Search Results (30)

Lithium iron phosphate (LiFePO₄, LFP) batteries dominate grid-scale energy storage, yet their cycle life is capped by its capacity fade issues. Conventional failure workflows suffer from redundant tests, high cost, and long turnaround time because the underlying mechanisms remain unclear. Herein, multi-scale characterization coupled with electrochemical tests have been quantitatively established to reveal four synergistic fade modes of LFP: active-Li loss, FePO₄ secondary-phase formation, SEI rupture, and particle fracture. A two-tier “screen–validate” protocol is proposed to accurately and efficiently disclose its mechanism. In the screening tier, capacity, cyclic voltammetry, electrochemical impedance spectroscopy, low-magnification scanning electron microscopy, and snapshot X-ray diffraction (XRD) rapidly flag the most probable failure cause. The validation tier then deploys mechanism-matched in situ/ex situ tools (operando XRD, TEM, XPS, ToF-SIMS, etc.) to build a comprehensive evidence chain of dynamic structural evolution, materials loss tracking, and quantitative proof. The streamlined workflow preserves scientific rigor and reproducibility while cutting analysis time and cost, offering a closed-loop route for fast failure diagnosis and targeted optimization of next-generation LFP batteries. Full article

The operational failure of lithium-ion batteries under extreme temperatures (−40~60 °C) stems primarily from electrolyte limitations. While prior efforts improved either low-temperature or high-temperature performance independently, holistic electrolyte design with practical validation remains elusive. Herein, we develop an all-climate electrolyte (ACE) through synergistic coordination of solvent, Li salt, and additive, achieving low viscosity (<10 mPa·s at −40 °C) and high ionic conductivity (7.0 mS cm⁻¹ at −40 °C). Raman and NMR spectra reveal MA and EC co-occupying Li⁺ solvation sheath while EMC acts as a diluent, enabling rapid ion transport. Consequently, LiFePO₄ (LFP)|graphite (Gr) cell delivers unprecedented cyclability: zero capacity decay over 500 cycles at 0 °C, stable operation across −40~60 °C, and 94.1% retention after 100 cycles at 45 °C in Ah-level pouch cells. XPS and SEM analysis demonstrate lithium difluorophosphate (LiDFP) and lithium bis(fluorosulfonyl)imide (LiFSI) collaboratively remodel SEI/CEI interphases, enriching them with LiF, Li₃PO₄, and Li₂SO₄. This inorganic-dominant architecture enhances interfacial Li⁺ kinetics and all-climate stability compared to the baseline electrolyte. Our tripartite electrolyte strategy provides a material-agnostic solution for all-climate energy storage. Full article

This study investigates the thermal behavior of SnS₂ anodes for lithium-ion batteries at seven different states of charge (fully discharged (lithiated) at 0 mAh/g, partially charged at 100, 200, 300, 400, and 500 mAh/g, and fully charged (delithiated) at 550 mAh/g) using differential scanning calorimetry (DSC). To better understand the observed thermal behavior, complementary XRD and XPS analyses were performed. Generally, in all electrodes, the thermal decomposition of the electrode material is initiated by the exothermic decomposition of the SEI followed by a binder decomposition reaction around 265 °C. Interestingly, with increased states of delithiation from 400 mAh/g, endothermic peaks in the heat-flow signal of the DSC measurements are observed, which can be correlated with the structural and compositional changes in the electrode material as determined by XRD and XPS, respectively. These analyses confirmed the progressive formation of metallic tin on advanced delithiation. Additionally, the total heat generation from the electrodes decreased with increased delithiation. The results of this study serve as the basis for better understanding the thermal decomposition of SnS₂-based anodes, which are considered promising for advanced lithium-ion battery chemistries. Full article

