Heterointerfaces: Unlocking Superior Capacity and Rapid Mass Transfer Dynamics in Energy Storage Electrodes.

Heterogeneous electrode materials possess abundant heterointerfaces with a localized "space charge effect", which enhances capacity output and accelerates mass/charge transfer dynamics in energy storage devices (ESDs). These promising features open new possibilities for demanding applications such as electric vehicles, grid energy storage, and portable electronics. However, the fundamental principles and working mechanisms that govern heterointerfaces are not yet fully understood, impeding the rational design of electrode materials. In this study, the heterointerface evolution during charging and discharging process as well as the intricate interaction between heterointerfaces and charge/mass transport phenomena, is systematically discussed. Guidelines along with feasible strategies for engineering structural heterointerfaces to address specific challenges encountered in various application scenarios, are also provided. This review offers innovative solutions for the development of heterogeneous electrode materials, enabling more efficient energy storage beyond conventional electrochemistry. Furthermore, it provides fresh insights into the advancement of clean energy conversion and storage technologies. This review contributes to the knowledge and understanding of heterointerfaces, paving the way for the design and optimization of next-generation energy storage materials for a sustainable future.

Fermented bile acids improved growth performance and intestinal health by altering metabolic profiles and intestinal microbiome in Micropterus salmoides.

A type of fermented bile acids (FBAs) has been produced through a biological method, and its effects on growth performance, metabolism, and intestinal microbiota in largemouth bass were investigated. The results demonstrated that incorporating 0.03 %-0.05 % FBAs diet could improve the final weight, weight gain and specific growth rate, and decrease the feed conversion ratio. Dietary FBAs did not significantly affect the levels of high-density lipoprotein, low-density lipoprotein, and triglycerides, but decreased the activities of α-amylase in most groups. Adding FBAs to the diet significantly increased the integrity of the microscopic structure of the intestine, thickened the muscular layer of the intestine, and notably enhanced its intestinal barrier function. The addition of FBAs to the diet increased the diversity of the gut microbiota in largemouth bass. At the phylum level, there was an increase in the abundance of Proteobacteria, Firmicutes, Tenericutes and Cyanobacteria and a significant decrease in Actinobacteria and Bacteroidetes. At the genus level, the relative abundance of beneficial bacteria Mycoplasma in the GN6 group and Coprococcus in the GN4 group significantly increased, while the pathogenic Enhydrobacter was inhibited. Meanwhile, the highest levels of AKP and ACP were observed in the groups treated with 0.03 % FBAs, while the highest levels of TNF-α and IL-10 were detected in the group treated with 0.04 % FBAs. Additionally, the highest levels of IL-1ß, IL-8T, GF-ß, IGF-1, and IFN-γ were noted in the group treated with 0.06 % FBAs. These results suggested that dietary FBAs improved growth performance and intestinal wall health by altering lipid metabolic profiles and intestinal microbiota in largemouth bass.

The Influence of Ions on the Electrochemical Stability of Aqueous Electrolytes.

The electrochemical stability window of water is known to vary with the type and concentration of dissolved salts. However, the underlying influence of ions on the thermodynamic stability of aqueous solutions has not been fully understood. Here, we investigated the electrolytic behaviors of aqueous electrolytes as a function of different ions. Our findings indicate that ions with high ionic potentials, i.e., charge density, promote the formation of their respective hydration structures, enhancing electrolytic reactions via an inductive effect, particularly for small cations. Conversely, ions with lower ionic potentials increase the proportion of free water molecules-those not engaged in hydration shells or hydrogen-bonding networks-leading to greater electrolytic stability. Furthermore, we observe that the chemical environment created by bulky ions with lower ionic potentials impedes electrolytic reactions by frustrating the solvation of protons and hydroxide ions, the products of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. We found that the solvation of protons plays a more substantial role than that of hydroxide, which explains a greater shift for OER than for HER, a puzzle that cannot be rationalized by the notion of varying O-H bond strengths of water. These insights will help the design of aqueous systems.

Dynamically Adaptive Bubbling for Upgrading Oxygen Evolution Reaction Using Lamellar Fern-Like Alloy Aerogel Self-Standing Electrodes.

