We demonstrate that in situ impedance spectroscopy is a marker method to follow LaNiO3 decomposition upon hydrogen reduction and is highly potent for the in situ detection of bulk- and surface-located chemical and structural transitions. Combined with in situ X-ray diffraction (XRD), it simultaneously proved the possibility to assess the electrochemical properties of oxygen-deficient phases and the full decomposition products La2O3 and Ni. In situ correlation of impedance and differential thermoanalytic data allows quantitatively pinpointing distinct exothermic peaks to LaNiO2.5 and La2O3 + Ni formation. The initial impedance increase at low temperatures is related by in situ near-ambient pressure X-ray photoelectron spectroscopy to near-surface redox transformations. Equilibrium impedance investigations revealed a pronounced kinetic delay in the structural transformations at low temperatures. In situ impedance spectroscopy upon redox cycling between reductive (H2) and oxidative (O2) conditions allowed us to clearly discriminate between reversible and irreversible transformations and demonstrated exceptional sensitivity to surface reorganization, including the reoccupation of oxygen vacancies and recompensation of structural defects. Frequency-dependent investigations demonstrate that LaNiO3 exhibits an inductive reactance in O2. Formation of oxygen-deficient LaNiO2.5 and irreversible decomposition into La2O3 + Ni are reflected in the frequency-dependent investigations and expressed via increasing capacitance. p-type semiconduction profoundly influences the impedance behavior of NiO in oxidative and reductive atmospheres and was found to be the key conduction contribution of LaNiO3 decomposition at 600 °C. Our work highlights the strength of in situ impedance spectroscopy as a noninvasive, highly responsive marker for surface chemistry, defect dynamics, and bulk structural transformations during redox experiments in perovskites, as evidenced for LaNiO3.

Characterization of brake wear particle emissions from passenger cars: A case study of particle agglomeration and fragmentation.

The sensing mechanism of Rh3 doped GaSe monolayer toward SF6 decomposition products: A first-principle study

High temperature reactor system for molten salt stability monitoring based on gas-phase decomposition product analysis

Perfluorooctane sulfonate (PFOS) has been widely utilized in products such as cotton textiles, hydraulic oils, coatings, pharmaceuticals, cosmetics, etc. Now it is widely distributed in various environmental media, wildlife, and human bodies. Polystyrene (PS) as a kind of plastics, their products under the physical, chemical, and biological decomposition in the environment are widely distributed in the air, soil, oceans, surface water, and sediments. However, PS and PFOS often coexist in the environment, making the study of their combined exposure mechanisms more aligned with actual conditions. This research integrates network toxicology and molecular biology techniques to predict the toxicity and common differentially expressed gene enrichment pathways of PFOS and PS. This study investigates the toxic effects of combined exposure to PFOS and PS on the mouse growth and development, immune functions, and other aspects. Additionally, it delves into the expression differences in various genes in mice after stimulation by PFOS and PS, the pathological changes in multiple organs, and the toxic effects on organs such as the liver, kidneys, and intestines. The results reveal that combined exposure to PFOS and PS does not significantly damage the kidney but leads to morphological damage in the liver and intestinal tissues, reduced antioxidant capacity, and the occurrence of inflammation. Based on the network toxicology findings, it is hypothesized that during combined exposure to PFOS and PS, the exacerbation of inflammatory responses further mediates the reduction in antioxidant capacity and the intensification of oxidative stress, ultimately resulting in tissue damage. This study provides innovative theoretical and research directions for the detection and prevention of combined exposure to PFOS and PS, offering a new paradigm for toxicological research, with significant theoretical and practical implications.

Stabilizing high-voltage cathodes in lithium metal batteries (LMBs) remains a key challenge due to severe interfacial degradation. Although anion-derived, inorganic-rich cathode-electrolyte interphases (CEIs) offer a promising solution, most conventional anions are chemically inert and lack the multifunctionality required to undergo both chemical and electrochemical decomposition across a wide potential window. Existing strategies to enhance anion reactivity often involve trade-offs in salt concentration, anodic stability, or environmental concern, highlighting the need for novel anion design with intrinsic and synergistic interfacial activity. In this study, we designed a multifunctional anion, 1,1,1-trifluoro-2,5,8-trioxa-1-borate (FTOB), by integrating a chelating polyethylene glycol backbone with a terminal -BF3 group as a CEI precursor. The reactive B-O bond facilitates a stepwise interphase formation mechanism: chemical decomposition of FTOB and PF6- at lower potentials (<4.5 V vs Li+/Li) via their mutual interactions, followed by direct electrochemical oxidation of FTOB at higher potentials. These dual pathways enable the construction of LiF- and borate-rich CEIs, supporting stable cycling of LMBs with both 4.3-V high-nickel layered cathode and 5-V cobalt-free spinel cathode. This work highlights the potential of rational anion design to integrate multiple interfacial formation mechanisms, advancing interphase engineering for high-voltage LMBs.

