Longevous Cycling of Rechargeable Zn-Air Battery Enabled by "Raisin-Bread" Cobalt Oxynitride/Porous Carbon Hybrid Electrocatalysts.

Developing commercially viable electrocatalyst lies at the research hotspot of rechargeable Zn-air batteries, but it is still challenging to meet the requirements of energy efficiency and durability in realistic applications. Strategic material design is critical to addressing its drawbacks in terms of sluggish kinetics of oxygen reactions and limited battery lifespan. Herein, a "raisin-bread" architecture is designed for a hybrid catalyst constituting cobalt nitride as the core nanoparticle with thin oxidized coverings, which is further deposited within porous carbon aerogel. Based on synchrotron-based characterizations, this hybrid provides oxygen vacancies and Co-Nx -C sites as the active sites, resulting from a strong coupling between CoOx Ny nanoparticles and 3D conductive carbon scaffolds. Compared to the oxide reference, it performs enhanced stability in harsh electrocatalytic environments, highlighting the benefits of the oxynitride. Furthermore, the 3D conductive scaffolds improve charge/mass transportation and boost durability of these active sites. Density functional theory calculations reveal that the introduced N species into hybrid can synergistically tune the d-band center of cobalt and improve its bifunctional activity. As a result, the obtained air cathode exhibits bifunctional overpotential of 0.65 V and a battery lifetime exceeding 1350 h, which sets a new record for rechargeable Zn-air battery reported so far.

Metal-Organic Frameworks Reinforce the Carbon Nanotube Sponge-Derived Robust Three-Dimensional Sulfur Host for Lithium-Sulfur Batteries.

Sulfur is a prospective material for next-generation batteries with high theoretical capacity, but its drawbacks hinder its commercialization. To overcome the low conductivity of natural sulfur and the shuttle effect of lithium polysulfide, the study proposes a novel sulfur film coated with three-dimensional nitrogen and cobalt-codoped polyhedral carbon wrapped on a multiwalled carbon nanotube sponge (3D-S@NCoCPC sponge) composite as a high-performance cathode material for rechargeable lithium-sulfur batteries. The interconnected conductive carbon network with abundant pores provides more room for the homogeneous distribution of sulfur within the composite and creates a favorable pathway for electrolyte permeability and lithium-ion diffusion. Moreover, the strong interaction between cobalt and lithium polysulfides leads to efficient suppression of the shuttle effect. In addition, the homogeneous distribution of sulfur and cobalt within the composite enhances electronic transfer for the conversion reaction of sulfur. As expected, the cathode with a high sulfur content of 77.5 wt % in the composite achieved a high initial discharge capacity of 1192 mA h g-1 and high Coulombic efficiency of 99.98% after 100 cycles at 100 mA g-1 current density. Stable performance was achieved with 92.9% capacity retention after 200 cycles at 1000 mA/g current density.

Li7La3Zr2O12 Garnet Solid Polymer Electrolyte for Highly Stable All-Solid-State Batteries.

All-solid-state batteries have gained significant attention as promising candidates to replace liquid electrolytes in lithium-ion batteries for high safety, energy storage performance, and stability under elevated temperature conditions. However, the low ionic conductivity and unsuitability of lithium metal in solid polymer electrolytes is a critical problem. To resolve this, we used a cubic garnet oxide electrolyte (Li7La3Zr2O12 - LLZO) and ionic liquid in combination with a polymer electrolyte to produce a composite electrolyte membrane. By applying a solid polymer electrolyte on symmetric stainless steel, the composite electrolyte membrane shows high ionic conductivity at elevated temperatures. The effect of LLZO in suppressing lithium dendrite growth within the composite electrolyte was confirmed through symmetric lithium stripping/plating tests under various current densities showing small polarization voltages. The full cell with lithium iron phosphate as the cathode active material achieved a highest specific capacity of 137.4 mAh g-1 and a high capacity retention of 98.47% after 100 cycles at a current density of 50 mA g-1 and a temperature of 60°C. Moreover, the specific discharge capacities were 137 and 100.8 mAh g-1 at current densities of 100 and 200 mA g-1, respectively. This research highlights the capability of solid polymer electrolytes to suppress the evolution of lithium dendrites and enhance the performance of all-solid-state batteries.

