The Magnesium-Sulfur Battery with High Rate and Improved Capacity Using Cu Nanoparticle Additives

Abstract

The metallic Mg anode has a very high theoretical volumetric capacity of 3832 mAh/cm3, in comparison to 2062 mAh/cm3 for Li. Moreover, Mg has widespread natural abundance and is of lower cost. Sulfur is also a cheap and safe material which can be used as cathode for Mg batteries. However, the Mg/S battery has several disadvantages which block its practical application. One of these challenges is the polysulfide shuttle effect which is common in metal-sulfur batteries and results in decreased coulombic efficiency and battery lifespan. To solve this problem, many inorganic compounds have been used as additives to adsorb polysulfides in the Li/S battery cathode. The same method may also be effective in the Mg/S battery. It has been reported that the Mg/S battery with a Cu current collector is able to cycle for more 25 cycles while using other current collectors, the Mg/S cell has much poorer performance. This result suggests that the Cu-S interaction can influence the performance of Mg/S battery and improve the cycling stability. To study the interaction between Cu and S, Cu nanoparticles are synthesized and mixed with the sulfur cathode. It is found that Cu2S forms on the Cu surface and facilitates the reduction of sulfur in the Mg/S battery. The inclusion of Cu nanoparticles enables the battery to charge/discharge at higher current densities and also improves the cycling stability. The Mg/S battery with Cu additives can run at 0.5 C for more than 50 cycles and deliver a significant capacity.