Organic compounds with active sites for lithiation can be used as electrode materials for lithium batteries. Their tunable structures allow a variety of materials to be made and investigated. Herein, a spectrum of dipyridyl polysulfides (Py2S x , 3 ≤ x ≤ 8) is prepared in electrolyte by a one-pot synthesis method from dipyridyl disulfide (Py2S2) and elemental sulfur. It renders up to seven dipyridyl polysulfides (i.e., Py2S3, Py2S4, Py2S5, Py2S6, Py2S7, and Py2S8) which show fully reversible electrochemical behavior in lithium batteries. In the discharge, the initial lithiation occurs at 2.45 V leading to the breakage of Sα-Sβ bonds in Py2S x and formation of lithium 2-pyridinethiolate, in which lithium is coordinated in between N and S atoms. The left sulfur species act as elemental sulfur, showing two voltage plateaus at 2.3 and 2.1 V. The molecular dynamics simulations show the attraction between pyridyl groups and lithium polysulfides/sulfide via N···Li···S bonds, which enable good retention of soluble discharge products within electrodes and stable cycling performance. In the recharge, low-order Py2S x (e.g., Py2S3, Py2S4, and Py2S5) remain as the charged products. The mixture catholyte exhibits superlong cycle life at 1C rate with 1200 cycles and 70.5% capacity retention.

中文翻译：

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长周期寿命的可充电锂电池用有机多硫化物阴极电解液。

具有锂化活性位点的有机化合物可用作锂电池的电极材料。它们的可调结构允许制造和研究各种材料。在此，通过一锅合成法由二吡啶基二硫化物（Py2S2）和元素硫制备二吡啶基多硫化物（Py2S x，3≤x≤8）的光谱。它呈现多达七个二吡啶基多硫化物（即Py2S3，Py2S4，Py2S5，Py2S6，Py2S7和Py2S8），在锂电池中表现出完全可逆的电化学行为。在放电中，初始锂化发生在2.45 V，导致Py2S x中的Sα-Sβ键断裂并形成2-吡啶硫醇锂，其中锂在N和S原子之间配位。剩余的硫物种充当元素硫，在2.3和2.1 V时显示两个电压平稳段。分子动力学模拟表明，吡啶基与多硫化锂/硫化锂之间通过N···Li···S键相互吸引，这使得可溶放电产物在电极内保持良好并具有稳定的循环性能。在充电中，低阶Py2S x（例如Py2S3，Py2S4和Py2S5）保留为被充电产品。混合物阴极电解液在1C速率下具有1200个循环和70.5％的容量保持率，显示出超长的循环寿命。