Investigation of the size effect of graphene nano-platelets (GnPs) on the anti-corrosion performance of polyurethane/GnP composites.

In this article, polyurethane/graphene nano-platelet (PU/GnP) composites were fabricated via planetary centrifugal mixer (PCM) and cast on polyethylene terephthalate (PET) and copper substrates. Four different grades of GnP are used to investigate the effect of GnP size on the anti-corrosion performance of the composites. Tafel, Nyquist, and Bode plots are used to quantify and compare the anti-corrosion performance of the composites, and these plots are obtained by electrochemical analysis. In addition to the anti-corrosion performance, mechanical properties and morphologies of the composites are analyzed. Various parameters indicating the anti-corrosion performance illustrate that smaller size of GnP in the composites shows higher anti-corrosion performance on copper substrate. The results show that the smaller size of GnP is not only uniformly dispersed within PU, but also offers a high surface area which helps construct an efficient filler pathway that suppresses the diffusion of a corrosive agent into the polymer matrix. Nevertheless, mechanical properties of the composites are partially improved. Essentially, this study demonstrates that the size of GnP plays a central role in determining the anti-corrosion performance of PU/GnP composites.

Molecular Functionalization of Graphene Oxide for Next-Generation Wearable Electronics.

Acquiring reliable and efficient wearable electronics requires the development of flexible electrolyte membranes (EMs) for energy storage systems with high performance and minimum dependency on the operating conditions. Herein, a freestanding graphene oxide (GO) EM is functionalized with 1-hexyl-3-methylimidazolium chloride (HMIM) molecules via both covalent and noncovalent bonds induced by esterification reactions and electrostatic πcation-π stacking, respectively. Compared to the commercial polymeric membrane, the thin HMIM/GO membrane demonstrates not only slightest performance sensitivity to the operating conditions but also a superior hydroxide conductivity of 0.064 ± 0.0021 S cm(-1) at 30% RH and room temperature, which was 3.8 times higher than that of the commercial membrane at the same conditions. To study the practical application of the HMIM/GO membranes in wearable electronics, a fully solid-state, thin, flexible zinc-air battery and supercapacitor are made exhibiting high battery performance and capacitance at low humidified and room temperature environment, respectively, favored by the bonded HMIM molecules on the surface of GO nanosheets. The results of this study disclose the strong potential of manipulating the chemical structure of GO to work as a lightweight membrane in wearable energy storage devices, possessing highly stable performance at different operating conditions, especially at low relative humidity and room temperature.

Sulfur Nanogranular Film-Coated Three-Dimensional Graphene Sponge-Based High Power Lithium Sulfur Battery.

To meet the requirements of both high energy and power density with cycle durability of modern EVs, we prepared a novel nanosulfur granular assembled film coated on the three-dimensional graphene sponge (3D-GS) composite as a high-performance active material for rechargeable lithium sulfur batteries. Instead of conventional graphene powder, three-dimensional rGO sponge (3D-rGO) is employed for the composite synthesis, resulting in a sulfur film directly in contact with the underlying graphene layer. This significantly improves the overall electrical conductivity, strategically addressing challenges of conventional composites of low sulfur utilization and dissolution of polysulfides. Additionally, the synthesis mechanism of 3D-GS is elucidated by XPS and DFT analyses, where replacement of hydroxyl group of 3D-rGO sponge by sulfur (S8) is found to be thermodynamically favorable. As expected, 3D-GS demonstrates outstanding discharge capacity of 1080 mAh g(-1) at a 0.1C rate, and 86.2% capacity retention even after 500 cycles at a 1.0C rate.