This study explores the thermo-mechanical coupling mechanism of cyclotrimethylene trinitramine particles during high-speed collisions by combining molecular dynamics simulations and an analytical model, with a focus on elucidating how plastic deformation triggers hotspot formation. Analytical models of particle collisions with varying sizes and velocities were established to analyze the evolution of contact forces and temperature increase during the collision process. Both numerical and analytical results demonstrate that plastic deformation is a key factor that leads to the localized temperature rise, featured by a universal correlation between the proportion of atoms in severely plastic deformed regions and high-temperature atoms, clarifying the quantitative relationship between plasticity and heating. Furthermore, the analysis of C–N bond evolution reveals how collision-induced plasticity initiates the potential chemical decomposition. This research provides a critical foundation for understanding mechanical–thermal transition during high-speed collisions of energetic materials.

Introduction Battery technologies have been attracting attention in recent years as a key solution for achieving a carbon-neutral society, owing to their potential for renewable energy storage and use as a power source. In particular, all-solid-state batteries (ASSBs) using non-volatile and flame-resistant solid electrolytes, are being actively investigated worldwide for practical implementation due to their expected safety advantages. Solid polymer electrolytes (SPEs) are of particular interest due to their high flexibility and processability. In polyether-based SPEs, cations are solvated by the host polymer and occur in ionic conduction through cooperative transport associated with segmental motion. In this study, we focused on gel polymer electrolytes (GPEs) and compared their ionic conductivity and transport properties with those of SPEs. These characteristics are influenced by the electrolyte and salt structures, as well as by the solvation and desolvation processes of cations and their decomposition reactions. To investigate these effects, we fabricated [Li | electrolyte | Li] symmetric cells and evaluated the ionic transport processes in SPEs and GPEs of varying concentrations using operando Raman spectroscopy.1) Specifically, we examined SPEs and GPEs incorporating LiN(SO2CF3)2 (LiTFSI) and LiN(SO2C2F5)2 (LiBETI) as Li salts, aiming to investigate the impact of anion structure, molecular weight, and electrolyte composition on ionic transport mechanisms under actual reaction conditions. Experiments Li-based SPEs were prepared by mixing a cross-linked polyether-based macromonomer, P(EO/PO) (EO: PO = 8:2), with Li salts (LiTFSI, LiBETI) and the photopolymerization initiator DMPA in acetonitrile under an Ar atmosphere in a glove box. The resulting solutions were vacuum-dried overnight. Li-based GPEs were prepared using the same materials but with tetraglyme (G4) as a solvent under an Ar atmosphere. Each prepared SPE and GPE material was filled between glass plates with a 0.5 mm thickness spacer and fabricated by UV irradiation. Raman spectroscopy measurements were performed to analyze the solvation structure and salt dissociation characteristics of SPEs and GPEs (salt concentration: [Li]/[O]=0.04-0.16) under static conditions, where no external field was applied. For in-situ monitoring of concentration variations during electrochemical reactions, a 9 mm × 9 mm rectangular-shaped [Li | SPE/GPE([Li]/[O]=0.10) | Li] symmetric cell was prepared. The cell was placed in a sealed cell with a quartz glass observation window and connected to a potentiostat (HZ-7000, Hokuto Denko). During operando Raman spectroscopy, Raman spectrum were recorded from the regions near the working electrode (W.E.) and counter electrode (C.E.) inside the SPE and GPE while applying a voltage of 300 mV. Measurements were taken at approximately 10-30 µm from the electrode/electrolyte interface. The obtained Raman spectra were normalized to the peak position of a standard sample (polypropylene) and the peak area of the CH2 band (1440-1500 cm-1) in the electrolyte. Results & Discussion Raman spectrum of the P(EO/PO)-LiTFSI (SPE) and P(EO/PO)-G4-LiTFSI (GPE) systems were obtained under static conditions (Figs. 1 and 2). Both systems exhibited a peak at approximately 740 cm-1, corresponding to the SNS vibration of the TFSA anion.2 ) The intensity of this peak increased with salt concentration, making it a useful indicator for evaluating concentration changes within SPEs and GPEs during a electrode reactions. To evaluate the ionic transport properties, operando Raman spectroscopy measurements were performed on [Li | SPE/GPE([Li]/[O]=0.10) | Li] symmetric cells. The peak area change (A/A 0 ) from the initial state was calculated from the obtained Raman spectrum. Fig. 3 shows the relationship between A/A 0 and voltage application time at measurement points near the W.E. and C.E. in both SPE and GPE systems. The results show that concentrations levels near the W.E. and C.E. increased or decreased in response to voltage application. Notably, in both systems, A/A 0 exhibited a rapid increase near W.E., suggesting that this concentration increase is associated with Li dissolution. However, the timing of this increase differed between the systems. In the GPE system, the A/A 0 increase was observed after 4 hours, whereas in the SPE system, it occurred immediately upon voltage application. This delay in the GPE system is attributed to its superior high ionic transport properties and cation transference properties, which are influenced by its electrolyte structure. These findings indicate that the ionic transport mechanisms under reaction conditions differ depending on the electrolyte structure. In the presentation, additional operando Raman spectroscopy results for the LiBETI system and the application of GPEs in Li-ion batteries will also be discussed.(1) K. Hiraoka and S. Seki, J. Phys. Chem. C, 127, 11864 (2023).(2) I. Rey, et al, J. Electrochem. Soc., 145, 3034 (1998). Figure 1

