ACS Applied Energy Materials最新文献

Conventional carbon fiber (CF) yarn current collectors suffer from severe localized Joule heating and scarce active sites, limiting the high-rate performance and safety of fiber-shaped supercapacitors. Herein, we construct 3D branched burr-structured CF yarns (CFY2, CFY3, and CFY4) via a scalable twist-fracture wrapping strategy. By tuning the twisting intensity, the burr density is systematically regulated from 29.33% to 62.02%. This multipath conduction skeleton promotes macroscopic current sharing, redistributes localized Joule heating, and enhances lateral heat spreading, as evidenced by a significant drop in saturation temperature from 70.1 to 50.2 °C and a broadening of the radial thermal profile full width at half maximum from 43 to 96 pixels. This electrothermal advantage persists after polyaniline (PANI) deposition. The abundant protruding burrs provide an enlarged exposed interface that favors more continuous PANI deposition. Benefiting from the enlarged electrochemically accessible interface, enhanced local ion accessibility to PANI redox sites, and favorable charge-transfer characteristics, the optimized PANI@CFY4 electrode delivers a specific capacitance of 410.0 F g^–1 at 0.5 A g^–1 with 96.4% retention at 5 A g^–1, a charge-transfer resistance of 0.33 Ω·cm². The assembled symmetric fiber supercapacitor achieves a 1 V voltage window, 26.8 Wh kg^–1 at 236.9 W kg^–1, and 70.4% capacitance retention after 10,000 cycles under an electrolyte-maintained protocol, while stably powering wearable electronics.

Photo-rechargeable batteries, which integrate energy conversion and storage in a single device, significantly enhance solar energy utilization. Halide perovskites, especially the two-dimensional (2D) counterparts, have emerged as promising photocathodes in photo-rechargeable Li-ion batteries. However, the photocathodes suffer from the lack of three-dimensional (3D) Li-ion migration and charge transport due to the presence of organic spacer cations separating the inorganic layers, which act as a barrier between them. In this work, using density functional theory, we rationalize the Li-ion migration during charging and discharging in lead-iodide-based 2D perovskites with n-butyl-, cyclohexyl ethyl-, phenyl ethyl-, and pyrene ethyl-ammonium spacer cations. Our results show that the Li-ion migration along the organic spacer cations can be improved by choosing a cation with less dense packing. However, during the charging process under illumination, we find that the large hole polaron creates a positively charged polaronic medium that increases the Li-ion migration barrier along the horizontal direction. Interestingly, if the organic spacer cation does not contribute to the electronic band edges of the material, the Li-ion migration barrier along the spacer cations becomes easier due to the lower migration barrier; however, the barrier significantly increases for electroactive spacer cations. Furthermore, our calculations show that an optimal balance between the spacer’s length and electroactive nature can significantly lower the effective carrier mass along the vertical direction, enabling 3D charge transport in layered metal halide perovskites (MHPs). Thus, our study demonstrates that selecting an organic spacer cation with less dense packing, short length, and non-electroactive nature enhances the 3D Li-ion migration and charge transport. Our study opens the door to spacer-cation engineering for the development of 2D MHP-based photo-rechargeable batteries.

Zinc-polyiodide redox flow batteries (ZIFBs) are promising for large-scale grid energy storage applications. The membrane plays a vital role by enabling selective ion transport while preventing polyiodide crossover, ensuring the long-term performance of the system. Widely used perfluorosulfonic acid membranes, such as Nafion, are expensive and, due to their fluorinated nature, raise environmental concerns. In this work, a fluorine-free sulfonated polyethylene-styrene-co-divinylbenzene (S-PE-PSt-DVB) regenerable interpolymer membrane is designed for ZIFB as an alternative to fluorine-containing membranes such as Nafion. A ZIFB assembled with this membrane demonstrates a volumetric capacity of 20 Ah L^–1 at 40 mA cm^–2 on a 100 cm² cell, with 87% capacity retention even after 500 cycles. Notably, this work demonstrates the first validation of membrane reusability (other than Nafion, to the best of our knowledge) in ZIFB via simple water cleaning, thereby enabling recovery of membrane functionality after cycling. These results highlight the potential of the S-PE-PSt-DVB regenerable membrane for durable and scalable ZIFB. To the best of our knowledge, this study demonstrates a large-area cell with decent areal capacity that achieved over 500 cycles.

