Electrochemical Characterization of LiTi2(PO4)3 as Anode Material for Aqueous Rechargeable Lithium Batteries

Abstract

RAPET (Reactions under Autogenic Pressure at Elevated Temperature) method has been used to synthesize lithium titanium phosphate anode material. The prepared compound is characterized by X-ray diffraction analysis. The electrochemical behavior has been studied in different aqueous electrolytes using cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques. CV peak current is proportional to the square root of scan rate. The system satisfies the required conditions for a reversible redox system. LiTi2(PO4)3 is found to undergo lithium insertion at all concentrations of LiNO3 electrolyte. The values of –Z″ when all the points of the impedance spectra measured in 2 M Li2SO4 electrolyte compared at 5 mHz are found to show a minimum at the potential close to the CV peak potential during charge and discharge. The cell, LiTi2(PO4)3/2 M Li2SO4/LiNi1/3Mn1/3Co1/3O2 delivers a discharge capacity of 116 mAh g−1 in the first cycle at an applied current of 0.2 mA cm−2 (C/5rate) and it retains a capacity of 107 mAh g−1 over 100 cycles with good rate capability. The non-aqueous cell, Li/1 M LiAsF6/EC-DMC/LiTi2(PO4)3 delivers a discharge capacity of 125 mAh g−1 with a voltage plateau around 2.4 V vs Li/Li+.