Ultrasmall metal oxide nanocrystals embedded in nitrogen-doped carbon networks based on one-step pyrolysis of bi-functional metallo-organic molecules for high-performance lithium-ion batteries

Design and Optimization of Polyaniline/SWCNT Anodes for Improved Lithium-Ion Storage

The integration of polyaniline (PANI) with single-walled carbon nanotubes (SWCNTs) offers a promising technique to improve the electrochemical performance of lithium-ion battery (LIB) anodes. In this work, we report on the synthesis and advanced optimization of PANI/SWCNT composite anodes aimed toward further developing lithium-ion (Li+) storage capacity. A proper characterization, including SEM and XRD, revealed the well-defined morphology and synergistic collaboration among PANI and SWCNTs. Electrochemical evaluations showed that the PANI anodes display predominant Li+ storage capacities, with a high specific capacity of 528 mA g-1 at 100 mA g-1, and the 10 wt% SWCNT-doped PANI (PANI/10 wt% SWCNT) composite demonstrated an exceptional cycling performance of 830 mA g-1 at 100 mA g-1 and excellent capacity retention (101% after 200 cycles). Cyclic voltammetry demonstrated reduced charge transfer resistance and improved ion diffusion kinetics. These improvements originate from the correlative properties of PANI's redox activity and SWCNT's conductivity, which enable effective Li+ transport and intercalation. This work features the capability of PANI/SWCNT composites as superior-performance anode materials for advanced LIBs, tending to key difficulties of energy density and cycling stability. The discoveries establish the importance of additional investigation of polymer-carbon nanocomposites in advanced energy storage systems.

High-Performance Anode Material Based on Zinc Naphthalocyanine/Graphene Composite

Transition metal oxides are a potential anode material owing to their high theoretical capacity. Nonetheless, their large volume changes and low electrical conductivities lead to poor cycling performance and rate capabilities. In this article, an effective strategy is proposed and developed for preparing a ZnO/N-doped graphene composite (ZnNc/GO-5). The key point of this strategy is to use zinc tetra tert-butyl-naphthalocyanine (ZnNc) as a codoped source of N atoms and zinc ions, and graphene oxide (GO) which is combined with ZnNc by π-π deposition as a carbon matrix. After calcination, ZnO microcrystals coated with N-doped graphene are obtained. The unique features of the composite and synergistic effect between N-doped reduced graphene oxide and ZnO microcrystals enable good electrochemical performance by the composites when used in lithium-ion batteries. As an anode material, the as-synthesized ZnNc/GO-5 composite delivers a high first capacity of 1942.9 mAh g-1 and excellent cyclic stability of 861.4 mAh g-1 after 150 cycles at 100 mA g-1. This strategy may offer a new method of designing the anode materials of lithium-ion batteries and promote the practical use of organic molecules in next-generation lithium-ion batteries.

Synthesis of copper naphthalocyanine/graphene oxide composites as anode materials for lithium-ion batteries

Naphthalocyanine and its derivatives are new types of functional materials with wide application prospects. This paper discusses the synthesis of copper tetra tert-butyl-naphthalocyanine (CuNc) and analyses its molecular and electronic structure. Next, CuNc is combined with graphene oxide (GO) through π-π interaction and then pyrolyzed to form a CuNc/GO composite. A systematic investigation of the morphology, structure, composition and properties of CuNc/GO revealed that N-doped graphene is decorated with CuO particles. The electrochemical properties of CuNc/GO are compared with those of directly pyrolysed CuNc. The prepared CuNc/GO (1 : 1) electrode shows a large specific capacity (655.1 mA h g-1) after 100 cycles at 100 mA g-1. Its high capacity, enhanced cycling stability and strong rate performance are attributed to the synergetic effect of N-doped graphene and CuO particles. Besides expanding the use of naphthalocyanine compounds, this work presents a promising candidate material for lithium-ion battery anodes.

Hierarchical-Structured Fe2O3 Anode with Exposed (001) Facet for Enhanced Lithium Storage Performance

The hierarchical structure is an ideal nanostructure for conversion-type anodes with drastic volume expansion. Here, we demonstrate a tin-doping strategy for constructing Fe₂O₃ brushes, in which nanowires with exposed (001) facets are stacked into the hierarchical structure. Thanks to the tin-doping, the conductivity of the Sn-doped Fe₂O₃ has been improved greatly. Moreover, the volume changes of the Sn-doped Fe₂O₃ anodes can be limited to ~4% vertical expansion and ~13% horizontal expansion, thus resulting in high-rate performance and long-life stability due to the exposed (001) facet and the unique hierarchical structure. As a result, it delivers a high reversible lithium storage capacity of 580 mAh/g at a current density of 0.2C (0.2 A/g), and excellent rate performance of above 400 mAh/g even at a high current density of 2C (2 A/g) over 500 cycles, which is much higher than most of the reported transition metal oxide anodes. This doping strategy and the unique hierarchical structures bring inspiration for nanostructure design of functional materials in energy storage.

A Novel Hierarchical Structure of SnCu2Se4/d-Ti3C2Tx/NPC for a Lithium/Sodium Ion Battery and Hybrid Capacitor with Long-Term Cycling Stabilities

To alleviate kinetics imbalance and capacity insufficiency simultaneously, a novel hierarchical structure (SnCu₂Se₄/d-Ti₃C₂T_x/NPC) composed of delaminated Ti₃C₂T_x, SnCu₂Se₄ nanoparticles, and N-doped porous carbon layers is designed as a battery-type anode for lithium/sodium ion hybrid capacitor (LIC/SIC). The combination of SnCu₂Se₄ nanoparticles with high specific capacity, d-Ti₃C₂T_x with accelerated ion diffusion path, and NPC with enhanced electronic conductivity makes the SnCu₂Se₄/d-Ti₃C₂T_x/NPC composite possess excellent cycling stabilities in half-cell lithium-ion and sodium-ion batteries (LIB and SIB), with capacities of 114 mAh g^-1 after 6000 cycles at 10 A g^-1 for LIB and 296 mAh g^-1 after 900 cycles at 1.0 A g^-1 for SIB. The rate performance is also outstanding, with recovered capacity of 738 mAh g^-1 at 0.1 A g^-1 after cycles at current densities up to 50 A g^-1 for LIB. Subsequently, LIC and SIC based on the SnCu₂Se₄/d-Ti₃C₂T_x/NPC anode and activated carbon cathode exhibit high energy densities of 147.9 and 158.6 Wh kg^-1 at a power density of 100 W kg^-1, respectively. They also possess distinctive long lifespans with capacity retentions of 78 and 81% after 10,000 cycles at 1.0 A g^-1, respectively, demonstrating the feasibility of SnCu₂Se₄/d-Ti₃C₂T_x/NPC toward energy devices requiring high energy density, power density, and long-term stability.

Contribution of Ex-Situ and In-Situ X-ray Grazing Incidence Scattering Techniques to the Understanding of Quantum Dot Self-Assembly: A Review

Quantum dots are under intense research, given their amazing properties which favor their use in electronics, optoelectronics, energy, medicine and other important applications. For many of these technological applications, quantum dots are used in their ordered self-assembled form, called superlattice. Understanding the mechanism of formation of the superlattices is crucial to designing quantum dots devices with desired properties. Here we review some of the most important findings about the formation of such superlattices that have been derived using grazing incidence scattering techniques (grazing incidence small and wide angle X-ray scattering (GISAXS/GIWAXS)). Acquisition of these structural information is essential to developing some of the most important underlying theories in the field.