ACS Applied Energy Materials最新文献

Li-rich manganese-based layered oxides (LMR) are pivotal for next-generation high-energy-density lithium-ion batteries due to their capacity exceeding 250 mAh/g. Although previous studies have investigated morphology control and performance comparisons between carbonate and hydroxide precursors for ternary cathode materials, research on the critical structural parameter of primary particle thickness in hydroxide precursors remains fragmented and lacks systematic summarization. Consequently, a clear structure–property relationship linking this parameter to the electrochemical performance of the final cathode material has yet to be established. Research indicates that reducing the thickness of the precursor primary particles enhances the uniformity of lithiation during sintering. Simultaneously, cathode materials synthesized from thinner precursor primary particles typically exhibit higher porosity, which can effectively mitigate stress accumulation during charge–discharge cycles and significantly improve the lithium-ion migration efficiency. The final study showed that the sheet thickness was reduced from 190 to 98 nm, the first-cycle discharge capacity was increased to 266.63 mAh·g^–1, and the discharge capacity retention at 5C relative to 0.1C was increased by 46% (from 42.4 to 61.9%). It establishes primary particle thickness as a key descriptor for precursor design, enabling targeted optimization of ion-transport kinetics. This work establishes a microcrystalline engineering strategy that reconciles the rate–stability trade-off in Mn-based cathodes, advancing the commercialization of LMR for emerging applications requiring high energy density and longevity.

Depleted perovskites, a new class of functional materials distinct from conventional doped perovskites, present a transformative approach to enhancing proton conduction. This study introduces Nd-alumina as an A-site-depleted perovskite, systematically comparing its properties with those of the well-known BaZr_0.8Y_0.2O_3−δ (BZY) perovskite. Notably, with the same cation deficit concentration, e.g., 20 mol % Nd-depleted alumina (0.8-NAO), achieves three times the oxygen vacancy (O_vac.) concentration compared to 20 mol % Y³⁺ doping in BaZrO₃ (BZY). Electrochemical performance reveals an 0.8-NAO electrolyte with excellent ionic conductivity above 0.20 S cm^–1 and a power density of 966.4 mW cm^–2 at 550 °C. Furthermore, the A-site-depleted perovskite was successfully operated at low temperatures of up to 320 °C, achieving a power density of 109.3 mW cm^–2. Complementary density functional theory (DFT) calculations reveal vacancy-induced midgap states and orbital hybridization effects (O-2p, Al-p, Nd-4f), which rationalize the observed band gap narrowing and enhanced proton mobility. Beyond conductivity, the depleted structure enhances proton transport while maintaining excellent thermal stability under fuel cell conditions. Preliminary results reveal that 0.8-NAO not only enhances proton mobility but also significantly improves thermal stability, outperforming traditional BZY perovskite oxides. These findings underscore the potential of 0.8-NAO as a promising alternative to conventional perovskite designs, making it a superior candidate for fuel cells and relevant proton-conducting applications.

Bimetallic oxide/sulfide (BMO/BMS) heterostructures have emerged as attractive electrode materials for supercapacitors, leveraging the synergistic effects of high redox activity from BMO and high electrical conductivity from BMS. However, the majority of existing approaches for constructing BMO/BMS yield homometallic heterostructures, suffering from limited redox activity and inadequate interfacial electronic interactions. Herein, NiFe-MOF-74 was employed as a sacrificial template to fabricate hierarchical porous multimetallic Co₂MnS₄@NiFe₂O₄/CC heterostructures via in situ growth on conductive Co₂MnS₄/CC nanowires followed by calcination. The NiFe-MOF-74 template not only introduces heterometals but also enables optimization of the sulfide-to-oxide ratio through precise modulation of the NiFe-MOF-74 content. In the optimized (Co₂MnS₄)_0.48@(NiFe₂O₄)_0.52/CC, the highly redox-active NiFe₂O₄ shell synergizes with the highly conductive Co₂MnS₄ core to provide rich and diverse active sites alongside efficient charge transport pathways. The enhanced electronic interactions at heterometallic BMO/BMS heterointerfaces accelerate charge/ion transfer kinetics, while the hierarchical porous structure exposes sufficient redox-active sites and establishes efficient ion diffusion pathways. This design achieves an exceptional specific capacity of 1197 C·g^–1 at 1 A·g^–1 with 76.6% rate retention (10 A·g^–1). The assembled flexible (Co₂MnS₄)_0.48@(NiFe₂O₄)_0.52/CC//NC/CC device delivers a high energy density of 76.5 Wh·kg^–1 at 750 W·kg^–1, retaining 93.86% capacity after 10,000 cycles, outperforming most reported composites based on BMO or BMS.