Supercapacitors and batteries both have great potential to store energy, albeit based on different storage mechanisms. Batteries can store large amount of energy via faradaic processes but the energy is delivered at a comparatively slower rate. In contrast, supercapacitors are able to rapidly deliver the stored energy, i.e., have high power properties. This ability is mostly achieved through the storage mechanism that is based on the formation of electric double layers by adsorption of the electrolyte ions at porous carbon-based electrodes.[1] The electrolyte is the vital component of the supercapacitor as many properties of the supercapacitors can be influenced through the electrolyte.[2] Three main characteristics are of utmost importance for an optimal electrolyte: conductivity, viscosity and stability. Thermal stability and material compatibility are also important. Viscosity and conductivity have a direct influence on the ion transport and thus performance of the supercapacitors. The stability or more specifically, the electrochemical window of the electrolyte is of particular interest due to the proportionality of the energy to the voltage (E=0.5*C*U 2).[3] Thus it is possible to significantly enhance the energy density through modest increases of the voltage.Ionic liquids, which are salts in the liquid phase below 100°C, are interesting as “solvent-free” electrolytes. The properties of ILs can be tailored through the choice of anion and cation and as such they are sometimes considered “designer solvents”.[3,4 ,5 ] Room temperature ionic liquids (RTILs), salts which are liquid at room temperature, have attracted attention due to the possibility to obtain a device with a voltage above 3 V. The perceived disadvantage of ILs, i.e., low conductivity and high viscosity, can be tweaked by utilizing weakly-coordinating anions.[3] Borate-based anions are of particular interest in this regard. Electrolytes based on [B(CN)4]− have been tested in supercapacitors and exhibit good conductivity/viscosity and wide stability.[6] This improvement can be pushed further with cyano(fluoro)borates without significant loss of stability.[7] However, [B(CN)4]− ionic liquids are reported to polymerize if they decompose.[8,9] Our results shown that the cyano(fluoro)borate-based RTIL electrolytes in combination with microporous activated carbon exhibit behaviour during cyclic voltammetry that suggests a passivation of the surface/ blocking of the porous network. From a variety of candidates, N-butyl-N-methyl-pyrrolidinium tricyanomonofluoroborate, Pyr14MFB, and 1-ethyl-3-methyl-immidazolium tricyanomonofluoroborate, EMImMFB, have been selected as subjects for in-depth study. To investigate blocking of the micropores, cyclic voltammetry and voltage floating will be conducted also with a mesoporous carbon material. Furthermore, the impact of conductive additives upon the long-term stability of the microporous activated carbon will be examined. Finally, we will present our approach to identify possible decomposition products mainly responsible for ageing of the microporous electrodes by performing NMR measurements on electrolytes aged under potentiostatic conditions.[1] A. Noori, M. F. El-Kady, M. S. Rahmanifar, R. B. Kaner, M. F. Mousavi, Chem. Soc. Rev. 2019, 48, 1272–1341.[2] C. Zhong, Y. Deng, W. Hu, J. Qiao, L. Zhang, J. Zhang, Chem. Soc. Rev. 2015, 44, 7484–7539.[3] J. Feng, Y. Wang, Y. Xu, Y. Sun, Y. Tang, X. Yan, Energy Environ. Sci. 2021, 14, 2859–2882.[4] A. Balducci, J. Power Sources 2016, 326, 534–540.[5] A. Brandt, S. Pohlmann, A. Varzi, A. Balducci, S. Passerini, MRS Bull. 2013, 38, 554–559.[6] V. L. Martins, A. J. R. Rennie, N. Sanchez-Ramirez, R. M. Torresi, P. J. Hall, ChemElectroChem 2018, 5, 598–604.[7] J. Riefer, L. Zapf, J. A. P. Sprenger, R. Wirthensohn, S. Endres, A.-C. Pöppler, M. Gutmann, L. Meinel, N. V. Ignat'ev, M. Finze, Phys. Chem. Chem. Phys. 2023, 25, 5037–5048.[8] J. Kruusma, A. Tõnisoo, R: Pärna, E. Nõmmiste, I. Kussik, M. Vahtrus. I. Tallo, T. Romann, E. Lust, J. Electrochem. Soc. 2017, 164, A3393-A3402.[9] T. Romann, E. Anderson, P. Pikma, H. Tamme, P. Möller, E. Lust Electrochem. Commun. 2017, 74, 38-41.The authors thank Solvionic for providing the IL cation precursors within the scope of the EMPHASIS project.This project has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement N° 101091997. This output reflects only the authors’ view and the European Union cannot be held responsible for any use that may be made of the information contained therein.

