ACS Applied Energy Materials最新文献

Due to the exceptionally high energy density and compatibility with the existing battery manufacturing process, the anode-free lithium metal battery (AFLMB) exhibits significant potential for practical implementation. However, the lifespan of the AFLMB is severely limited by the highly reactive lithium metal anode. Although enhanced cycling stability has been achieved through advanced electrolyte and anode design, the poor initial Coulombic efficiency (ICE) inevitably leads to reduced capacity in AFLMB. In this study, the environmentally resilient lithium oxalate (Li₂C₂O₄) is introduced as a cathode prelithiation additive for AFLMB to offer in situ lithium supply. Complete decomposition of Li₂C₂O₄ within 4.5 V is realized with an optimized conductive network. Characterizations including SEM, XRD, and XPS reveal that the adoption of Li₂C₂O₄ does not adversely impact the cathode significantly, with the electrochemical performance remaining essentially unaltered. Consequently, the capacity degradation of AFLMB is markedly suppressed, with the 20% Li₂C₂O₄-containing LFP|sodium alginate@Ag@Cu full battery exhibiting stable operation for 130 cycles without any noticeable capacity degradation.

A novel high-donor 3-fluoropyridine (3FPy) electrolyte has been introduced for use in Li–S batteries, demonstrating an inhibition effect on the polysulfide shuttle, even without the addition of LiNO₃. In this study, fluoropyridine electrolytes, including 2-fluoropyridine (2FPy) and 3FPy electrolytes, are studied using electrochemical analysis, mass spectrometry (MS), and high-performance liquid chromatography (HPLC) methods. Collision-induced dissociation spectra revealed that Li⁺ preferentially solvates with different fluoropyridines, with 2FPy exhibiting a stronger interaction due to ortho-fluorine’s influence, compared to 4FPy and 3FPy. However, MS and HPLC analyses showed that 2FPy is reactive with polysulfides, while 3FPy offers high solubility for polysulfides and sulfur without reacting with them at room temperature. Despite 3FPy performing well at room temperature, further electrochemistry studies at elevated (60 °C) and reduced (0 °C) temperatures reveal the challenges. At high temperatures, LiNO₃ is essential to suppress the polysulfide shuttle; and at low temperatures, the performance with the 3FPy electrolyte significantly lags behind that of the ether-based electrolyte.

The commercialization of silicon anodes requires polymer binders that are both mechanically robust and electrochemically stable in order to ensure that they can accommodate the volume expansion experienced during cycling. In this study, we examine the use of both low and high molecular weight (MW) polyacrylic acids (PAAs), and sodium polyacrylates (Na-PAAs), at different degrees of partial neutralization, as a possible binder candidate for use in silicon graphite anodes. High MW PAAs were found to have stable capacity retentions of 672 mAh g^–1 for over 100 cycles, whereas with the low MW PAAs the capacity was found to already have declined to 373 mAh g^–1 after the first 30 cycles. Furthermore, the partial neutralization of Na-PAA binder system was found to provide superior cycling performances, as compared to non-neutralized or fully neutralized PAA systems. The high MW and partially neutralized PAAs were also found to provide the electrode coatings with higher cohesion strengths, which allow for the electrodes’ microstructure to be more effectively maintained over several cycles. Overall, these findings suggest that partially neutralized and higher MW PAAs are the more suitable polymer binder candidates for use within silicon–graphite anodes.

In lithium (Li)-metal batteries (LMBs), the functional electrolytes need to be compatible with both a high-voltage cathode and a highly reactive anode. However, the carbonate-based electrolytes in commercial lithium-ion batteries (LIBs) exhibit insufficient reductive stability due to severe side reactions and the formation of lithium dendrites on the Li anode. In this study, the use of LiPF₆ and lithium difluorobis(oxalato) phosphate (LiDFBOP) dual-salt electrolyte composed of ester and ether cosolvents (FEC/DME) enables the stabilization of the high-voltage LMBs through modulating the interfacial electrochemistry. Such an electrolyte design strategy is demonstrated to regulate the Li plating/stripping behavior by forming a robust anion-derived solid electrolyte interphase (SEI) film on the anode and to improve the cathode/electrolyte interfacial stability under high-voltage conditions. As a result, the as-developed electrolyte exhibits stable cycling over 800 h in Li∥Li symmetric cells and ultralong lifespans with capacity retention of 66% after 2000 cycles in Li∥LiFePO₄. Targeted electrolyte engineering is presented as a promising approach for practical high-performance Li-metal batteries.

For commercial use and large-scale applications of proton exchange membrane (PEM) fuel cells, using Pt as an electrocatalyst is a significant hindrance due to its low abundance and high cost. To make the PEM fuel cells commercially viable, cost-effective materials with performance comparable to that of Pt are required. In this work, a NiO/reduced graphene oxide (rGO) composite is synthesized and tested as an efficient electrocatalyst for the oxygen reduction reaction (ORR). The ORR activity of NiO/rGO composite, in terms of onset potential (i.e., ∼−0.04 V at −0.1 mA/cm²), half-wave potential (i.e., ∼−0.3 V), and limiting current density (∼4 mA/cm²-geo) are excellent for a non-noble metal containing electrocatalyst for ORR. The efficient ORR activity of the NiO/rGO composite is attributed to the presence of Ni²⁺/Ni³⁺ redox couples and oxygen defects in the material, as revealed by different characterization results.

