ACS Applied Energy Materials最新文献

Mixtures of lithium bis(trifluoromethylsulfonyl)amide (LiTFSI) salt and glyme-based solvents are potential alternative candidates for commonly used electrolytes. We perform classical molecular dynamics simulations to study the effect of concentration and temperature on translational and rotational dynamics. The radial distribution function shows stronger coordination of Li⁺ ions with tetraglyme (G4), as shown in earlier studies, and forms a stable [Li(G4)]⁺ cation complex. The self-diffusion coefficients are lower than the values experimentally observed but show improvement over other classical force fields without charge scaling. An increase in the salt concentrations leads to a higher viscosity of the system and reduces the overall ionic mobility of Li⁺ ions. Diluting the system with a larger number of G4 molecules leads to shorter rotational relaxation times for both TFSI and G4. Ion-residence times show that Li⁺ ions form stable and long-lasting complexes with G4 molecules rather than TFSI anions. The residence time of the [Li(G4)]⁺ complex increases in the highly concentrated system due to the availability of fewer G4 molecules to coordinate with a Li⁺ ion. G4 is also seen to form polydentate complexes with Li⁺ ions without shared coordination, allowing rotation without breaking coordination, unlike TFSI, which requires coordination disruption for rotation. This distinction explains the poor correlation between rotation and residence time for G4 and the strong correlation for TFSI.

Developing highly active and stable oxygen reduction reaction (ORR) electrocatalysts is crucial for practical energy devices. This study synthesizes PtFe alloy nanoparticles supported on nitrogen-doped carbon (PtFe–N–C) via a microflower-templated strategy. A zinc-based microflower scaffold directs the in situ growth of a polymeric Schiff base (PSB), which coordinates Fe³⁺ and Pt precursors. During pyrolysis under nitrogen, the coordinated metals are synergistically reduced to form PtFe–N–C. The resulting catalyst exhibits exceptional ORR performance in acidic media, with a half-wave potential of 0.84 V vs RHE and a mass activity 4.3 times higher than commercial Pt/C. It also demonstrates outstanding durability, with significantly less performance decay after 30,000 cycles. Inductively coupled plasma–mass spectrometry quantitative analysis reveals that the Pt loading in the catalyst is only 1.15 wt %, which highlights its superior Pt utilization efficiency. This work presents a high-performance ORR electrocatalyst and establishes a design principle for carbon-supported precious metal alloy nanoparticles through rational interface engineering.

We investigate the use of phthalocyanine, from the family of multipurpose functional organic complexes, as an interlayer between the hole-selective contact and the perovskite in self-assembled monolayer-based p-i-n perovskite solar cells. This phthalocyanine interlayer effectively mitigated recombination losses that were occurring between the self-assembled hole-extraction monolayer based on the carbazole functional group and the perovskite film. Furthermore, the crystallinity of the perovskite semiconductor was enhanced, which reduced nonradiative recombination and resulted in an increase in shunt resistance and a higher open-circuit voltage. The efficiency improved from 18.4% to 20.2%. A similar boost in efficiency was found under indoor lighting conditions (from 27.3% to 30.1%). The tetra-3,5-dimethylphenoxy-zinc phthalocyanine (DMPO4) molecule synthesized for this work also enhanced device stability under ISOS-D1 tests with the average T₈₀ increasing from 1134 h to 1347 h with its incorporation. A purpose-designed synthetic strategy, yielding a total E-factor below 200, broadens the practical applicability of these versatile and cost-effective molecular materials.

Hydrogen is a promising source of noncarbon-based energy that is steadily replacing fossil fuels. As an alternative fuel, hydrogen production, its separation, and storage are critical components of advancing a global green energy economy. In this study, the syntheses and hydrogen sorption characteristics of three vanadium-based MOFs [MIL-47(V), MIL-88B(V), and MIL-101(V)] are presented. Additionally, graphene quantum dots (GQDs) having distinctive physiochemical properties were synthesized using a rapid, straightforward, and cost-effective technique and subsequently incorporated with MoS₂ nanoparticles at varying molar ratios. The GQDs^(0.4)/MoS₂ electrode showed outstanding electrochemical hydrogen storage performance, achieving a maximum value of 9100 mAh g^–1 after 20 cycles under a steady current of 1 mA, which represents a growth of more than 1.4 times in comparison with the pure MoS₂ electrode. In addition, GQDs^(0.4)/MoS₂/MIL-101(V) nanocomposites are prepared and optimized via an environmentally friendly method at room temperature. The GQDs^(0.4)/MoS₂/MIL-101(V)-2 nanocomposites demonstrate superior electrochemical hydrogen storage efficiency, delivering a capacity of 10500 mAh g^–1, nearly 1.2 times greater than the that for GQDs^(0.4)/MoS₂ nanoparticles and approximately 4.6 times higher than that of the MIL-101(V) framework.

