Unique Tridentate Coordination Tailored Solvation Sheath Toward Highly Stable Lithium Metal Batteries.

ABSTRACT

Electrolyte optimization by solvent molecule design is recognized as an effective approach for stabilizing lithium (Li) metal batteries. However, the coordination pattern of Li ions (Li+ ) with solvent molecules is sparsely considered. Here, an electrolyte design strategy is reported based on bi/tridentate chelation of Li+ and solvent to tune the solvation structure. As a proof of concept, a novel solvent with multi-oxygen coordination sites is demonstrated to facilitate the formation of an anion-aggregated solvation shell, enhancing the interfacial stability and de-solvation kinetics. As a result, the as-developed electrolyte exhibits ultra-stable cycling over 1400 h in symmetric cells with 50 µm-thin Li foils. When paired with high-loading LiFePO4 , full cells maintain 92% capacity over 500 cycles and deliver improved electrochemical performances over a wide temperature range from -10 to 60 °C. Furthermore, the concept is validated in a pouch cell (570 mAh), achieving a capacity retention of 99.5% after 100 cycles. This brand-new insight on electrolyte engineering provides guidelines for practical high-performance Li metal batteries.