CoNi-Based Bimetal-Organic Framework Derived Carbon Composites Multifunctionally Modified Separators for Lithium-Sulfur Batteries
The commercial application of lithium-sulfur batteries (LSB) is still limited by the irreversible capacity fading caused by the shuttle of polysulfides (LIPS). To address this issue, a bimetal-organic framework (MOF)-derived carbon (Ni, Co)/C was prepared to modify the separator. The multifunctional modified separator effectively captures polysulfides, ensuring the stability and reversibility of sulfur fixation, while providing catalytic activity and improving ionic conductivity. The cobalt metal has a larger coordination number, more pore structure distribution, larger specific surface area, more surface C=O, and smaller particle size to achieve a large and rapid chemical sulfur fixation. The high conductivity provided by nickel, the catalytic activity and the ability to block LIPS shuttling enabled the reversibility of sulfur inhibition. The synergistic effect of cobalt-nickel bimetals significantly improves the cycling stability and rate capability of LSB. At a current density of 1 C, the capacity of the (Ni, Co)/C modified separator battery can reach 1035.6 mAh·g-1 in the first cycle, and the capacity remains at 662.2 mAh·g-1 after 500 cycles, the capacity retention rate was 63.9%.