Steric molecular combing effect enables Self-Healing binder for silicon anodes in Lithium-Ion batteries.

Silicon is a promising anode material for lithium-ion batteries with its superior capacity. However, the volume change of the silicon anode seriously affects the electrode integrity and cycle stability. The waterborne guar gum (GG) binder has been regarded as one of the most promising binders for Si anodes. Here, a unique steric molecular combing approach based on guar gum, glycerol, and citric acid is proposed to develop a self-healing binder GGC, which would boost the structural stability of electrode materials. The GGC binder is mainly designed to weaken van der Waals' forces between polymers through the plasticizing effect of glycerol, combing and straightening the guar molecular chain of GG, and exposing the guar hydroxyl sites of GG and the carboxyl groups of citric acid. The condensation reaction between the hydroxyl sites of GG and the carboxyl groups of citric acid forms stronger hydrogen bonds, which can help achieve self-healing effect to cope with the severe volume expansion effect of silicone-based materials. Silicon electrode lithium-ion batteries prepared with GGC binders exhibit outstanding electrochemical performance, with a discharge capacity of up to 1579 mAh/g for 1200 cycles at 1 A/g, providing a high capacity retention rate of 96%. This paper demostrates the great potential of GGC binders in realizing electrochemical performance enhancement of silicon anode.

Interfacial self-healing polymer electrolytes for Long-Cycle silicon anodes in High-Performance solid-state lithium batteries.

For all-solid-state lithium-ion batteries (ASSLIBs), silicon (Si) stands out as an appealing anodes material due to its high energy density and improved safety compared to lithium metal. However, the substantial volume changes during cycling result in poor solid-state physical contact and electrolyte-electrode interface issues, leading to unsatisfactory electrochemical performance. In this study, we employed in-situ polymerization to construct an integrated Si anodes/self-healing polymer electrolyte for ASSLIBs. The polymer chain reorganization stems from numerous dynamic bonds in the constructed self-healing dynamic supermolecular elastomer electrolyte (SHDSE) molecular structure. Notably, SHDSE also serves as a Si anodes binder with enhanced adhesive capability. As a result, the well-structured Li|SHDSE|Si-SHDSE cell generates subtle electrolyte-electrode interface contacts at the molecular level, which can offer a continuous and stable Li+ transport pathway, reduce Si particle displacement, and mitigate electrode volume expansion. This further enhances cyclic stability (>500 cycles with 68.1 % capacity retention and >99.8 % Coulombic efficiency). More practically, the 2.0 Ah wave-shaped Si||LiCoO2 soft-pack battery with in-situ cured SHDSE exhibits strongly stabilized electrochemical performance (1.68 Ah after 700 cycles, 86.2 % capacity retention) in spite of a high operating temperatures up to 100 °C and in various bending tests. This represents a groundbreaking report in flexible solid-state soft-pack batteries containing Si anodes.

Coupling redox flow desalination with lithium recovery from spent lithium-ion batteries.

Electrochemical redox flow desalination is an emerging method to obtain freshwater; however, the costly requirement for continuously supplying and regenerating redox species limits their practical applications. Recycling of spent lithium-ion batteries is a growing challenge for their sustainable utilization. Existing battery recycling methods often involve massive secondary pollution. Here, we demonstrate a redox flow system to couple redox flow desalination with lithium recovery from spent lithium-ion batteries. The spontaneous reaction between a battery cathode material (LiFePO4) and ferricyanide enables the continuous regeneration of the redox species required for desalination. Several critical operating parameters are optimized, including current density, the concentrations of redox species, salt concentrations of brine, and the amounts of added LiFePO4. With the addition of 0.5920 g of spent LiFePO4 in five consecutive batches, the system can operate over 24 h, achieving 70.46 % lithium recovery in the form of LiCl aqueous solution at the concentration of 6.716 g·L-1. Simultaneously, the brine (25 mL, 10000 ppm NaCl) was desalinated to freshwater. Detailed cost analysis shows that this redox flow system could generate a revenue of ¥ 13.66 per kg of processed spent lithium-ion batteries with low energy consumption (0.77 MJ kg-1) and few greenhouse gas emissions indicating excellent economic and environmental benefits over existing lithium-ion battery recycling technologies, such as pyrometallurgical and hydrometallurgical methods. This work opens a new approach to holistically addressing water and energy challenges to achieve sustainable development.

Molecular characterization of TNF-ß and IFN-γ in yellowfin seabream (Acanthopagrus latus, Hottuyn, 1782) and their immune responses to density stress during transport.

