Tavorite LiFePO4OH hydroxyphosphate as an anode for aqueous lithium-ion batteries

Abstract

In pursuit to find stable economic anode for aqueous lithium-ion batteries, tavorite structured LiFePO4OH hydroxyphosphate has been investigated in aqueous battery for the first time. First, the target compound is tested with organic electrolyte, giving the highest reported discharge capacity of 140 mAh g−1 with an Fe3+/Fe2+ redox potential of 2.6 V with excellent reversibility. LiFePO4OH is found to work as a promising anode in aqueous electrolyte with capacity ∼153 mAh g−1 (at 0.42 V vs. Ag/AgCl) with good cycling stability. An all-phosphate LiFePO4 | LiFePO4OH aqueous full cell has been fabricated having the first cycle capacity of 120 mAh g−1 (energy density ∼ 97 Wh kg−1). Tavorite LiFePO4OH forms an economic potential anode for aqueous Li-ion batteries.