Lithium–sulfur (Li–S) batteries are promising candidates for next-generation energy storage systems, yet their practical implementation is severely hindered by the shuttle effect of soluble lithium polysulfides (LiPSs) and sluggish multistep sulfur redox kinetics. Here, we design a ZnCoNi zeolitic imidazolate framework (ZnCoNi-ZIF) that is in situ grown on acid-treated multiwalled carbon nanotubes (MWCNTs) and subsequently carbonized to afford an N-doped carbon/MWCNT composite embedded with Zn–Co–Ni nanoparticles (denoted as ZnCoNi-NC@MWCNT). This composite is employed as a functional coating on commercial polypropylene separators. The cooperative effect of trimetallic active sites and the conductive carbon matrix endows the separator with polar M-N_x and pyridinic N sites, a high-surface-area mesoporous architecture, and continuous electron pathways, enabling physical confinement, chemical anchoring, and electrocatalytic conversion of LiPSs. Specifically, uniformly distributed Zn–Co–Ni nanoparticles act as electrocatalytic centers to accelerate the reversible multistep sulfur transformation, while the synergistic interplay among these components mitigates the shuttle effect and reinforces the electrode–electrolyte interface stability. Consequently, Li–S cell with this modified separator delivers 894 mAh g^–1 at 5.2 mg cm^–2 sulfur loading and 0.2 C, and maintains stable cycling over 1908 cycles at 2.2 mg cm^–2 and 0.5C with a low capacity decay of ≈0.041% per cycle and Coulombic efficiency approaching 100%. This work presents a trimetallic-catalyst-based separator engineering strategy for high-performance, long-life Li–S batteries.

At present, lithium-ion batteries face two major challenges in low-temperature applications: mitigating capacity degradation caused by low-temperature operation to enhance overall performance and suppressing the formation of lithium dendrites on the negative electrode to improve safety. A comprehensive understanding of the battery degradation mechanisms under low-temperature conditions is essential for enhancing safety, and developing effective strategies for capacity recovery. This study, through differential voltage analysis, incremental capacity curves, and postcycling disassembly, reveals that the desolvation energy of lithium ions determines whether they intercalate into active materials or deposit as dendrites. After aging at −20 °C, capacity attenuation is primarily due to interfacial degradation, while the electrode bulk structure remains largely intact, indicating recoverable capacity. A key recovery strategy is proposed: implementing low-current charging during the voltage plateau phase. This approach effectively activates electrodes and reconstructs a stable interface film, thereby repairing aging damage and restoring battery capacity. Concurrently, the number and length of lithium dendrites on the anode are significantly reduced, effectively preventing separator penetration and internal short circuits, substantially enhancing subsequent operational safety. Therefore, this study proposes a viable strategy for restoring the capacity of batteries following low-temperature aging, while simultaneously improving the safety of subsequent operation.

Relaxor ferroelectrics, characterized by slim polarization–electric (P–E) hysteresis loops, are promising candidates for energy storage applications. Relaxor behavior in ABO₃ perovskites is induced by multication doping, which enhances the configurational entropy and disrupts long-range ferroelectric ordering. In this study, we investigate the origin of relaxor behavior in (K_0.2Bi_0.2Ba_0.2Sr_0.2Ca_0.2)TiO₃ (KBBSCTO) using experimental techniques and first-principles calculations. Extended X-ray absorption fine structure (EXAFS) analysis, together with theoretical studies, reveal reduced Ti–O hybridization resulting from the multication substitution at the A-site. This substitution disrupts long-range Coulombic interactions, thereby inducing relaxor behavior. The projected density of states (PDOS) further supports these findings. Temperature-dependent Raman spectroscopy demonstrates the displacement of TiO₆ vibrational modes and the disruption of phonon propagation caused by multication disorder. Dielectric measurements yield a diffusion constant within the range characteristic of relaxors, while ferroelectric studies exhibit slim, unsaturated P-E loops associated with polar nanoregions (PNRs). UV–Vis diffused reflectance spectroscopy (DRS) indicates a wide bandgap, consistent with values reported for other relaxor ferroelectrics and in agreement with first-principles calculations. These results emphasize that induced relaxor behavior arising from cation-doped perovskites holds significant promise for advancing energy storage technologies.

