Alluaudite LiMnPO4: a new Mn-based positive electrode for Li rechargeable batteries

Abstract

A novel, Na-pillared LiMnPO4 (Li0.78Na0.22MnPO4) with an alluaudite structure is successfully prepared for the first time and proposed as a new positive electrode for Li rechargeable batteries. Approximately 0.8 Li+ ions are reversibly extracted from and reinserted into LiMnPO4 via Mn2+/Mn3+ redox reactions. The alluaudite LiMnPO4 (a-LiMnPO4) structure is sufficiently robust during repeated Li extraction/insertion such that similar to 92% of the initial capacity is retained after 50 charge/discharge cycles. An ex situ XRD study of the electrochemical cell during cycling indicates that Li de/intercalation in alluaudite LiMnPO4 occurs via the one-phase (solid-solution) reaction instead of the two-phase reaction observed in olivine LiMnPO4.