Lithium metal batteries (LMBs) paired with high – voltage cathodes like Li and Mn-rich (LMR) offer high energy density exceeding 400 Wh/kg. However, their commercial adoption is hindered by electrolyte decomposition, cathode electrolyte interface (CEI) instability, dendrite formation, and capacity fade due to structural degradation at high voltages (> 4.6 V). In this study, we present a novel dual – salt localized high-concentration electrolyte (D-LHCE) formulation. This D-LHCE integrates LiPF6 and LiTFSI in a fluoroethylene carbonate (FEC), Dimethyl carbonate (DMC), with 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as a diluent. The dual-salt strategy aims to optimize solvation by enhancing the formation of contact ion pairs (CIP) and aggregates (AGG). This innovative electrolyte formulation is tailored to enhance the stability of both the cathode-electrolyte interphase (CEI) and the solid-electrolyte interphase (SEI) on the lithium metal anode, mitigating oxidative decomposition and parasitic reactions that degrade battery performance.The D-LHCE demonstrated a solvation structure with dual salts AGGs and CIPs, analyzed using Raman and 7Li NMR. For example, Raman spectroscopy showed a shift in peaks at 745 cm-1 for coordinated PF₆- and 741 cm-1 for TFSI- indicating a solvation structure dominated by CIP and AGG resulted from reduced free solvent molecules. 7Li NMR exhibited upfield shifts such as -1.258 ppm and -1.322 ppm indicating enhanced Li-ion interaction with both PF6 - and TFSI- anions, a synergic effect resulted in D-LHCE.Electrochemical property of D-LHCE was compared with a series of electrolytes including a baseline (1 M LiPF6 in EC/EMC), FEC-baseline (1 M LiPF6 in FEC/DMC), and single-salt LHCEs (3 M LiPF6 or 3 M LiTFSI in FEC/DMC with TTE), and D-LHCE (2 M LiPF6 + 1 M LiTFSI in FEC/DMC with TTE). Attributed to its increased interionic interaction and a reduction in the HOMO energy, the D-LHCE presented its superior anodic stability up to 4.75 Vvs.Li, compared with the baseline (4.3 Vvs.Li) and the single-salt LHCE (4.6 Vvs.Li) electrolytes. As a result, D-LHCE electrolyte significantly extended the cycle life of LMR/Li cells, achieving 90.2% capacity retention after 100 cycles at 25oC, compared to 21.9% with the baseline.The influence of D-LHCE on the properties of SEI and CEI layers in LMR/Li cells were investigated after 100 cycles at 25oC. X-ray photoelectron spectroscopy (XPS) shows that Li SEI layer in D-LHCE has LiF rich composition (74.8%) compared with the baseline electrolyte (56.1% LiF), with no detectable Mn signals, indicating robust protection against transition metal dissolution. In addition, scanning electron microscopy (SEM) reveals that D-LHCE produces a compact and uniform SEI layer on Li, whereas the baseline electrolyte produces thicker and porous SEI with significant cracks.The CEI on aged LMR cathodes also benefits significantly from D-LHCE. XPS analysis revealed a thin, LiF-rich CEI layer (60.9%) on LMR compared to the baseline electrolyte (31.7% LiF). SEM images show minimal surface deposits on LMR after 100 cycles in D-LHCE, unlike the thick layers in baseline and FEC-baseline samples. Electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analyses indicate a low interfacial impedance (Rint = 40.4 Ω in D-LHCE vs. 168.4 Ω in baseline), reflecting suppressed CEI growth. These results, demonstrating enhanced CEI stability, will be discussed in detail in the presentation.

Gas evolution and subsequent swelling are critical safety concerns for lithium-ion power batteries during long-term cycling. In this work, commercial power lithium-ion cells were subjected to extended charge–discharge testing, including high-rate pulse charging, where significant swelling was observed. To clarify the origin of this phenomenon, gas analysis was performed using gas chromatography–mass spectrometry (GC–MS), enabling both qualitative and quantitative identification of evolved gases such as CO₂, CO, H₂, and hydrocarbons. In parallel, we investigated long-term degradation behaviours including capacity loss, loss of lithium inventory (LLI), and loss of active material (LAM), and correlated them with gas generation. The results demonstrate that high-rate pulse charging accelerates electrolyte decomposition, lithium plating, and other side reactions, thereby intensifying gas evolution, internal pressure build-up, and cell swelling. This study provides direct evidence linking charging rate, gas evolution pathways, and classical degradation modes, offering new insights into the mechanisms of automotive power battery aging. The findings highlight the importance of optimized fast-charging strategies and advanced electrolyte formulations to mitigate gas evolution, extend cycle life, and improve safety.

