Kinetics of lithium insertion into LiMnPO4 from aqueous saturated LiOH: A study using galvanostatic and potentiostatic intermittent titration techniques

Galvanostatic and potentiostatic intermittent titration techniques have been used to study the lithium ion insertion into LiMnPO4 from aqueous sat. LiOH electrolyte and 1 M LiPF6/EC-DMC. The potential–time and current–time responses of LiMnPO4 obtained from chronopotentiometry and chronoamperometry respectively have been discussed for lithium insertion into LiMnPO4 from the aqueous electrolyte and it is compared with that obtained with the non-aqueous electrolyte. The PITT technique is very useful in describing the whole intercalation mechanism. The effects of ohmic potential drops and charge-transfer resistances have been taken into account while predicting the current transients obtained with aqueous electrolyte and non-aqueous electrolyte. The characteristic diffusion time constant (to) in sat. LiOH is found to be 24.1 s and that in non-aqueous 1 M LiPF6/EC-DMC electrolyte is 51.2 s. The chemical diffusion coefficient (D), an important kinetic parameter, calculated from GITT and PITT during intercalation process is found to be varying between 10−11 and 10−13 cm2 s−1 in both aqueous and non-aqueous electrolytes.