Preparation of oxygen-deficient WO3- nanosheets and their characterization as anode materials for high-performance Li-ion batteries

Textured Asymmetric Membrane Electrode Assemblies of Piezoelectric Phosphorene and Ti3C2Tx MXene Heterostructures for Enhanced Electrochemical Stability and Kinetics in LIBs

Black phosphorus with a superior theoretical capacity (2596 mAh g-1) and high conductivity is regarded as one of the powerful candidates for lithium-ion battery (LIB) anode materials, whereas the severe volume expansion and sluggish kinetics still impede its applications in LIBs. By contrast, the exfoliated two-dimensional phosphorene owns negligible volume variation, and its intrinsic piezoelectricity is considered to be beneficial to the Li-ion transfer kinetics, while its positive influence has not been discussed yet. Herein, a phosphorene/MXene heterostructure-textured nanopiezocomposite is proposed with even phosphorene distribution and enhanced piezo-electrochemical coupling as an applicable free-standing asymmetric membrane electrode beyond the skin effect for enhanced Li-ion storage. The experimental and simulation analysis reveals that the embedded phosphorene nanosheets not only provide abundant active sites for Li-ions, but also endow the nanocomposite with favorable piezoelectricity, thus promoting the Li-ion transfer kinetics by generating the piezoelectric field serving as an extra accelerator. By waltzing with the MXene framework, the optimized electrode exhibits enhanced kinetics and stability, achieving stable cycling performances for 1,000 cycles at 2 A g-1, and delivering a high reversible capacity of 524 mAh g-1 at - 20 ℃, indicating the positive influence of the structural merits of self-assembled nanopiezocomposites on promoting stability and kinetics.

Architecting Hierarchical WO3 Agglomerates Assembled With Straight and Parallel Aligned Nanoribbons Enabling High Capacity and Robust Stability of Lithium Storage

The pursuit of electrochemical energy storage has led to a pressing need on materials with high capacities and energy densities; however, further progress is plagued by the restrictive capacity (372 mAh g⁻¹) of conventional graphite materials. Tungsten trioxide (WO₃)-based anodes feature high theoretical capacity (693 mAh g⁻¹), suitable potential, and affordable cost, arousing ever-increasing attention and intense efforts. Nonetheless, developing high-performance WO₃ electrodes that accommodate lithium ions remains a daunting challenge on account of sluggish kinetics characteristics and large volume strain. Herein, the well-designed hierarchical WO₃ agglomerates assembled with straight and parallel aligned nanoribbons are fabricated and evaluated as an anode of lithium-ion batteries (LIBs), which exhibits an ultra-high capacity and excellent rate capability. At a current density of 1,000 mA g⁻¹, a reversible capacity as high as 522.7 mAh g⁻¹ can be maintained after 800 cycles, corresponding to a high capacity retention of ∼80%, demonstrating an exceptional long-durability cyclic performance. Furthermore, the mechanistic studies on the lithium storage processes of WO₃ are probed, providing a foundation for further optimizations and rational designs. These results indicate that the well-designed hierarchical WO₃ agglomerates display great potential for applications in the field of high-performance LIBs.

Two-dimensional WO3 nanosheets for high-performance electrochromic supercapacitors

The 2D single crystal WO3 nanosheets with (101) preferred orientation facets self-assembled on an FTO substrate and were applied to an aqueous electrochromic-supercapacitor.

Synthesis and Characterization of Tungsten Suboxide WnO3n-1 Nanotiles

W_nO_3n-1 nanotiles, with multiple stoichiometries within one nanotile, were synthesized via the chemical vapour transport method. They grow along the [010] crystallographic axis, with the thickness ranging from a few tens to a few hundreds of nm, with the lateral size up to several µm. Distinct surface corrugations, up to a few 10 nm deep appear during growth. The {102}_r crystallographic shear planes indicate the W_nO_3n-1 stoichiometries. Within a single nanotile, six stoichiometries were detected, namely W₁₆O₄₇ (WO_2.938), W₁₅O₄₄ (WO_2.933), W₁₄O₄₁ (WO_2.928), W₁₃O₃₈ (WO_2.923), W₁₂O₃₅ (WO_2.917), and W₁₁O₃₂ (WO_2.909), with the last three never being reported before. The existence of oxygen vacancies within the crystallographic shear planes resulted in the observed non-zero density of states at the Fermi energy.