The inflammatory cytokines TNF-ß and IFN-γ are important mediators of the vertebrate inflammatory response and coordinators of the immune system in regard to NF-κB signalling pathways. In this study, the TNF-ß and IFN-γ genes of yellowfin seabream, Acanthopagrus latus were identified, and the multiple sequence alignments, evolutionary relationships and gene expressions of the two genes were also determined. AlTNF-ß contained a 762 bp open reading frame (ORF) encoding 253 amino acids, while AlIFN-γ contained a 582 bp ORF encoding 193 amino acids. An amino-acid sequence alignment analysis showed that these proteins have highly conserved transmembrane structural domains among teleosts. Moreover, AlTNF-ß has a close affinity with TNF-ß of yellowfin seabream while AlIFN-γ has a high evolutionary correlation with A. regius and Sparus aurata. In addition, the mRNAs of AlTNF-ß and AlIFN-γ are widely expressed in various tissues. AlTNF-ß is highly expressed in gill and intestinal tissues, and the mRNA levels of AlIFN-γ are higher in spleen, skin, and gill tissues than in other tissues. Under transportation density stress, the mRNA level of AlTNF-ß was significantly elevated in the intestine of the high-density group, while AlTNF-ß transcription in the gills did not vary significantly among the density groups. Furthermore, AlIFN-γ expression was increased in liver, intestinal, and gill tissues under high transportation density. The results of this study show that TNF-ß and IFN-γ expression in yellowfin seabream is greatly affected by density stress. The density of 125 per bag for 4-5 cm fry or 1200 per bag for 1-2 cm fry is most suitable for the transportation of live fish. These results might provide a reference for further studies on the immunomodulatory response process and auxiliary function of immune stress of TNF and IFN genes in fish under density stress.

Ruthenium-Alloyed Iron Phosphide Single Crystal with Increased Fermi Level for Efficient Hydrogen Evolution.

Transition metal phosphide alloying is an effective approach for optimizing the electronic structure and improving the intrinsic performance of the hydrogen evolution reaction (HER). However, obtaining 3d transition metal phosphides alloyed with noble metals is still a challenge owing to their difference in electronegativity, and the influence of their electronic structure modulated by noble metals on the HER reaction also remains unclear. In this study, we successfully incorporated Ru into an Fe2P single crystal via the Bridgeman method and used it as a model catalyst, which effectively promoted HER. Hall transport measurements combined with first-principles calculations revealed that Ru acted as an electron dopant in the structure and increased the Fermi level, leading to a decreased water dissociation barrier and an improved electron-transfer Volmer step at low overpotentials. Additionally, the (21̅1) facet of Ru-Fe2P was found to be more active than its (001) facet, mainly due to the lower H desorption barrier at high overpotentials. The synergistic effect of Ru and Fe sites was also revealed to facilitate H* and OH* desorption compared with Fe2P. Therefore, this study elucidates the boosting effect of Ru-alloyed iron phosphides and offers new understanding about the relationship between their electronic structure and HER performance.

Identification of Interface Structure for a Topological CoS2 Single Crystal in Oxygen Evolution Reaction with High Intrinsic Reactivity.

Transition metal chalcogenides such as CoS2 have been reported as competitive catalysts for oxygen evolution reaction. It has been well confirmed that surface modification is inevitable in such a process, with the formation of different re-constructed oxide layers. However, which oxide species should be responsible for the optimized catalytic efficiencies and the detailed interface structure between the modified layer and precatalyst remain controversial. Here, a topological CoS2 single crystal with a well-defined exposed surface is used as a model catalyst, which makes the direct investigation of the interface structure possible. Cross-sectional transmission electron microscopy of the sample reveals the formation of a 2 nm thickness Co3O4 layer that grows epitaxially on the CoS2 surface. Thick CoO pieces are also observed and are loosely attached to the bulk crystal. The compact Co3O4 interface structure can result in the fast electron transfer from adsorbed O species to the bulk crystal compared with CoO pieces as evidenced by the electrochemical impedance measurements. This leads to the competitive apparent and intrinsic reactivity of the crystal despite the low surface geometric area. These findings are helpful for the understanding of catalytic origins of transition metal chalcogenides and the designing of high-performance catalysts with interface-phase engineering.

Vertical 2-dimensional heterostructure SnS-SnS2 with built-in electric field on rGO to accelerate charge transfer and improve the shuttle effect of polysulfides.

Traditional carbon materials as sulfur hosts of Li-sulfur(Li-S) cathodes have slightly physical constraint for polysulfides, due to their no-polar property. Therefore, it is necessary to further enhance the affinity between sulfur hosts and polysulfides, and relieve the shuttle effects in the Li- S batteries. Herein, we report a novel vertical 2-dimensional (2D) p-SnS/n-SnS2 heterostructure sheets which grown on the surface of rGO. The excellent electrochemical properties of SnS-SnS2@rGO as Li-S cathode are ascribed to the stronger absorption effect of metal sulphides for polysulfides and the smooth trapping-diffusion-conversion effect of p-SnS/n-SnS2 heterostructure for polysulfides. As a conductive carrier for the growth of vertical 2D p-SnS/n-SnS2 heterostructure nanosheets, rGO can protect the steadiness and enhance the cycle stability of electrode, compared with heterostructure without rGO. In addition, the built-in electric field in the 2D p-SnS/n-SnS2 heterostructure during the discharge/charge processes can effectively accelerate charge transfer, and the charge transfer mechanism in SnS-SnS2 heterostructure during cycling has been investigated. At a rate capability of 2C, the designed SnS-SnS2@rGO as Li-S cathode delivers high specific capacities of 907 mAh g-1 and 571 mAh g-1 after the first cycle and 500 cycles, respectively, which shown excellent cycling ability.

