The electrical conductivities of Sr 2 CoRO 6 (R=Mo, Nb) under different oxygen partial pressures and their crystal structures were investigated. Their conducting mechanisms were proposed. X-ray photoelectron spectra revealed that the dominated oxidation state of Co 2+ was in Sr 2 CoMoO 6 but Co 3+ in Sr 2 CoNbO 6 . The crystal lattice structures of Sr 2 CoRO 6 were identified by X-ray diffraction and their parameters were calculated by using Rietveld method. The refined crystal structures of Sr 2 CoRO 6 have been used to construct their own conducting channel model. And the electrical conductivities were measured by using an electrochemical workstation with four-terminals method through controlling the oxygen partial pressure of the testing environment. The results show that the electrical conductivity of Sr 2 CoMoO 6 is 0.36 S·cm
¹1, much lower than that of Sr 2 CoNbO 6 (7.81 S·cm
¹1) in air at 973 K, which is assigned to the difference of their conducting channels. And the electrical conductivity of Sr 2 CoMoO 6 increased linearly with the decrease in P O2 , reaching 2.05 S·cm ¹1 when P O2 = 10 ¹21 atm at 973 K, while Sr 2 CoNbO 6 presented an opposite trend. It was supposed that the different valences of cobalt in Sr 2 CoMoO 6 and Sr 2 CoNbO 6 lead to the different electron conducting channels and different changing trends of electrical conductivities with the decrease in oxygen partial pressure.
Li‐S batteries (LSBs) have attracted worldwide attention owing to their characteristics of high theoretical energy density and low cost. However, the commercial promotion of LSBs is hindered by the irreversible capacity decay and short cycling life caused by the shuttle effect of lithium‐polysulfides (LiPSs). Herein, a hybrid interlayer consisting of MoO3, conductive Ni foam, and Super P is prepared to prevent the shuttle effect and catalyze the LiPSs conversion. MoO3 with a reversible lithiation/delithiation behavior between Li0.042MoO3 and Li2MoO4 within 1.7–2.8 V versus Li/Li+ combines the Li+ insertion and LiPSs immobilization and efficiently improve the LSBs redox kinetics. Benefiting from the reversible Li+ insertion/extraction in lithium molybdate (LixMoOy) and the highly conductive Ni foam substrate, the sulfur cathode coupled with such electrochemical activation derived catalytic interlayer exhibits a high initial discharge capacity of 1100.1 mAh g−1 at a current density of 1 C with a low decay rate of 0.09% cycle−1. Good capacity retention can still be obtained even the areal sulfur loading is increased to 13.28 mg cm−2.
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