High performance Prussian Blue cathode for nonaqueous Ca-ion intercalation battery

Abstract Potassium iron hexacyanoferrate, or Prussian blue (PB), is investigated as a cathode material for nonaqueous divalent calcium ion batteries. PB is an attractive prospect due to its high specific capacity, nontoxicity, low cost, and simple synthesis. Charge/discharge performances are examined at current densities of 23 mAg −1 , 45 mAg −1 , 90 mAg −1 , and 125 mAg −1 that produced reversible specific capacities ranging from 150 mAhg −1 (at 23 mAg −1 current density) to over 120 mAhg −1 (at 125 mAg −1 current density). These are the highest storage capacities to date for a divalent calcium ion cathode over extended period of charge/discharge cycling and are comparable in performance to monovalent intercalating ions.