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Sodium-ion batteries (SIBs) are promising candidates for the replacement of lithium-ion batteries (LIBs) because of sodium's abundant reserves and the lower cost of sodium compared to lithium. This is a topic of interest for developing novel anodes with high storage capacity. Owing to their low cost, high stability, and conductivity, carbon-based materials have been studied extensively. However, sp2-C based carbon materials have low-rate capacities. Intensive density functional theory calculations have been implemented to explore the applicability of α, β, and γ graphyne nanotubes (αGyNTs, βGyNTs, and γGyNTs, respectively) as SIB anodes. Results suggest that (3, 0)-αGyNT, (2, 2)-βGyNT, and (4, 0)-γGyNT have, respectively, maximum Na storage capacities of 1535, 1302, and 1001 mAh/g, which exceeds the largest reported value of carbon materials (N-doped graphene foams with 852.6 mAh/g capacity). It was determined that αGyNTs have the largest storage capacity of the three types because they possess the largest specific surface area. Moreover, the larger pores of αGyNTs and βGyNTs allow easier diffusion and penetration of Na atoms compared to those of γGyNTs, which could result in better rate capacity. [ABSTRACT FROM AUTHOR]

Ideal Li-ion battery materials should have a low Li-ion diffusion barrier and a suitable binding energy. Here, first-principles calculations were performed to investigate the potential of SnS monolayer as a Li-ion battery material. Our study reveals that Li ions can be strongly bonded on the SnS monolayer with a binding energy of around 2 eV, and donate electrons into the SnS monolayer. Consequently, Li intercalation of SnS monolayer gives rise to a semiconducting to metallic transition, and leads to a good electrical conductivity. Interestingly, in spite of the existence of strong chemical interaction, the energy barrier (0.45 eV) of Li diffusion on the SnS monolayer is quite low. Moreover, the estimated open circuit voltage is about 1.98 V, which is much better than that of commercial graphite. Thus, given these advantages, it is expected that SnS monolayer will be a promising anode material for Li ion batteries. [ABSTRACT FROM AUTHOR]

Novel hierarchical porous carbon microspheres (HPCM) with quantities of micropores and mesopores have been prepared by an alcohol-in-oil emulsion technique using thermoplastic phenolic formaldehyde resin (PF) as the carbon source and copper nitrate (CN) as the template precursor. The effects of CN loading content on the morphology and structure of HPCM were investigated. The results showed that, when the mass ratio of PF and CN is 1:4, the HPCM not only can maintain hierarchical porous microsphere structure, but also display high electrochemical performance with a reversible capacity of 585 mA h g −1 at a current density of 50 mA g −1 and favorable high-rate performance when used as the anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

To buffer the volume expansion of silicon during charge-discharge process, a 3D carbon-coated stable silicon/graphene/CNT (C@Si/GN/CNT/PDA-C) composite was prepared. Si nanoparticles (SiNPs) were first modified by hexadecyl trimethyl ammonium bromide (CTAB) to enhance their stability and dispersibility in water, then uniformly distributed in graphene/carbon nanotubes (GN/CNT) by electrostatic self-assembly, and ultimately encapsulated by carbonized poly-dopamine carbon layer (PDA-C) at high-temperature. PDA-C not only alleviates the volume expansion of Si and inhibits the direct contact of Si with electrolyte, but also acts as a bridge between the conductive GN/CNT and Si to maintain electrode integrity. As an anode material for lithium-ion batteries, the C@Si/GN/CNT/PDA-C exhibits a superior reversible capacity of 1946 mAh g − 1 after 100 cycles with the capacity retention of 68.9% at a current density of 0.1 A g − 1, and over 1306 mAh g − 1 after 100 cycles at 1 A g − 1. The excellent electrochemical performance of C@Si/GN/CNT/PDA-C is attributed to the stable hierarchical structure. [Display omitted] [ABSTRACT FROM AUTHOR]

• The crystalline silicon nanoparticles coated with an amorphous silicon layer (a-coated-c-SiNPs) were continuously prepared by non-thermal plasma pyrolyzing of silane with the help of hydrogen and argon. • The a-Si layer with good tolerance to volume expansion prevented the electrode pulverization, while the c-Si improved the electronic conductivity. The crystallinity of the a-coated-c-SiNPs was controled by the hydrogen etching. • The combination of a-coated-c-SiNPs with a three-component polymer binder (PAA-PVA/SBR) improved the electrochemical performance of Si-based anode. The crystalline silicon nanoparticles coated with an amorphous silicon layer was prepared by continuously pyrolysing the mixture of silane and hydrogen in a non-thermal arc plasma reactor. The hydrogen in the gas mixture effectively controls the thickness of the amorphous silicon layer and further improves the electrochemical performance of the silicon anode. The mechanism of the hydrogen was investigated by experiments. At the same time, a three-component polymer binder was concocted and introduced to tolerate the volume expansion of silicon effectively. Combining the silicon nanoparticles prepared at the optimal conditions with the novel polymer binder, the resulting silicon anode exhibits excellent electrochemical performance of 2120 mAh g−1 at 400 mA g−1 after 100 cycles. [Display omitted] [ABSTRACT FROM AUTHOR]