With the increasing interest in transition metal chalcogenides, sulfide minerals containing the disulfide unit (S₂^2-) have gained intensive attention for potential applications in energy storage devices, such as lithium-ion batteries (LIBs). Vanadium tetrasulfide (VS₄) possesses a unique linear-chain structure with a Peierls distortion and shows great promise for application in LIBs. However, its electrochemical reaction mechanism is still controversial, mainly due to the amorphous nature of the intermediates and final products. Here, by applying multiple X-ray spectroscopies, we reveal that VS₄ undergoes lithium intercalation and conversion reactions sequentially during the first discharge process, which are partially reversible in the subsequent charge process. However, an anomalous intercalation/conversion mixed reaction mechanism is dominant for the second cycle, mainly owing to the amorphization of the VS₄ electrode during the first cycle. In addition, the sulfur atoms are also involved in the redox reaction during cycling, with the anionic contribution of S₂^2- $\leftrightarrow$ 2S^2- transformation. Furthermore, we find that the formation process of the solid electrolyte interphase is highly dynamic during the discharge and charge processes. The present study provides deeper insights into the complex reaction mechanism of VS₄. This knowledge can accelerate the development of high-performance VS₄-based electrode materials for LIBs.

随着对过渡金属硫属元素化物的兴趣不断增加，含二硫键单元（S ₂ ^2-）的硫化物矿物已在能量存储设备（如锂离子电池（LIB））中的潜在应用中引起了广泛关注。四硫化钒（VS ₄）具有独特的带有Peierls畸变的线性链结构，显示了在LIB中的广阔应用前景。然而，其电化学反应机理仍是有争议的，主要是由于中间体和最终产物的无定形性质。在这里，通过应用多个X射线光谱学，我们发现VS ₄在第一个放电过程中依次经历锂嵌入和转化反应，这些反应在随后的充电过程中部分可逆。然而，异常的嵌入/转化混合反应机制在第二个循环中占主导地位，这主要是由于VS ₄电极在第一个循环中的非晶化所致。此外，硫原子也参与循环过程中的氧化还原反应，其中阴离子对S ₂ ^2-具有贡献。 $\leftrightarrow$2S ^2-转换。此外，我们发现固体电解质中间相的形成过程在放电和充电过程中是高度动态的。本研究为VS ₄的复杂反应机理提供了更深刻的见解。这些知识可以加快LIB高性能基于VS ₄的电极材料的开发。