The importance of interface chemistries to optimize ion dynamics in all solid-state batteries
E. Querel1, I. Seymour1, R. Brugge1, A. Cavallaro1, N. Nabi1, F. Pesci1 and A. Aguadero1,2
1. Department of Materials, Imperial College London, SW7 2AZ, London UK
2. Instituto de Ciencia de Materiales de Madrid, CSIC, 28049, Cantoblanco, Spain
The need to develop safer batteries with enhanced energy densities is promoting the development of non-flammable solid electrolytes and their integration with alkali metal negative electrodes. A major challenge is the optimization of the dynamic metal/solid electrolyte interfaces that lead to premature cell degradation specially at high current densities. Whereas some of these problems can be solved by the application of high pressures or temperatures during operation, the integration of these systems requires optimization of performance in unpressurised systems at room temperature. Two of the best solid state alkaline-ion conductors are derivatives of Li7La3Zr2O12 Garnet-type structures for Li and Na3Zr2Si2PO12 NaSICON type structures for Na able to reach values of 15-10-1 mS/cm at RT
1,2. In this work, we focus on the study of Na/NaSICON and Li/Garnet interfaces paying particular attention to the effect that surface chemistry has on the charge transfer resistance and stability under high current densities. The study brings a combination of surface sensitive techniques (ex situ and operando) including secondary ion mass spectrometry, low energy ion scattering and x-ray photoelectron spectroscopy with electrochemical and computational analysis. We prove that the surface chemistry of solid electrolytes has a dominant role on the design of stable, high-performance metal/solid electrolyte interfaces and that the tuning of the surface chemistry is a powerful tool to improve the performance of these devices at high current densities3,4.
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