Matter最新文献

Compressive strain engineering improves perovskite stability. Two-dimensional compressive strain along the in-plane direction can be applied to perovskites through the substrate; however, this in-plane strain results in an offsetting tensile strain perpendicular to the substrate, linked to the positive Poisson ratio of perovskites. Substrate-induced strain engineering has not yet resulted in state-of-the-art operational stability. Here, we seek instead to implement hydrostatic strain in perovskites by embedding lattice-mismatched perovskite quantum dots (QDs) into a perovskite matrix. QD-in-matrix perovskites show a homogeneously strained lattice as evidenced by grazing-incidence X-ray diffraction. We fabricate mixed-halide wide-band-gap (E_g; 1.77 eV) QD-in-matrix perovskite solar cells that maintain >90% of their initial power conversion efficiency (PCE) after 200 h of one-sun operation at the maximum power point (MPP), a significant improvement relative to matrix-only devices, which lose 10% (relative) of their initial PCE after 5 h of MPP tracking.

Fundamental understanding of stress buildup in solid-state batteries is elusive due to the challenges in observing electro-chemo-mechanical phenomena inside solid electrolytes. In this work, we address this problem by developing a method to directly measure stresses within solid-state electrolytes. As a proof-of-concept, we provide the first direct measurements of the stress fields generated around the lithium metal dendrites in a model garnet electrolyte, Li_6.75La₃Zr_1.75Ta_0.25O₁₂, and show that these are consistent with the predictions for an internally loaded crack in an elastic solid. The measurements are based on employing the principle of photoelasticity to probe the stress fields during operando electrochemical cycling in a plan-view cell. This new experimental methodology provides a means to access chemo-mechanical events in solid-state batteries and has the potential to provide insight into a variety of chemo-mechanical failure modes.

Developing advanced electrolytes is indispensable for next-generation lithium-metal batteries (LMBs). Unfortunately, the best electrolytes to date are volatile flammable liquids, which pose safety hazards, or solid-state inorganics, which have poor mechanical properties and resistive electrode/electrolyte interfaces. In this study, we report solvent-free inorganic molten salts—mixtures of alkali-based bis(fluorosulfonyl)amide salts—as electrolytes for LMBs that combine the nonvolatility and safety of solids with the improved electrode/electrolyte interfaces and conductivity of liquids. Li_0.3K_0.35Cs_0.35FSA ternary molten salts with a low melting transition of ∼45°C show higher conductivities and higher oxidative stabilities, support higher current densities, and have improved cycling compared to nonvolatile ionic liquids and solid-state polymer and inorganic conductors. They show excellent compatibility with both Li metal anodes (Coulombic efficiency ∼99.8%) and high-voltage cathodes (no oxidation up to 6 V) without corrosion of the aluminum current collector. Solvent-free molten salt electrolytes provide a new class of electrolytes for a wide range of next-generation battery chemistries.

The relentless pursuit of higher efficiencies in perovskite solar cells relies on the use of spiro-OMeTAD as a hole transport material, resulting in an impressive efficiency record of 25.7%. However, these high-efficiency cells have proven vulnerable to harsh heat conditions at 85°C. Here, we employed direct arylation polycondensation to efficiently synthesize a semiconducting polymer (p-O5H-E-POZ-E), the main chain of which consists of a strategic alternation of oxa[5]helicene, 3,4-ethylenedioxythiophene, phenoxazine, and 3,4-ethylenedioxythiophene. The air-doped composite of p-O5H-E-POZ-E and lithium bis(trifluoromethanesulfonyl)imide exhibits a room temperature conductivity of 75 μS cm⁻¹ and an exceptional glass-transition temperature of 187°C. Compared to spiro-OMeTAD, p-O5H-E-POZ-E demonstrates a comparable highest occupied molecular orbital energy level for efficient hole extraction while exhibiting enhanced elastic modulus and fracture strength and reduced water permeation in its composite film. Using p-O5H-E-POZ-E in the hole transport layer, we demonstrate perovskite solar cells with an average efficiency of 24.9% and thermostability at 85°C.

