PNNL

Abstract

Mg batteries have potential advantages in terms of safety, cost and reliability over existing battery chemistries, but their practical implementation is hindered substantially by the lack of amenable high voltage cathode materials. The development of cathode materials is complicated by a limited understanding of the unique divalent Mg ion electrochemistry. Here we show that highly dispersed vanadium oxide nanoclusters supported on porous carbon frameworks were able to react with Mg ions reversibly in electrolytes that are compatible with Mg metal, and exhibited high capacities and good reaction kinetics. Electrodes with the composite materials were able to deliver initial capacities exceeding 300 mAh/g at 40 mA/g in the voltage window of 0.5 to 2.8V. The combined electron microscope, spectroscopy and electrochemistry characterizations suggest the reaction is surface-controlled and may be best described as through a molecular reaction mechanism. This work could provide a new approach of using nanoclusters and the molecular energy storage mechanism to design electrode materials for Mg batteries.