Heterostructured nickel-cobalt metal alloy and metal oxide nanoparticles as a polysulfide mediator for stable lithium-sulfur full batteries with lean electrolyte

Batteries that utilize low-cost elemental sulfur and light metallic lithium as electrodes have great potential in achieving high energy density.However,building a lithium-sulfur(Li-S)full battery by controlling the electrolyte volume generally produces low practical energy because of the limited electrochemical Li-S redox.Herein,the high energy/high performance of a Li-S full battery with practical sulfur loading and minimum electrolyte volume is reported.A unique hybrid architecture configured with Ni-Co metal alloy(NiCo)and metal oxide(NiCoO_(2))nanoparticles heterogeneously anchored in carbon nanotube-embedded selfstanding carbon matrix is fabricated as a host for sulfur.This work demonstrates the considerable improvement that the hybrid structure's high conductivity and satisfactory porosity promote the transport of electrons and lithium ions in Li-S batteries.Through experimental and theoretical validations,the function of NiCo and NiCoO_(2) nanoparticles as an efficient polysulfide mediator is established.These particles afford polysulfide anchoring and catalytic sites for Li-S redox reaction,thus improving the redox conversion reversibility.Even at high sulfur loading,the nanostructured Ni-Co metal alloy and metal oxide enable to have stable cycling performance under lean electrolyte conditions both in half-cell and full-cell batteries using a graphite anode.