First-principles studies of Mn-doped LiCoPO₄

This paper investigates Mn-doped LiCoPO₄ material using first-principles calculations. Results indicate that the volume change of LiMn_xCo_1-xPO₄ to Mn_xCo_1-xPO₄ is smaller than that of undoped LiCoPO₄, which is responsible for the excellent tolerance of repeated cycling in lithium ion batteries. Combining first-principles calculations with basic thermodynamics, we calculate the average intercalation voltage of Mn-doped LiCoPO₄. It is shown that the redox couple Mn³⁺/Mn²⁺ can be observed with increasing Mn content. Therefore, the Mn ion displays some electrochemical activity during discharge/charge of LiMn_xCo_1-xPO₄ due to the coexistence of Co and Mn.