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Fe/Co-based diatomic catalysts decorated on an N-doped graphene substrate are investigated by first-principles calculations to improve the electrochemical properties of Li–S batteries. Our results demonstrate that FeCoN8@Gra not only possesses moderate adsorption energies towards Li2S n species, but also exhibits superior catalytic activity for both reduction and oxidation reactions of the sulfur cathode. Moreover, the metallic property of the diatomic catalysts can be well maintained after Li2S n adsorption, which could help the sulfur cathode to maintain high conductivity during the whole charge–discharge process. Given these exceptional properties, it is expected that FeCoN8@Gra could be a promising diatomic catalyst for Li–S batteries and afford insights for further development of advanced Li–S batteries.

Two-dimensional transition metal dichalcogenides are promising anode materials for Na ion batteries (NIBs). In this study, we carried out a comprehensive investigation to analyze the structural, electrochemical characteristics, and diffusion kinetics of bulk WX2 (X = Se, Te) by employing first-principles calculation in the framework of density functional theory. We deeply studied the full intercalation of Na+ in WX2 and diagnosed Na y X phase through conversion reaction mechanism. The voltage range of 2.05–0.48 V vs Na/Na+ for Na y WSe2 and 2.26–0.65 V for Na y WTe2 (y = 0–3) have been noted. Density of states analysis showed metallic behavior of WX2 (X = Se, Te) during sodiation. The facile pathways for Na+ mobility through WX2 have shown that tungsten dichalcogenides are inferred as excellent electrode material for NIBs.

Porous ZnMn2O4 microspheres were prepared via a facile co-precipitation method followed by calcination at various temperatures and evaluated as anode materials for lithium ion batteries. The sample prepared at 600 °C outperformed the other samples in terms of electrochemical performance with high reversible capacity, high-rate capability, and excellent cycling performance. The capacity of the sample remained as high as 999 mAh g−1 at a current rate of 100 mA g−1 after 50 cycles—one of the best ever reported for ZnMn2O4-based materials. A high reversible capacity of 400 mAh g−1 was retainable at a current density of 2000 mA g−1 after 2500 cycles. A novel electrochemical reaction mechanism of ZnMn2O4 anodes was established and investigated at length. The Mn3O4 observed during the charge process was largely responsible for the enhanced performance, as confirmed by x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The relatively large surface area, abundant porosity, large ion exchange space, and strong mechanical stability of the porous connected 3D framework were responsible for the unique oxidation/reduction Mn2+ ↔ Mn3+ process we observed.

Based on fully self-consistent first-principles density functional theory (DFT) calculations as well as classical spin analysis, we study the electronic structure and magnetic interactions of the spinel-related compound LiMnVO4. Four possible ordered spin states have been considered by spin-polarized generalized gradient approximation (GGA) calculations. The antiferromagnetic (AFM) configuration with both intra-chain and inter-chain AFM coupling interactions is energetically favorable among these magnetic ordered states. The calculated AFM solution agrees well with a series of experimental measurements. The intra-atomic exchange splitting of the Mn 3d spin-up and spin-down states results in the insulating behavior of LiMnVO4. The Heisenberg Hamiltonian is used to deduce the magnetic coupling parameters by adopting Noodleman's broken symmetry method. The intra-chain AFM interactions are much stronger than the inter-chain AFM interactions and thus LiMnVO4 can be described as a weakly coupled edge-sharing spin chain system. We propose that the presence of the side groups of edge-sharing LiO4 and VO4 tetrahedra are contributing to the intra-chain AFM interactions in the nearly 90° Mn–O–Mn bond configuration of the edge-sharing MnO4 chains.