VACNTs decorated with SnO 2 nanoparticles exhibit enhanced charge storage through synergistic EDLC and pseudocapacitance, delivering high gravimetric specific capacitance, energy, and power densities for supercapacitor applications.

The integration of catalysts onto the surface of membranes enables simultaneous physical separation and catalytic transformation of constituents in a feed stream, facilitating improved contaminant removal and fouling mitigation. Distillation membranes are a particularly attractive platform for catalytic membranes because they reject nonvolatile species and exhibit exceptional resistance to oxidative and radical-driven degradation. However, imparting catalytic functionality onto hydrophobic, porous distillation membranes has proven challenging since the membranes used are chemically inert and difficult to modify. Furthermore, catalysts on the membrane surface can decrease hydrophobicity and increase the membrane's susceptibility to pore wetting and failure. In this work, we create a catalytic distillation membrane by coating a polytetrafluoroethylene membrane surface with titanium dioxide (TiO2) via plasma-assisted atomic layer deposition (ALD). By precisely tuning the ALD parameters, we demonstrate localized growth of TiO2 near (within approximately 1 μm) the surface of polytetrafluoroethylene membranes, forming a catalytically active interface while preserving the underlying hydrophobic pore structure. Localized growth of TiO2 is confirmed by electron microscopy and spectroscopy techniques, and membranes coated with 500 cycles of ALD show pressure tolerance up to 12.8 bar and higher than 95% salt rejection in pressure-driven distillation. Photocatalytic activity is demonstrated via the degradation of methylene blue dye under UV irradiation, where increasing TiO2 loading leads to an enhancement in dye degradation. These results establish a general strategy for integrating catalytic functionality into chemically inert, hydrophobic membranes without compromising distillation performance, providing a pathway toward multifunctional membranes that couple advanced oxidation with membrane separation for water treatment.

The integration of catalysts onto the surface of membranes enables simultaneous physical separation and catalytic transformation of constituents in a feed stream, facilitating improved contaminant removal and fouling mitigation. Distillation membranes are a particularly attractive platform for catalytic membranes because they reject nonvolatile species and exhibit exceptional resistance to oxidative and radical-driven degradation. However, imparting catalytic functionality onto hydrophobic, porous distillation membranes has proven challenging since the membranes used are chemically inert and difficult to modify. Furthermore, catalysts on the membrane surface can decrease hydrophobicity and increase the membrane's susceptibility to pore wetting and failure. In this work, we create a catalytic distillation membrane by coating a polytetrafluoroethylene membrane surface with titanium dioxide (TiO2) via plasma-assisted atomic layer deposition (ALD). By precisely tuning the ALD parameters, we demonstrate localized growth of TiO2 near (within approximately 1 mu m) the surface of polytetrafluoroethylene membranes, forming a catalytically active interface while preserving the underlying hydrophobic pore structure. Localized growth of TiO2 is confirmed by electron microscopy and spectroscopy techniques, and membranes coated with 500 cycles of ALD show pressure tolerance up to 12.8 bar and higher than 95% salt rejection in pressure-driven distillation. Photocatalytic activity is demonstrated via the degradation of methylene blue dye under UV irradiation, where increasing TiO2 loading leads to an enhancement in dye degradation. These results establish a general strategy for integrating catalytic functionality into chemically inert, hydrophobic membranes without compromising distillation performance, providing a pathway toward multifunctional membranes that couple advanced oxidation with membrane separation for water treatment.

Reduced graphene oxide (RGO) forward osmosis (FO) membranes have emerged as promising candidates for efficient wastewater management and osmotic energy harvesting, due to their enhanced chemical stability and superior FO performance for low-energy waste brine treatments, such as volume reduction in oxidative chromium brine for cost-effective disposal. This study examines the oxidation resistance of RGO forward osmosis membranes against chromate Cr(VI). Our findings reveal that both the water flux and the reverse salt flux of RGO membranes are suppressed, accompanying an enhanced reverse flux selectivity after exposure to an acidic or neutral medium of Cr(VI) (pH 2.0–7.0). After exposure to a basic Cr(VI) medium of pH 10.0, an increase in reverse salt flux and a reduction in reverse flux selectivity are observed, which could be due to the synergistic effect of both pH and ionic solutes on the RGO membranes, not due to Cr(VI) oxidation. Remarkably, after the removal of chromate with a full rinse, the RGO membranes show a nearly complete recovery of their FO performance.

