School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University , 1, Gwanak-ro, Gwanak-gu, Seoul 08826, South Korea.
School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , 50, UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, South Korea.
ACS Appl Mater Interfaces. 2016 Apr 6;8(13):8554-60. doi: 10.1021/acsami.6b01352. Epub 2016 Mar 22.
Thanks to the advantages of low cost and good safety, magnesium metal batteries get the limelight as substituent for lithium ion batteries. However, the energy density of state-of-the-art magnesium batteries is not high enough because of their low operating potential; thus, it is necessary to improve the energy density by developing new high-voltage cathode materials. In this study, nanosized Berlin green Fe2(CN)6 and Prussian blue Na(0.69)Fe2(CN)6 are compared as high-voltage cathode materials for magnesium batteries. Interestingly, while Mg(2+) ions cannot be intercalated in Fe2(CN)6, Na(0.69)Fe2(CN)6 shows reversible intercalation and deintercalation of Mg(2+) ions, although they have the same crystal structure except for the presence of Na(+) ions. This phenomenon is attributed to the fact that Mg(2+) ions are more stable in Na(+)-containing Na(0.69)Fe2(CN)6 than in Na(+)-free Fe2(CN)6, indicating Na(+) ions in Na(0.69)Fe2(CN)6 plays a crucial role in stabilizing Mg(2+) ions. Na(0.69)Fe2(CN)6 delivers reversible capacity of approximately 70 mA h g(-1) at 3.0 V vs Mg/Mg(2+) and shows stable cycle performance over 35 cycles. Therefore, Prussian blue analogues are promising structures for high-voltage cathode materials in Mg batteries. Furthermore, this co-intercalation effect suggests new avenues for the development of cathode materials in hybrid magnesium batteries that use both Mg(2+) and Na(+) ions as charge carriers.
得益于低成本和良好安全性的优势，镁金属电池作为锂离子电池的替代品备受关注。然而，由于其工作电位较低，最先进的镁电池的能量密度还不够高；因此，有必要通过开发新的高压阴极材料来提高能量密度。在这项研究中，纳米级柏林绿 Fe2(CN)6 和普鲁士蓝 Na(0.69)Fe2(CN)6 被比较作为镁电池的高压阴极材料。有趣的是，虽然 Mg(2+) 离子不能嵌入 Fe2(CN)6 中，但 Na(0.69)Fe2(CN)6 显示出可逆的 Mg(2+) 离子嵌入和脱嵌，尽管它们除了存在 Na(+) 离子之外具有相同的晶体结构。这种现象归因于 Mg(2+) 离子在含有 Na(+) 的 Na(0.69)Fe2(CN)6 中比在不含 Na(+) 的 Fe2(CN)6 中更稳定，表明 Na(0.69)Fe2(CN)6 中的 Na(+) 离子在稳定 Mg(2+) 离子方面起着至关重要的作用。Na(0.69)Fe2(CN)6 在 3.0 V 相对于 Mg/Mg(2+) 时提供约 70 mA h g(-1) 的可逆容量，并在 35 次循环中表现出稳定的循环性能。因此，普鲁士蓝类似物是镁电池高压阴极材料的有前途的结构。此外，这种共嵌入效应为使用 Mg(2+) 和 Na(+) 离子作为电荷载流子的混合镁电池的阴极材料的开发提供了新的途径。