With the rapid advancement of energy storage technologies, there is a growing demand for affordable, efficient, and environmentally benign battery systems. Sodium-ion batteries (SIBs) present a promising alternative to lithium-ion systems due to sodium’s high abundance and similar electrochemical properties. Particular attention is given to developing NASICON -sodium (Na) super ionic conductor, type cathode materials, especially Na3V2(PO4)3, which exhibits high thermal and structural stability. This study focuses on the sol–gel synthesis of Na₃V₂(PO₄)₃ using citric acid and ethylene glycol, as well as investigating the effect of annealing temperature (400–1000 °C) on its structural and electrochemical properties. Phase composition, morphology, textural characteristics, and electrochemical performance were systematically analyzed. Above 700 °C, a highly crystalline NASICON phase free of secondary impurities was formed, as confirmed by X-ray diffraction (XRD). Microstructural evolution revealed a transition from a loose amorphous structure to a dense granular morphology, accompanied by changes in specific surface area and porosity. The highest surface area (67.40 m²/g) was achieved at 700 °C, while increasing the temperature to 1000 °C caused pore collapse due to sintering. X-ray photoelectron spectroscopy (XPS) confirmed the predominant presence of V³⁺ ions and the formation of V⁴⁺ at the highest temperature. The optimal balance of high crystallinity, uniform elemental distribution, and stable texture was achieved at 900 °C. Electrochemical testing in a Na/NVP half-cell configuration delivered an initial capacity of 70 mAh/g, which decayed to 55 mAh/g by the 100th cycle, attributed to solid-electrolyte interphase (SEI) formation and irreversible Na⁺ trapping. These results demonstrate that the proposed approach yields high-quality Na₃V₂(PO₄)₃ cathode materials with promising potential for sodium-ion battery applications. Full article

Aqueous zinc-ion batteries (AZIBs) have attracted significant attention for large-scale energy storage owing to their high safety, low cost, and environmental friendliness. However, issues such as dendrite growth, hydrogen evolution, and corrosion at the zinc anode severely limit their cycling stability. In this study, a “synergistic solvation shell–interfacial adsorption regulation” strategy is proposed, employing potassium gluconate (KG) and dimethyl sulfoxide (DMSO) as composite additives to achieve highly reversible zinc anodes. DMSO integrates into the Zn²⁺ solvation shell, weakening Zn²⁺-H₂O interactions and suppressing the activity of free water, while gluconate anions preferentially adsorb onto the zinc anode surface, inducing the formation of a robust solid electrolyte interphase (SEI) enriched in Zn(OH)₂ and ZnCO₃. Nuclear magnetic resonance(NMR), Raman, and Fourier transform infrared spectroscopy(FTIR) analyses confirm the reconstruction of the solvation structure and reduction in water activity, and X-ray photoelectron spectroscopy(XPS) verifies the formation of the SEI layer. Benefiting from this strategy, Zn||Zn symmetric cells exhibit stable cycling for over 1800 h at 1 mA cm⁻² and 1 mAh cm⁻², and Zn||Cu cells achieve an average coulombic efficiency of 96.39%, along with pronounced suppression of the hydrogen evolution reaction. This work provides a new paradigm for the design of low-cost and high-performance electrolyte additives. Full article

Natural graphite (NG) is abundant and has a high capacity for lithium-ion storage, but its narrow interlayer spacing and poor cyclic stability limit its use in high-performance lithium-ion batteries (LIBs). To address this, a N/S co-doped micro-expanded graphite composite (BFAC@MEG) was prepared by coating micro-expanded graphite (MEG) with N/S-containing amorphous carbon derived from biochemical fulvic acid (BFAC). This enhanced the electrochemical kinetics of lithium ions, improving charge transfer rates and reducing diffusion resistance. GITT results showed a higher Li⁺ diffusion coefficient than MEG and spherical graphite (SG). BFAC@MEG exhibited excellent rate performance, robust storage capacity and remarkable cycling stability. It had a specific capacity of 333 mAh g⁻¹ at 1 C, 205 mAh g⁻¹ at 3 C, and retained 81.57% capacity after 500 cycles. Even at 5 C, BFAC@MEG exhibits a high reversible capacity of 98 mAh g⁻¹ after 200 cycles. After cycling, SEM and XPS analyses revealed a low expansion rate of 15.96% cross-sectional expansion after 300 cycles at 3 C and a stable solid electrolyte interphase (SEI) film rich in LiF and Li₂CO₃. Full article

