Solid State Ionics, Vol.187, No.1, 58-63, 2011
Determination of the chemical diffusion coefficient of Li+ in intercalation-type Li3V2(PO4)(3) anode material
The chemical diffusion coefficients of lithium ion (DLi+) in intercalation-type Li3V2(PO4)(3) (LVP) anode material as a function of cell voltage between 3.0 and 0.0 V are systematically determined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). The true chemical diffusion coefficients (D-Li+(true)) obtained from EIS and GITI- for the single-phase region (1.6-0.0 V vs. Li+/Li) are in the range of 10(-10) to 10(-9) cm(2) s(-1) and 10(-11) to 10(-10) cm(2) s(-1), respectively, and exhibit a decreasing trend of the change of D-Li+(true) vs. voltage as the discharge and charge proceeded. The apparent chemical diffusion coefficients (D-Li+(app)) measured from CV and GITT for the two-phase regions (around 2.5-1.6 V) are in the range of 10(-10) cm(2) s(-1) and 10(-12) to 10(-10) cm(2) s(-1), respectively. For GITT, D-Li+(app) vs. voltage plots display a characteristic of "W" shape due to the strong interactions of Li+ with surrounding ions. Finally, the DLi+ values of LVP anode are compared with other anode materials, illustrating that LVP can also be used as a potential anode material to achieve high rate capability. (C) 2011 Elsevier B.V. All rights reserved.