Jadhav Ankur L, Juran Taylor R, Kim Matthew A, Bruck Andrea M, Hawkins Brendan E, Gallaway Joshua W, Smeu Manuel, Messinger Robert J
Department of Chemical Engineering, The City College of New York, CUNY, New York, New York 10031, United States.
Department of Physics, Binghamton University, SUNY, Binghamton, New York 13902, United States.
J Am Chem Soc. 2023 Jul 26;145(29):15816-15826. doi: 10.1021/jacs.3c02542. Epub 2023 Jul 13.
Rechargeable multivalent-ion batteries are of significant interest due to the high specific capacities and earth abundance of their metal anodes, though few cathode materials permit multivalent ions to electrochemically intercalate within them. The crystalline chevrel phases are among the few cathode materials known to reversibly intercalate multivalent cations. However, to date, no multivalent-ion intercalation electrodes can match their reversibility and stability, in part due to the lack of design rules that guide how ion intercalation and electron charge transfer are coupled up from the atomic scale. Here, we elucidate the electronic charge storage mechanism that occurs in chevrel phase (MoSe, MoS) electrodes upon the electrochemical intercalation of multivalent cations (Al, Zn), using solid-state nuclear magnetic resonance spectroscopy, synchrotron X-ray absorption near edge structure measurements, operando synchrotron diffraction, and density functional theory calculations. Upon cation intercalation, electrons are transferred selectively to the anionic chalcogen framework, while the transition metal octahedra are redox inactive. This reversible electrochemical anionic redox, which occurs without breaking or forming chemical bonds, is a fundamentally different charge storage mechanism than that occurring in most transition metal-containing intercalation electrodes using anionic redox to enhance energy density. The results suggest material design principles aimed at realizing new intercalation electrodes that enable the facile electrochemical intercalation of multivalent cations.
可充电多价离子电池因其金属负极的高比容量和丰富的地球储量而备受关注，尽管很少有阴极材料能让多价离子在其中进行电化学嵌入。晶体 Chevrel 相是已知的少数几种能可逆嵌入多价阳离子的阴极材料之一。然而，迄今为止，没有多价离子嵌入电极能与其可逆性和稳定性相匹配，部分原因是缺乏从原子尺度指导离子嵌入和电子电荷转移如何耦合的设计规则。在这里，我们使用固态核磁共振光谱、同步加速器 X 射线吸收近边结构测量、原位同步加速器衍射和密度泛函理论计算，阐明了在 Chevrel 相（MoSe、MoS）电极中，多价阳离子（Al、Zn）电化学嵌入时发生的电荷存储机制。阳离子嵌入时，电子选择性地转移到阴离子硫族元素骨架上，而过渡金属八面体则无氧化还原活性。这种可逆的电化学阴离子氧化还原过程，在不破坏或形成化学键的情况下发生，是一种与大多数利用阴离子氧化还原提高能量密度的含过渡金属嵌入电极中发生的电荷存储机制根本不同的机制。研究结果提出了旨在实现新型嵌入电极的材料设计原则，这些电极能够实现多价阳离子的便捷电化学嵌入。
