Amorphous MoS3-modified porous Co4S3-embedded N,S co-doped carbon polyhedron as new high-capacity and high-rate anode materials for sodium-ion half/full cells

In this study, amorphous MoS 3 -modified porous Co 4 S 3 -embedded N,S co-doped carbon polyhedron (Co 4 S 3 @NSC/MoS 3 ) was rationally prepared via a multi-step method. One-dimensional linear-like MoS 3 with a high specific capacity of 894 mAh g −1 and abundant active sites compensated for the low capacity of Co 4 S 3 , thus enhancing the sodium ion storage capacity of the entire electrode. Moreover, three-dimensional N,S co-doped carbon networks (NSC) significantly inhibited large volumetric fluctuations in Co 4 S 3 and MoS 3 , thereby sustaining the structural stability and enhancing the electron transfer efficiency. As a new anode material for sodium-ion half batteries, the constructed Co 4 S 3 @NSC/MoS 3 with rapid Na + diffusion and charge transfer kinetics demonstrated better sodium storage properties than Co 4 S 3 @NSC. At a rate of 0.5 A g −1 over 100 cycles, the reversible specific capacity of Co 4 S 3 @NSC/MoS 3 reached 594 mAh g −1 . Even when cycled at a rate of 2 A g −1 for 600 cycles, the charge capacity was stable at 435 mAh g −1 . The rate performance of Co 4 S 3 @NSC/MoS 3 was also found to be remarkable; when the rate increased to 10 A g −1 , the average capacity was retained at 382 mAh g −1 . Apart from half cells, reduced graphene oxide (rGO)-modified Na 3 V 2 (PO 4 ) 3 composite (Na 3 V 2 (PO 4 ) 3 @rGO) was used as the cathode material to match with Co 4 S 3 @NSC/MoS 3 . The assembled full batteries were analyzed and their electrochemical properties were discussed. They also exhibited outstanding rate capability and high-rate long-life cyclic property. Even at 1 A g −1 over 500 cycles, the discharge capacity was stably maintained at 246 mAh g −1 . The outstanding sodium storage properties of Co 4 S 3 @NSC/MoS 3 mainly depended on the cooperative effects of MoS 3 and Co 4 S 3 @NSC, indicating the potential application of Co 4 S 3 @NSC/MoS 3 in energy storage fields.