Hydrophobic Molecule Monolayer Brush-Tethered Zinc Anodes for Aqueous Zinc Batteries

Aqueous zinc batteries are of great interest as a rechargeable energy storage system, particularly owing to the low cost and high safety of aqueous electrolytes, as well as the high capacity of zinc anodes. Unfortunately, the wide commercialization of aqueous zinc batteries is impeded by the irreversible water reduction and irregular zinc evolution issues on the anode side. Hereby, a hydrophobic and ultrathin polystyrene molecule brush layer is tethered onto the surface of zinc metal anodes to tackle the above limitations. Experimental investigations reveal that the waterproof artificial layer can sustain fast interfacial ionic transportation, minimize hydrogen evolution, and smoothen Zn deposition, thus conferring enhanced electrochemical performance to the as-protected Zn anode in both symmetric Zn//Zn cells and Zn//LiV3O8 full cells

Hydrophobic Molecule Monolayer Brush-Tethered Zinc Anodes for Aqueous Zinc Batteries

Aqueous zinc batteries are of great interest as a rechargeable energy storage system, particularly owing to the low cost and high safety of aqueous electrolytes, as well as the high capacity of zinc anodes. Unfortunately, the wide commercialization of aqueous zinc batteries is impeded by the irreversible water reduction and irregular zinc evolution issues on the anode side. Hereby, a hydrophobic and ultrathin polystyrene molecule brush layer is tethered onto the surface of zinc metal anodes to tackle the above limitations. Experimental investigations reveal that the waterproof artificial layer can sustain fast interfacial ionic transportation, minimize hydrogen evolution, and smoothen Zn deposition, thus conferring enhanced electrochemical performance to the as-protected Zn anode in both symmetric Zn//Zn cells and Zn//LiV3O8 full cells

Hydrophobic Molecule Monolayer Brush-Tethered Zinc Anodes for Aqueous Zinc Batteries

Aqueous zinc batteries are of great interest as a rechargeable energy storage system, particularly owing to the low cost and high safety of aqueous electrolytes, as well as the high capacity of zinc anodes. Unfortunately, the wide commercialization of aqueous zinc batteries is impeded by the irreversible water reduction and irregular zinc evolution issues on the anode side. Hereby, a hydrophobic and ultrathin polystyrene molecule brush layer is tethered onto the surface of zinc metal anodes to tackle the above limitations. Experimental investigations reveal that the waterproof artificial layer can sustain fast interfacial ionic transportation, minimize hydrogen evolution, and smoothen Zn deposition, thus conferring enhanced electrochemical performance to the as-protected Zn anode in both symmetric Zn//Zn cells and Zn//LiV3O8 full cells

A Water-in-Salt Electrolyte for Room-Temperature Fluoride-Ion Batteries Based on a Hydrophobic–Hydrophilic Salt

Realizing room-temperature, efficient, and reversible fluoride-ion redox is critical to commercializing the fluoride-ion battery, a promising post-lithium-ion battery technology. However, this is challenging due to the absence of usable electrolytes, which usually suffer from insufficient ionic conductivity and poor (electro)chemical stability. Herein we report a water-in-salt (WIS) electrolyte based on the tetramethylammonium fluoride salt, an organic salt consisting of hydrophobic cations and hydrophilic anions. The new WIS electrolyte exhibits an electrochemical stability window of 2.47 V (2.08–4.55 V vs Li+/Li) with a room-temperature ionic conductivity of 30.6 mS/cm and a fluoride-ion transference number of 0.479, enabling reversible (de)fluoridation redox of lead and copper fluoride electrodes. The relationship between the salt property, the solvation structure, and the ionic transport behavior is jointly revealed by computational simulations and spectroscopic analysis

Altering Ligand Fields in Single-Atom Sites through Second-Shell Anion Modulation Boosts the Oxygen Reduction Reaction

Single-atom catalysts based on metal–N4 moieties and anchored on carbon supports (defined as M–N–C) are promising for oxygen reduction reaction (ORR). Among those, M–N–C catalysts with 4d and 5d transition metal (TM4d,5d) centers are much more durable and not susceptible to the undesirable Fenton reaction, especially compared with 3d transition metal based ones. However, the ORR activity of these TM4d,5d–N–C catalysts is still far from satisfactory; thus far, there are few discussions about how to accurately tune the ligand fields of single-atom TM4d,5d sites in order to improve their catalytic properties. Herein, we leverage single-atom Ru–N–C as a model system and report an S-anion coordination strategy to modulate the catalyst’s structure and ORR performance. The S anions are identified to bond with N atoms in the second coordination shell of Ru centers, which allows us to manipulate the electronic configuration of central Ru sites. The S-anion-coordinated Ru–N–C catalyst delivers not only promising ORR activity but also outstanding long-term durability, superior to those of commercial Pt/C and most of the near-term single-atom catalysts. DFT calculations reveal that the high ORR activity is attributed to the lower adsorption energy of ORR intermediates at Ru sites. Metal–air batteries using this catalyst in the cathode side also exhibit fast kinetics and excellent stability

Pt–Fe–Cu Ordered Intermetallics Encapsulated with N‑Doped Carbon as High-Performance Catalysts for Oxygen Reduction Reaction

