Stabilization of Lithium-Sulfur Batteries via In Situ-Formed Organic-Inorganic Hybrid Cathode Electrolyte Interfaces

Despite the several advantages of Li-S batteries compared to Li-ion batteries, their real-world application is limited because of the rapid capacity fading associated with the low electronic conductivity of sulfur and polysulfide formation. Herein, we present a high-performance Li-S battery enabled by an organic-inorganic hybrid cathode-electrolyte interface (CEI) on a sulfur-carbon composite cathode. This hybrid surface film is formed by the in situ reaction of the citric acid (CA) cathode additive with the electrolyte solution and by unavoidable LiTFSI/LiNO₃ decomposition during the charge-discharge process. The Li-S battery cathode (SCB55-CA5) containing an optimized CEI composition exhibits high specific capacity (1207 mAh g^-1 at 50 mAh g^-1), rate performance (406 mAh g^-1 at 1 A g^-1), and cycling stability (405 mAh g^-1 after 500 cycles at 500 mAh g^-1, 0.075% loss per cycle) compared to the reference cathode (38 mAh g^-1 after 400 cycles at 500 mAh g^-1, 0.33% loss per cycle). Impedances of the hybrid CEI-containing Li-S batteries are also considerably reduced due to the formation of hybrid CEI, leading to an increased shelf life. The technique presented in this work enabled the use of an inexpensive carbon matrix for high-performance Li-S batteries, which is a crucial factor for their commercialization. This study also illustrates the crucial role of the CEI in the electrochemical performance of Li-S batteries.