Coordination Supramolecular Network Synergized with Reduced Graphene Oxide Accelerating Redox Kinetics of Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries have an ultrahigh specific capacity and low budget. However, their practical application is impeded by the critical issue of sluggish kinetics as well as polysulfide shuttling. Coordination Supramolecular Networks (CSNs) exhibit an excellent charge transport capability and structural dynamic reversibility via their weak bond associations such as hydrogen bonding, pi-pi stacking, and so on, which provide the possibility to solve the problems existing in Li-S batteries. Herein, we demonstrate the preparation of a 3D structure composite based on Ni-PDA (PDA = pyridine-2, 3-dicarboxylate) CSN with reduced graphene oxide (rGO). FT-IR, XPS, DFT, and electrochemical tests indicate that the Ni-PDA has been introduced into the cathode. The strong affinity of Ni-PDA to polysulfides effectively suppresses their dissolution and diffusion into the electrolyte; meanwhile, the pi-pi interaction of Ni-PDA with rGO promoted the charge transmission inside the cathode. The synergy of the interactions leads to excellent cycling performance and conversion kinetics in Li-S batteries. The S@Ni-PDA@rGO cell shows a discharge capacity of 1063 mAh g-1 under 0.2 C and obtains a high discharge capacity of 864 mAh g-1 after 100 cycles under 0.5 C with an excellent capacity retention ratio of 100%. This material engineering method can potentially be expanded to other CSN systems, paving an avenue in constructing more efficient and reliable Li-S batteries.