Adopting renewable electricity to produce "green" hydrogen has been a critical challenge because at a high current density the mass transfer capability of most catalytic electrodes deteriorates significantly. Herein, a unique lamellar fern-like alloy aerogel (LFA) electrode, showing a unique dynamically adaptive bubbling capability and can effectively avoid stress concentration caused by bubble aggregation is reported. The LFA electrode is intrinsically highly catalytic-active and shows a highly porous, resilient, hierarchically ordered, and well-percolated conductive network. It not only shows superior gas evacuation capability but also exhibits significantly improved stability at high current densities, showing the record lowest oxygen evolution reaction (OER) overpotential of 244 mV at 1000 mA cm-2 and stably over 6000 h. With the merits of mechanical robustness, excellent electron transport, and efficient bubble evacuation, LFA can be self-standing catalytic electrode and gas diffusion layers in anion-exchange-membrane water electrolysis (AEMWE), which can achieve 3000 mA cm-2 at a low voltage of 1.88 V and can sustain stable electrolysis at 2000 mA cm-2 for over 1300 h. This strategy can be extended to various gas evolution reactions as a general design rule for multiphase catalysis applications.

Electrolyte Interphases in Aqueous Batteries.

The narrow electrochemical stability window of water poses a challenge to the development of aqueous electrolytes. In contrast to non-aqueous electrolytes, the products of water electrolysis do not contribute to the formation of a passivation layer on electrodes. As a result, aqueous electrolytes require the reactions of additional components, such as additives and co-solvents, to facilitate the formation of the desired solid electrolyte interphase (SEI) on the anode and cathode electrolyte interphase (CEI) on the cathode. This review highlights the fundamental principles and recent advancements in generating electrolyte interphases in aqueous batteries.

Reversible Cl/Cl- redox in a spinel Mn3O4 electrode.

A unique prospect of using halides as charge carriers is the possibility of the halides undergoing anodic redox behaviors when serving as charge carriers for the charge-neutrality compensation of electrodes. However, the anodic conversion of halides to neutral halogen species has often been irreversible at room temperature due to the emergence of diatomic halogen gaseous products. Here, we report that chloride ions can be reversibly converted to near-neutral atomic chlorine species in the Mn3O4 electrode at room temperature in a highly concentrated chloride-based aqueous electrolyte. Notably, the Zn2+ cations inserted in the first discharge and trapped in the Mn3O4 structure create an environment to stabilize the converted chlorine atoms within the structure. Characterization results suggest that the Cl/Cl- redox is responsible for the observed large capacity, as the oxidation state of Mn barely changes upon charging. Computation results corroborate that the converted chlorine species exist as polychloride monoanions, e.g., [Cl3]- and [Cl5]-, inside the Zn2+-trapped Mn3O4, and the presence of polychloride species is confirmed experimentally. Our results point to the halogen plating inside electrode lattices as a new charge-storage mechanism.

Li2 MnO3 : A Catalyst for a Liquid Cl2 Electrode in Low-Temperature Aqueous Batteries.

Li2 MnO3 has been contemplated as a high-capacity cathode candidate for Li-ion batteries; however, it evolves oxygen during battery charging under ambient conditions, which hinders a reversible reaction. However, it is unclear if this irreversible process still holds under subambient conditions. Here, the low-temperature electrochemical properties of Li2 MnO3 in an aqueous LiCl electrolyte are evaluated and a reversible discharge capacity of 302 mAh g-1 at a potential of 1.0 V versus Ag/AgCl at -78 °C with good rate capability and stable cycling performance, in sharp contrast to the findings in a typical Li2 MnO3 cell cycled at room temperature, is observed. However, the results reveal that the capacity does not originate from the reversible oxygen oxidation in Li2 MnO3 but the reversible Cl2 (l)/Cl- (aq.) redox from the electrolyte. The results demonstrate the good catalytic properties of Li2 MnO3 to promote the Cl2 /Cl- redox at low temperatures.

Strengthening Aqueous Electrolytes without Strengthening Water.

