High temperature electrochemical performance of hydrothermally prepared LiMn1 − xMxPO4 (M = Fe, Mg)

• LiMn1 − xFexPO4 has been prepared hydrothermally in water–EMI_TFSI at 260 ºC.
• Electrochemical tests were successfully carried out in galvanostatic mode at 100 ºC.
• LiMn0.5Fe0.5PO4 exhibiting the largest capacity
• LiMn0.9Mg0.1PO4 is also reported and exhibited highest energy density.

We report on the hydrothermal synthesis of LiMn1 − xFexPO4 where x = 0.1, 0.2, 0.5, 0.8 and LiMn0.9Mg0.1PO4 at 260 °C, using water–EMI_TFSI mixture as reacting medium. Electrochemical tests carried out in galvanostatic mode at 100 ºC show that LiMn0.5Fe0.5PO4 presents the best performance in terms of capacity (ca.120 mAh/g), therefore this capacity is equally parted between 3.5 and 4.1 V plateaus. This contrasts with LiMn0.9Mg0.1PO4 which is more attractive energy density wise, as it exhibits a single reversible plateau having a capacity of 120 mAh/g at higher voltage (ca. 4.1 V vs. Li+/Li).