Enhanced electrochemical properties of Li2MgCl4 by Zn substitution for all-solid-state batteries.

Halides have currently been discovered to be ideal electrolytes for all-solid-state Li batteries (ASSLBs) due to their variability, splendid electrochemical stability, and high Li+ conductivities. Here, we studied the electrochemical properties of Li 2-2 x Zn x MgCl 4 (x = 0–0.3) and their application in ASSLBs. By Zn substitution into the Li site of Li 2 MgCl 4 , the Li + conductivities of Li 1.6 Zn 0.2 MgCl 4 (1.2 × 10−5 S/cm) at room temperature is two orders higher than that of Li 2 MgCl 4 (1.9 × 10−7 S/cm). The activation energy is reduced to 0.28 eV for Li 1.6 Zn 0.2 MgCl 4 (Li 2 MgCl 4 is 0.47 eV). We attributed the enhanced electrochemical performance to Li vacancies generated from the Zn substitution. In addition, we fabricated a Li | Li 1.6 Zn 0.2 MgCl 4 | Li cell to appraise the electrochemical performance in the lithiation and stripping. It is demonstrated that Li 1.6 Zn 0.2 MgCl 4 can cycle for 100 h under a current density of 0.07 mA/cm2. This study demonstrates that introducing Li vacancy into Li 2 MgCl 4 may be a valid way to promote the electrochemical properties of the halides. In this work, we report the electrochemical properties of the Zn-substituted Li 2 MgCl 4 (Li 2-2 x Zn x MgCl 4 (x = 0–0.3)). Based on the enhanced electrochemical properties, we fabricate a Li | Li 1.6 Zn 0.2 MgCl 4 | Li symmetric half-cell to evaluate the electrochemical stability during the lithiation and stripping processes. This study shows that the introduction of Li vacancy greatly improves the Li+ conductivities of the halide solid electrolytes, which provides constructive insights into the design of new superior solid electrolytes. [Display omitted] • The electrochemical properties of the Zn-substituted Li2MgCl4 (Li2-2 x Zn x MgCl4 (x = 0–0.3)) were studied. • Li vacancy introduction through Zn substitution into the Li site improves Li+ conductivities by two orders. • A Li.|Li1.6Zn0.2MgCl4|Li symmetric half-cell was fabricated to evaluate the electrochemical stability. [ABSTRACT FROM AUTHOR]