Transition metal decorated phthalocyanine as a potential host material for lithium polysulfides: a first-principles study

The shuttle effect caused by the soluble long-chain lithium polysulfides greatly hinders the practical application of lithium–sulfur (Li–S) batteries. Therefore, the introduction of suitable anchoring materials is more effective to mitigate this problem. Transition metal phthalocyanines (TMPc) are regarded as a new class of sulfur host materials. Here, 4d transition metal (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) decorated phthalocyanines are designed and systematically researched for the performance analysis of anchoring S(8)/LiPSs by first-principles calculations. The results reveal that the bonding strength of LiPSs can be well adjusted by introducing suitable 4d transition metals into the phthalocyanine structure. The electronic structure analysis indicates the formation of TM–S bonds between the TMPc substrate materials and the LiPSs, which is essential to weaken the Li–S bonds and hence slow down the shuttle effect of LiPSs. ZrPc and NbPc both exhibit excellent potential and thermal stability for facilitating the conversion of LiPSs, as well as a better promoting effect for the sulfur reduction reactions (SRR) with a reduced Gibbs free energy in the rate-determining step (*Li(2)S(2) → *Li(2)S) during the discharge reaction process. These findings in our work may encourage further experimental and theoretical research for anchoring LiPSs with TMPc as a host material.