Storing solar-/electro-thermal energy within organic or inorganic phase-change materials (PCMs) is an attractive way to provide stable renewable heating. Herein, we report a facile dynamic charging strategy for rapid harvesting of solar-/electro-thermal energy within PCMs while retaining ∼100% latent heat storage capacity. A bioinspired multifunctional Fe-Cr-Al mesh with high solar absorptance (∼94%), high electrical conductivity (6,622 S/cm), strong corrosion resistance, and high-temperature stability was used as the movable solar-/electro-thermal charger, which can dynamically track the receding solid/liquid interface. Such dynamic charging has demonstrated rapid thermal response (<1 min) and steady fast-charging rates (≥1.1 mm/min), can be driven by low voltage (≤1 V) and low-flux solar illumination (≤500 mW/cm²), and has achieved a high phase-change solar-thermal (∼90.1%) and electro-thermal (∼86.1%) storage efficiency. The dynamic charging approach is a promising route to efficiently harvest renewable thermal energy from intermittent solar and wind power.

Massively fabricating graphene with high density and high ion conductivity is critical but challenging for large-scale compact capacitive energy storage with high energy and power densities. Here, we demonstrate an efficient, kilogram-scale method for fabricating dense, turbostratic graphene by turbulent flow and isotropic capillary compression at violent boiling temperature, successfully resolving the trade-off between high density and high ion conductivity, as well as scale producing. Turbostratic graphene exhibits 5.4× enhanced ion conductivity, high density of up to 1.12 g cm⁻³, and volumetric capacitance of 234 F cm⁻³. Stack cells deliver an energy density of 83.2 Wh L⁻¹ and power density of 14 kW L⁻¹, a milestone in capacitive energy storage. Moreover, orientation and porosity of turbostratic graphene can be tuned by precursors, demonstrating flexibility and viability for diverse applications. Furthermore, all-solid-state pouch cells are fabricated using ionic gel electrolyte, exhibiting multiple optional outputs and being leakage free at bending and folding states.

Molten hydrate electrolytes are promising in tackling severe issues facing aqueous zinc-metal batteries (ZMBs), but their flexible equivalents commensurate with the full “flexible vision” of emerging electronics are still lacking. Here, we advance a general salt-tolerance training strategy to fabricate such electrolytes simply by induction of water molecules and ion migration in rationalized hydrogels. Combined characterizations and simulations verify that there are no free water molecules within the electrolyte. This unique flexible electrolyte features desirable mechanical and electrochemical properties and enables exceptional stability of both the cathode and the Zn anode. Warranted by these features of the electrolytes, the assembled flexible ZMBs deliver an unprecedented cumulative areal capacity of 10.3 Ah cm⁻², and pouch cells with practical areal capacities are realized. Solid-state batteries also demonstrate great potential as reliable flexible power sources. This work opens up an avenue for leveraging flexible molten hydrate electrolytes for energy-dense and stable ZMBs.

Internal stresses that develop during electrochemical cycling can create microstructural electrode damage and capacitance fade. For example, two-dimensional (2D) nanomaterial supercapacitor electrodes can experience damage due to mechanical “breathing” as ions intercalate in and out. However, the coupling between electrochemical and mechanical processes remains extensively unexplored. Here, using a unique instrument designed to measure in situ electrochemo-mechanical coupling, the consequences of stress, strain, and electrochemical charge in 2D supercapacitor electrodes are revealed. Under varying applied tensile strains (up to 1%) on individual electrodes, the capacitance can decrease by as much as 37%. Notably, the in situ development of internal stress in individual electrodes during electrochemical cycling is revealed, in which the total stress changes by about 5% with the adsorption and release of ions. A micromechanics model using an eigenstrain to capture the electrochemical charge explains the resulting coupling. This combined approach provides insight into other 2D nanomaterial electrodes.

Cell-derived formulations possess the potential to combat bacterial infection by adsorbing pathological agents. In this issue of Matter, Gao and coworkers implement intracellular gelation technology to preserve the intact membrane protein receptors of bacteria-pretreated macrophages, enabling them to effectively neutralize toxins, inflammatory cytokines, and bacterial cells.