Designing polysulfides adsorption‐conversion on g‐C₃N₄‐based separator via doping heteroatoms boron and phosphorus toward high‐performance lithium‐sulfur batteries

Abstract

The notorious “shuttle effect” of lithium polysulfides (LiPSs) has suppressed the large‐scale commercial application of lithium‐sulfur batteries (LSBs). Also, the intrinsic advantages including inhibiting the shuttling‐circulation and promoting the conversion of LiPSs, on the separator are deemed as stimulating blocks on the exploitation of LSBs. Herein, guided by theoretical calculations, we have designed doping‐heteroatoms boron (B) and phosphorus (P) on graphitic carbon nitride (g‐C3N4), to suppress the “shuttle effect” of LiPSs and improve the battery cycling performance. Theoretical calculations show strong chemical bonding between Li atom and N substance of g‐C3N4, and corroborates synergistic mechanism of electron transfer and van der Waals interaction. The high adsorption energies with doping B/P atoms enable LiPSs adsorption on the separators inhibiting shuttle loss. As expected, the experiment data also demonstrate that superior electrochemical performance are achieved by utilizing B‐doped g‐C3N4 (BCN) separator. Incorporating the B‐doped g–C3N4 (BCN) separator in LSBs delivered an initial specific capacity of 1050 mAh g−1 at 1 C and 920 mAh g−1 at 2 C. Notably, it achieved a decay rate of 0.08% and 0.1% at 1 and 2 C, respectively, after 500 cycles. This study furthers our understanding of B/P doping separator enhancement and restraining LiPSs shuttling loss for an improved LSBs performance.

Lithium Dredging and Capturing Dual‐Gradient Framework Enabling Step‐Packed Deposition for Dendrite‐Free Lithium Metal Anodes

“…(Figure 3c-e; Table S1, Supporting Information). [31,[35][36][37] And the corresponding projected density of state (PDOS) analysis of the adsorbed Li atoms and its nearest neighboring S atom in Ni 3 S 2 (101) and P atom in Ni 2 P (001) was also carried out. As shown in Figure 3f, the orbital hybridization between Li-s and P-2p states is higher than that of Li-s and S-2p states, which indicates a stronger interaction between Ni 2 P and adsorbed Li.…”

The d‐band energy level splitting of ferric group (Fe, Co, Ni) metals drives the adsorption‐conversion of polysulfides

“…In reality, the heteroatoms can increase the affinity to LiPSs and improve its utilization to some extent, thus it is feasible to introduce atomic heteroatoms doping such as N, B, P, S on the separator to promote the chemisorption ability. [24][25][26][27] Zhao et al applied nitrogen-doped hollow carbon nanospheres on the commercial separators, in which abundant heteroatoms nitrogen showed strong chemisorption. 28 Zhang et al…”

“…However, the non‐polar nature of the carbon skeleton disenables effectively capture and catalyze the conversion of polar LiPSs, resulting in constrained electrochemical performance of the long‐term development for Li‐S batteries. In reality, the heteroatoms can increase the affinity to LiPSs and improve its utilization to some extent, thus it is feasible to introduce atomic heteroatoms doping such as N, B, P, S on the separator to promote the chemisorption ability 24–27 . Zhao et al applied nitrogen‐doped hollow carbon nanospheres on the commercial separators, in which abundant heteroatoms nitrogen showed strong chemisorption 28 .…”