熔体快淬Al(80-x)Si(20)Mnx锂离子电池负极材料的电化学性能

Electrochemical properties of melt-spun Al_(80-x)Si_(20)Mn_x alloy anodes for lithium-ion batteries

采用熔体快淬法制备了化学组成为Al80-xSi20Mnx(x=0、5%、7%、10%(摩尔分数))的锂离子电池合金负极材料。分析了合金的相组成、热力学状态、微观组织和与锂离子电池相关的电化学性能。结果显示,当Mn含量位于5%～7%时,熔体快淬Al80-xSi20Mnx合金可得到单一的过饱和固溶体和部分非晶,前10次电化学循环中具有比Al70-xSi30Mnx(x=0、5%、7%、10%(摩尔分数))多相合金高的容量,与含40%Si、相同Mn含量的合金相近。分析表明,在含20%～40%Si、5%～10%Mn的熔体快淬Al基合金中,锂主要储存在过饱和固溶体中,晶界和相界对储锂有重要贡献。合金的循环性能与Al基过饱和固溶体的成分有关,第三组元Mn的加入提高固溶体的过饱和度,并通过影响Li原子的扩散,改善循环性能。

Al80-xSi20Mnx（x=0,5%,7%,10%） ribbons were prepared by melt spinning.The phase constitutions,thermodynamic state,microstructures and electrochemical performances have been measured.The results reveal that when Mn contents are in a range of 5%-7%,only a supersaturated solid solution of Si and Mn in fcc-Al and some metallic glass can be detected.The specific capacities is similar with that of Al60-xSi40Mnx（x=0,5%,7%,10mol%）,but higher than Al70-xSi30Mnx（x=0,5%,7%,10mol%）.It is considered that Li atoms are mainly stored in the Al-Si-Mn supersaturated solid solution,when Si and Mn contents are in a range of 20%-40%,5%-7%,respectively.The grain boundaries and phase boundaries have a significant contribution for Li storage.The cycle ability of the alloys is relevant to the compositions.Mn additions can promote more atoms to dissolve in the Al-based supersaturated solid solution,resulting in an improvement of the cycle performance by an effect on the diffusion of Li atoms.