Rare Earth Elements (REE) as Ionic Conductive Material

One thing that we should always remember about battery storage is a transfer energy. This process involves moving electron from cathode to anode using electrolytes. On the beyond lithium battery, the existence of solid electrolyte (e.g. advanced ionic conductive material) will increase the electron transfer effectivity.  The common method  to increase battery performance is doping. This kind of improvement is truly interesting topic for rare earth elements (REE) in solid electrolytes. The lithium ion conductivity potentially increase by proper doping so as to disturb the lattice structure.

This discovery revealed for the first time in 1989. When Sugimoto's research group reported improving the lithium ion conductivity LiTi2(PO4)3 by partly replacing Ti4+ with rare earth Scandium (Sc3+), Yttrium (Y3+), and Lanthanum (L3+). When the Ti site is partly substituted by Sc3+ with slightly larger ionic radii, the lattice size. increases, the improvement of conductivity can be a consequence of increased size of bottleneck. However, the replacement of Ti4+ by even larger Y3+ or La3+ resulted in the formation of a mixed phase of LiTi2(PO4)3 and Li3Ln2(PO4)3 (Ln = Y or La). For further the the ionic conductivity will be obviously influenced by the doping amount of REE, too much doping results in a sharp decrease of conductivity on the contrary. In fact, the increases of lithium concentration and material density are also causes for the increase of conductivity.

Date : 29 June 2021
Written by : NBRI
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