The climate crisis has compelled the scientific community to explore new methods of energy generation, storage, and transportation. In addition to the energy carrier, consideration must also be given to how it is converted into usable energy. For hydrogen (H2) and ammonia (NH3), fuel cells are potentially the overall efficient technology for converting these gases into electricity. Among these, hydrogen solid oxide fuel cells (SOFCs) demonstrate high efficiency, although they operate at elevated temperatures. In direct ammonia solid oxide fuel cells (DA-SOFCs), ammonia can be fed directly into the cell, as the anode catalyses the decomposition reaction: 2NH3 → 3H2 + N2. This is typically done using common nickel-based materials such as Ni-YSZ and Ni-GDC.While experimental methods are the conventional means to analyse the performance of a cell, they often present challenges that are difficult to overcome, mostly due to budget and/or time constraints. As a result, computational simulation has emerged as a practical alternative for understanding the physical processes involved in SOFC operation. In this study, the material properties serve as adjustable parameters to represent different materials, allowing for the evaluation of physical fields anywhere within the system.In this work we utilise a DA-SOFC to measure the effect of temperature and fuel composition on power output through computational and experimental methods. The cell consists of a 31 cm tall vertical, 2.55 mm thick alumina tube with a 14.4 mm diameter. Tangent to its interior left wall there is an alumina fuel inlet, 29.96 cm tall, 0.6 mm thick and a diameter of 2.6 mm. At the top of the large tube lies a shorter, 2.8 mm tall alumina tube of the same diameter and thickness. Inside its opening a 200 μm thick LSGM electrolyte disc acts as a sealed lid. There is a 50 μm thick, 1 cm by 1 cm porous square Ni-GDC anode at the center of this disc, on its lower face. Similarly, above it there is a porous square cathode of the same dimensions made of SrCo0.95Re0.05O3-δ. This ensemble is placed inside a cylindrical furnace 29 cm tall with a diameter of 22 cm so that the electrolyte remains at the centre. The top and bottom of the furnace are exposed to the atmosphere. The experimental setup can be seen in Figure 1 (A). For a visual representation of the cell (not to scale) see Figure 1 (B).Simulations are implemented in the software COMSOL Multiphysics®. The stationary model consists of fluid dynamics and species transport in both free flow and porous regions; ionic and electronic current in the active cell phase; heat transfer in the entire domain, and finally electrochemical and ammonia cracking reactions. Boundary conditions are used to prescribe furnace temperature, operational voltage and fuel composition. Physical parameters are measured in-house when possible, otherwise they are obtained from literature or estimated. Equations are coupled and solved with the finite element method using a multi-step procedure. The model is summarized in Figure 1 (C).For a given furnace temperature, a room-temperature mixture of hydrogen and ammonia is supplied through the inlet. A voltage difference is applied between the anode and the cathode to generate polarization and power curves in the range 0.22 to 1.12 V. In the case of the simulation, a step of 0.1 V is used; in this way, a simulated polarization curve has 10 points. This procedure is repeated for furnace temperatures of 650 °C, 700 °C and 750 °C and inlet ammonia fractions of 0, 0.5, 1 (pure hydrogen, 50% ammonia and pure ammonia). Given that electrochemical reactions consume hydrogen only, it is expected that pure hydrogen fuel has better performance.Preliminary results for pure H2 and pure NH3 shown in Figure 1 (D) demonstrate that H2 provides greater power output, as hypothesized. Power peaks using NH3 are approximately half of those using H2. The simulated curves are comparable to experimental results without resorting to prior curve fitting. It can also be observed in Figure 1 (E) that average anode temperatures are lower than furnace temperatures, and this phenomenon is more apparent when pure NH3 is used as fuel. The loss of efficiency when transitioning from H2 to NH3 as fuel can be attributed to the endothermic nature of the reaction 2NH3 → 3H2 + N2, which reduces the temperature in the electrochemically active region which in turn negatively affects the electronic and ionic conductivity of components. Finally, the opportunities for optimum functioning of the cell are further explored computationally considering various operating conditions and potential new materials.Figure 1: (A) Experimental setup, (B) Model geometry (not to scale), (C) Scheme of multiphysics coupling, (D) Experimental and computational power curves for 750 °C, (E) Average anode temperature in relation of furnace temperature. Figure 1

Type-III deep eutectic solvents (DESs) have combinatorial design spaces and have been leveraged as “green” metal leaching agents while being used at elevated temperatures. However, their thermal instability hinders their sustainable, environmentally-friendly advantage, as choline-chloride-based DESs tend to decompose into toxic compounds at these high temperatures. To understand the origin of these instabilities, we assess the long-term thermal stability of ethaline, a 2:1 molar ratio of ethylene glycol: choline chloride, at room temperature (60 °C), and report that at this lower temperature, ethaline already partially decomposes into 2-methoxyethanol, trimethylamine, chloromethane, and diethylaminoethanol. We model the origin of this instability using machine learning interatomic potential simulations, fitted to quantum chemical accuracy, and find that the strong hydrogen-bonding network in ethaline is responsible for binding chlorine in high-energy sites, initiating the uphill SN2 decomposition reaction. We emphasize that the extent of hydrogen bonding appears to significantly modify the potential energy landscape of DESs and should be considered as another design consideration in the creation of new DESs. Our insights and generalizable computational workflow can be applied to several other under-explored solvents, including other types of DESs, ionic liquids, and molten salts. [1][1] Julia H .Yang, Amanda Whai Shin Ooi, Zachary A.H. Goodwin, Yu Xie, Jingxuan Ding, Stefano Falletta, Ah-Hyung Alissa Park, Boris Kozinsky. Room-temperature decomposition of the ethaline deep eutectic solvent, The Journal of Physical Chemistry Letters, in press. DOI: 10.1021/acs.jpclett.4c03645J.H.Y. gratefully acknowledges support from Harvard University Center for the Environment and startup funds from Georgia Institute of Technology.

