Microwave-assisted synthesis of Cr₃C₂@C core shell structure anchored on hierarchical porous carbon foam for enhanced polysulfide adsorption in Li-S batteries

In this paper, we use microwave reduction strategy to synthesize a new bi-functional sulfur host material at the service of cathode substrate for lithium-sulfur batteries (LSBs), the composite is made of hierarchical porous carbon foam supported carbon-encapsulated chromium carbide nano-particles (Cr₃C₂@C/HPCF), in which the well-distributed conductive Cr₃C₂ nano-particles can act as powerful chemical adsorbent and are effective in restraining the shuttle effect of lithium polysulfides (LiPSs). Test results show that the Cr₃C₂@C/HPCF based sulfur electrodes with 75 wt.% of sulfur exhibit a high initial discharging capacity of 1,321.1 mAh·g^-1 at 0.1 C (3.5 mg·cm^-2), and a reversible capacity can still maintain stability at 1,002.1 mAh·g^-1 after 150 cycles. Even increasing the areal sulfur loading to 4 mg·cm^-2, the electrodes can still deliver an initial discharging capacity of 948.0 mAh·g^-1 at 0.5 C with ultra-slow capacity decay rate of 0.075% per cycle during 500 cycles. Furthermore, the adsorption energy between the Cr₃C₂ surface and LiPSs as well as theoretic analysis based on first-principles is also investigated.