Lithium metal has become an ideal anode for high-energy-density lithium-ion batteries due to its unique theoretical capacity and potential advantages. However, the volume effect, uneven deposition, and dendrite growth of lithium metal can seriously shorten the service life of the battery. A 3D structural design and a lithium-friendly interface are considered effective ways to improve lithium metal negative electrodes. Hence, this article successfully prepared a sponge carbon (SC) scaffold rich in N-sites using melamine as the raw material. Pyridine N and pyrrole N, which can enhance surface activity, are distributed in the SC structure and can serve as lithium nucleation sites to promote the uniform deposition of lithium metal. Compared with hard carbon (HC), SC exhibits significant improvements in polarization potential and cycle life. The deposition overpotential of the SC battery is only 36 mV, and its cycle life is as long as 1800 h, while it maintains a high Coulombic efficiency of over 98%. Even at a high deposition capacity of 10 mAh cm^–2, SC can still stably deposit for over 1000 h. In addition, the 3D flexible carbon skeleton of SC provides a large space for buffering the volume expansion of lithium metal, which effectively suppresses the growth of lithium dendrites. The full-cell performance results demonstrate that the SC still retains a capacity retention rate of 98.4% after 200 cycles at 1 C, whereas the capacity retention rate of HC drops to 73.5%. Moreover, the long cycle performance and rate capability of SC full cells are both superior to those of HC full cells. This article improves the reversibility of lithium metal deposition/stripping by constructing a 3D self-doped N-sponge carbon skeleton and provides a reference for the development of long-life lithium metal batteries.

Upgrading from a single S-scheme to a double S-scheme heterojunction by inserting another semiconductor affords a challenging means of concurrently augmenting the charge-transfer dynamics and surface reaction kinetics while preserving extraordinary redox ability. Herein, a 2D Cu_xSe_y nanosheet is inserted between a 1D CoTiO₃ nanorod and 2D petals of a NiCo-LDH nanoflower to construct a double S-scheme CoTiO₃/Cu_xSe_y/NiCo-LDH 1D/2D/2D ternary heterojunction through a combination of calcination and hydrothermal processes. In comparison to NiCo-LDH and CoTiO₃/NiCo-LDH, the ternary hybrid exhibited 7.2 and 2.5 times higher H₂ evolution rates, respectively, and it also displayed a better H₂O₂ production of 978 μmol h^–1 g^–1, which was 2.8, 2.1, and 1.6 times higher than those of CoTiO₃, NiCo-LDH, and the CoTiO₃/NiCo-LDH nanohybrid, respectively. Further, it parades the conversion efficiencies of 9.1 and 0.013% for H₂ and H₂O₂ production, respectively. The enhanced activities are due to the formation of a double S-scheme heterojunction, where Cu_xSe_y acts as a charge-transfer mode switcher. The Ni/Ti–Se bond at the dual interface of the ternary heterojunction served as a bridge for the effective separation of charge carriers. The double S-scheme charge transfer was validated by the scavenger experiment, work function, in situ XPS, and in situ KPFM analysis. This study provides a valuable understanding of the double S-scheme charge transfer with an increasing overall efficiency of the photoredox behavior.

Materials and cell components used in CO₂ electrolysis have largely been adapted from technologies initially developed for water electrolysis and fuel cells. However, electrochemical CO₂ reduction introduces distinct material challenges due to the unique chemical environment in this process. In this study, we conducted ex-situ 1000 h stability tests on commonly used anion exchange membranes, exposing them exclusively to electrolytes and organic molecules used or produced during CO₂ electrolysis, at concentrations relevant to and compatible with postseparation processes. Notably, 15% w/w n-propanol and 5 M acetic acid caused complete dissolution or partial disintegration of the membranes unless cross-linking was present and remained stable throughout the test. When the membranes stayed physically intact, most of them exhibited excellent chemical stability in alkaline medium containing alcohols or formic acid, which was confirmed by vibrational spectroscopy and ion exchange capacity measurements. However, exposure to alcohol-and acid-containing solutions led to a substantial increase in swelling and water uptake, with potential implications for mechanical stability, ion/product crossover, and compression management of adjacent components. The potential effects of CO₂ electroreduction products on membrane stability, their subsequent impact on electrolyzer performance, and mitigation strategies are discussed.

