytes in aqueous organic redox flow batteries (AORFBs), but reported lifetime of them is limited. We find that the increase of Hirshfeld charge decreases the Gibbs free energy change (ΔG) values of side reactions of TEMPO, a near-linear relationship, and then exacerbates their degradation. Here we predict and synthesize a TEMPO derivative, namely TPP-TEMPO, by analyzing the Hirshfeld charge. TPP-TEMPO, with the smallest Hirshfeld charge and highest ΔG, is an order of magnitude more stable than TMA-TEMPO (N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride, a control with the largest Hirshfeld charge and lowest ΔG). We further elaborate on their decomposition pathways, identify byproducts, and mitigate degradation by supporting electrolyte engineering. Finally, a TPP-TEMPO/BTMAP-Vi (1,1'-bis[3-(trimethylammonio)propyl]-4,4'-bipyridinium tetrachloride) cell achieves a capacity density of ~12 Ah L and a low capacity fade rate of 0.0018% per cycle (or 0.0067% per hour).
2,2,6,6-四甲基哌啶-1-氧基（TEMPO）衍生物是水系有机氧化还原液流电池（AORFBs）中的典型阴极电解液，但据报道其寿命有限。我们发现，Hirshfeld电荷的增加会降低TEMPO副反应的吉布斯自由能变化（ΔG）值，二者呈近似线性关系，进而加剧其降解。在此，我们通过分析Hirshfeld电荷预测并合成了一种TEMPO衍生物，即TPP-TEMPO。TPP-TEMPO的Hirshfeld电荷最小，ΔG最高，其稳定性比TMA-TEMPO（N,N,N-2,2,6,6-七甲基哌啶基氧基-4-氯化铵，一种Hirshfeld电荷最大、ΔG最低的对照物）高一个数量级。我们进一步阐述了它们的分解途径，鉴定了副产物，并通过支持电解质工程减轻降解。最后，一个TPP-TEMPO/BTMAP-Vi（1,1'-双[3-(三甲基铵)丙基]-4,4'-联吡啶四氯化物）电池实现了~12 Ah L的容量密度和每循环0.0018%（或每小时0.0067%）的低容量衰减率。
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