Atomic layer deposition of solid-state electrolytes for next-generation lithium-ion batteries and beyond: Opportunities and challenges

Currently there has an ever-growing interest in inorganic solid-state electrolytes (iSEs), given the fact that traditional organic liquid electrolytes (oLEs) have become a major limiting factor for next-generation high-energy lithium-ion batteries (LIBs) and beyond. In this context, iSEs are currently undergoing an intensive investigation in order to accomplish solid-state batteries (SSBs) with reliable safety, longer lifetime, lower cost, and higher energy and power density. To date there have been many methods developed for synthesizing iSEs. Among them, atomic layer deposition (ALD) has recently emerged as a new technique with exceptional capabilities to enable atomic-scale rational designs, in situ uniform and conformal growth, low process temperature, and high operational flexibility, and large variety of material choices. To this end, in this work we conduct the first comprehensive survey on iSEs by ALD, covering 6 material categories, 15 iSEs, and 25 processes. We outline 4 technical strategies with ALD processes and elucidate the underlying mechanisms. Furthermore, we make a thorough account of the promising applications of the iSEs in LIBs and lithium batteries and clarify their distinguished benefits for securing excellent electrochemical performance. We expect that this work will greatly motivate more efforts in pursuing excellent iSEs using ALD.