Structural modulation in the high capacity battery cathode material LiFeBO3

Environment and Co-occurring Native Mussel Species, but Not Host Genetics, Impact the Microbiome of a Freshwater Invasive Species (Corbicula fluminea)

The Asian clam Corbicula fluminea (Family: Cyneridae) has aggressively invaded freshwater habitats worldwide, resulting in dramatic ecological changes and declines of native bivalves such as freshwater mussels (Family: Unionidae), one of the most imperiled faunal groups. Despite increases in our knowledge of invasive C. fluminea biology, little is known of how intrinsic and extrinsic factors, including co-occurring native species, influence its microbiome. We investigated the gut bacterial microbiome across genetically differentiated populations of C. fluminea in the Tennessee and Mobile River Basins in the Southeastern United States and compared them to those of six co-occurring species of native freshwater mussels. The gut microbiome of C. fluminea was diverse, differed with environmental conditions and varied spatially among rivers, but was unrelated to host genetic variation. Microbial source tracking suggested that the gut microbiome of C. fluminea may be influenced by the presence of co-occurring native mussels. Inferred functions from 16S rRNA gene data using PICRUST2 predicted a high prevalence and diversity of degradation functions in the C. fluminea microbiome, especially the degradation of carbohydrates and aromatic compounds. Such modularity and functional diversity of the microbiome of C. fluminea may be an asset, allowing to acclimate to an extensive range of nutritional sources in invaded habitats, which could play a vital role in its invasive success.

Active-Site-Specific Structural Engineering Enabled Ultrahigh Rate Performance of the NaLi3Fe3(PO4)2(P2O7) Cathode for Lithium-Ion Batteries

Iron-based mixed-polyanionic cathode Na₄Fe₃(PO₄)₂(P₂O₇) (NFPP) has advantages of environmental benignity, easy synthesis, high theoretical capacity, and remarkable stability. From NFPP, a novel Li-replaced material NaLi₃Fe₃(PO₄)₂(P₂O₇) (NLFPP) is synthesized through active Na-site structural engineering by an electrochemical ion exchange approach. The NLFPP cathode can show high reversible capacities of 103.2 and 90.3 mA h g^-1 at 0.5 and 5C, respectively. It also displays an impressive discharge capacity of 81.5 mA h g^-1 at an ultrahigh rate of 30C. Density functional theory (DFT) calculation demonstrates that the formation energy of NLFPP is the lowest among NLFPP, NFPP, and NaFe₃(PO₄)₂(P₂O₇), indicating that NLFPP is the easiest to form and the conversion from NFPP to NLFPP is thermodynamically favorable. The Li substitution for Na in the NFPP lattice causes an increase in the unit cell parameter c and decreases in a, b, and V, which are revealed by both DFT calculations and in situ X-ray powder diffraction (XRD) analysis. With hard carbon (HC) as the anode, the NLFPP//HC full cell shows a high reversible capacity of 91.1 mA h g^-1 at 2C and retains 82.4% after 200 cycles. The proposed active-site-specific structural tailoring via electrochemical ion exchange will give new insights into the design of high-performance cathodes for lithium-ion batteries.

Factors that affect volume change during electrochemical cycling in cathode materials for lithium ion batteries

Intergranular cracks originating from volume change during charging/discharging have been observed in many cathodes of lithium ion batteries, which are considered to be closely related to capacity fading. Using first principles calculations to systematically study the volume behavior of representative intercalation cathodes during delithiation, we have elucidated how Coulombic interaction and bond length affect the volume behaviors of cathodes with different structural flexibility. Jahn-Teller distortions, dopants, ionic radii, site-exchanges, and deintercalation mechanisms have also been discussed to account for the volume change of different cathode materials. This study attempts to give an integrated picture of volume change in typical lithium intercalation cathodes and strives to provide helpful clues to the design of high-capacity-maintaining cathodes.

Where the extraordinaries meet: a cascade of isosymmetrical superionic phase transitions and negative thermal expansion in a novel silver salt-inclusion borate halide

A new silver iodide borate, Ag3B6O10I, is presented as a promising solid-state electrolyte with a δ ↔ γ ↔ β ↔ α cascade of the isosymmetric superionic phase transitions.

Expanding the chemistry of borates with functional [BO2]- anions

More than 3900 crystalline borates, including borate minerals and synthetic inorganic borates, in addition to a wealth of industrially-important boron-containing glasses, have been discovered and characterized. Of these compounds, 99.9 % contain only the traditional triangular BO₃ and tetrahedral BO₄ units, which polymerize into superstructural motifs. Herein, a mixed metal K₅Ba₂(B₁₀O₁₇)₂(BO₂) with linear BO₂ structural units was obtained, pushing the boundaries of structural diversity and providing a direct strategy toward the maximum thresholds of birefringence for optical materials design. ¹¹B solid-state nuclear magnetic resonance (NMR) is a ubiquitous tool in the study of glasses and optical materials; here, density functional theory-based NMR crystallography guided the direct characterization of BO₂ structural units. The full anisotropic shift and quadrupolar tensors of linear BO₂ were extracted from K₅Ba₂(B₁₀O₁₇)₂(BO₂) containing BO₂, BO₃, and BO₄ and serve as guides to the identification of this powerful moiety in future and, potentially, previously-characterized borate minerals, ceramics, and glasses.

