Revealing the relation between the structure, Li-ion conductivity and solid state battery performance for the argyrodite Li6PS5Br solid electrolyte

Revealing the relation between the structure, Li-ion conductivity and solid state battery performance for the argyrodite Li6PS5Br solid electrolyte

Yu, C. (TU Delft RST/Fundamental Aspects of Materials and Energy)
Ganapathy, S. (TU Delft RST/Fundamental Aspects of Materials and Energy)
van Eck, Ernst R H (Radboud Universiteit Nijmegen)
van Eijck, L. (TU Delft RST/Neutron and Positron Methods in Materials)
Basak, S.
Liu, Yanyan (State Key Laboratory of Metastable, Materials Science and Technology, Yanshan University)
Zhang, Long (State Key Laboratory of Metastable, Materials Science and Technology, Yanshan University)
Zandbergen, H.W. (TU Delft QN/Zandbergen Lab)
Wagemaker, M. (TU Delft RST/Fundamental Aspects of Materials and Energy)

2017-09-14

Based on its high Li-ion conductivity, argyrodite Li6PS5Br is a promising solid electrolyte for all-solid-state batteries. However, more understanding is required on the relation between the solid electrolyte conductivity and the solid-state battery performance with the argyrodite structure, crystallinity and particle size that depend on the synthesis conditions. In the present study, this relationship is investigated using neutron and X-ray diffraction to determine the detailed structure and impedance as well as 7Li solid state NMR spectroscopy to study the Li-ion kinetics. It is found that depending on the synthesis conditions the distribution of the Br dopant over the crystallographic sites in Li6PS5Br is inhomogeneous, and that this may be responsible for a larger mobile Li-ion fraction at the interface regions in the annealed argyrodite materials. Comparing the bulk and interface properties of the differently prepared Li6PS5Br materials, it is proposed that optimal solid-state battery performance requires a different particle size for the solid electrolyte only region and the solid electrolyte in the cathode mixture. In the electrolyte region, the grain boundary resistance is minimized by annealing the argyrodite Li6PS5Br resulting in relatively large crystallites. In the cathode mixture however, additional particle size reduction of the Li6PS5Br is required to provide abundant Li6PS5Br-Li2S interfaces that reduce the resistance of this rate limiting step in Li-ion transport. Thereby the results give insight in how to improve solidstate battery performance by controlling the solid electrolyte structure.

http://resolver.tudelft.nl/uuid:ff792e10-311b-45b1-82ca-f0ab80ff720d

https://doi.org/10.1039/C7TA05031C

2050-7488

Journal of Materials Chemistry A, 1-25

Institutional Repository

journal article

© 2017 C. Yu, S. Ganapathy, Ernst R H van Eck, L. van Eijck, S. Basak, Yanyan Liu, Long Zhang, H.W. Zandbergen, M. Wagemaker