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Lithium-sulfur (Li–S) battery is one of the most promising candidates for the next generation energy storage systems. However, several barriers, including polysulfide shuttle effect, the slow solid-solid surface reaction pathway in the lower discharge plateau, and corrosion of Li anode still limit its practical applications, especially under the lean electrolyte condition required for high energy density. Here, we propose a solution-mediated sulfur reduction pathway to improve the capacity and reversibility of the sulfur cathode. With this method, a high coulombic efficiency (99%) and stable cycle life over 100 cycles were achieved under application-relevant conditions (S loading: 6.2 mg cm⁻²; electrolyte to sulfur ratio: 3 mL_E g_s⁻¹; sulfur weight ratio: 72 wt%). This result is enabled by a specially designed Li₂S₄-rich electrolyte, in which Li₂S is formed through a chemical disproportionation reaction instead of electrochemical …