Abstract:
The development of the most promising next-generation Li–S
batteries with high utilization of sulfur while retaining high capacity is
one of the great challenges of the 21st century. Here, we reported
sandwich polyoxometalate [WZn3(H2O)2(ZnW9O34)2]
12 (ZnPOM) over
a poly(1-vinyl-3(2-(2-methoxyethoxy)ethyl)imidazolium) cation
(PVIMo) matrix as a binder-free cathode catalyst for a high-capacity LiS
battery with a high areal loading of 7.68 mg cm 2 and high areal
capacity of 11.14 mA h cm 2 (70% sulfur). The synergistic effect
between PVIMo and ZnPOM resulted in outstanding initial discharge
capacity of 1450 mA h g 1 at 0.5 C with high capacity retention (97%),
high coulombic efficiency (>98%) and a negligible capacity fading rate
of 0.02% per cycle at an electrolyte/sulfur ratio of 10 mL(E) mg(S) 1 and
capacity fading of only 0.02% per cycle. The cationic polymer PVIMo
held the negatively charged polysulfide ions at the cathode and
ZnPOM facilitated the conversion of polysulfides to sulfur. Quantitative estimation by EQCM, UV-Vis analysis and potentiometric titration
demonstrated negligible loss of sulfur even after 120 cycles of the
charge–discharge process.
