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Correlating Material Structure with Key Properties for Solid-State Batteries

This paper reports work by Jeff Sakamoto and his collaborators to correlate the effects of pressure and temperature, enabling a close to theoretical density for a Li2S‐P2S5 solid electrolyte. The findings enable a five‐fold increase in ionic conductivity and a two‐fold increase in elastic modulus. The mechanistic insight gained from this study can guide efforts to stabilize interfaces in solid‐state batteries.

ABSTRACT

A combination of high ionic conductivity and facile processing suggest that sulfide‐based materials are promising solid electrolytes that have the potential to enable Li metal batteries. Although the Li2S‐P2S5 (LPS) family of compounds exhibit desirable characteristics, it is known that Li metal preferentially propagates through microstructural defects, such as particle boundaries and/or pores. Herein, it is demonstrated that a near theoretical density (98% relative density) LPS 75‐25 glassy electrolyte exhibiting high ionic conductivity can be achieved by optimizing the molding pressure and temperature. The optimal molding pressure reduces porosity and particle boundaries while preserving the preferred amorphous structure. Moreover, molecular rearrangements and favorable Li coordination environments for conduction are attained. Consequently, the Young’s Modulus approximately doubles (30 GPa) and the ionic conductivity increases by a factor of five (1.1 mS cm−1) compared to conventional room temperature molding conditions. It is believed that this study can provide mechanistic insight into processing‐structure‐property relationships that can be used as a guide to tune microstructural defects/properties that have been identified to have an effect on the maximum charging current that a solid electrolyte can withstand during cycling without short‐circuiting.

Read more at:

Garcia‐Mendez, R.Smith, J. G.Neuefeind, J. C.Siegel, D. J.Sakamoto, J.Correlating Macro and Atomic Structure with Elastic Properties and Ionic Transport of Glassy Li2S‐P2S5 (LPS) Solid Electrolyte for Solid‐State Li Metal BatteriesAdv. Energy Mater. 202010, 2000335. 
https://doi.org/10.1002/aenm.202000335