Aqueous electrolytes typically suffer from poor electrochemical stability; however, eutectic aqueous solutions-25 wt.% LiCl and 62 wt.% H3 PO4 -cooled to -78 °C exhibit a significantly widened stability window. Integrated experimental and simulation results reveal that, upon cooling, Li+ ions become less hydrated and pair up with Cl- , ice-like water clusters form, and H⋅⋅⋅Cl- bonding strengthens. Surprisingly, this low-temperature solvation structure does not strengthen water molecules' O-H bond, bucking the conventional wisdom that increasing water's stability requires stiffening the O-H covalent bond. We propose a more general mechanism for water's low temperature inertness in the electrolyte: less favorable solvation of OH- and H+ , the byproducts of hydrogen and oxygen evolution reactions. To showcase this stability, we demonstrate an aqueous Li-ion battery using LiMn2 O4 cathode and CuSe anode with a high energy density of 109 Wh/kg. These results highlight the potential of aqueous batteries for polar and extraterrestrial missions.

Microbial inactivation of milk by low intensity direct current electric field: Inactivation kinetics model and milk characterization.

Microbial inactivation by pulsed electric field (PEF) has been studied widely although with high operational risk, while few studies on the potential of low intensity electric fields for microbial inactivation have been reported. In this study, the feasibility of inactivating microorganisms in milk by low intensity direct current (DC) electric field was investigated. Then a kinetics model was proposed based on the inactivation curves. Finally, the effect of electric field on the microflora and physicochemical properties of milk was analyzed. Results showed that the bacterial reduction >5 log CFU/mL could be achieved at 50-55°C, 0.3 A-0.6 A, and with 5 min starting intensity of 5 V/cm-9 V/cm. The inactivation kinetics consisted of three stages, therein, the middle stage, main part of the inactivation curve, followed 1st-order reaction kinetics, and the effect of temperature on it was consistent with the Arrhenius Law, which implied that the electric field itself can inactivate bacteria without thermal inactivating effect. The microflora analysis showed that naturally occurring bacteria in the milk contained typical potential pathogenic bacteria (e.g., 56.9% of Acinetobacter spp.) and spoilage bacteria (e.g., 27.5% of Pseudomonas spp.), and the electric field can inactivate them. Moreover, the inactivation chemically preserved the milk's fresh-like characteristics (according to indexes of whey protein denaturation rate, furosine content), and physical stability (turbidity, zeta potential, particle size, color and so on). Therefore, a promising approach is provided for microbial inactivation in dairy industry.

Reversible Copper Cathode for Nonaqueous Dual-Ion Batteries.

Most reported cathodes of nonaqueous dual-ion batteries (DIBs) host anions via insertion reactions. It is necessary to explore new cathode chemistry to increase the battery energy density. To date, transition metals have yet to be investigated for nonaqueous DIBs, albeit they may offer high capacity in anodic conversion reactions. Here, we report that bulk copper powder exhibits a high reversible capacity of 762 mAh g-1 at 3.2 V vs. Li+ /Li and relatively stable cycling in common organic electrolytes. The operation of the copper electrode is coupled with the transfer of anion charge carriers. An anion exchange membrane separator is employed to prevent Cu2+ from crossing from the catholyte to the anode side. We designed an unbalanced electrolyte with a more concentrated anolyte than a catholyte. This addresses the concentration overpotential ensued during charge and facilitates the high specific capacity and enhanced reversibility. This finding provides a promising direction for high-energy DIBs.

Polymorph Evolution Mechanisms and Regulation Strategies of Lithium Metal Anode under Multiphysical Fields.

Lithium (Li) metal, a typical alkaline metal, has been hailed as the "holy grail" anode material for next generation batteries owing to its high theoretical capacity and low redox reaction potential. However, the uncontrolled Li plating/stripping issue of Li metal anodes, associated with polymorphous Li formation, "dead Li" accumulation, poor Coulombic efficiency, inferior cyclic stability, and hazardous safety risks (such as explosion), remains as one major roadblock for their practical applications. In principle, polymorphous Li deposits on Li metal anodes includes smooth Li (film-like Li) and a group of irregularly patterned Li (e.g., whisker-like Li (Li whiskers), moss-like Li (Li mosses), tree-like Li (Li dendrites), and their combinations). The nucleation and growth of these Li polymorphs are dominantly dependent on multiphysical fields, involving the ionic concentration field, electric field, stress field, and temperature field, etc. This review provides a clear picture and in-depth discussion on the classification and initiation/growth mechanisms of polymorphous Li from the new perspective of multiphysical fields, particularly for irregular Li patterns. Specifically, we discuss the impact of multiphysical fields' distribution and intensity on Li plating behavior as well as their connection with the electrochemical and metallurgical properties of Li metal and some other factors (e.g., electrolyte composition, solid electrolyte interphase (SEI) layer, and initial nuclei states). Accordingly, the studies on the progress for delaying/suppressing/redirecting irregular Li evolution to enhance the stability and safety performance of Li metal batteries are reviewed, which are also categorized based on the multiphysical fields. Finally, an overview of the existing challenges and the future development directions of metal anodes are summarized and prospected.