Generally, formamidinium (FA)-based halide perovskite thin films are fabricated using halide precursors, such as PbI₂ and FAI, but this approach often leads to stoichiometric distortions, resulting in perovskite films with structural defects and reduced crystallinities. These problems can adversely influence power conversion efficiencies and open-circuit potentials of perovskite solar cells. In this study, we propose a microcrystalline perovskite powder (MCP) synthesized by controlling the stoichiometry of the FAI precursor. We optimize the synthesis of α-FAPbI₃ powder using 1.1 equiv of FAI. Interestingly, the synthesized black powder produced an excellent crystallinity and phase stability for up to six months. Remarkably, the MCP forms large colloids in solutions that are stably cohesive, promoting spontaneous nucleation and enabling the fabrication of low-defect thin films. Consequently, perovskite solar cells fabricated using the MCP display significantly improved efficiencies of 23.12% compared to those (19.64%) of the cells fabricated using the conventional PbI₂ and FAI precursors. This approach highlights the potential of MCPs for use in enhancing the performances and stabilities of perovskite-based devices.

The development of stable Ni-rich cathodes is critical to the advancement of high-energy lithium-ion batteries. Their practical deployment, however, remains severely limited by rapid interfacial degradation and capacity fading that stem from their inherent surface reconstruction, oxygen evolution, strenuous phase transitions, and micro- and crystal structure degradation, especially when cycled above 4.1 V. Herein, we report an electrolyte design strategy employing tris(trimethylsilyl) borate (TMSB) and vinylene carbonate (VC) as additives to enhance the electrochemical performance of Li[Ni_0.9Co_0.05Mn_0.05]O₂ (NCM90) cathodes. Electrochemical evaluation reveals that the TMSB-VC combination achieves an exceptional capacity retention of 97.3% after 100 cycles at 0.5 C (90 mA g^–1). The inclusion of TMSB in the electrolyte formulation promotes hydrofluoric acid scavenging, suppresses parasitic reactions, and promotes the formation of an inorganic-rich cathode–electrolyte interface that preserves the cathode morphology, minimizes polarization during the critical H2 ↔ H3 phase transition, and significantly enhances bulk Li⁺ transport kinetics. Our findings provide experimental evidence of TMSB-VC synergy, which differs from a previously reported computational prediction, to demonstrate the effectiveness of TMSB as a cathode interface stabilizing additive when paired with VC.

Organic semiconductors present a promising alternative for solar-hydrogen production (SHP) due to their cost-effectiveness and environmentally friendly nature. However, their availability is limited, and they often exhibit lower efficiency than inorganic semiconductors. This inefficiency is primarily attributed to their intrinsic Frenkel excitons with high binding energy, which restrict charge separation and transport. This study explores hydrogen bonding interactions in donor–acceptor conjugated polymer heterojunctions (PHJs) incorporating mesoporous C₃N₅, C₃N₆, and C₃N₇ nanostructures. The fluorine (–F) atoms in poly(5,6-difluoro-4-methyl-7-(7-methyl-9,9-dioctyl-9H-fluoren-2-yl)benzo[c][1,2,5]thiadiazole) and the amino (−NH₂) groups in C₃N₅, C₃N₆, and C₃N₇ facilitate hydrogen bonding interactions, ensuring strong interfacial contact. These interactions enhance charge separation and light absorption, improving photocatalytic performance. Experimental results demonstrate that incorporating the donor unit into the polymer structure enhances light capture ability and improves charge transport. Among the tested materials, the strongest electron-donating donor–acceptor unit, poly(5,6-difluoro-4-methyl-7-(7-methyl-9,9-dioctyl-9H-fluoren-2 yl)benzo[c][1,2,5]thiadiazole), exhibits the highest light absorption and charge separation efficiency. This optimized structure significantly enhances SHP, achieving an impressive hydrogen evolution rate of 2992.7 μmol g^–1 h^–1. These findings provide valuable insights into the development of organic semiconductor-based photocatalysts, contributing to the advancement of renewable hydrogen production.