Ternary platinum (Pt)-based ordered intermetallics represent a group of promising electrocatalysts in energy-conversion applications, because of their multielemental coupling that can potentially boost the activity and durability of the oxygen reduction reaction (ORR). Yet, the achievable catalysis performance is still susceptible to the inevitable transition metal leaching that can hardly be eliminated in an acidic environment. Herein, we report a nitrogen (N)-modified carbon (shell) encapsulated Pt–Fe–Cu ordered intermetallic nanoparticles (core) electrocatalyst for acidic ORR, where the Pt–Fe–Cu core presents a face-centered tetragonal (fct) phase. It is demonstrated that N-doped carbon shells can not only protect Pt–Fe–Cu cores from dissolution, agglomeration, coalescence, and Ostwald ripening but also enable the electronic structure regulation of the central Pt sites through the strong Fe–N coordination. The optimized Pt–Fe–Cu intermetallic with N-doped carbon shells delivers superior ORR activity and is more chemically stable over disordered Pt–Fe–Cu alloy, Pt–Fe–Cu intermetallics without a N-doped carbon shell, and commercial Pt/C, where the achievable ORR mass and specific activities are nearly 5-fold and 4-fold higher than those of commercial Pt/C in the acidic media, respectively

Deep-Learning Aided Atomic-Scale Phase Segmentation toward Diagnosing Complex Oxide Cathodes for Lithium-Ion Batteries

Phase transformationa universal phenomenon in materialsplays a key role in determining their properties. Resolving complex phase domains in materials is critical to fostering a new fundamental understanding that facilitates new material development. So far, although conventional classification strategies such as order-parameter methods have been developed to distinguish remarkably disparate phases, highly accurate and efficient phase segmentation for material systems composed of multiphases remains unavailable. Here, by coupling hard-attention-enhanced U-Net network and geometry simulation with atomic-resolution transmission electron microscopy, we successfully developed a deep-learning tool enabling automated atom-by-atom phase segmentation of intertwined phase domains in technologically important cathode materials for lithium-ion batteries. The new strategy outperforms traditional methods and quantitatively elucidates the correlation between the multiple phases formed during battery operation. Our work demonstrates how deep learning can be employed to foster an in-depth understanding of phase transformation-related key issues in complex materials

Shape-Tailorable Graphene-Based Ultra-High-Rate Supercapacitor for Wearable Electronics

With the bloom of wearable electronics, it is becoming necessary to develop energy storage units, <i>e</i>.<i>g</i>., supercapacitors that can be arbitrarily tailored at the device level. Although gel electrolytes have been applied in supercapacitors for decades, no report has studied the shape-tailorable capability of a supercapacitor, for instance, where the device still works after being cut. Here we report a tailorable gel-based supercapacitor with symmetric electrodes prepared by combining electrochemically reduced graphene oxide deposited on a nickel nanocone array current collector with a unique packaging method. This supercapacitor with good flexibility and consistency showed excellent rate performance, cycling stability, and mechanical properties. As a demonstration, these tailorable supercapacitors connected in series can be used to drive small gadgets, <i>e</i>.<i>g</i>., a light-emitting diode (LED) and a minimotor propeller. As simple as it is (electrochemical deposition, stencil printing, <i>etc</i>.), this technique can be used in wearable electronics and miniaturized device applications that require arbitrarily shaped energy storage units

Structural Insights into the Lithium Ion Storage Behaviors of Niobium Tungsten Double Oxides

Niobium-based transitional metal oxides are emerging as promising fast-charging electrodes for lithium-ion batteries. Although various niobium-based double oxides have been investigated (Ti–Nb–O, V–Nb–O, W–Nb–O, Cr–Nb–O, etc.), their underlying structure–property relationships are still poorly understood, which hinders the structural optimization for Nb-based electrodes. In this work, niobium tungsten oxides (WNb2O8, W3Nb14O44, and W10.3Nb6.7O47) featured with different structural openings are selected as model systems to investigate the role of crystal structures in their lithium ion storage behaviors. The three crystal structures showed different voltage windows to maintain the stable and high-rate lithium ion (de)­intercalation. In detail, WNb2O8 exhibits a wide stability window (cutoff voltage below 0.5 V vs Li/Li+), benefiting from its evenly distributed quadrilateral tunnels. In contrast, W3Nb14O44 and W10.3Nb6.7O47, with larger structural openings, required higher cutoff voltages (1.0 and 1.3 V vs Li/Li+, respectively) to maintain their structural stabilities during lithium (de)­insertion. The best rate performance is found in W10.3Nb6.7O47 crystals, benefiting from its large pentagonal tunnels that offered a low lithium intercalation barrier and possible two-dimensional lithium ion pathways. Despite a medium-sized tunnel opening, the Wadsley–Roth structure of W3Nb14O44 shows the highest lithium storage capability and specific capacity due to its abundant lithium intercalation sites. We expect that our systematic investigation of the three representative structures could offer more inspiration for the future structural optimization of Nb-based electrodes toward different energy storage systems

FTIR spectra of EDOT and NNA@PEDOT.

<p>FTIR spectra of EDOT and NNA@PEDOT.</p