Coaxial Co 3 O 4 @polypyrrole core-shell nanowire arrays for high performance lithium ion batteries

Influence of Polypyrrole on Phosphorus- and TiO2-Based Anode Nanomaterials for Li-Ion Batteries

Phosphorus (P) and TiO2 have been extensively studied as anode materials for lithium-ion batteries (LIBs) due to their high specific capacities. However, P is limited by low electrical conductivity and significant volume changes during charge and discharge cycles, while TiO2 is hindered by low electrical conductivity and slow Li-ion diffusion. To address these issues, we synthesized organic-inorganic hybrid anode materials of P-polypyrrole (PPy) and TiO2-PPy, through in situ polymerization of pyrrole monomer in the presence of the nanoscale inorganic materials. These hybrid anode materials showed higher cycling stability and capacity compared to pure P and TiO2. The enhancements are attributed to the electrical conductivity and flexibility of PPy polymers, which improve the conductivity of the anode materials and effectively buffer volume changes to sustain structural integrity during the charge and discharge processes. Additionally, PPy can undergo polymerization to form multi-component composites for anode materials. In this study, we successfully synthesized a ternary composite anode material, P-TiO2-PPy, achieving a capacity of up to 1763 mAh/g over 1000 cycles.

OER catalytic performance of a composite catalyst comprising multi-layer thin flake Co3O4 and PPy nanofibers

The oxygen evolution reaction (OER) plays a crucial role in energy conversion and storage processes, highlighting the significance of searching for efficient and stable OER catalysts. In this study, we have developed a composite catalyst, PPy@Co3O4, with outstanding catalytic performance for the OER. The catalyst was constructed by integrating multi-layer thin flake Co3O4 with attached PPy nanofibers, utilizing the rich active sites of Co3O4 and the flexibility and tunability of PPy nanofibers to optimize the catalyst structure. Through comprehensive characterization and performance evaluation, our results demonstrate that the PPy@Co3O4 (0.1 : 1) catalyst exhibits remarkable OER catalytic activity and stability. This research provides new strategies and insights for the development of efficient and stable OER catalysts, holding promising prospects for energy conversion and storage applications in relevant fields.

Mesoporous polyvalent Ni-Mn-Co-O composite nanowire arrays towards integrated anodes boosting high-properties lithium storage

Ternary transition metal oxides (TMOs) are potentially promising anode materials for lithium storage with high power and energy density. Designing appropriate electrode structures is an effective strategy to sufficiently exhibit the advantages of TMOs for lithium storage. Here, we present the synthetic process and electrochemical properties of carbon-coated mesoporous Ni-Mn-Co-O (NMCO) nanowire arrays (NWAs) grown on Ni foam as an integrated electrode for lithium-ion batteries (LIBs). The electrochemical measurements show that the carbon-coated NMCO integrated electrode exhibits high capacity and cycling properties. In addition, we have also developed an all one-dimensional (1D) structural full cell using an LiMn₂O₄ nanorod cathode and an NMCO/Ni NWAs@C-550 anode, which exhibits relatively outstanding cycling properties.

Carbon coating on metal oxide materials for electrochemical energy storage

During the past decades, nano-structured metal oxide electrode materials have received growing attention due to their low development cost and high theoretical specific capacity, accordingly, quite a lot of metal oxide electrode materials are being used in electrochemical energy storage devices. However, the further development was limited by the relatively low electrical conductivity and the volume expansion during electrochemical reactions. Thus, many approaches have been proposed to obtain high-efficiency metal oxide electrode materials, such as designing nanomaterials with ideal morphology and high specific surface area, optimizing with carbon-based materials (such as graphene and glucose) to prepare nanocomposites, combining with conductive substrates to enhance the conductivity of electrodes, etc. Owning to the advantages of low cost and high chemical stability of carbon materials, core-shell structure formed by carbon-coated metal oxides is considered to be a promising solution to solve these problems. Therefore, this review mainly focuses on recent research advances in the field of carbon-coated metal oxides for energy storage, summarizing the advantages and disadvantages of common metal oxides and different types of carbon sources, and proposing methods to optimize the material properties in terms of structure and morphology, carbon layer thickness, coating method, specific surface area and pore size distribution, as well as improving electrical conductivity. In addition, the double or multi-layer coating strategy is also a reflection of the continuous development of carbon coating method. Hopefully, this rereview may provide a new direction for the renewal and development of future energy storage electrode materials.