Pre-lithiation using Li–Si alloy-type additives is a promising technical approach to address the drawbacks of Si-based anodes, such as a low initial Coulombic efficiency (ICE) and inevitable capacity decay during cycling. However, its commercial application is limited by the air sensitivity of the highly reactive Li–Si alloys, which demands improved environmental stability. In this work, a protective membrane is constructed on Li₁₃Si₄ alloys using low-surface-energy paraffin and highly conductive carbon nanotubes through liquid-phase deposition, exhibiting enhanced hydrophobicity and improved Li⁺/e⁻ conductivity. The Li₁₃Si₄@Paraffin/carbon nanotubes (Li₁₃Si₄@P-CNTs) composite achieves a high pre-lithiation capacity of 970 mAh g⁻¹ and superb environmental stability, retaining 92.2% capacity after exposure to ambient air with 45% relative humidity. DFT calculations and in situ XRD measurements reveal that the paraffin-dominated coating membrane, featuring weak dipole–dipole interactions with water molecules, effectively reduces the moisture-induced oxidation kinetics of Li₁₃Si₄@P-CNTs in air. Electrochemical kinetic analysis and XPS depth profiling reveal the enhancement in charge transfer dynamics and surface Li⁺ transport kinetics (SEI rich in inorganic lithium salts) in P-SiO@C pre-lithiated by Li₁₃Si₄@P-CNTs pre-lithiation additives. Benefitting from pre-lithiation via Li₁₃Si₄@P-CNTs, the pre-lithiated SiO@C(P-SiO@C) delivers high ICE (103.7%), stable cycling performance (981 mAh g⁻¹ at 200 cycles) and superior rate performance (474.5 mAh g⁻¹ at 3C) in a half-cell system. The LFP||P-Gr pouch-type full cell exhibits a capacity retention of 83.2% (2500 cycles) and an energy density of 381 Wh kg⁻¹ after 2500 cycles. The Li₁₃Si₄@P-CNTs additives provide valuable design concepts for the development of pre-lithiation materials. Full article

This paper presents a composed lithium phosphate (LiPON) solid electrolyte interface (SEI) film which was coated on a lithium electrode via an electrodeposit method in a lithium–sulfur battery, and the structure of the product was characterized through infrared spectrum (IR) analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), environment scanning electron microscope (ESEM), etc. Meanwhile, the electrochemical impedance spectrum and the interface stability of the lithium electrode with the LiPON film was analyzed, while the coulomb efficiency and the cycle life of the lithium electrode with the LiPON film in the lithium–sulfur battery were also studied. It was found that this kind of film can effectively inhibit the charge from transferring at the interface between the electrode and the solution, which can produce a more stable interface impedance on the electrode, thereby improving the interface contact with the electrolyte, and effectively improve the discharge performance, cycle life, and the coulomb efficiency of the lithium–sulfur battery. This is of great significance for the further development of solid electrolyte facial mask technology for lithium–sulfur batteries. Full article

Lithium salt LiHDI (lithium 4,5-dicyano-2-(n-heptafluoropropyl)imidazolide) is proposed as a solid electrolyte interphase-stabilising additive for lithium-ion batteries, which can be added in a smaller amount than fluoroethylene carbonate (FEC) and vinylene carbonate (VC) additives. Electrolytes containing either lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI) or battery-standard LiPF₆ were tested with various amounts of LiHDI additive. Chemical stability in the presence of water and the thermal stability of LiHDI are on par with LiTDI. LiHDI additive does not negatively affect the properties of electrolytes. Conductivity measurements of solutions, galvanostatic cycling of graphite-LiFePO₄ cells at room temperature, cells’ cycling at 60 °C, internal cell resistance monitoring during cycling, and XPS analysis of electrodes’ surfaces after cycling have been performed. LiHDI, unlike the FEC-VC mixture, does not negatively affect the properties of the electrolyte. Cycling showed improved capacity retention with LiHDI additive with both graphite and LiFePO₄ as capacity-limiting electrodes over samples without additives. At elevated temperatures, samples with LiHDI exhibited better capacity retention during cycling than those with FEC-VC. Internal cell resistance can be correlated with capacity retention. XPS results show changes in the composition of SEI depending on the composition of the electrolyte and the duration of cycling. Full article

