Michael F. Toney

The widespread adoption of high-energy-density all-solid-state batteries (ASSBs) for electric vehicles, aviation, defense, and other safety-critical applications requires robust tolerance against accidental mechanical abuse. Despite growing attention on thermal instabilities in ASSBs, their response to mechanical abuse remains largely unexplored. Here, we present a comprehensive investigation of mechanical abuse in industry-relevant ASSB pouch cells comprising dry-processed LiNi0.8Mn0.1Co0.1O2 (NMC811) composite cathodes, slurry-processed Li6PS5Cl (LPSCl) separators, and high-capacity Si and Li metal anodes. Controlled indentation experiments on Si-based ASSBs reveal fundamentally different failure behavior from conventional lithium-ion batteries, characterized by extended plastic deformation, delayed internal short-circuit (ISC) initiation, and soft-short behavior under zero stack pressure. X-ray computed tomography reveals a shear-dominated fracture mechanism triggering an ISC through crack-induced layer sliding and cathode-anode contact. While thicker separators can moderately improve mechanical abuse tolerance, increasing stack pressure promotes low-resistance ISC pathways that significantly intensify failure severity, identifying stack pressure as a critical operating parameter governing ASSB safety under mechanical abuse. Experimentally informed thermo-electrochemical modeling further highlights that high state-of-charge (>50%) and elevated stack pressures (5 MPa) poses a critical bottleneck during mechanical abuse, driving ASSBs into thermal runaway scenarios. Finally, we reveal that, unlike Si anode, Li metal-based ASSBs exhibit a fundamentally different failure mechanism, wherein lithium creep and plastic extrusion through mechanically damaged regions lead to catastrophic ISC even under zero-stack-pressure condition. Collectively, this work establishes the mechanistic framework linking mechanical failure, ISC formation, and thermal instability in practical ASSBs, while providing actionable design and operational guidelines for safer, more mechanically resilient ASSBs.

Electrolytes composed of mixed solvents are of significant scientific and technological importance in lithium-ion and beyond-lithium-ion batteries, and more broadly across physical chemistry. Their emergence has highlighted the importance of multiscale phenomena, particularly the development of nanoscale solution heterogeneities. It is therefore essential to assess how these inhomogeneities and nanoscale aggregates influence solvation, transport, and electronic properties. Here we investigate the solution structure and transport properties of aqueous zinc sulfate electrolytes with acetonitrile (ACN) additives, where the addition of ACN leads to improved cyclability. Using complementary anomalous small-angle X-ray scattering, X-ray pair distribution function, electrochemistry, and NMR, we identify the presence of salt-rich-water-rich and salt-poor-ACN-rich nanoheterogeneities and, at higher ACN concentrations, liquid–liquid phase separation. We find that the size of zinc sulfate ion clusters in the water domains increases slightly upon ACN addition, while the ACN-rich domains grow much larger as phase separation is approached. The inverse Haven ratio, determined using the ionic conductivity and diffusivity, is much less than unity and decreases slightly upon addition of ACN, which shows ion–ion interactions. We speculate that the increased ion–ion interactions with increased ACN are a result of a reduction in free water, the increase in zinc sulfate cluster size, and/or an increase in solution tortuosity. This work highlights key phenomena to consider when engineering new water-organic-salt electrolyte systems and establishes a phase diagram for water–ACN–ZnSO4 that can guide advances, such as self-adaptive electrolytes.

High energy/power density solid state batteries require composite cathode optimization. This study reveals optimal electronic/ionic percolation with carbon fibers happens at lower mass ratios (3–5 wt %) compared to particulate carbon (>5 wt %).

Electrolytes composed of mixed solvents are of significant scientific and technological importance in lithium-ion and beyond–lithium-ion batteries, and more broadly across physical chemistry. Their emergence has highlighted the importance of multiscale phenomena, particularly the development of nanoscale solution heterogeneities. It is therefore essential to assess how these inhomogeneities and nanoscale aggregates influence solvation, transport, and electronic properties. Here we investigate the solution structure and transport properties of aqueous zinc sulfate electrolytes with acetonitrile (ACN) additives, where the addition of ACN leads to improved cyclability. Using complementary anomalous small-angle X-ray scattering, X-ray pair distribution function, electrochemistry, and NMR, we identify the presence of salt-rich-water-rich and salt-poor-ACN-rich nano-heterogeneities, and at higher ACN concentrations, liquid-liquid phase separation. We find that the size of zinc-sulfate ion clusters in the water domains increases slightly upon ACN addition, while the ACN-rich domains grow much larger as phase separation is approached. The inverse Haven ratio, determined using the ionic conductivity and diffusivity, is much less than unity and decreases slightly on addition of ACN, which shows ion-ion interactions. We speculate that the increased ion-ion interactions with increased ACN is a result of a reduction in free water, the increase in zinc sulfate cluster size and/or an increase in solution tortuosity. This work highlights key phenomena to consider when engineering new water-organic-salt electrolyte systems and establishes a phase diagram for water-ACN-ZnSO4 that can guide advances, such as self-adaptive electrolytes.