Anticatalytic Strategies to Suppress Water Electrolysis in Aqueous Batteries.

Aqueous electrolytes are the leading candidate to meet the surging demand for safe and low-cost storage batteries. Aqueous electrolytes facilitate more sustainable battery technologies due to the attributes of being nonflammable, environmentally benign, and cost effective. Yet, water's narrow electrochemical stability window remains the primary bottleneck for the development of high-energy aqueous batteries with long cycle life and infallible safety. Water's electrolysis leads to either hydrogen evolution reaction (HER) or oxygen evolution reaction (OER), which causes a series of dire consequences, including poor Coulombic efficiency, short device longevity, and safety issues. These are often showstoppers of a new aqueous battery technology besides the low energy density. Prolific progress has been made in the understanding of HER and OER from both catalysis and battery fields. Unfortunately, a systematic review on these advances from a battery chemistry standpoint is lacking. This review provides in-depth discussions on the mechanisms of water electrolysis on electrodes, where we summarize the critical influencing factors applicable for a broad spectrum of aqueous battery systems. Recent progress and existing challenges on suppressing water electrolysis are discussed, and our perspectives on the future development of this field are provided.

Exploration of the form factors of turbulence kinetic energy transfer for shear exfoliation of graphene.

Mass production of defect-free and large-lateral-size 2D materials via cost-effective methods is very important. Recently, shear exfoliation has shown great promise for large-scale production due to its simple operation, environmental-benignity and wide adaptability. However, a long-standing challenge is that with the production of more nanosheets, a ceiling yield and shattered products are encountered, which significantly limits their wider application. The method and efficiency of energy transfer in fluid is undoubtedly the key point in determining exfoliation efficiency, yet its in-depth mechanism has not yet been described. Thus, a thorough investigation of turbulence energy transfer is critically necessary. Herein, we identify two main factors that critically determine the exfoliation yield and provide a statistical analysis of the relationship between these factors and the exfoliation yield. In the initial shearing process, the coexistence of the 2D nanosheets and raw particles is the dominant factor; as time passes, the dimensional change of raw materials gradually has a greater influence on the energy transfer. These factors together lead to attenuated efficiency and a power function relationship between yield and exfoliation time. This investigation gives a statistical explanation of shear exfoliation technology for 2D material preparation and provides valuable insights for mechanical exfoliating high-quality 2D materials.

Polypyrrole coated δ-MnO2 nanosheet arrays as a highly stable lithium-ion-storage anode.

Manganese dioxide (MnO2) with a conversion mechanism is regarded as a promising anode material for lithium-ion batteries (LIBs) owing to its high theoretical capacity (∼1223 mA h g-1) and environmental benignity as well as low cost. However, it suffers from insufficient rate capability and poor cyclic stability. To circumvent this obstacle, semiconducting polypyrrole coated-δ-MnO2 nanosheet arrays on nickel foam (denoted as MnO2@PPy/NF) are prepared via hydrothermal growth of MnO2 followed by the electrodeposition of PPy on the anode in LIBs. The electrode with ∼50 nm thick PPy coating exhibits an outstanding overall electrochemical performance. Specifically, a high rate capability is obtained with ∼430 mA h g-1 of discharge capacity at a high current density of 2.67 A g-1 and more than 95% capacity is retained after over 120 cycles at a current rate of 0.86 A g-1. These high electrochemical performances are attributed to the special structure which shortens the ion diffusion pathway, accelerates charge transfer, and alleviates volume change in the charging/discharging process, suggesting a promising route for designing a conversion-type anode material for LIBs.