An additional discharge plateau of Mn^{3 +} in LiFe_0.5Mn_0.5PO₄ at high current rates

LiFe_0.5Mn_0.5PO₄ typically exhibits two pairs of plateaus in charge/discharge curves associated with MnPO₄/LiMnPO₄ and FePO₄/LiFePO₄ phase transformation. In this work, an additional plateau was observed at about 3.7 V in the discharge curve at relative high current rates, but not in the charge process. The additional plateau is identified to Mn^{3 +} reduction by capacity analysis, cyclic voltammograms (CV) and galvanostatic intermittent titration technique (GITT) measurement. The capacity of additional plateau increases with the increase of discharge rates. LiFe_0.5Mn_0.5PO₄ discharge mainly proceeds at this plateau at high current rate.