Fossil fuels derived from coal or petroleum have served as the primary global energy resource for over a century. However, their combustion releases carbon dioxide and other greenhouse gases that contribute to global warming and climate change. Given the significant threat that climate change poses to humanity, considerable efforts are being directed toward the decarbonization of energy supplies. The growing adoption of power-generation systems utilizing wind or solar energy has further driven research into energy-storage devices. In this context, various electrochemical energy-storage systems, including lithium-ion batteries (LIBs) and electrical double-layer capacitors (EDLCs), have been widely explored to improve energy efficiency and sustainability. Parallel to the advancements in battery technologies, EDLCs have received considerable attention due to their high power capabilities, long life cycles, wide range of operating temperatures and rapid charge/discharge characteristics. However, challenges remain in the production of activated carbon electrodes, including low material yield and the inherently low energy density of EDLCs, which is proportional to their capacitance. Although nitrogen doping of activated carbon has been found effective in increasing the capacitance of EDLCs, conventional doping methods such as chemical vapor deposition and plasma treatment are often complex and difficult to implement.Cellulose, as a primary component of plant cell walls and fibers, serves as a highly useful model substance to produce plant-derived activated carbon. There have been reports indicating that the addition and activation of nitrogen-containing organic flame retardants to cellulose can improve both the yield and capacitance of the resulting activated carbon. However, the specific effects of these nitrogen-containing organic flame retardants on yield and capacitance remain unclear. The aim of this study is to elucidate these effects and to determine the optimal conditions for producing carbon electrodes for EDLC applications.Activated carbons were prepared using CO2 activation by adding nitrogen-containing organic flame retardants—melamine sulfate and a structurally similar nitrogen-containing aromatic compound (guanine sulfate)—as well as the thermal decomposition products of melamine, to cellulose. The pore structure of the activated carbons was characterized using nitrogen adsorption–desorption isotherms, with specific surface area, micropore volume, and mesopore volume determined by the BET, MP, and DH methods, respectively. Elemental composition and chemical states were evaluated through elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Two-electrode capacitor cells were fabricated using prepared activated carbons as electrodes. Electrochemical properties were evaluated by constant current charge–discharge testing at 0–0.9 V and a current density of 0.4–2.0 A/g in a 30 °C thermostatic chamber. The specific capacitance C (F/g) was calculated using the charge–discharge curves and the following equation: C = I / ( m ∙ ∆V / ∆t )where I is the discharge current, ΔV the voltage window, Δt the discharge time, and m the mass of active carbon. Electrochemical impedance spectroscopy (EIS) was also performed at a frequency range of 10⁻³–10⁶ Hz with a 5 mV amplitude.The addition of melamine sulfate resulted in a huge increase in activated carbon yield from 10.8% to 24.4%. Depending on the additive, 5% to 11% of nitrogen was introduced into the activated carbon. Even carbon samples with BET specific surface areas below 1000 m² g⁻¹ exhibited enhanced capacitance, exceeding that of a commercial EDLC carbon material with a BET specific surface area of approximately 2000 m² g⁻¹ (33 F g⁻¹ at current density of 0.5A g⁻¹). Moreover, it was found that specific surface area correlated more strongly with capacitance than nitrogen content. Furthermore, a significant correlation was also observed between diffusion resistance of electrolyte ions and capacitance, with mesopore volume having a greater influence on diffusion resistance than nitrogen content. A future challenge lies in identifying the physicochemical factors that contribute to reducing diffusion resistance.

The abundant sodium resources inspired research efforts in developing cost-effective sodium-based batteries as an alternative to Li-ion batteries. Nonaqueous sodium batteries that allow fast charging and low-temperature operation holds the promise to completement available Li-ion batteries used in electric cars and power tools. Highly crystalline sodium manganese ferrocyanide microcubes (Mn-HCF) have emerged as a leading candidate. [1−3] The Mn-HCF features a double perovskite framework, consisting of interconnected Mn─N6 and Fe─C6 octahedra, which ensures facile Na+ mobility and allows for adaptive volume changes during cycling. [4] However, the open framework faces several challenges. Firstly, the interstitial water within these frameworks reduces the availability of Na+ ions and obstructs ion channels. [5] Secondly, metal ions leaching from these structures compromise their structural integrity. [6] Thirdly, the poor electronic conductivity of the crystal structure restricts charge transfer. [7, 8]To address these issues, modifications such as modulating crystal structure, coating organic polymers (pyrrole), and incorporating carbon additives (acetylene black, graphene, carbon nanotubes) have been explored respectively. The crystal structure modulation method can significantly suppress the content of interstitial water and coordinated water, thereby ensuring sufficient Na+ ions transfer and high specific capacity. Organic polymer coating not only improves the structural integrity of the cathode material but also contributes to improved interfacial stability that protects the active material from attacking by electrolyte decomposition products. Carbon additives enhance the electronic conductivity of the microcubes, facilitating better charge transfer during operation. This work presents the synthesis and characterization of these modified Mn-HCF microcubes, emphasizing their unique crystal structure and morphology. Utilizing an aqueous synthesis method, we achieve uniform microcubes with high crystallinity, which are systematically analyzed through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Electrochemical testing reveals that the sodium manganese ferrocyanide microcubes exhibit a high specific capacity, and prolonged cycling stability, underscoring their suitability for practical sodium batteries applications. This research highlights the potential of sodium manganese ferrocyanide microcubes as a viable cathode material, contributing to the advancement of sustainable and cost-effective sodium batteries for future energy storage solutions.

