Low Concentration Sulfolane‐Based Electrolyte for High Voltage Lithium Metal Batteries

Abstract Electrolyte engineering is crucial for the commercialization of lithium metal batteries. Here, lithium metal is stabilized in the highly reactive sulfolane‐based electrolyte under low concentration (0.25 M) for the first time. Inorganic‐polymer hybrid solid electrolyte interphase (SEI) with high ionic conductivity, low bonding with lithium and high flexibility enables dense chunky lithium deposition and high plating/stripping efficiency. Low concentration electrolyte (LCE) also enables excellent cycling stability of LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523)/Li cells at 1 C (90.7 % retention after 500 cycles) and 0.3 C (83.3 % retention after 1000 cycles). With a low N/P ratio (≈2), the capacity retention for NCM523/Li cells can achieve 94.3 % after 100 cycles at 0.3 C. Exploring the LCE is of paramount significance because it provides more possibilities of the lithium salt selections, especially reviving some lithium salts that are excluded before due to their low solubility. More importantly, LCE has the significant advantage of commercialization due to its cost‐effectiveness.