Abstract：
Rechargeable Mg batteries are a promising energy storage technology to overcome the limitations inherent to Li ion batteries. A critical challenge in advancing Mg batteries is the lack of suitable cathode materials. In this work, we report a cathode design that incorporates S functionality into two-dimensional metal-organic-frameworks (2D-MOFs). This new cathode material enables good Mg2+ storage capacity and outstanding cyclability. It was found that upon the initial Mg2+ insertion and disinsertion, there is an apparent structural transformation that crumbles the layered 2D framework, leading to amorphization. The resulting material serves as the active material to host Mg2+ through reduction and/or oxidation of S and, to a limited extent, O. The reversible nature of S and O redox chemistry was confirmed by spectroscopic characterizations and validated by density functional calculations. Importantly, during the Mg2+ insertion and disinsertion process, the 2D nature of the framework was maintained, which plays a key role in enabling the high reversibility of the MOF cathode.
摘要：
可充电镁电池是一种有前途的储能技术，可以克服锂离子电池固有的局限性。发展Mg电池的关键挑战是缺乏合适的阴极材料。在这项工作中,我们报告了将S功能整合到二维金属有机框架（2D-MOFs）中的阴极设计。这种新的阴极材料能够实现良好的Mg2+储存容量和优异的循环能力。发现在最初的Mg2+插入和脱出时，有一个明显的结构转变，瓦解了分层的2D框架，导致非晶化。所得材料作为活性材料，通过还原和/或氧化S来承载Mg2+，在有限的程度上,O.S和O氧化还原化学的可逆性通过光谱表征得到证实，并通过密度泛函计算得到验证。重要的是,在Mg2+插入和脱插过程中，保持了框架的2D性质，这在实现MOF阴极的高可逆性方面起着关键作用。
