Ammonium benzenesulfonate as an electrolyte additive to relieve the irreversible accumulation of lithium sulfide for high-energy density lithium-sulfur battery

Based on the dissolution and conversion mechanism of lithium-sulfur (Li-S) batteries, insulating solid short-chain polysulfides (Li 2 S 2 /Li 2 S) will continuously passivate and corrode the active interface of cathode and anode, which seriously affects its performance. Herein, ammonium benzenesulfonate (NH 4 BS) is proposed as a soluble ammonium salt to dissolve Li 2 S in the ether electrolyte, according to the inductive effect of NH 4 + cation and O atom on Li-S bond. This is beneficial to alleviate the interface problem of electrodes and irreversible loss of active materials. Noticeably, soluble Li 2 S regulates its deposition behavior from 2D to 3D, which is conducive to the more effective use of conductive surface. Moreover, the addition of NH 4 BS can increase the dissociation degree of long-chain polysulfides, so that the diffusion rate and reaction kinetics of active substances are improved. Profiting from these functions, the Li-S cells with NH 4 BS act out excellent cyclic stability in the long cycle of 0.5 C and 2 C. Under the extreme conditions of high sulfur loading and low electrolyte-sulfur ratio, the cells with NH 4 BS can cycle stably for 196 cycles, which significantly prolongs the battery life. The proposal of NH 4 BS broadens a new idea to solve the interface problem of Li-S cells and stimulate the research enthusiasm of developing soluble ammonium salt.