The solid electrolyte interphase (SEI) layer plays a pivotal role in governing the stability and performance of Li-ion batteries, yet its structural and chemical complexity continues to present significant challenges for characterization 1. Understanding the SEI layer formed on silicon anodes is critical for improving the stability of next-generation Li-ion batteries 2,3. In this work, ex-situ X-ray photoelectron spectroscopy (XPS) depth profiling is employed to probe the SEI layer formed on thin-film silicon anodes after electrochemical cycling. The electrodes consist of 25 nm amorphous Si films deposited by direct current magnetron sputtering on Cu substrates. Electrochemical cycling is performed under controlled conditions to form a stable SEI on the Si anodes, including initial formation steps and subsequent low-potential lithiation in a LiPF6-based carbonate electrolyte. To preserve SEI integrity, all samples are recovered by opening the cells inside an Ar-filled glovebox and are transferred to the XPS chamber using an air-free sample holder, avoiding any exposure to ambient conditions. High-resolution XPS spectra reveal the depth-dependent composition of the SEI, including organic and inorganic decomposition products of the carbonate electrolyte and LiPF6 salt. These results provide mechanistic insights into the chemical evolution of the SEI on Si anodes under extended low-potential holds, a condition highly relevant for capacity fading and interfacial instability in Si-based Li-ion batteries. Acknowledgments This research was supported by King Fahd University of Petroleum and Minerals (KFUPM) International Summer Research Program (ISP24209). Work at the Molecular Foundry was supported by the Office of Basic Energy Sciences of the U.S. Department of Energy under contract No. DE-AC02-05CH11231. References Wu, M. Ihsan-Ul-Haq, Y. Chen, and J. K. Kim, Nano Energy, 89, 106489 (2021).Ihsan-Ul-Haq, J. M. Larson, H. Cha, A. Dopilka, and R. Kostecki, Meet. Abstr. MA2024-01 2617 (2024).A. Ahad, T. Kennedy, and H. Geaney, ACS Energy Lett., 9, 4, 1548–1561 (2024).

Non-aqueous rechargeable metal-air batteries are very attractive for energy storage due to their high theoretical specific energies compared to state-of-the art Li-ion batteries. While Li-O2 batteries are often seen as the primary alternative, Na-O2 cells offer advantages over their lithium counterparts due to more reversible chemistry. Since the (electro)chemistry of this system is still in its infancy, one aspect we address is the stability of the aprotic electrolytes due to the high oxidation and reduction potentials in the operating environment. There is intrinsic disparity in understanding the interfaces at atomic/molecular level in organic-based solvents. This is partly due to the previously used poorly defined, polycrystalline, and/or high-surface area electrode materials in organic electrolytes containing trace levels of impurities. By employing electrochemical and in situ surface characterization methods on well-defined metal single crystal surfaces, we establish the stability range and reveal the decomposition products. Additionally, we demonstrate the impact of impurities on interfacial properties in organic environments, adding another piece to the overall understanding of selected aprotic electrolyte stability. We believe that this fundamental insight provides a pathway for the rational design of stable organic electrolytes, which are essential for the development of high-capacity sodium-air batteries.___________________The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan

Given concerns about the low earth abundance of lithium (Li) in Li-ion batteries, there is growing interest in developing a beyond-Li materials basis for rechargeable batteries. Batteries based on sodium (Na) are a compelling alternative due to the ~1000-fold higher concentration of Na in the earth’s crust, along with high charge capacities (1166 mAh/g, 1128 mAh/cm3) if Na is used as a metallic anode. A major issue with Na metal, however, is its chemical reactivity. Conventional carbonate-based battery electrolytes react with Na to form a thick, heterogeneous, and organic-rich solid electrolyte interphase (SEI) that exacerbates plating nonuniformity and capacity loss during cycling.[1,2] In comparison, ether-based electrolytes have been observed to promote the formation of a relatively compact, inorganic-rich SEI on plated Na, which can enable extended cycle life in certain formulations such as NaPF6 in glyme.[1,2] One important yet underexplored aspect of Na electrochemistry, however, is the “pre-cycling” SEI, which forms on the current collector (CC) via electrolyte decomposition before Na plating onset. In Li metal systems, for example, chemical inhomogeneities on the CC can cause current focusing during Li nucleation, intensifying the heterogeneity of Li deposits,[3] and plated Li has even been found to chemically react with surface oxide species on the CC[4] — which is of elevated concern for Na. This study quantitatively examines the pre-cycling SEI formation in a range of relevant ether-based Na electrolytes; we systematically examine various Na salts in glymes of different lengths in order to explore the relationship between the Na+ coordination environment, SEI composition, and ensuing electrochemical behavior.The electrolytes examined herein are 1 M of a Na salt (NaPF6, NaBF4, NaFSI, or NaTFSI) in either 1,2-dimethoxyethane (G1), bis(2-methoxyethyl) ether (G2), triethylene glycol dimethyl ether (G3), or tetraethylene glycol dimethyl ether (G4), if soluble. Raman spectroscopy measurements in different glymes demonstrate varying degrees of ion pairing, providing an avenue for quantitative comparison between Na+--anion coordination and SEI formation products. Na-Al cells are utilized for electrochemical analysis; both galvanostatic reduction and linear sweep voltammetry (LSV) at slow rates reveal small but significant reductive capacities (~0.005 mA/cm2) before Na plating onset in each electrolyte. Cyclic voltammetry is then performed between 0 and 2 V vs. Na, revealing that roughly half of the 1st cycle reductive capacity can in fact be attributed to irreversible electrolyte decomposition. LSV of G3- and G4-based electrolytes in three different Na salts exhibit distinct current density peaks, providing electrochemical signatures of enhanced decomposition for these particular glymes. Next, Al electrodes are systematically polarized to different positive potentials vs. Na; XPS and FTIR analyses reveal both anion and solvent decomposition products on the CC surface. Interphase composition is dependent on polarization potential, which suggests the presence of different electrolyte decomposition pathways. Finally, the impact of the pre-cycling SEI on ensuing electrochemistry is examined. This work further reveals the impact that electrolyte composition can have on the very early stages of battery operation, with lessons relevant to both Na metal and Na-ion battery research.[1] Seh, Z. W., Sun, J., Sun, Y. & Cui, Y. A Highly Reversible Room-Temperature Sodium Metal Anode. ACS Central Science 1, 449-455 (2015).[2] Sayahpour, B. et al. Quantitative analysis of sodium metal deposition and interphase in Na metal batteries. Energy & Environmental Science 17, 1216-1228 (2024).[3] Sanchez, A. J. & Dasgupta, N. P. Lithium Metal Anodes: Advancing our Mechanistic Understanding of Cycling Phenomena in Liquid and Solid Electrolytes. Journal of the American Chemical Society 146, 4282-4300 (2024).[4] Yoon, J. S. et al. Thermodynamics, Adhesion, and Wetting at Li/Cu(-Oxide) Interfaces: Relevance for Anode-Free Lithium–Metal Batteries. ACS Applied Materials & Interfaces 16, 18790-18799 (2024).

