Phase-transformed Mo4P3 nanoparticles as efficient catalysts towards lithium polysulfide conversion for lithium–sulfur battery

Lithium-sulfur (Li–S) battery has aroused intensive attention due to its intrinsicly high capacity and energy density. However, the sluggish kinetics of lithium polysulfide (LiPS) redox conversion and shuttle effect severely damage the sulfur utilization, rate performance, and cycling stability of Li–S batteries. In this work, we report that Ru-doping induced phase transformation from MoP to Mo4P3 (Ru–Mo4P3) could significantly facilitate the electrocatalytic conversion of LiPS. When Ru–Mo4P3 nanoparticles (NPs) are decorated on hollow carbon spheres (HCS), the S/HCS-Ru-Mo4P3 electrode delivers high reversible capacities of 1178 mAh g−1 and 660 mAh g−1 at 0.5C and 4C in Li–S battery, respectively. The rate performance of the developed S/HCS-Ru-Mo4P3 is among the best of the reported transition metal phosphide cathodes for Li–S batteries. When the S loading is as high as 6.6 mg cm−2, S/HCS-Ru-Mo4P3 retains a reversible areal capacity of 5.6 mAh cm−2 after 50 cycles, higher than that of the commercial Li-ion battery (4 mAh cm−2). The excellent Li–S battery performance can be attributed to the intrinsically active Ru–Mo4P3 phase combining with hollow carbon structure, which significantly facilitates the electrocatalytic conversion and entrapment of LiPS.