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镁二次电池具有安全性高、价格低廉等优点,是一种具有潜在应用前景的高能量密度电池体系.目前,镁二次电池的研究重点之一是寻找合适的电极材料.最近,我们通过水热和热处理相结合的方法成功制备了具有三维导电网络结构的锡纳米颗粒/石墨烯纳米片复合电极材料.研究发现,在石墨烯的三维导电网络片层上,均匀分布了粒径小于100 nm的锡纳米颗粒.将锡纳米颗粒/石墨烯纳米片复合材料作为镁二次电池电极材料,当电流密度为15 mA·g~(-1)和300 mA·g~(-1)时,首次放电容量分别达到了545.4 mAh·g~(-1)和238.8 mAh·g~(-1),经过150圈后,容量保持率达到了93%,库伦效率为99%,表现出了较高的电化学活性.研究还发现,镁离子嵌入复合材料中形成镁锡合金,当镁离子脱出后,再次形成锡纳米颗粒/石墨烯纳米片复合电极材料,镁离子的脱出和嵌入具有很高的可逆性.这对未来研究设计高性能镁离子电极材料具有十分重要的意义.
Magnesium secondary batteries with high safety, low price, etc., is a potentially promising high-energy density battery system.At present, magnesium secondary batteries, one of the focuses of research is to find the right electrode material.We recently passed Hydrothermal and heat treatment were combined to successfully prepare a three-dimensional conductive network structure of tin nanoparticle / graphene nanosheet composite electrode material.It was found that graphene three-dimensional conductive network layer, the uniform distribution of particle size less than 100 nm tin nano-particles.When tin nano-particles / graphene nanosheets were used as the electrode materials of magnesium secondary batteries, when the current density was 15 mA · g -1 and 300 mA · g -1, The first discharge capacity reached 545.4 mAh · g -1 and 238.8 mAh · g -1, respectively. After 150 cycles, the capacity retention rate reached 93%, and the coulombic efficiency was 99% .It is also found that the magnesium ions are embedded in the composite material to form a magnesium-tin alloy, and when the magnesium ions are taken off, the tin nanoparticle / graphene nanosheet composite electrode material is formed again, and the magnesium ions are desorbed and embedded with high Reversible, which is of high design for future research Magnesium ion electrode material is of great significance.