氨分子动力学调节提高Mg(BH4)2的离子导电率及作用机制

镁离子电池有望在未来成为的重要能源存储器件，然而镁电池的开发受制于缺乏良好的电解质等关键材料。相对于液态电解质，固态电解质具有更高的安全性。目前报导的固态材料在室温下的镁离子导电率偏低，一般不超过0.1 mS/cm，不能满足固态电池的运行要求。前期我们发现，Mg(BH4)2(NH3)1.5在60°C下的离子电导率达到1 mS/cm。Mg(BH4)2(NH3)x体系还存在如下科学问题：1）NH3如何促进镁离子实现快速传导；低于55°C晶态-非晶态相变温度时，离子导电率随着温度降低迅速下降。本申请拟系统地研究NH3含量对离子导电特性的影响，深入探索镁离子传导的机制，通过纳米氧化物复合化抑制材料的晶态-非晶态相变并提高离子导电率，构筑并测试固态电池。通过本项目的实施，有望为镁离子固态电解质的设计提出新的思路，为进一步开发高性能的全固态镁离子电池提供理论与技术支撑。

All-solid-state Mg-ion batteries have the potential to be ulitized as important devices for energy storage in the future. However, their development is seriously hindered by the shortage of solid-state Mg-ion electrolyte with sufficient conductivity at room temperature. Recently, we discovered that the ionic conductivity of Mg(BH4)2 can be largely improved by combination with NH3 molecules. For instance, Mg(BH4)2(NH3)1.5 shows a high Mg-ion conductivity of 1.0 mS/cm at 60℃. However, there remain a few scientifc challenges for Mg(BH4)2(NH3)x including: 1) the mechanism of how NH3 aids the movement of Mg2+ cations is unknown and 2) below the temperature of the crystalline-noncrystalline phase transition at 55℃, the ionic conductivity drops rapidly with the decrease of temperature. Within this project, we propose to systematically study the effect of NH3 numbers on ionic conducting properties, uncover the ion conduction mechanism, investigate the suppression of phase transition by addition of metal oxide nanopowders (e.g. MgO), examine the compatibility of this type of materials with cathodic and anodic materials to confirm their possibility to be utilized as electrolyte in all-solid-state batteries. The success of this project may lead to the establishment of new design principles for Mg-ion conductors and facilitate the development of high-performance all-solid-state Mg-ion battery in the near future.