The interfacial instability of the lithium-metal anode and shuttling of lithium polysulfides in lithium-sulfur (Li-S) batteries hinder the commercial application. Herein, we report a bifunctional electrolyte additive, i.e., 1,3,5-benzenetrithiol (BTT), which is used to construct solid-electrolyte interfaces (SEIs) on both electrodes from in situ organothiol transformation. BTT reacts with lithium metal to form lithium 1,3,5-benzenetrithiolate depositing on the anode surface, enabling reversible lithium deposition/stripping. BTT also reacts with sulfur to form an oligomer/polymer SEI covering the cathode surface, reducing the dissolution and shuttling of lithium polysulfides. The Li–S cell with BTT delivers a specific discharge capacity of 1,239 mAh g⁻¹ (based on sulfur), and high cycling stability of over 300 cycles at 1C rate. A Li–S pouch cell with BTT is also evaluated to prove the concept. This study constructs an ingenious interface reaction based on bond chemistry, aiming to solve the inherent problems of Li–S batteries.

锂金属负极的界面不稳定性和锂硫（Li-S）电池中多硫化锂的穿梭阻碍了商业应用。在此，我们报告了一种双功能电解质添加剂，即 1,3,5-苯三硫醇 (BTT)，用于通过原位有机硫醇转化在两个电极上构建固体电解质界面 (SEI)。BTT 与锂金属反应形成 1,3,5-苯三硫醇锂沉积在阳极表面，实现可逆的锂沉积/剥离。BTT还与硫反应形成覆盖正极表面的低聚物/聚合物SEI，减少多硫化锂的溶解和穿梭。采用 BTT 的锂硫电池可提供 1,239 mAh g ^{−1的比放电容量}（基于硫），以及在 1C 速率下超过 300 个循环的高循环稳定性。还对具有 BTT 的 Li-S 软包电池进行了评估以证明这一概念。本研究基于键化学构建了一个巧妙的界面反应，旨在解决锂硫电池的固有问题。