Isostructural and Multivalent Anion Substitution toward Improved Phosphate Cathode Materials for Sodium-Ion Batteries

Polyanion-type phosphate materials are highly promising cathode candidates for next-generation batteries due to their excellent structural stability during cycling; however, their poor conductivity has impeded their development. Isostructural and multivalent anion substitution combined with carbon coating is proposed to greatly improve the electrochemical properties of phosphate cathode in sodium-ion batteries (SIBs). Specifically, multivalent tetrahedral SiO₄ ^4- substitute for PO₄ ^3- in Na₃ V₂ (PO₄ )₃ (NVP) lattice, preparing the optimal Na_3.1 V₂ (PO₄ )_2.9 (SiO₄ )_0.1 with high-rate capability (delivering a high capacity of 82.5 mAh g^-1 even at 20 C) and outstanding cyclic stability (≈98% capacity retention after 500 cycles at 1 C). Theoretical calculation and experimental analyses reveal that the anion-substituted Na_3.1 V₂ (PO₄ )_2.9 (SiO₄ )_0.1 reduces the bandgap of NVP lattice and enhanced its structural stability, Na⁺ -diffusion kinetics and electronic conductivity. This strategy of multivalent and isostructural anion substitution chemistry provides a new insight to develop advanced phosphate cathodes.

Effect of Ti-doping on the electrochemical performance of sodium vanadium(iii) phosphate

Na₃V_2−xTi_x(PO₄)₃ (x = 0.00, 0.05, 0.10, and 0.15) was successfully synthesized by a conventional solid-state route. The XRD results show that Ti is incorporated in the lattice of Na₃V₂(PO₄)₃ and the tetragonal structure has not been changed after doping. Among all the composites, the Na₃V_1.9Ti_0.1(PO₄)₃ composite delivers the highest discharge capacity of 114.87 mA h g⁻¹ at 0.1C and possesses a capacity retention of 96.23% after 20 cycles at 0.1C, demonstrating the better rate performance and cycle stability in the potential range of 2.0–3.8 V. Electrochemical impedance spectroscopy (EIS) results reveal that the Na₃V_1.9Ti_0.1(PO₄)₃ composite has a lower charge transfer resistance and a higher Na-ion diffusion coefficient compared to other composites. The results indicate that Ti-doping in Na₃V₂(PO₄)₃ can effectively enhance the electrochemical performance of this tetragonal compound, especially at a high charge/discharge rate.

Na₃V_2−xTi_x(PO₄)₃ (x = 0.00, 0.05, 0.10, 0.15) was synthesized by a conventional solid-state route. Ti doping can effectively enhance the electrochemical performance of this tetragonal compound, especially under high charge–discharge rates.

A density functional theory study of the carbon-coating effects on lithium iron borate battery electrodes

Density functional theory modelling shows that carbon coatings on a LiFeBO₃ cathode material does not impede the Li transport in a Li-ion battery.

Mechanical Milling Assisted Synthesis and Electrochemical Performance of High Capacity LiFeBO3 for Lithium Batteries

Borate chemistry offers attractive features for iron based polyanionic compounds. For battery applications, lithium iron borate has been proposed as cathode material because it has the lightest polyanionic framework that offers a high theoretical capacity. Moreover, it shows promising characteristics with an element combination that is favorable in terms of sustainability, toxicity, and costs. However, the system is also associated with a challenging chemistry, which is the major reason for the slow progress in its further development as a battery material. The two major challenges in the synthesis of LiFeBO3 are in obtaining phase purity and high electrochemical activity. Herein, we report a facile and scalable synthesis strategy for highly pure and electrochemically active LiFeBO3 by circumventing stability issues related to Fe(2+) oxidation state by the right choice of the precursor and experimental conditions. Additionally, we carried out a Mössbauer spectroscopic study of electrochemical charged and charged-discharged LiFeBO3 and reported a lithium diffusion coefficient of 5.56 × 10(-14) cm(2) s(-1) for the first time.

Rechargeable Sodium-Ion Battery: High-Capacity Ammonium Vanadate Cathode with Enhanced Stability at High Rate

Sodium-ion battery (NIB) cathode performance based on ammonium vanadate is demonstrated here as having high capacity, long cycle life and good rate capability. The simple preparation process and morphology study enable us to explore this electrode as suitable NIB cathode. Furthermore, density functional theory (DFT) calculation is envisioned for the NH4V4O10 cathode, and three possible sodium arrangements in the structure are depicted for the first time. Relevant NIB-related properties such as average voltage, lattice constants, and atomic coordinates have been derived, and the estimated values are in good agreement with the current experimental values. A screening study shows ammonium vanadate electrodes prepared on carbon coat onto Al-current collector exhibits a better electrochemical performance toward sodium, with a sustained reversible capacity and outstanding rate capability. With the current cathode with nanobelt morphology, a reversible capacity of 190 mAh g(-1) is attained at a charging rate of 200 mA g(-1), and a stable capacity of above 120 mAh g(-1) is retained for an extended 50 cycles tested at 1000 mA g(-1) without the addition of any expensive electrolyte additive.