Photocatalytic hydrogen evolution represents a promising approach for sustainable solar-to-hydrogen conversion; however, the practical application of CdS photocatalysts is still limited by inefficient charge separation and poor stability. Herein, a V-doped CdS/NiS₂ (VCN) heterostructured photocatalyst was successfully constructed via a facile, in situ hydrothermal strategy for interfacial electronic regulation. The optimized VCN-1 photocatalyst achieves a hydrogen evolution rate of 8704.8 μmol g^–1 h^–1 under visible-light irradiation, which is approximately 133.7 times higher than that of pristine CdS. This enhanced photocatalytic performance is attributed to the synergistic effects of NiS₂ coupling and V doping. The CdS/NiS₂ heterojunction facilitates interfacial electron transfer, while V doping modulates the electronic structure and promotes charge migration. In addition, the VCN-1 photocatalyst maintains stable hydrogen evolution performance during repeated photocatalytic cycles. This work provides an effective strategy for regulating heterointerfaces and electronic structures toward the development of efficient CdS-based photocatalysts for solar energy conversion.

Two-dimensional pentagonal materials have attracted significant attention in thermoelectrics due to their unique geometric symmetry and intrinsic anisotropy. However, breaking the strong coupling between electron and phonon transport at the atomic scale to achieve synergistic optimization remains a critical challenge in this field. Here, based on first-principles calculations combined with Boltzmann transport theory and the self-consistent phonon method, we systematically investigate the electronic properties, lattice dynamics, and thermoelectric properties of pentagonal MSe₂ (M = Pt, Mg, Hg) monolayers. By contrasting PtSe₂, dominated by strong covalent bonding, and MgSe₂, governed by ionic bonding, we elucidate how HgSe₂ achieves a favorable balance between electrical and thermal transport through its distinctive chemical bond characteristics. Our findings reveal that HgSe₂ constructs an ideal “phonon glass-electron crystal” model via weak chemical bonding between the constituted heavy atoms. On one hand, the weak bonding feature caused by size and mass fluctuations induces strong lattice anharmonicity, significantly suppresses phonon group velocities, and enhances multiphonon scattering, resulting in an ultralow room-temperature lattice thermal conductivity of 0.66 W/mK. On the other hand, the weak Hg–Se and covalent Se–Se bonds optimize the band structure, achieving an excellent power factor via high hole mobility and a large Seebeck coefficient. Benefiting from these special transport characteristics, the p-type HgSe₂ monolayer exhibits a remarkable thermoelectric figure of merit of 2.44 at 500 K, substantially surpassing analogous systems. This work uncovers the competitive regulatory mechanism of constituent element attributes and cation electronic configurations on carrier transport and lattice anharmonicity, providing important theoretical guidance for the design of next-generation high-efficiency low-dimensional thermoelectric materials through chemical bond engineering.

Localized heat accumulation in electronic devices degrades performance, safety, and cycle life. Phase change materials (PCMs) have been widely investigated for passive thermal regulation; however, conventional core–shell encapsulated PCMs often exhibit limited effective heat absorption because shell materials remain thermally inactive and heat transport in composite systems remains uncontrolled. In this study, the naturally derived materials gum arabic and gelatin were used as shell materials. The gum arabic/gelatin shell exhibited endothermic reactions over a wider range, providing additional heat absorption beyond the intrinsic phase change enthalpy of the PCM core. Two functionally differentiated composite systems were developed. To mitigate localized heat accumulation, two differentiated composites were developed to address localized heat generation in electronic devices. An insulation-oriented heptadecane and silica aerogel (SA) based composite (BPA/Heptadecane/SA) exhibits a through-plane thermal conductivity of 0.15 W/mK and a heat absorption capacity of 54.7 J/g, whereas eicosane and a heat-spreading-expanded graphite (EG) based composite (BPA/Eicosane/EG) exhibits an in-plane thermal conductivity of 4.80 W/mK and a heat absorption capacity of 59.3 J/g. The results confirm that the proposed enthalpy-enhanced shell structure functions as an active thermal damper and that the hierarchical composite architecture enables simultaneous thermal insulation and directional heat management to mitigate localized heating.

