(Invited) Unveiling the Mechanism of Magnesium Battery Cathode

Li-ion battery plays a dominant role in portable electronic devices. Yet in large scale applications the requirement remains to find new chemistry with improved performances such as energy density and power density as well as lower cost. Magnesium battery is one of such candidates,[1] as the bivalency of Mg 2+ ion provides good potential to exceed the energy density of current Li-ion technology. Metal Mg has a volumetric capacity of 3833 mAh/cc, nearly twice that of Li. However, the great hurdle to realize a practical Mg battery lies in the lack of appropriate cathode that can marry metal Mg anode with good capacity, cyclability and rate capability. In this talk, we will discuss the mechanism of magnesiation for several Mg battery cathodes. In comparison with Li-ion battery, we demonstrated that the chemistry of Mg battery cathode is more complicated. Even for classical intercalation-type Li-ion battery cathodes, the magnesiation can deviate from the intercalation reaction and follow the conversion pathway.[2-8] Hence the intercalation of Mg is not only challenged by the sluggish mobility of bivalent Mg 2+ ions. Necessary consideration about the stronger structural deformation and side reactions is also essential for the discovery of cathode candidates. The effect of conversion reaction will be carefully examined and discussed in details. Finally, we conclude our talk by suggesting several methods to avoid the challenges brought by intercalation with given examples.[9-11] Reference: [1]. D. Aurbach, Nature, 2001, 407, 73 [2]. R. Zhang, et al. Electrochem. Commun., 2012, 23, 110 [3]. T. S. Arthur, et al. ACS Appl. Mater. Interfaces, 2014, 6, 7004 [4]. C. Ling, et al. Chem. Mater., 2012, 24, 3943 [5]. R. Zhang, et al. J. Power Sources, 2015, 282, 630 [6]. C. Ling, Chem. Mater., 2015, 27, 5799 [7]. C. Ling, et al. in preparation [8]. C. Ling, et al. submitted [9]. C. Ling, et al. Chem. Mater., 2013, 25, 3062 [10]. R. Zhang, Chem. Commun., 2015, 51, 1108 [11]. R. Zhang, Chem. Commun., 2015, 51, 1457