The practical application of lithium–sulfur (Li–S) batteries is seriously restricted by the “shuttle effect” of polysulfide ions. The design of functional interlayers is one of the effective solutions to overcome this defect. In this work, titanium molybdenum nitride (TMN) solid solution nanoparticles have been successfully decorated on electrospun carbon nanofibers (CNFs) to form a continuous flexible TMN@CNF membrane through a one-step calcination process under NH3 atmosphere. By regulating the mass ratio of titanium acetylacetonate TiO­(acac)2 and molybdenum acetylacetonate MoO2(acac)2, the dissolved amount of Mo into TiN can be precisely controlled. Through the visible adsorption test, cyclic voltammetry test of Li2S6-based symmetric cells, and potentiostatic discharge measurement, such a TMN@CNF membrane has been confirmed to exhibit excellent adsorption and catalytic capacity on lithium polysulfides. With the help of DFT calculations, the adsorption capacity of TMN phase is confirmed to be greatly enhanced when compared with that of TiN, which can be attributed to the improved overlap of the electronic state after the introduction of Mo to TiN. By using such a membrane as the interlayer in Li–S batteries, it can effectively increase the cell’s initial capacity to 1205 mA h g–1 at 0.5 C when the dissolved amount of Mo reaches 50%. At the current density of 2 C, the discharge capacity of the cell by using such a multifunctional interlayer can reach up to 947 mA h g–1 and remains at 390 mA h g–1 after 1000 cycles, corresponding to a 0.059% capacity decay per cycle. This work provides a feasible method to prepare a flexible interlayer with a regulated electronic fine structure and strong chemisorption and catalytic ability for the development of the high performance Li–S batteries.

Magnéli phase titanium oxide (TinO2n-1, 4≤n≤10) has wide application prospects in energy storage, catalysis and other fields. During the preparation of TinO2n-1 phase from TiO2 by carbothermal reduction reaction (CRR),...

Magnéli phases Ti n O2n–1 (3 ≤ n ≤ 10) have been widely utilized in various electrochemical fields due to the adjustable phase composition and band structure. In addition, the excellent electrical conductivity and regularly distributed oxygen vacancies of Ti n O2n–1 phases lead to superior electrocatalytic activity. This work successfully synthesized different types of dual-phase Ti n O2n–1 nanoparticle-decorated electrospun carbon nanofibers (CNFs) to act as high-performance oxygen reduction reaction (ORR) electrocatalysts. Based on the precisely controlled calcination temperature and holding time, the combinations among two of TiO(T1), Ti2O3(T2), and Ti3O5(T3) dual-phase nanoparticle-decorated CNF composite catalysts can be obtained after a one-step calcination process. The CNF/T1/T3 catalysts with an ideal 4-electron transfer path exhibit the best ORR catalytic activity with the onset and half-wave potential of 0.91 and 0.77 V, respectively. Compared with commercial Pt/C catalysts, such composite catalysts possessed better methanol tolerance and chemical stability with less than 20% relative current density attenuation after a 80,000 s-long cycle process. Furthermore, density functional theory (DFT) calculations suggest the different reaction energy barriers of ORR steps on the surface of different Ti n O2n–1 phases. Compared with the single-phase CNF/Ti n O2n–1 catalysts, the energy barrier of the rate-determining step can be reduced significantly through the diffusion of intermediate products, which proved the synergistic catalytic effect of the dual-phase Ti n O2n–1 nanoparticles.