One-Compartment InGaN Nanowire Fuel Cell in the Light and Dark Operating Modes.

A one-compartment H2O2 photofuel cell (PFC) with a photoanode based on InGaN nanowires (NWs) is introduced for the first time. The electrocatalytic and photoelectrocatalytic properties of the InGaN NWs are studied in detail by cyclic voltammetry, current versus time measurements, photovoltage measurements, and electrochemical impedance spectroscopy. In parallel, IrO x (OH) y as the co-catalyst on the InGaN NWs is evaluated to boost the catalytic activity in the dark and light. For the PFC, Ag is the best as the cathode among Ag, Pt, and glassy carbon. The PFC operates in the dark as a conventional fuel cell (FC) and under illumination with 25% increased electrical power generation at room temperature. Such dual operation is unique, combining FC and PFC technologies for the most flexible use.

Anisotropic Piezoelectric Response from InGaN Nanowires with Spatially Modulated Composition and Topography over a Textured Si(100) Substrate.

An anisotropic piezoelectric response is demonstrated from InGaN nanowires (NWs) over a pyramid-textured Si(100) substrate with an interfacet composition and topography modulation induced by stationary molecular beam epitaxy growth conditions, taking advantage of the unidirectional source beam flux. The variations of InGaN NWs between the pyramid facets are verified in terms of morphology, element distribution, and crystalline properties. The piezoelectric response is investigated by electrical atomic force microscopy (AFM) with a statistic analyzing method. Representative pyramids from the ensemble, on top of which InGaN NWs grown with a substrate held at an oblique angle, were characterized for understanding and confirming the degree of anisotropy. The positive deviated oscillation of the peak force error is identified as a measure of the effective AFM tip/NW interaction with respect to the electrical contact and mechanical deformation. The Schottky contact between the metal-coated AFM tip and the NWs on the different facets reveals distinctions consistent with the interfacet composition variation. The interfacet variation of the piezoelectric response of the InGaN NWs is first evaluated by electrical AFM under zero bias. The average current monotonically depends on the scan frequency, which determines the average peak force error, that is, mechanical deformation, with a facet characteristic slope. A piezoelectric nanogenerator device is fabricated out of a sample with an ensemble of pyramids, which exhibits anisotropic output under periodic directional pressing. This work provides a universal strategy for the synthesis of composite semiconductor materials with an anisotropic piezoelectric response.

Multi-wavelength light emission from InGaN nanowires on pyramid-textured Si(100) substrate grown by stationary plasma-assisted molecular beam epitaxy.

We demonstrate multi-wavelength light emission from InGaN nanowires (NWs) monolithically grown on pyramid-textured Si(100) substrates by plasma-assisted molecular beam epitaxy (MBE) under stationary conditions. Taking advantage of the highly unidirectional source material beam fluxes, the In content of the NWs is tuned on the different pyramid facets due to varied incidence angle. This is confirmed by distinct NW morphologies observed by scanning electron microscopy (SEM) and by energy-dispersive X-ray (EDX) element mapping. Photoluminescence and cathodoluminescence (CL) reveal multiple lines originating from InGaN NWs on the different pyramid facets. The anomalous temperature dependence of the emission wavelength results from carrier redistribution between localized or confined states, spontaneously formed within the NWs due to composition fluctuations, verified by high-resolution EDX elemental analysis. First-principles calculations show that the pyramid facet edges act as a barrier for atom migration and enhance atom incorporation. This leads to uniform composition within the facets for not too high a growth temperature, consistent with the SEM, EDX and CL results. At elevated temperature, InGaN decomposition and In desorption are enhanced on facets with low growth rate, accompanied by Ga inter-facet migration, leading to non-uniform composition over the Ga migration length which is deduced to be around 580 nm. Our study presents a method for the fabrication of multi-wavelength light sources by highly unidirectional MBE on textured Si substrates towards color temperature-tunable solid-state lighting and RGB light-emitting diode displays.

Spatial Surface Charge Engineering for Electrochemical Electrodes.

We introduce a novel concept for the design of functional surfaces of materials: Spatial surface charge engineering. We exploit the concept for an all-solid-state, epitaxial InN/InGaN-on-Si reference electrode to replace the inconvenient liquid-filled reference electrodes, such as Ag/AgCl. Reference electrodes are universal components of electrochemical sensors, ubiquitous in electrochemistry to set a constant potential. For subtle interrelation of structure design, surface morphology and the unique surface charge properties of InGaN, the reference electrode has less than 10 mV/decade sensitivity over a wide concentration range, evaluated for KCl aqueous solutions and less than 2 mV/hour long-time drift over 12 hours. Key is a nanoscale charge balanced surface for the right InGaN composition, InN amount and InGaN surface morphology, depending on growth conditions and layer thickness, which is underpinned by the surface potential measured by Kelvin probe force microscopy. When paired with the InN/InGaN quantum dot sensing electrode with super-Nernstian sensitivity, where only structure design and surface morphology are changed, this completes an all-InGaN-based electrochemical sensor with unprecedented performance.