As an emerging electrochemical energy storage technology, sodium-ion batteries (SIBs) are considered a possible alternative for the existing lithium-ion batteries, especially for large scale application (e.g., smart grids) owing to the potential low cost of manufacturing. However, the development of high-performance SIB systems is hindered by the lack of proper cathode materials of high capacity, long cycle life, and low cost. To date, various sodium transition metal oxides have been studied as potential cathode materials for SIBs. In particular, sodium manganese oxides with different compositions and crystal structures have attracted much attention because of their high initial capacity and the use of earth abundant element Mn. In this presentation, we report our findings in designing Mn-based high capacity and long cycle life cathodes with a strategy of tuning the phase evolution pathway. We will highlight the results of synthesis, crystal structure characterization and electrochemical testing of a group of layered sodium manganese cathode materials doped with lithium. Many of them demonstrated very high initial capacity (&gt;200 mAh/g) and good capacity retention. Further, we have performed in-operando X-ray diffraction (XRD), Rietveld refinement and 7Li solid state NMR to elucidate the cycling mechanisms of the materials. The stability of the Li-doped structure, the effects of lithium doping, and the fate of lithium in extended cycling will also be discussed. Figure 1. The CV scan curves (a) and in operando XRD patterns (b) of the lithium doped sodium manganese oxide cathode.

Design of high capacity intercalation cathode materials for sodium ion batteries with single-phase pathways

254th National Meeting (2017)

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