Joule最新文献

In the recent research article by Yuan et al.¹ published in Nature, well-defined faceted lithium metal polyhedra were obtained on ultramicroelectrodes (UMEs) at ultrahigh current densities, yet were surprisingly independent of the choices of electrolyte chemistry and UME materials. The use of UMEs avoids the ion depletion at the electrode-electrolyte interface, allowing the reliable acceleration of the reaction rate of lithium-ion reduction to outpace the reaction rate of formation of the solid electrolyte interphase (SEI), therefore minimizing the influence from SEIs in metal growths. This study revealed, for the first time, the chemistry-independent intrinsic morphology of lithium deposits and opened a new window of viewing the growth mechanisms of lithium plating in lithium-ion and lithium-metal batteries.

Lithium metal batteries (LMBs) have recently received enormous interest as a higher energy density alternative to conventional lithium-ion batteries (LIBs). However, the commercialization of LMBs is currently impeded by poor cycle life due to inhomogeneous lithium deposition and active lithium loss. These are controlled by the solid electrolyte interphase (SEI) that forms on the anode surface, and there have been numerous reported strategies to produce SEIs with desired properties. However, these have not been sufficient to achieve the high cycling stabilities necessary for widespread LMB commercialization, requiring additional understanding of the SEI. In this perspective, we highlight recent progress in characterizing the SEI that forms in LMBs and outline the need to consider SEI nanostructure, transport, and mechanical properties together. We conclude by prescribing several key research fronts necessary for an accurate, systematic study of the SEI that will guide future electrolyte design and enable the development of safe and stable LMBs.

Solution-processable polycrystalline hybrid halide perovskite solar cells have achieved extraordinary efficiencies. However, severe film heterogeneity is prevalent at multiple scales, including composition, lattice structures, and defects, which significantly affects device lifetime. To date, the molecular assembly over lattice-sublattice transformations during film growth is not fully understood. Herein, we reveal the mechanisms of topochemical assembly, wherein a solid-solid transition occurs habitually along the PbI₂/perovskite interface. By introducing intermediates, crystal growth follows an alternative pathway along a different coherent interface. As a result, we obtained an optimal (001)-oriented film with minimized lattice heterogeneity, microstructure defects, and electronic disorder. The corresponding inverted device passed the light-induced degradation test certified by the independent third party following the IEC61215 protocols, which retained over 95% of original power conversion efficiency (PCE) after 500 h (AM 1.5G, one sun). Our work unveils the underlying mechanism that governs perovskite crystal synthesis, which is universally obeyed in two-dimensional and inorganic perovskites.

In a recent Nature Nanotechnology article, Gao et al. improve the wall plug efficiency of quantum dot (QD) light-emitting diodes (LEDs) by reducing the QD packing number. This reduces the need for thermal management and brings QD-LEDs a crucial step closer to the performance of conventional LEDs.

The ability to control thermal emission is crucial for the thermal regulation of devices, barrier coatings, and thermophotovoltaic (TPV) systems. However, only a limited number of naturally occurring materials are stable at high temperatures (>1,800°C), and their emission spectra are set a priori by their intrinsic optical properties. Optical structures involving nanoscale textures can result in tunable emission spectra, albeit stable only at much lower temperatures. Here, we present an alternative approach that enables temperatures beyond 1,800°C through a bilayer stack achieved by combining the optical and thermal properties of 2,809 coating/substrate pairs. By varying the film thickness, we tailor the emission spectrum to create high-temperature, stable emitters. We illustrate this effect in combination with the most common TPV systems (GaSb, Ge, InGaAs, and InGaAsSb), showing power conversion efficiencies approaching 50% and power outputs as high as 10.2 W cm⁻². These concepts can be expanded to other high-temperature photonic applications for the spectral control of thermal emission.

An improved understanding of the degradation pathways under external stimuli is needed to address stability challenges in two-dimensional (2D) perovskite semiconductor materials. In this study, in situ synchrotron nanoprobe X-ray fluorescence (nano-XRF) is used to investigate the evolution of halide redistribution within various 2D halide perovskite (n = 1–3) lateral heterostructures under ultraviolet (UV) exposure. The results show that iodine (I) experiences a loss in all cases, with the rate of change following the perovskite dimensionality monotonically. In contrast, bromine (Br) is relatively more stable than I in n = 2 and 3 heterostructures, with no significant change in the total Br concentration but a visible amount of Br diffusion to the previously I-rich regime. Combining nano-XRF and X-ray absorption spectroscopy (XAS), we found a reduction of dimensionality in crystals with n > 1 after UV exposure, indicating significant structural reconfiguration beyond ion migration.

Electrochemical CO reduction can potentially serve as an intermediate step for the efficient conversion of CO₂ to chemical fuels using renewable electricity. Although membrane electrode assembly (MEA) CO electrolyzers are industrially relevant, they currently suffer from a low energy efficiency (EE) due to a high-cell voltage (typically >3 V at 1,000 mA cm⁻²). In this work, we reveal that water and hydroxide transport at the quasi-two-phase interface of the cathode limits the performance of MEA electrolyzers at high current densities. By developing a system that allows for sufficiently rapid interfacial mass transport, we obtain an electrolyzer that has a cell voltage of only 2.4 V at 1,000 mA cm⁻². The electrolyzer has a Faradaic yield of more than 90% for C₂₊ products and demonstrates a stability of more than 100 h.

The electrochemical CO₂ reduction reaction (CO₂RR) has progressed but suffers an energy penalty from CO₂ loss due to carbonate formation and crossover. Cascade CO₂ to CO conversion followed by CO reduction addresses this issue, but the combined figures of carbon efficiency (CE), energy efficiency (EE), selectivity, and stability require improvement. We posited that increased CO availability near active catalytic sites could maintain selectivity even under CO-depleted conditions. Here, we present a heterojunction carbon reservoir catalyst (CRC) architecture that combines copper nanoparticles with porous carbon nanoparticles. The pyridinic and pyrrolic functionalities of CRC can absorb CO enabling high CE under CO-depleted conditions. With CRC catalyst, we achieve ethanol FE and CE of 50% and 93% (CE∗Faradaic efficiency [FE] = 47%) in flow cell at 200 mA cm⁻², fully doubling the best prior CE∗FE to ethanol. In membrane electrode assembly (MEA) system, we show sustained efficiency over 85 h at 100 mA cm⁻².

Organic thermoelectric (TE) attracts considerable interest as a next-generation energy conversion technology; however, its practical application is still restricted by low power factors. Herein, we report a generally applicable solvent-combination doping method for improving TE properties of conjugated polymers (CPs). Residual solvents in a ternary solvent enlarged the free volume in the CP films. This beneficial effect boosted both dopant diffusion efficiency and charge carrier density in the doped films, resulting in the remarkable enhancement of electrical conductivity in the CPs. When the doped CP films processed with a ternary solvent were applied to TE devices, excellent power factors were achieved, attributed to a durable Seebeck coefficient along with ultrahigh electrical conductivity.