Conventional electrochemistry centers on well-defined charge-transfer processes at idealized, “clean” solid–liquid interfaces. In contrast, next-generation energy systems—such as high-energy-density lithium-metal batteries (LMBs)—present a far more complex interfacial landscape, where the formation of a solid–electrolyte interphase (SEI) fundamentally reshapes electron–ion interactions. Although essential for enabling LMBs, the molecular formation mechanisms, evolving structure, and spatial heterogeneity of the SEI remain incompletely understood.In this talk, I will present our recent efforts to decode the molecular principles governing SEI functionality. By combining electrochemical analysis, non-washing X-ray photoelectron spectroscopy (XPS), and synchrotron-based X-ray absorption spectroscopy (XAS), we elucidate how decomposition pathways and microscale heterogeneities dictate SEI composition and performance. Our findings reveal that not all decomposition products remain in the SEI—many persist dissolved—highlighting the critical role of semi-soluble, anion-derived species (e.g., LiF) in forming robust, porous, electrolyte-trapping interphases.Furthermore, we reinterpret the classical electric double layer (EDL) within nanoconfined SEI environments, uncovering key interfacial properties that govern the reversibility of lithium plating and stripping. By retro-engineering the EDL at the molecular scale, we establish essential design principles to optimize the next-generation LMBs. These insights bridge molecular interfacial chemistry with macroscopic battery performance, providing a rational framework for electrolyte and interface engineering toward durable, high-efficiency energy storage systems.

Solid-state Na-ion batteries are an attractive format due to their potential lower cost compared to Li-based systems and higher energy density compared to liquid electrolyte Na-ion systems. To achieve these potential benefits, energy-dense layered-oxides are the typical cathode active material of choice. However, Na-based solid electrolytes must exhibit sufficient oxidative stability (~ 4 V vs. Na/Na+) and chemical compatibility to be paired with layered-oxide cathodes. Halide solid electrolytes have gained significant interest recently as catholytes because they fit these criteria. However, most halides with sufficient electrochemical properties utilize rare and/or expensive metals such as Y, Er, Zr, Nb, Ta, and La, which undermines the cost benefits of Na-based batteries. NaAlCl4 is a promising electrolyte due to its basis on low-cost, extremely abundant aluminum and its oxidative stability to ~ 4 V vs. Na/Na+, but it suffers from low ionic conductivity.This presentation focuses on effective strategies to tailor the anion chemistry of NaAlCl4-based solid electrolytes to enhance key electrochemical properties: ionic conductivity and oxidative stability. Introduction of O2- anions result in a drastic boost in ionic conductivity by 2-3 orders of magnitude, depending on the oxide precursor and synthesis method employed, due to the formation of highly amorphous, mixed phase oxychlorides. Additionally, preliminary F- anion incorporation results suggest that mixed aluminum-halide complexes can effectively extend the oxidative decomposition voltage of the solid electrolyte beyond 4 V vs. Na/Na+, likely due to the formation of passivating, F-rich decomposition products. This improved stability is also accompanied by a moderate increase in ionic conductivity. An expanded oxidative stability limit can support higher voltage cutoff cycling in all-solid-state batteries, achieving higher cathode-level capacity and energy density. Spectroscopic techniques, such as solid-state magic angle spinning NMR, prove to be invaluable for elucidating the complex, mixed-anion local structure of the resultant solid electrolytes and provide insights into the origin of the improved electrochemical properties. These results showcase the ongoing work in our lab to develop high-performing, next-generation battery materials, while maintaining an outlook toward sustainability and practical material costs.