Stabilization of all-solid-state Li–S batteries with a polymer–ceramic sandwich electrolyte by atomic layer deposition

Abstract

All-solid-state lithium–sulfur batteries (ASSLSBs) are promising candidates as the power source for future electric vehicles due to their high energy density and superior safety properties. However, one of the major challenges of state-of-the-art ASSLSBs is related to the high interfacial resistance resulting from the instability between the solid-state electrolyte (SSE) and electrodes and/or the side reactions between polysulfides and SSE. Herein, we propose and demonstrate the significant enhancement of the cycling stability of an ASSLSB through atomic layer deposition interfacial engineering on the polymer/oxide ceramic/polymer sandwich-structured SSE. The results show that as few as 10 cycles of ALD Al₂O₃ on the LATP can endow ASSLSBs with a discharge capacity of 823 mA h g⁻¹ after 100 charge/discharge cycles, which is almost two times higher than that of the ASSLSB without an ALD coating and that of a Li–S battery with a liquid-based electrolyte. Such improvement is attributed not only to the blocking of the polysulfide shuttling effect via the use of a sandwich SSE but also the significant reduction of the side reaction between the polysulfide and oxide ceramic SSE, which introduces high interfacial resistance and degrades the electrochemical performance. The protection role and mechanism of the ALD layer is also confirmed and revealed by XRD, SEM and XPS measurements.