Lithium squarate (Li₂C₄O₄) is a high-capacity cathode prelithiation additive, but its full decomposition voltage (∼4.5 V) induces severe side reactions, necessitating a reduction to 4.2 V for Ni-rich cathodes. This study prepares a carbon-composited Li₂C₄O₄ prelithiation additive and investigates the impact of a 4.2 V potentiostatic activation protocol on its decomposition efficiency, interface evolution, and cell performance. A 24 h potentiostatic step at 4.2 V enables nearly complete decomposition of the additive in half cells, with a first-cycle charge capacity 64.78% higher than under galvanostatic activation. In NCM811 half cells, 100% decomposition is achieved under 4.2 V potentiostatic activation, comparable to 4.5 V galvanostatic activation, while forming a denser cathode-electrolyte interphase (CEI) that reduces impedance and suppresses side reactions. These half cells show 4.76% higher capacity retention after 150 cycles at 1C and deliver 114 mAh g^–1 at 10C. Pouch full-cell tests confirm improved additive decomposition and optimized interphases, raising capacity retention to 92.6% after 150 cycles. This study demonstrates that 4.2 V potentiostatic activation enables efficient prelithiation without high voltage side reactions, providing experimental and theoretical support for industrial applications in Ni-rich ternary systems.

The porphyrin-like M-N₄ coordination environment embedded in two-dimensional (2D) lattices represents a compelling design principle for single-atom electrocatalysts (SACs) targeting the electrochemical nitrogen reduction reaction (eNRR). Density functional theory (DFT) calculations were employed to investigate 2D tetraaza[8]circulene framework (2D-TAC) that provides a periodic array of well-defined M-N₄ active sites and harbours a flat-band electronic structure near the Fermi level. Systematic screening of 25 transition metals based on thermodynamic and electrochemical stability, N₂ activation, and selectivity against the hydrogen evolution reaction (HER) identified Ti, Fe, Mo, and Ta as the most viable candidates. Spin-polarized PDOS, Bader charge, crystal orbital Hamilton population (COHP), local density of states (LDOS), and local magnetic moment analyses collectively confirm that Mo and Ta achieve superior N₂ activation through a backdonation-dominated mechanism amplified by flat-band-derived electronic states. Quantitative LDOS comparison with graphene-N₄ catalysts (GN₄) provides quantitative support for the hypothesis that the flat-band character of 2D-TAC enhances the metal d-electron density at the active site by 4.04-fold for Mo and 1.31-fold for Ta relative to the same coordination on a conventional 2D support. Mo-N₄ achieves a near-zero limiting potential (U_L = 0.00 V vs RHE within the implicit solvation CHE framework) along the distal pathway, among the most favorable limiting potentials reported for 2D M-N₄ catalysts within the CHE framework, while Ta-N₄ delivers U_L = –0.19 V vs RHE. The combined electronic and mechanistic analyses yield four interconnected design principles that extend beyond the present 2D-TAC system and provide consistent guidelines for the rational design of flat-band-enabled single-atom electrocatalysts.

Faceted monoclinic BiVO₄ is a representative visible-light-responsive photocatalyst for water oxidation and solar H₂O₂ production, but its performance strongly depends on crystal morphology, defect density, and charge transport. Here, we optimized the solid–liquid synthesis of faceted BiVO₄ particles from layered K₃V₅O₁₄ and Bi(NO₃)₃ by controlling Mo doping and key reaction parameters. The optimized synthesis promoted the formation of highly crystalline faceted BiVO₄ particles with suppressed defect-related absorption. Time-resolved imaging analysis revealed that the optimized particles contained a larger fraction of active regions, where photogenerated electrons and holes exhibited 3–5 times longer lifetimes. Consequently, the optimized BiVO₄ photocatalyst showed 1.4-fold higher H₂O₂ generation activity from pure water and a 1.2-fold higher O₂ evolution activity in AgNO₃ solution than the reference sample. These results demonstrate that solid–liquid crystal-growth control is an effective strategy for improving faceted BiVO₄ photocatalysts for artificial photosynthesis.

Vanadium redox flow batteries (VRFBs) have garnered distinguished attention for their feasibility to enable cost-effective large-scale energy storage. Nonetheless, the electrochemical activity of electrodes is constrained during vanadium redox reactions, posing a problem for accomplishing high-performance VRFBs. Herein, we prepare a defect-rich Fe-coal-based carbon nanofiber electrode (Fe-ECNFs-600) via electrospinning followed by high-temperature carbonization. The Fe-ECNFs-600 contains moderate oxygen defects, Fe₃O₄ nanoparticles, and oxygen-containing functional groups, which can regulate the electronic structure, improve electrical conductivity, electrolyte wettability, and catalytic activity for the VO₂⁺/VO²⁺ and V³⁺/V²⁺ redox couples. The VRFB with the Fe-ECNFs-600 electrode exhibits improved discharge capacity and energy efficiency compared with ECNFs-600 at 100 mA cm^–2. This work may provide a defect regulation strategy for developing self-supporting electrode materials for VRFBs.