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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]

[Display omitted] Binders play a key role in maintaining the integrity of high-capacity silicon anodes, which otherwise experience serious capacity decay during cycling caused by huge volume variation of the silicon. With an aim to developing a highly efficient polymeric binder to mitigate this capacity decay, we present a novel binder synthesized from polyacrylic acid (PAA) and polymerized β-cyclodextrin (β-CDp) for Si anodes for the lithium-ion batteries. This PAA-β-CDp binder has a 3D network structure, which provides strong adhesion between the active material and the current collector. PAA-β-CDp binder makes silicon anode achieve a specific capacity of 2326.4 mAhg−1 at the current density of 0.2 A g−1 with a capacity retention of 64.6% after 100 cycles. The experimental results show that the PAA-β-CDp binder can effectively mitigate the huge volume change and improve the capacity and cycling performance of Si anodes. [ABSTRACT FROM AUTHOR]

A high-performance silicon-carbon nanocomposite facilely prepared by one-step magnetoelectric plasma pyrolysis of the mixture of methane, silane, and hydrogen is proposed for lithium-ion batteries. The ratio of silane, methane, and hydrogen was studied to optimize the properties of the composite. When the ratio of hydrogen/silane/methane is 1:1:3, the composite is composed of spherical Si nanoparticles that uniformly attach to the surface of the tremelliform carbon nanosheets framework, in which the tremelliform carbon nanosheets can effectively resist the volumetric change of the Si nanoparticles during the cycles and serve as electronic channels. The silicon-carbon nanocomposite exhibits a high reversible capacity (1007 mAh g−1 after 50 cycles), a low charge transfer resistance, and an excellent rate performance. In addition, the proposed process for synthesizing silicon-carbon nanocomposite without expensive materials or toxic reagents is an environmentally friendly and cost-effective method for mass production. [ABSTRACT FROM AUTHOR]

In this paper, a mechanical separation and thermal treatment process is developed to recover valuable metals and graphite from the −0.25 mm crushed products of spent lithium-ion batteries (LiBs). Effect of key parameters for roasting such as the temperature and roasting time are investigated to determine the most efficient conditions for surface modification of the mixed electrode materials by roasting. The roasted mixed electrode materials are separated by flotation operation to recover the cathode material and anode materials respectively. The results show that most of the organic outer layer coated on the surface of the mixed electrode materials can be removed at the temperature of 450 °C for 15 min. After roasting treatment, the original wettability of LiCoO 2 and graphite is regained. The −0.25 mm crushed products of spent LiBs can be separated into LiCoO 2 concentrate and graphite concentrate by flotation process efficiently. The enrichment ratios of Co, Mn, Cu and Al are 1.35, 1.29, 1.25 and 1.19, their recovery rates are 97.66%, 93.66%, 90.14% and 86.29%, respectively. This process proposed for the recovery of valuable materials is simple and of high efficient for the spent lithium-ion batteries recycling industry. [ABSTRACT FROM AUTHOR]

The doping of Co heteroatom in the CuS lattice can optimize the electronic structure of CuS, provide more active sites for the adsorption of lithium ions and form more suitable diffusion paths for rapid transport of Li-ion in Cu 2 S 2 layers, thereby resulting in enhanced cycling performance. [Display omitted] • N -type Co doped CuS 1-x with abundant S vacancies in its structure is firstly used as anode material in lithium-ion batteries. • Cobalt doping simultaneously improves Li ion migration and electron transfer kinetics. • A highly conductive and active sites adjacet to the Co atoms are conducive to more rapid electron transfer and energy conversion. • Co-doped CuS 1-x shows impressive rate capability and long cycling stability as the anode material of lithium-ion batteries. Slow Li ion diffusion kinetics and disordered migration of electrons are two most crucial obstacles to be resolved in electrode material design for higher rate capability of Li-ion batteries. Herein, the Co-doped CuS 1- x with abundant high active S vacancies is proposed to accelerate the electronic and ionic diffusion during the energy conversion process, because contraction of Co-S bond can cause the expansion of atomic layer spacing, thus promoting the Li ion diffusion and directional electron migration parallel to the Cu 2 S 2 plane, and also induce the increasing of active sites to improve the Li+ adsorption and electrocatalytic conversion kinetics. Especially, the electrocatalytic studies and plane charge density difference simulations demonstrate that electron transfer near the Co site is more frequent, which is conducive to more rapid energy conversion and storage. Those S vacancies formed by Co-S contraction in CuS 1- x structure obviously increase Li ion adsorption energy in Co-doped CuS 1- x to 2.21 eV, higher than the 2.1 eV for CuS 1- x and 1.88 eV for CuS. Taking these advantages, the Co-doped CuS 1- x as anode of Li-ion batterie shows an impressive rate capability of 1309 mAh·g−1 at 1A g−1, and long cycling stability (retaining 1064 mAh·g−1 capacity after 500 cycles). This work provides new opportunities for the design of high-performance electrode material for rechargeable metal-ion batteries. [ABSTRACT FROM AUTHOR]

In this paper, a Fenton reagent assisted flotation process is developed to recover valuable electrode materials LiCoO 2 and graphite from spent lithium-ion batteries (LiBs). At room temperature, effect of key parameters for Fenton reaction such as the ratios of H 2 O 2 /Fe 2+ (40–280) and liquid-solid (25–100) are investigated to determine the most efficient conditions of surface modification of electrode materials by Fenton reagent. The modified electrode materials are separated by flotation operation to recover the cathode material and anode materials respectively. The results show that in the optimum conditions that the Fe 2+ /H 2 O 2 ratio is 1:120, and the liquid-solid ratio is 75:1, most of the organic outer layer coated on the surface of electrode materials can be removed. After modified by Fenton reagent, the original wettability of LiCoO 2 and graphite is regained. The −0.25 mm crushed products of spent LiBs can be separated into LiCoO 2 concentrate and graphite concentrate by flotation process efficiently. [ABSTRACT FROM AUTHOR]