Antimony Nanoparticles Encapsulated in Self-Supported Organic Carbon with a Polymer Network for High-Performance Lithium-Ion Batteries Anode

Antimony (Sb) demonstrates ascendant reactive activation with lithium ions thanks to its distinctive puckered layer structure. Compared with graphite, Sb can reach a considerable theoretical specific capacity of 660 mAh g^-1 by constituting Li₃Sb safer reaction potential. Hereupon, with a self-supported organic carbon as a three-dimensional polymer network structure, Sb/carbon (3DPNS-Sb/C) composites were produced through a hydrothermal reaction channel followed by a heat disposal operation. The unique structure shows uniformitarian Sb nanoparticles wrapped in a self-supported organic carbon, alleviating the volume extension of innermost Sb alloying, and conducive to the integrality of the construction. When used as anodes for lithium-ion batteries (LIBs), 3DPNS-Sb/C exhibits a high invertible specific capacity of 511.5 mAh g^-1 at a current density of 0.5 A g^-1 after 100 cycles and a remarkable rate property of 289.5 mAh g^-1 at a current density of 10 A g^-1. As anodes, LIBs demonstrate exceptional electrochemical performance.

The ternary phase Li8SbxSn3-x with 0.3 ≤ x ≤ 1.0

In the frame of the studies on the phase relations in the ternary system Li–Sb–Sn at 300 °C the new ternary phase Li8SbxSn3-x (0.3 ≤ x ≤ 1.0) was synthesized and characterized predominantly by single crystal and powder X-ray diffraction. The title compound crystallizes trigonally in the space group R 3 ‾ $‾{3}$ m (no. 166), the lattice parameters are a = 4.6962(11) Å and c = 31.536(6) Å. The crystal structure of Li8SbxSn3-x is described in the present paper. In addition, the stereochemical and topological relations to the phases with similar composition, namely Li13Sn5, Li5Sn2 as well as cubic Li3Sb, besides native Li are discussed.

A New Reversible Phase Transformation of Intermetallic Ti3Sn

Ti₃Sn has received increasing attention as a high damping metallic material and as an anode material for rechargeable lithium-ion batteries. However, a heated dispute concerning the existence of solid state phase transformation of stoichiometric Ti₃Sn impedes its development. Here, thermal-induced reversible phase transformation of Ti₃Sn is demonstrated to happen at around 300 K by the means of in-situ variable-temperature X-ray diffraction (XRD) of Ti₃Sn powder, which is also visible for bulk Ti₃Sn on the thermal expansion curve by a turning at 330 K. The new phase’s crystal structure of Ti₃Sn is determined to be orthorhombic with a space group of Cmcm and the lattice parameters of a = 5.87 Å, b = 10.37 Å, c = 4.76 Å respectively, according to selected area electron diffraction patterns in transmission electron microscope (TEM) and XRD profiles. The hexagonal → orthorhombic phase transformation is calculated to be reasonable and consistent with thermodynamics theory. This work contributes to a growing knowledge of intermetallic Ti₃Sn, which may provide fundamental insights into its damping mechanism.

Electrochemical Mechanism and Effect of Carbon Nanotubes on the Electrochemical Performance of Fe1.19(PO4)(OH)0.57(H2O)0.43 Cathode Material for Li-Ion Batteries

A hydrothermal synthesis route was used to synthesize iron(III) phosphate hydroxide hydrate-carbon nanotube composites. Carbon nanotubes (CNT) were mixed in solution with Fe_1.19(PO₄)(OH)_0.57(H₂O)_0.43 (FPHH) precursors for one-pot hydrothermal reaction leading to the FPHH/CNT composite. This produces a highly electronic conductive material to be used as a cathode material for Li-ion battery. The galvanostatic cycling analysis shows that the material delivers a specific capacity of 160 mAh g^-1 at 0.2 C (0.2 Li per fu in 1 h), slightly decreasing with increasing current density. A high charge-discharge cyclability is observed, showing that a capacity of 120 mAh g^-1 at 1 C is maintained after 500 cycles. This may be attributed to the microspherical morphology of the particles and electronic percolation due to CNT but also to the unusual insertion mechanism resulting from the peculiar structure of FPHH formed by chains of partially occupied FeO₆ octahedra connected by PO₄ tetrahedra. The mechanism of the first discharge-charge cycle was investigated by combining operando X-ray diffraction and ⁵⁷Fe Mössbauer spectroscopy. FPHH undergoes a monophasic reaction with up to 10% volume changes based on the Fe³⁺/Fe²⁺ redox process. However, the variations of the FPHH lattice parameters and the ⁵⁷Fe quadrupole splitting distributions during the Li insertion-deinsertion process show a two-step behavior. We propose that such mechanism could be due to the existence of different types of vacant sites in FPHH, including vacant "octahedral" sites (Fe vacancies) that improve diffusion of Li by connecting the one-dimensional channels.