Zinc‐air batteries based on non‐precious‐metal catalysts are promising for sustainable energy conversion, yet their performance is hindered by sluggish oxygen reduction reaction (ORR) kinetics and limited understanding of pathway regulation in metal–organic framework (MOF)‐based catalysts. Herein, we report a bimetallic electron‐conductive Co‐Fe framework based on 2,3,6,7,10,11‐hexaiminotriphenylene (HITP), in which Fe incorporation shifts the ORR toward a greater four‐electron contribution. Structural, electrochemical, and density functional theory (DFT) analyses reveal complementary dual‐site roles: Co sites favor peroxide formation via the 2e ⁻ pathway, whereas Fe sites promote O─O bond activation and subsequent reduction of peroxide intermediates. Peroxide intermediates generated on Co sites can be further converted to OH ⁻ at Fe sites. As a result, the Co _2.2 Fe _0.8 (HITP) ₂ catalyst exhibits enhanced ORR activity and enables a rechargeable zinc‐air battery with an open‐circuit voltage of 1.37 V, a peak power density of 154.2 mW cm ⁻² , and a high specific capacity of 843 mAh g _Zn ⁻¹ along with enhanced cycling stability. This work establishes electron‐conductive MOFs as a well‐defined platform for probing ORR mechanisms and highlights dual‐metal site engineering as an effective strategy for modulating ORR pathways and improving electrocatalytic performance.

Tin halide perovskites (THPs) offer narrower bandgaps and improved environmental safety compared with the widely studied lead-based perovskites, but their air sensitivity has hindered their progress and demands new material design to enable their practical applications. Here we report stable and efficient 2D/3D tin perovskite solar cells enabled by new ultrastable 2D and quasi-2D THPs based on the 4-chloro-phenethylammonium (4ClPEA) cation. The stronger π-stacking interactions and tighter interlayer packing in (4ClPEA)₂SnI₄ among (4XPEA)₂SnI₄ structures (X = H, F, Cl, Br) substantially impede oxygen and water diffusion, enabling superior air and moisture stability and bright photoluminescence lasting several months in ambient air. The addition of 4ClPEA markedly improves 2D/3D THP film crystallinity and orientation, leading to 16.2% efficient 2D/3D THP solar cells that show prolonged storage stability and operational stability at 55 °C surpassing 1,000 h. This study establishes a new strategy for designing stable and efficient THPs towards their practical applications.

Magic-sized clusters are atomically precise nanoparticles that eliminate heterogeneous broadening, thereby enabling narrow ensemble emission. However, the discrete structural stability that causes only certain-sized clusters to exist also inherently disallows continuous optoelectronic tunability. New strategies are required to allow magic-sized clusters to continuously cover regions of the visible spectrum. Herein, we investigate the atomic structures of two oleate-ligated Cd3P2-450 and Cd3As2-525 clusters and conclude that they are structurally homologous based on pair distribution function analysis. The structural similarities between Cd3P2-450 and Cd3As2-525 allow alloying of P and As in these magic-sized clusters without perturbing the structure or the impressive optical properties. Ligand exchange for phosphinate then produces Cd3P2–xAsx magic-sized clusters with continuously tunable, narrow, and bright emission from blue (λmax = 469 nm) to green (λmax = 550 nm).

Solution species govern crystallization pathways that define the morphology of metal halide perovskite thin films, making understanding their behavior essential for predicting film formation. Despite this importance, the structures of iodoplumbate species in widely used solvents, including N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), remain undetermined. Here, we combine optical absorption spectroscopy, X-ray scattering and spectroscopy, and atomistic simulations to demonstrate solvent coordination strength regulates iodide ligand sharing between Pb centers, thereby shaping iodoplumbate structure in lead iodide (PbI ₂ ) and methylammonium lead iodide (MAPbI ₃ ) inks. Weakly coordinating DMF promotes iodo(poly)plumbate formation (> 1 Pb ²⁺ per species), whereas DMSO stabilizes localized iodo(mono)plumbates. Molecular dynamics and computed absorption spectra attribute ~415 nm absorption in MAPbI ₃ –DMF to the formation of short-lived polyplumbate structures. In situ GIWAXS connects these solvent-dependent solution populations to solvate intermediate formation during drying, establishing mechanistic insights for predicting and controlling perovskite crystallization through ink formulation.