Nanostructured MgFeSiO4/C Cathode Prepared By a Modified Sol-Gel Method for Rechargeable Mg-Ion Batteries

The rechargeable magnesium ion battery is currently investigated in response to several challenges of lithium ion batteries,[1] such as cost, resource availability and safety issues related to risk of thermal runaway.  The lithium ion batteries have and are predicted to dominate the portable battery market for a long time due to the high superior power density, while rechargeable magnesium batteries may play an important role in stationary energy storage systems and auxiliary power applications where the low cost and high reliability under a wide temperature range are more important than low weight and high power density.

Based on similar principles as the lithium ion battery, rechargeable magnesium ion batteries involve a reversible insertion/extraction of magnesium ions into/from a host matrix (cathode or anode materials) during the discharging and charging, and two electrons can be transferred accompanying one magnesium ion migration. Thus the specific volumetric capacity of magnesium metal can reach 3833 mAh/cm³, which is higher than that for lithium metal (2046 mAh/cm³). [2]

Similar to lithium ion batteries, it is mainly the cathode materials which limits the batterie’s properties such as energy density, safety and life cycle. In this work, nanostructured MgFeSiO₄/C composite cathodes are prepared by a modified sol-gel method combined with carbothermal reduction. Fig. 1 demonstrates the Pawley fitting of the X-ray diffraction for the MgFeSiO₄/C composite. The composite materials are investigated electrochemically using the developed composite materials as the cathode, magnesium alloys as the anode and a state-of-the art electrolyte. And in situXRD is used to characterize phase evolution in the materials during cycling.

1. Novák, P.; Imhof, R.; and Haas, O., Magnesium insertion electrodes for rechargeable nonaqueous batteries — a competitive alternative to lithium? Electrochimica Acta, 1999. 45(1–2): p. 351.

2. Yoo, H.D.; Shterenberg, I.; Gofer, Y.; Gershinsky, G.; Pour, N.; and Aurbach, D., Mg rechargeable batteries: an on-going challenge. Energy & Environmental Science, 2013. 6(8): p. 2265.