Celgard-supported LiX zeolite membrane as ion-permselective separator in lithium sulfur battery

Abstract

A novel ion-permselective separator comprised the top layer of LiX zeolite membrane and the support layer of commercial Celgard membrane, namely LiX@Celgard, was prepared and employed for the first time in Li–S battery. The LiX zeolite membrane was obtained via the in situ hydrothermal synthesis of NaX zeolite over the X-type zeolite-seeded Celgard membrane and the subsequent Li+ ion-exchange. The characterizations of LiX/Celgard separator by means of XRD, SEM, EDS and XPS showed that a continuous and compact layer of LiX zeolite crystals, with a thickness of ca. 6 μm, has been tightly grafted over the surface of Celgard support. The LiX@Celgard separator was proved to possess an improved electrolyte wettability and high efficiency for inhibiting the penetration of polysulfide (PSs). The electrochemical performance determination indicated that the Li-ion conductivity, diffusion coefficient and transference number were all larger for the battery basing on the LiX/Celgard separator than for that basing on the pristine Celgard separator. The above superior properties of LiX/Celgard separator restrained significantly the shuttle of PSs and improved obviously the efficiency in the utilization of sulfur. At a C-rate of 0.2 C, a specific capacity of ca. 1083 mAh/g, with a capacity retention of 70% after 400 cycles, had been achieved for the Li–S battery employing the LiX/Celgard separator. The strategy adopted in this work can be an enlightenment for the development of ion-selective membranes used in rechargeable battery and other energy storage field.