Competitive lithium and sodium intercalation into sodium manganese phospho-olivine NaMnPO₄ covered with carbon black

Abstract

The study demonstrates unusual capabilities of phospho-olivine NaMnPO4 to intercalate lithium and sodium reversibly, which makes it attractive electrode material instead of the conventional lithium analogue LiMnPO4.

Lithium versus Mono/Polyvalent Ion Intercalation: Hybrid Metal Ion Systems for Energy Storage

“…To our knowledge there are no data about co‐intercalation of Na + and other metal ions (including Li + ) into olivine‐type NaFePO 4 . For olivine‐type NaMnPO 4 , however, a Li + /Na + co‐insertion has been verified based on electrochemical and ex‐situ diffraction, microscopic and spectroscopic techniques (Figure a,b) …”

“…It should be mentioned that till now, the electrochemical activity of a nanosized composite NaMnPO 4 /C has been only demonstrated by Boyadhzieva at al . It displays relatively good electrochemical activity when used as a cathode in model lithium ion cells: a specific capacity of 80–85 mAh g −1 can be retained for 15 cycles with a Columbic efficiency of 98 % . It has been also found that the NaMnPO 4 /C composite shows a chemical inertness after a prolonged soaking in the lithium electrolyte LiPF 6 /EC/DMC .…”

“…This method is very effective for low temperature synthesis of both lithium and sodium olivines, but with a remarkable difference in respect to the kinetics of the ion‐exchange reactions: extremely fast kinetics for the Li‐exchange (only 90 min synthesis at 270 °C) vs very slow Na‐exchange (15 h synthesis at 200 °C) ,. It should be mentioned that till now, the electrochemical activity of a nanosized composite NaMnPO 4 /C has been only demonstrated by Boyadhzieva at al . It displays relatively good electrochemical activity when used as a cathode in model lithium ion cells: a specific capacity of 80–85 mAh g −1 can be retained for 15 cycles with a Columbic efficiency of 98 % .…”

High‐Abundance and Low‐Cost Metal‐Based Cathode Materials for Sodium‐Ion Batteries: Problems, Progress, and Key Technologies

“…[155] NaMnPO 4 /C composite was prepared through an ion-exchange reaction and ball milling processes. [156] The as-prepared compound consists of well-crystallized olivine-phase NaMnPO 4 with disordered carbon species and no antisite defects, delivering a reversible capacity between 80 and 85 mAh g −1 in model lithium cells (Figure 13b). Although the electrochemical performance is unsatisfactory, it is demonstrated that NaMnPO 4 is capable of reversibly intercalating both Na + and Li + ions based on the chemical reaction Li x Na 1−x MnPO 4 ↔ Li 0.0 Na 0.5 MnPO 4 (0.25 ≤x ≤ 0.45).…”

“…Reproduced with permission. [156] Copyright 2015, Royal Society of Chemistry. c) Schematic illustration of Na + ion diffusion paths in Na 2 MnPO 4 F structure: (top left) possible paths with activation barrier lower than 650 meV, and in the b direction through the (top right) Na1-Na4 chain, (bottom left) Na2-Na3 chain, and (bottom right) interchain diffusion; and d) charge/discharge profiles of the first three cycles of Na 2 MnPO 4 F at a current density of 10 mA g −1 .…”