Fluoroethylene carbonate (FEC) has garnered widespread recognition for its beneficial role in improving the electrochemical performance of lithium (Li)-metal batteries; however, its role in alleviating interface instability of sodium (Na)-metal electrodes remains poorly understood. In this work, we show that, instead of stabilizing the Na electrode, in a conventional porous glass fiber separator-based cell, FEC induces spatial and chemical heterogeneities in the solid electrolyte interphase (SEI), resulting in nonuniform morphological growth at the anode interface. These heterogeneities lead to severe morphological instability and interfacial degradation, with stable cycling limited to less than 30 h, even at low current densities, highlighting the unresolved challenges of FEC utilization in standard separator conditions. Mesoscale modeling further describes how spatial heterogeneity of the SEI, compounded by localized chemical variations due to FEC, promotes nonuniform Na deposition and drives localized hotspots for nucleation and growth. To further interrogate the role of heterogeneity, we show that incorporating well-controlled anodized aluminum oxide separators facilitates uniform SEI formation. This approach mitigates the transport heterogeneity, leading to a more uniform plating/stripping morphology, and maintains a continuous operation for over 600 h with minimal overpotential fluctuation. This study reveals that long-term Na-metal stability in a carbonate electrolyte is governed not only by additive chemistry but also critically by the spatial and chemical homogeneity of the interface enabled through separator architecture.

Nickel-based electrocatalysts remain one of the key materials for industrial alkaline water electrolysis applications. However, the tradeoff between high current densities and durability remains a challenge for these materials, mainly due to the slow deactivation of Ni electrodes over time. Herein, we report that through the introduction of externally-applied acoustic stimulation, the electrochemical activity of Ni electrocatalysts for the oxygen evolution reaction (OER) can not only be significantly improved but also recovered for deactivated Ni electrodes. The conditioning of Ni electrodes via acoustic stimulation improved OER current density by 36%. OER activity was recovered by up to 34% from aged Ni electrodes using on-demand acoustic excitations. Our results show that the observed improvement and recovery of activity are a result of a thinner, reactivated NiOxHy catalyst layer. The demonstrated ability to improve and recover OER activity from Ni-based electrocatalysts will enable alkaline electrolyzer systems to operate at higher current densities by mitigating their degradation, significantly extending their operational lifecycle.

Lithium metal dendrite penetration and interfacial instabilities are critical challenges that hinder the widespread adoption of all-solid-state batteries (ASSBs). In this work, we systematically investigate the impact of viscoplastic deformation on these mechanisms, using Li6PS5Cl electrolyte as an example. This study focuses on evaluating rate-dependent behavior by applying moderate stack pressures with custom-designed electrochemical cycling protocols that employ zero-current holds and sinusoidal-like cycling. The highest critical current density achieved in our study was 4.8 mA/cm2. Our analysis indicates that relatively slow lithium creep mitigates interfacial void formation and enhances the critical current density and cycle life. It also indicates that the stresses in the vicinity of these voids are well above the reported yield stress for lithium metal. The overall findings highlight the critical role of mechanical properties in the stability of the electrolyte-metal interface and demonstrate that leveraging viscoplasticity can substantially enhance the sulfide-based ASSB cycling performance.

Rechargeable alkaline zinc batteries are promising candidates for safe and low-cost energy storage, but suffer from ZnO dissolution that causes irreversible active material loss and rapid capacity decay. Here, we report a seed-in-nanoshell ZnO anode architecture that mitigates dissolution by combining physical confinement with electrochemical restoration of dissolved zincate species. ZnO particles are encapsulated within an ion-sieving carbon nanoshell that restricts zincate diffusion, maintains electrical conductivity, and stabilizes repeated solid-solution-solid transformations. Silver (Ag) nanoparticles incorporated into the nanoshell act as zincophilic nucleation seeds, lowering the Zn deposition barrier and directing the redeposition of dissolved zincate back to metallic Zn during charging. This confinement-enabled restoration mechanism converts zincate dissolution from an irreversible loss pathway into a recoverable process, enabling improved performance under harsh test conditions. The anode also delivers 227.9 mAh g-1 at -40 degrees C. Finally, a scalable tens-of-gram synthesis of ZnO@Ag is demonstrated, underscoring the practical potential of this strategy for advanced aqueous zinc batteries.

Sodium-ion batteries (SIBs) provide a broader chemical design space for cathodes in terms of composition, crystal structure, and redox chemistry, yet current research largely remains confined to ordered layered frameworks. Recently, Li-excess cation-disordered rock-salt (DRX) cathodes have provided an alternative design space, enabled by their exceptional tunability in composition, stoichiometry, and stability/metastability. Inspired by these advances, we significantly expand the compositional space of Na-based cathodes by developing a series of metastable Na-based DRX cathodes based on Na-Ti-Mn-O systems spanning both stoichiometric and over-stoichiometric regimes. We reveal rich structural and chemical complexity arising from Na content and over-stoichiometry and demonstrate that unique local cation ordering motifs are closely correlated with enhanced anionic redox activity and Na-ion utilization. By systematically comparing the electrochemical and structural evolution of stoichiometric and over-stoichiometric compositions, we elucidate distinct metastability-driven mechanisms governing their electrochemical behavior. Our findings fill an important knowledge gap in metastable Na-based DRX chemistry.