(3 + 1)-Dimensional commensurately modulated structure and photoluminescence properties of diborate KSbOB2O5

This work reports the commensurately modulated structure of KSbOB₂O₅ using superspace formalism for aperiodic structures considering a modulation vector q = 5/12b*.

Synthesis and electrochemical investigation of novel phosphite based layered cathodes for Li-ion batteries

Reversible lithium storage has been demonstrated in novel phosphite containing cathode materials, A₂[(VO)₂(HPO₃)₂(C₂O₄)]; A = Li, Na and K.

The first investigation of the synthetic mechanism and lithium intercalation chemistry of Li9Fe3(P2O7)3(PO4)2/C as cathode material for lithium ion batteries

Li₉Fe₃(P₂O₇)₃(PO₄)₂ with mixed-polyanion groups is introduced as a novel cathode material for Li-ion batteries.

Unusual Mn coordination and redox chemistry in the high capacity borate cathode Li7Mn(BO3)3

The recently discovered lithium-rich cathode material Li₇Mn(BO₃)₃ has a high theoretical capacity and an unusual tetrahedral Mn²⁺ coordination.

Thin-film and bulk investigations of LiCoBO₃ as a Li-ion battery cathode

The compound LiCoBO3 is an appealing candidate for next-generation Li-ion batteries based on its high theoretical specific capacity of 215 mAh/g and high expected discharge voltage (more than 4 V vs Li(+)/Li). However, this level of performance has not yet been realized in experimental cells, even with nanosized particles. Reactive magnetron sputtering was therefore used to prepare thin films of LiCoBO3, allowing the influence of the particle thickness on the electrochemical performance to be explicitly tested. Even when ultrathin films (∼15 nm) were prepared, there was a negligible electrochemical response from LiCoBO3. Impedance spectroscopy measurements suggest that the conductivity of LiCoBO3 is many orders of magnitude worse than that of LiFeBO3 and may severely limit the performance. The unusual blue color of LiCoBO3 was investigated by spectroscopic techniques, which allowed the determination of a charge-transfer optical gap of 4.2 eV and the attribution of the visible light absorption peak at 2.2 eV to spin-allowed d → d transitions (assigned as overlapping (4)A2' to (4)A2″ and (4)E″ final states based on ligand-field modeling).

Hierarchical Li4Ti5O12/TiO2 composite tubes with regular structural imperfection for lithium ion storage

Hierarchical Li4Ti5O12/TiO2 tubes composed of ultrathin nanoflakes have been successfully fabricated via the calcination of the hydrothermal product of a porous amorphous TiO2 precursor and lithium hydroxide monohydrate. The hierarchical tubes are characterized by powder X-ray diffraction, nitrogen adsorption/desorption, scanning electron microscopy and transmission electron microscopy techniques. These nanoflakes exhibit a quite complex submicroscopic structure with regular structural imperfection, including a huge number of grain boundaries and dislocations. The lithium ion storage property of these tubes is evaluated by galvanostatic discharge/charge experiment. The product shows initial discharge capacities of 420, 225, and 160 mAh g(-1) at 0.01, 0.1, and 1.0 A g(-1), respectively. After 100 cycles, the discharge capacity is 139 mAh g(-1) at 1.0 A g(-1) with a capacity retention of 87%, demonstrating good high-rate performance and good cycleability. The high electrochemical performance is attributed to unique structure and morphology of the tubes. The regular structural imperfection existed in the nanoflakes also benefit to lithium ion storage property of these tubes. The hierarchical Li4Ti5O12/TiO2 tubes are a promising anode material for lithium-ion batteries with high power and energy densities.

Lithium and sodium battery cathode materials: computational insights into voltage, diffusion and nanostructural properties

Energy storage technologies are critical in addressing the global challenge of clean sustainable energy. Major advances in rechargeable batteries for portable electronics, electric vehicles and large-scale grid storage will depend on the discovery and exploitation of new high performance materials, which requires a greater fundamental understanding of their properties on the atomic and nanoscopic scales. This review describes some of the exciting progress being made in this area through use of computer simulation techniques, focusing primarily on positive electrode (cathode) materials for lithium-ion batteries, but also including a timely overview of the growing area of new cathode materials for sodium-ion batteries. In general, two main types of technique have been employed, namely electronic structure methods based on density functional theory, and atomistic potentials-based methods. A major theme of much computational work has been the significant synergy with experimental studies. The scope of contemporary work is highlighted by studies of a broad range of topical materials encompassing layered, spinel and polyanionic framework compounds such as LiCoO2, LiMn2O4 and LiFePO4 respectively. Fundamental features important to cathode performance are examined, including voltage trends, ion diffusion paths and dimensionalities, intrinsic defect chemistry, and surface properties of nanostructures.