A three-way electrolyte with ternary solvents for high-energy-density and long-cycling lithium-sulfur pouch cells

Lithium-sulfur (Li-S) batteries promise high-energy-density potential to exceed the commercialized lithium-ion batteries but suffer from limited cycling lifespan due to the side reactions between lithium polysulfides (LiPSs) and Li metal anodes. Herein, a three-way electrolyte with ternary solvents is proposed to enable high-energy-density and long-cycling Li-S pouch cells. Concretely, ternary solvents composed of 1,2-dimethoxyethane, di-isopropyl sulfide, and 1,3,5-trioxane are employed to guarantee smooth cathode kinetics, inhibit the parasitic reactions, and construct a robust solid electrolyte interphase, respectively. The cycling lifespan of Li-S coin cells with 50 mu m Li anodes and 4.0 mg cm-2 sulfur cathodes is prolonged from 88 to 222 cycles using the three-way electrolyte. Nano-heterogeneous solvation structure of LiPSs and organic-rich solid electrolyte interphase are identified to improve the cycling stability of Li metal anodes. Consequently, a 3.0 Ah-level Li-S pouch cell with the three-way electrolyte realizes a high energy density of 405 Wh kg-1 and undergoes 27 cycles. This work affords a three-way electrolyte recipe for suppressing the side reactions of LiPSs and inspires rational electrolyte design for practical high-energy-density and long-cycling Li-S batteries. A three-way electrolyte with ternary solvents is proposed to enable high-energy-density and long-cycling Li-S pouch cells. Concretely, the ternary solvents composed of 1,2-dimethoxyethane, di-isopropyl sulfide, and 1,3,5-trioxane are employed to guarantee smooth cathode kinetics, mitigate the parasitic reactions, and construct a robust organic-rich solid electrolyte interphase, respectively. image