Recent Trends and Developments in Conducting Polymer Nanocomposites for Multifunctional Applications

Electrically-conducting polymers (CPs) were first developed as a revolutionary class of organic compounds that possess optical and electrical properties comparable to that of metals as well as inorganic semiconductors and display the commendable properties correlated with traditional polymers, like the ease of manufacture along with resilience in processing. Polymer nanocomposites are designed and manufactured to ensure excellent promising properties for anti-static (electrically conducting), anti-corrosion, actuators, sensors, shape memory alloys, biomedical, flexible electronics, solar cells, fuel cells, supercapacitors, LEDs, and adhesive applications with desired-appealing and cost-effective, functional surface coatings. The distinctive properties of nanocomposite materials involve significantly improved mechanical characteristics, barrier-properties, weight-reduction, and increased, long-lasting performance in terms of heat, wear, and scratch-resistant. Constraint in availability of power due to continuous depletion in the reservoirs of fossil fuels has affected the performance and functioning of electronic and energy storage appliances. For such reasons, efforts to modify the performance of such appliances are under way through blending design engineering with organic electronics. Unlike conventional inorganic semiconductors, organic electronic materials are developed from conducting polymers (CPs), dyes and charge transfer complexes. However, the conductive polymers are perhaps more bio-compatible rather than conventional metals or semi-conductive materials. Such characteristics make it more fascinating for bio-engineering investigators to conduct research on polymers possessing antistatic properties for various applications. An extensive overview of different techniques of synthesis and the applications of polymer bio-nanocomposites in various fields of sensors, actuators, shape memory polymers, flexible electronics, optical limiting, electrical properties (batteries, solar cells, fuel cells, supercapacitors, LEDs), corrosion-protection and biomedical application are well-summarized from the findings all across the world in more than 150 references, exclusively from the past four years. This paper also presents recent advancements in composites of rare-earth oxides based on conducting polymer composites. Across a variety of biological and medical applications, the fact that numerous tissues were receptive to electric fields and stimuli made CPs more enticing.

Porous spherical NiO@NiMoO4@PPy nanoarchitectures as advanced electrochemical pseudocapacitor materials

In this work, a rational design and construction of porous spherical NiO@NiMoO₄ wrapped with PPy was reported for the application of high-performance supercapacitor (SC). The results show that the NiMoO₄ modification changes the morphology of NiO, and the hollow internal morphology combined with porous outer shell of NiO@NiMoO₄ and NiO@NiMoO₄@PPy hybrids shows an increased specific surface area (SSA), and then promotes the transfer of ions and electrons. The shell of NiMoO₄ and PPy with high electronic conductivity decreases the charge-transfer reaction resistance of NiO, and then improves the electrochemical kinetics of NiO. At 20Ag^-1, the initial capacitances of NiO, NiMoO₄, NiO@NiMoO₄ and NiO@NiMoO₄@PPy are 456.0, 803.2, 764.4 and 941.6Fg^-1, respectively. After 10,000 cycles, the corresponding capacitances are 346.8, 510.8, 641.2 and 904.8Fg^-1, respectively. Especially, the initial capacitance of NiO@NiMoO₄@PPy is 850.2Fg^-1, and remains 655.2Fg^-1 with a high retention of 77.1% at 30Ag^-1 even after 30,000 cycles. The calculation result based on density function theory shows that the much stronger Mo-O bonds are crucial for stabilizing the NiO@NiMoO₄ composite, resulting in a good cycling stability of these materials.

Strategies for Building Robust Traffic Networks in Advanced Energy Storage Devices: A Focus on Composite Electrodes

The charge transport system in an energy storage device (ESD) fundamentally controls the electrochemical performance and device safety. As the skeleton of the charge transport system, the "traffic" networks connecting the active materials are primary structural factors controlling the transport of ions/electrons. However, with the development of ESDs, it becomes very critical but challenging to build traffic networks with rational structures and mechanical robustness, which can support high energy density, fast charging and discharging capability, cycle stability, safety, and even device flexibility. This is especially true for ESDs with high-capacity active materials (e.g., sulfur and silicon), which show notable volume change during cycling. Therefore, there is an urgent need for cost-effective strategies to realize robust transport networks, and an in-depth understanding of the roles of their structures and properties in device performance. To address this urgent need, the primary strategies reported recently are summarized here into three categories according to their controllability over ion-transport networks, electron-transport networks, or both of them. More specifically, the significant studies on active materials, binders, electrode designs based on various templates, pore additives, etc., are introduced accordingly. Finally, significant challenges and opportunities for building robust charge transport system in next-generation energy storage devices are discussed.

Novel ternary transition metal oxide solid solution: mesoporous Ni–Mn–Co–O nanowire arrays as an integrated anode for high-power lithium-ion batteries

Mesoporous Ni–Mn–Co–O ternary solid solution nanowire arrays grown on Cu substrates as integrated anodes for high-power lithium-ion batteries.

