Iron Phosphate Polyanion Compounds as Anodes for Aqueous Lithium-Ion Batteries

Aqueous lithium-ion batteries offer the possibility of the gravimetric capacity, round trip efficiency, and high cycle life of lithium-ion battery materials coupled with the cost and safety advantages of aqueous electrolytes. A common challenge in these systems is the narrow voltage window of aqueous electrolytes and achieving suitable stability of the lithium-ion materials in the electrolyte. This paper will describe synthesis and characterization of iron phosphate compounds as anodes for aqueous lithium-ion batteries. While these materials are at or near the lower range of the stability window of water, oxygen in the electrolyte and subsequent oxygen reduction was the primary challenge in operation of these cells.