Developing high-performance supercapacitors requires electrode materials that combine high energy density, rapid charge transport, and long-term stability. In this study, we report a binder-free hybrid SnO2/vertically aligned carbon nanotubes (VACNTs) composite electrode by directly growing VACNTs on nickel foam via a plasma-enhanced chemical vapor deposition (PECVD) technique, followed by uniform SnO2 nanoparticles coating through a wet-chemical method. The hierarchical structure integrates the electric double-layer capacitance (EDLC) of VACNTs with the pseudocapacitance of SnO2, resulting in enhanced electrochemical performance. The SnO2/VACNTs electrode exhibited a high specific capacitance (262.39 F g-1 at 5 mV s-1) in 1 M KOH, significantly exceeding pristine VACNTs (24.02 F g-1). It delivered an energy density of 22.79 W h kg-1 at a power density of 0.18 kW kg-1 and retained 93% of its initial capacitance after 2000 cycles, demonstrating excellent rate capability and stability. Electrochemical impedance spectroscopy (EIS) revealed a low charge-transfer resistance (0.93 Omega) and small equivalent series resistance (1.65 Omega), indicating efficient electron and ion transport through the conductive VACNT framework. These results highlight the potential of SnO2/VACNTs composites as promising binder-free electrodes for next-generation high-energy, high-power supercapacitors.

Reactive carbide precursor‐based synthesis of NASICON‐type NZSP (Na 1+x Zr 2 Si x P 3‐x O 12 ) solid‐state electrolyte (SSE) is demonstrated, in contrast to the established oxide‐based approach. Exothermic decomposition of ZrC and SiC in air homogenizes microstructure, yielding 98% compact density after conventional sintering at 1200 °C. Quantitative stereology demonstrates that significant microstructural differences are present. Compacts of carbide‐derived Carb‐NZSP are 98% dense with a secondary zirconium oxide (ZrO 2 ) volume fraction of 0.2% ± 0.3%, versus 93% dense and 3% ± 1% for oxide‐derived baseline. For Carb‐NZSP, the secondary glassy phosphate phase is agglomerated, while for baseline, it is dispersed and percolated. Electrochemical testing combined with post‐mortem analysis demonstrates how microstructural control of secondary phases is critical for dendrite suppression: Carb‐NZSP critical current density (CCD) is 3.1 ± 0.8 mA cm − 2 at 0.1 mAh cm − 2 , versus 1.0 ± 0.7 mA cm −2 at 0.1 mAh cm −2 . Cryogenic focused ion beam (cryo‐FIB) analysis demonstrates that in both materials, the porous 2D sheet‐like sodium metal dendrites propagate around and subsume NZSP grains, likely following a path enriched with glassy phase and with porosity. Dendrites also flow around isolated zirconia particles. Phase field simulation reveals deflection of dendrites by mechanically tough zirconia, while brittle glassy phase accelerates dendrite growth, especially when finely distributed.

Metallic Zn is a nearly ideal anode for grid applications owing to its low cost ( ca. 2 USD kg −1 ), existing supply chain, environmental benignity, relative safety, and high stability in water [−0.76 V vs standard hydrogen electrode (SHE)]. The high theoretical capacity (2e − @ 820 mAh g −1 and 5855 mA h cm −3 ), and overall low polarizability (6 × 10 −8 Ω m) further motivate Zn-based battery development as alternatives to lead acid and lithium-ion batteries, despite their considerably lower operating voltages (< 2V).Despite many recent advances, the high-capacity utilization of Zn for thousands of cycles remains a challenge, with cycle life typically obtained at the expense of energy density. We recently began investigating the ability to cycle zinc-based electrodes in both alkaline and mildly acidic electrolytes. In each electrolyte, a dissolution precipitation reaction occurs upon cycling, cycling between metallic Zn and its soluble oxidized species: either zincate [Zn(OH) 4 2- ] in alkaline or Zn 2+ , in acidic electrolytes, with further chemical reactions leading to the formation of ZnO or Zinc hydroxy ‘ate’ species, respectively. In this talk we will cover approaches to stabilize the Zn conversion reactions and extend battery life in alkaline and/or acidic electrolytes with an emphasis on low-cost electrode additives, oxide-based formulations, new electrolyte formulations and/or the use of ion selective separators. Our emphasis is on cycling at high areal and volumetric capacities, properties that are requisite to take studies from the laboratory and adapt them to a commercial battery technology to support grid storage applications. Finally, we will highlight a recent project on the effect of pressure on the cycling behavior of zinc and other conversion cathode materials and the development of a new US-based Zinc battery consortium. This material is based upon work supported by the U.S. Department of Energy, Office of Electricity (OE), Energy Storage Division. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-program laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.