DMSO/DMF co-solvent precipitated nano-sulfur cathode for highly loading lithium-sulfur pouch cells

Abstract

We employ a simple anti-solvent precipitation method to prepare sulfur nanoparticles. Dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) are chosen as co-solvents, and cetyltrimethylammonium bromide (CTAB) is used as a stabilizer. By adjusting parameters such as the ratio of solvents and concentration, we precisely control the supersaturation, finely tuning the size of the sulfur particles. To enhance the electrical conductivity of the electrode materials, we uniformly composite sulfur with reduced graphene oxide (rGO). As the sulfur particle size decreases, the charge transfer resistance of the S@rGO cathode rapidly decreases, demonstrating excellent electrode kinetics. A lithium-sulfur coin cell assembled with S@rGO-75 exhibits a discharge specific capacity of 1272 mAh g−1. After 180 cycles, the capacity retention remains at 89.1 %, with a Coulombic efficiency of 98.9 %. Additionally, a pouch cell (PC-75) achieves stable charge–discharge behavior at a total sulfur loading of 300 mg, with an initial discharge specific capacity of 1047 mAh g−1 and a capacity retention of 63.7 % after 80 cycles. Under lean electrolyte conditions (E/S = 1.5 μl mg−1), PC-75 maintains outstanding energy density (392.3 Wh kg−1). Based on PC-75, a drone achieves an ultra-long flight time of 255 s, providing preliminary evidence of the practical application potential of PC-75.