Irreversible capacity loss during the initial charge–discharge process poses a significant challenge to the practical application of high-theoretical-capacity anodes in lithium-ion batteries. Therefore, prelithiation technology has emerged as a pivotal choice for the advancement of high-energy-density lithium-ion batteries. Herein, we introduce a bilayer coating strategy with Li₂S-polyacrylonitrile (Li₂S-PAN) as the prelithiation source. Specifically, Li₂S-PAN can selectively release active lithium ions during the initial charge process with a specific capacity of 695 mAh g^–1. When integrated into a LiFePO₄ cathode, Li₂S-PAN can achieve a 48.2% additional capacity. Furthermore, the LiFePO₄|SiC full cell exhibits a ∼20.0% initial lithium compensation with the reversible capacity increasing from 101 to 121 mAh g^–1. Overall, this work proposes a facile and scalable route for the future application of high-theoretical-capacity anodes (silicon, tin, etc.) in the lithium-ion battery industry.

A crucial factor for the success of hydrogen (H₂) as the backbone of energy transformation is the efficient production of green H₂, especially through the solar-to-hydrogen process. The key to greatly improving photocatalytic H₂ evolution lies in the design of catalyst materials, where nanostructure engineering plays a pivotal role in driving these advancements. Engineering the nanostructure of TiO₂ as a photocatalyst can significantly drive up its H₂ evolution performance by benefiting from the created large surface area and the suppressed charge recombination. Here we show the synthesis of dendritic fibrous nano silica–titania (DFNST) using in situ seed-microemulsion crystallization which demonstrate high performance H₂ evolution even without the addition of any cocatalyst. The impact of different TiO₂ crystalline phases on the formation of the DFNST composites and their H₂ photogeneration performance under visible light is thoroughly investigated. Synthesizing the composites using a low-temperature reflux method enhances the textural properties of the TiO₂. Significant influence of the inclusion of anatase, rutile, and mixed rutile–anatase TiO₂ phases on the morphology, optical, and catalytic characteristics of the DFNST is revealed. The formation of Si–O–Ti bonds acting as electron transfer bridges between TiO₂ and the SiO₂ framework boosts the photocatalytic activity. On the other hand, the increased hydrophilicity in DFNST_a and DFNST_m enhanced water molecule uptake, contributing to efficient H₂ ion generation and interaction with electrons to produce H₂. Based on our current finding, the surface area plays a key role in enhancing the photocatalytic H₂ evolution by providing the surface active sites, which supports other conditions, such as mesoporosity, band gap, and hydrophilicity, and is combined with defect control for facilitating effective charge carrier transfer and separation in the homojunction system, as observed in the mixed-phase DFNST_m that exhibit the highest H₂ photogeneration rate.

Hole selective layers (HSLs) play a crucial role in the efficiency of organic photovoltaics (OPVs). Self-assembled monolayers (SAMs) offer a powerful approach to engineer the interfacial properties of HSLs in OPVs. In this work, we utilized the 2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) SAM to modify the ITO/MoO₃ interface and the surface of MoO₃, thereby forming multilayer HSLs. 2PACz regulates the surface work function (WF) of the electrodes, leading to a more favorable energy level alignment, reduced interfacial resistance, and facilitated charge carrier transport and extraction. The resulting OPV devices demonstrated improved fill factor (FF) and power conversion efficiency (PCE). Additionally, the reduction in interface defects effectively suppressed carrier recombination, ultimately achieving a maximum PCE of 16.33%. This indicates that the design of composite HSLs with multilayer interface modification is an effective strategy for improving OPV efficiency and provides ideas for further advancing OPV development.

Developing high-capacity and fast-charging anode materials is critical for achieving high-performance Li-ion batteries (LIBs). Herein, polycrystalline quaternary transition metal silicon sulfides, Cu₂TSiS₄ (T = Fe, Mn), were synthesized using a solid-state method and investigated as anode materials in LIBs. Cu₂FeSiS₄ retains a reversible capacity of 670 mAh g^-1 at 200 mA g^-1 for 400 cycles, while Cu₂MnSiS₄ suffers from a fast capacity loss in the initial 50 cycles. More importantly, Cu₂FeSiS₄ can maintain a reversible capacity of 379 mAh g^-1 after 700 cycles at a high current density of 2 A g^-1, demonstrating high cyclic stability and fast-charging capacity. To further understand the structure degradation and phase transformation, we investigated the postcycling electrodes using multiple techniques, including the scanning electron microscope with energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy techniques. The results indicated that Cu₂FeSiS₄ undergoes reversible phase transitions with Li₂S as a major product component. To further assess the performance for practical applications, Cu₂FeSiS₄ was coupled with LiFePO₄ to make LiFePO₄||Cu₂FeSiS₄ full cells, which delivered superior electrochemical performance. These results demonstrate great promise for using quaternary transition metal silicon sulfides as anodes to achieve low-cost and sustainable LIBs.

A series of (dipole-) multicationic cross-linked SEBS-based AEMs were prepared using a multicationic cross-linking strategy with SEBS as the polymer skeleton, which has good alkali stability. By controlling the cross-linking degree, the performance of AEM can be regulated. Introducing a multicationic cross-linking agent DACEE-containing hydrophilic alkoxy chains (dipoles) to improve the performance of the AEMs. The difference in hydrophilicity/hydrophobicity of alkoxy chains in DACEE and the dipole interaction between oxygen atoms and cations contribute to the construction of microphase separation, broadening of ion transport channels, and promoting ion transport efficiency. The steric hindrance of cage-shaped cations in cross-linked structures and the hydrophilicity of alkoxy groups in cross-linking agent DACEE can enhance the alkaline stability of AEMs. The additional intermolecular forces generated after cross-linking enhance the mechanical properties of the cross-linked membrane. Among them, the SEBS-C6TMA-DACEE20% membrane with the best mechanical properties (Ts: 15.37 MPa, Eb: 250.83%) had an OH^– conductivity of 93.61 mS·cm^–1 at 80 °C, and after soaking in 2 M NaOH solution for 1500 h, the OH^– conductivity decreased by 16.3%.