The construction of a sandwich structured Co3O4@C@PPy electrode for improving pseudocapacitive storage

Sandwich structured hybrids consisting of a Co₃O₄ nanowire as the core, amorphous carbon (C) as the inner shell and a polypyrrole (PPy) outer layer as the exodermis are synthesized via a hydrothermal method and constant current electropolymerization. The formation mechanism and growth stage of PPy on carbon surfaces is investigated and it was discovered that PPy layer thickness, corresponding to nucleation time of the polymer, as the dynamic factor, can influence the pseudocapacitive properties of the obtained composites. The carbon layer acts as both a network to increase the electric conductivity and a buffer agent to reduce volume expansion of Co₃O₄ during ion insertion/extraction to achieve higher capacitance and better cyclic stability. So for a capacitor, the Co₃O₄@C@PPy electrode delivers a higher areal capacitance of 2.71 F cm⁻² at 10 mA cm⁻² (1663 F g⁻¹ at 6.1 A g⁻¹) and improved rate capability compared to Co₃O₄ and Co₃O₄@C. An asymmetric device is assembled by the Co₃O₄@C@PPy hybrids as a cathode and a relatively high energy density of 63.64 W h kg⁻¹ at a power density of 0.54 kW kg⁻¹ is obtained, demonstrating that the sandwich structured Co₃O₄@C@PPy hybrids have enormous potential for high-performance pseudocapacitors.

The fabrication of sandwich structural CO₃O₄@C@PPy electrode for improving rate capability and areal capacitance.

An urchin-like MgCo2O4@PPy core-shell composite grown on Ni foam for a high-performance all-solid-state asymmetric supercapacitor

In recent years, the electrochemical properties of supercapacitors have been greatly improved due to continuous improvement in their composite materials. In this study, an urchin-like MgCo2O4@PPy/NF (MgCo2O4@polypyrrole/Ni foam) core-shell structure composite material was successfully developed as an electrode for supercapacitors. The MCP-2 composite material, obtained by a hydrothermal method and in situ chemical oxidative polymerization, shows a high specific capacitance of 1079.6 F g-1 at a current density of 1 A g-1, which is much higher than that of MC (783.6 F g-1) under the same conditions. Simultaneously, it has low resistance and an excellent cycling stability of 97.4% after 1000 cycles. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) was assembled using MCP-2 as the positive electrode and activated carbon (AC) as the negative electrode. The MCP-2//AC ASC exhibits high specific capacitance (94 F g-1 at a current density of 0.4 A g-1), high energy density (33.4 W h kg-1 at a power density of 320 W kg-1), high volumetric energy density (17.18 mW h cm-3 at a volumetric power density of 0.16 W cm-3) and excellent cycling stability (retaining 91% of the initial value after 10 000 cycles). Simultaneously, the device has low leakage current and excellent self-discharge characteristics. All these results indicate that the MCP-2//AC ASC is a good energy storage device; it can support the function of two LEDs for 20 minutes. These results indicate that the MCP-2//AC ASC will play an important role in energy structures in the future.

Large Area Synthesis of Vertical Aligned Metal Oxide Nanosheets by Thermal Oxidation of Stainless Steel Mesh and Foil

We report here the synthesis of metal oxide nanosheets (MONs) directly grown on stainless steel substrates by thermal oxidation in the presence of trace amounts of water. The morphology and microstructure of MONs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and atomic force microscopy (AFM). The composition of MONs was determined by the energy dispersive system and X-ray diffraction patterns. The results showed that the as-synthesized MONs were ultrathin, vertically aligned, and mostly transparent. They were polycrystalline and were composed primarily of Cr₂O₃ and (Fe, Mn)₃O₄. The optimal condition to synthesize the MONs with an optimal ultra-high surface atom ratio were determined by varying the temperature and time required for the growth of the MONs. It was found that the lateral size of MONs gradually increases as the temperature rises from 1000 to 1100 °C. An optimal temperature of 1100 °C is obtained in terms of the growth density, size and transparency degree growth morphology, and quality. The structure of MONs changes from two-dimensional to three-dimensional networks when the synthesis time is prolonged to more than 1 h.

Cr2O3/carbon nanosheet composite with enhanced performance for lithium ion batteries

A Cr₂O₃/carbon nanosheet composite is directly synthesized by solution combustion synthesis using chromium nitrate as the chromium source and glucose as the carbon source. As anode materials for LIBs, the composite shows superior performance than pure Cr₂O₃.