Determination of lithium ion diffusion behaviors in tavorite LiVPO4F by galvanostatic intermittent titration technique

The Li+ chemical diffusion coefficient (DLi+) in tavorite LiVPO4F as cathode and anode materials was calculated and compared by galvanostatic intermittent titration technique for the first time. The result reveals that the Li+ diffusion coefficient is about 10−9–10−13 cm2 s−1 when LiVPO4F is used as cathode material. In contrast, LiVPO4F anode displays lower Li+ diffusion coefficient of 10−9–10−15 cm2. In addition, both LiVPO4F cathode and anode materials exhibit twist “W” shape for the evolution of Li+ diffusion coefficient during the whole lithiation–delithiation process. They also show the minimum Li+ diffusion coefficients of 10−13 (cathode) and 10−15 cm2 s−1 (anode) in biphasic domain, which may be due to the strong interactions of Li+ with surrounding ions during the two-phase transition process.