In the zinc ion capacitors (ZICs), Zn²⁺ storage is limited by the common carbon-based cathodes due to the sluggish kinetics of zinc ion diffusion. Porous carbon derived from metal–organic frameworks (MOFs) is a good candidate with the abundant micropores and mesopores. By using a one-step template-free solvothermal method, double-shell hollow Zn-MOF microspheres were directly synthesized, eliminating the traditional multistep activation process using KOH/HCl. During the carbonization procedure, urea has been used to provide an additional carbon source and activate the derived carbon, which is due to urea pyrolysis products, such as NH₃, cyanuric acid, and ammelide. The derived porous carbon (U-MPC) exhibits a high specific surface area of 1695.66 m² g^–1. The ZIC device assembled with U-MPC as the cathode has a high specific capacitance of 199.0 F g^–1 and a high energy density of 70.8 Wh kg^–1 at 0.1 A g^–1. The Zn//U-MPC ZICs demonstrate a good antiself-discharge performance, with a low self-discharge rate of only 3.1 mV h^–1 over 300 h, and can maintain 59.7% of the initial capacitance. Moreover, the ZICs exhibit good cyclic stability, showing a slight decrease after 20,000 cycles at 5 A g^–1, and the Coulombic efficiency is 90%.

Photoelectrochemical (PEC) water splitting is a clean method to produce hydrogen from visible light, but titanium dioxide (TiO₂), a common semiconductor, faces challenges due to limited absorption of visible light and rapid recombination of charge carriers. Creating defects in TiO₂ using laser irradiation has shown promise for improving its performance. However, the exact role of laser pulse duration on defect formation and resulting improvements in PEC and photocatalytic activity is not fully clear. This study investigates how femtosecond and nanosecond laser pulses affect TiO₂ nanoparticles differently. The nanosecond laser causes bulk defects by heating, leading to a phase change from anatase to rutile, increased lattice disorder, and a significant reduction in bandgap (from 3.2 to 2.13 eV). In contrast, the femtosecond laser creates defects mainly on the surface without causing phase changes, keeping the anatase structure intact and slightly reducing the bandgap (to 2.9 eV). Despite having a higher bandgap, femtosecond-treated TiO₂ nanoparticles showed better photocatalytic dye breakdown (51% degradation efficiency) and significantly improved PEC water splitting (66% higher photocurrent density compared to untreated TiO₂). These improvements come from better separation of charges due to surface defects. The study highlights the importance of defect location and type, rather than just lowering the bandgap, to enhance TiO₂ performance. This laser method provides a simple, accurate, and environmentally friendly way to control defects, helping improve solar hydrogen generation and pollution control applications.

Glass-ceramic synthesis allows for a faster, scalable, and facile fabrication procedure of ceramic electrolytes in a wide variety of shapes and thicknesses. Na₅YSi₄O₁₂ glass-ceramic electrolytes have shown promising electrochemical performance, exhibiting ionic conductivities in the range of 10^–4∼10^–3 S cm^–1. However, all previous studies used short crystallization durations to minimize sodium loss. While short sintering durations usually limit sodium loss by evaporation or volatilization, it may also be inadequate to crystallize the entirety of glass to pure Na₅YSi₄O₁₂ glass-ceramic. Crystallization of purely Na₅YSi₄O₁₂ glass-ceramic has not been reported or optimized previously. In this study, the crystallization of Na₂O–Y₂O₃–Si₂O glass was systematically investigated by X-ray diffraction measurements and Rietveld refinement. We obtained a glass-ceramic composition purely of Na₅YSi₄O₁₂. This glass-ceramic exhibited a relative density of 98.98%. Electrochemical impedance spectroscopic (EIS) analysis showed a total ionic conductivity of 1.15 × 10^–3 S cm^–1, which was significantly higher than the total ionic conductivity of the Na₅YSi₄O₁₂ electrolyte prepared with solid-state reaction (1.5 × 10^–4 S cm^–1) by our group, previously. Further electrochemical studies were performed to test the electrochemical stability window, electronic conductivity, critical current density, and plating/stripping performance. The glass-ceramic electrolyte lasted noticeably longer than the electrolyte prepared by solid-state reaction in galvanostatic plating/stripping at 15 μA cm^–2 current density without short-circuiting.