Metallic Sn-Based Anode Materials: Application in High-Performance Lithium-Ion and Sodium-Ion Batteries

With the fast-growing demand for green and safe energy sources, rechargeable ion batteries have gradually occupied the major current market of energy storage devices due to their advantages of high capacities, long cycling life, superior rate ability, and so on. Metallic Sn-based anodes are perceived as one of the most promising alternatives to the conventional graphite anode and have attracted great attention due to the high theoretical capacities of Sn in both lithium-ion batteries (LIBs) (994 mA h g-1) and sodium-ion batteries (847 mA h g-1). Though Sony has used Sn-Co-C nanocomposites as its commercial LIB anodes, to develop even better batteries using metallic Sn-based anodes there are still two main obstacles that must be overcome: poor cycling stability and low coulombic efficiency. In this review, the latest and most outstanding developments in metallic Sn-based anodes for LIBs and SIBs are summarized. And it covers the modification strategies including size control, alloying, and structure design to effectually improve the electrochemical properties. The superiorities and limitations are analyzed and discussed, aiming to provide an in-depth understanding of the theoretical works and practical developments of metallic Sn-based anode materials.

Iron-Based Electrodes Meet Water-Based Preparation, Fluorine-Free Electrolyte and Binder: A Chance for More Sustainable Lithium-Ion Batteries?

Environmentally friendly and cost-effective Li-ion cells are fabricated with abundant, non-toxic LiFePO4 cathodes and iron oxide anodes. A water-soluble alginate binder is used to coat both electrodes to reduce the environmental footprint. The critical reactivity of LiPF6 -based electrolytes toward possible traces of H2 O in water-processed electrodes is overcome by using a lithium bis(oxalato)borate (LiBOB) salt. The absence of fluorine in the electrolyte and binder is a cornerstone for improved cell chemistry and results in stable battery operation. A dedicated approach to exploit conversion-type anodes more effectively is also disclosed. The issue of large voltage hysteresis upon conversion/de-conversion is circumvented by operating iron oxide in a deeply lithiated Fe/Li2 O form. Li-ion cells with energy efficiencies of up to 92 % are demonstrated if LiFePO4 is cycled versus such anodes prepared through a pre-lithiation procedure. These cells show an average energy efficiency of approximately 90.66 % and a mean Coulombic efficiency of approximately 99.65 % over 320 cycles at current densities of 0.1, 0.2 and 0.3 mA cm-2 . They retain nearly 100 % of their initial discharge capacity and provide an unmatched operation potential of approximately 2.85 V for this combination of active materials. No occurrence of Li plating was detected in three-electrode cells at charging rates of approximately 5C. Excellent rate capabilities of up to approximately 30C are achieved thanks to the exploitation of size effects from the small Fe nanoparticles and their reactive boundaries.

Lithium transition metal pnictides – structural chemistry, electrochemistry, and function

Lithium-transition metal (T)-pnictides (Pn=P, As, Sb, Bi) are an interesting class of materials with greatly differing crystal structures. The transition metal and pnictide atoms build up covalently bonded networks that leave cavities or channels for the lithium atoms. Depending on the bonding of lithium to the polyanionic network, one observes mobility of the lithium atoms. The crystal chemistry, chemical bonding, 7Li solid-state NMR, and the electrochemical behavior of the pnictides are reviewed. The structural chemistry is compared with related tetrelides.

A novel mesoporous carbon@silicon–silica nanostructure for high-performance Li-ion battery anodes

A novel hierarchical nanostructure with graphite-like carbon and small Si nanocrystals, respectively, encapsulated in the mesopores and embedded in a silica framework of mesoporous silica nanoparticles is constructed for high-performance Li-ion batteries.