In Situ Phosphorization for Constructing Ni₅P₂-Ni Heterostructure Derived from Bimetallic MOF for Li-S Batteries

Heterostructured materials commonly consist of bifunctions due to the different ingredients. For host material in the sulfur cathode of lithium-sulfur (Li-S) batteries, the chemical adsorption and catalytic activity for lithium polysulfides (LiPS) are important. This work obtains a Ni₅P₂-Ni nanoparticle (Ni₅P₂-NiNPs) heterostructure through a confined self-reduction method followed by an in situ phosphorization process using Al/Ni-MOF as precursors. The Ni₅P₂-Ni heterostructure not only has strong chemical adsorption, but also can effectively catalyze LiPS conversion. Furthermore, the synthetic route can keep Ni₅P₂-NiNPs inside of the nanocomposites, which have structural stability, high conductivity, and efficient adsorption/catalysis in LiPS conversion. These advantages make the assembled Li-S battery deliver a reversible specific capacity of 619.7 mAh g^{- 1} at 0.5 C after 200 cycles. The in situ ultraviolet-visible technique proves the catalytic effect of Ni₅P₂-Ni heterostructure on LiPS conversion during the discharge process.