This study prepared silicon oxide anode materials with nitrogen-doped carbon matrices (SiO_x/C–N) through silicon-containing polyester thermal carbonization. Melamine was introduced as a nitrogen source during the experiment. This nitrogen doping process resulted in a porous structure in the carbon matrices, a fact confirmed by scanning electron microscopy (SEM). Pyridinic and quaternary nitrogen, but mainly tertiary nitrogen, were generated, as shown via X-ray photoelectron spectroscopy (XPS). Electrochemical tests confirmed that, as anode materials for a lithium-ion battery, SiO_x/C–N provided better cycle stability, improved rate capability, and lower Li⁺ diffusion resistance. The best performance showed an activated capacity at 493.5 mAh/g, preserved at 432.8 mAh/g after the 100th cycle, with 87.7% total Columbic efficiency. Those without nitrogen doping gave 1126.7 mAh/g, 249.0 mAh/g, and 22.1%, respectively. The most noteworthy point was that, after 100 cycles, anodes without nitrogen doping were pulverized into fine powders (SEM); meanwhile, in the case of anodes with nitrogen doping, powders of a larger size (0.5–1.0 µm) formed, with the accumulation of surrounding cavities. We suggest that the formation of more prominent powders may have resulted from the more substantial nitrogen-doped carbon matrices, which prevented the anode from further breaking down to a smaller size. The volume expansion stress decreased when the powders decreased to nanosize, which is why the nanosized silicon anode materials showed better cycling stability. When the anodes were cracked into powders with a determined diameter, the stress from volume expansion decreased to a level at which the powders could preserve their shape, and the breakage of the powders was stopped. Hence, the diameters of the final reserved powders are contingent on the strength of the matrix. As reported, nitrogen-doped carbon matrices are more robust than those not doped with nitrogen. Thus, in our research, anodes with nitrogen-doped carbon matrices presented more large-diameter powders, as SEM confirmed. Anodes with nitrogen doping will not be further broken at a larger diameter. At this point, the SEI film will not show continuous breakage and formation compared to the anode without doping. This was validated by the lower deposition content of the SEI-film-related elements (phosphorous and fluorine) in the cycled anodes with nitrogen doping. The anode without nitrogen doping presented higher content, meaning that the SEI films were broken many times during lithiation/delithiation (EDS mapping). Full article

Polyimide thin-film materials are widely used in aerospace and particle gas pedals, etc., but the phenomenon of secondary electron emission occurred under vacuum conditions. The graphene-coated polyimide materials were prepared for this phenomenon to suppress secondary electron emissions. The graphene coating was prepared on the polyimide surface through chemical vapor deposition (CVD). Scanning electron microscope images (SEM), X-ray photoelectron spectrometer images (XPS), Raman spectroscopy, atomic force microscopy (AFM), and other analytical methods were used to characterize the properties of the prepared materials. The C1s XPS fine spectra and Raman curve analyses showed that the material has an abundant sp2 hybridized structure, and the sp2 structure can reduce secondary electron emissions. The C, O, and N contents in the tested samples were 65.85, 20.47, and 13.68 at.%, respectively. It was examined that the graphene coating had an inhibitory effect on the secondary electron emissions of polyimide materials, and the secondary electron emission yield (SEY) was significantly reduced. The results of secondary electron tests showed that the maximum SEY (δmax) of the polyimide material decreased from 1.72 to 1.52 after the preparation of the graphene coating. The mechanism of using a graphene coating to reduce the SEY of polyimide was analyzed from experimental and theoretical perspectives. The results of this study can provide research ideas for polyimide thin film materials in aerospace, particle gas pedals, and other applications. Full article

Over the last few years, there has been increasing interest in the use of amorphous carbon thin films with low secondary electron yield (SEY) to mitigate electron multipacting in particle accelerators and RF devices. Previous works found that the SEY increases with the amount of incorporated hydrogen and correlates with the Tauc gap. In this work, we analyse films produced by magnetron sputtering with different contents of hydrogen and deuterium incorporated via the target poisoning and sputtering of C_xD_y molecules. XPS was implemented to estimate the phase composition of the films. The maximal SEY was found to decrease linearly with the fraction of the graphitic phase in the films. These results are supported by Raman scattering and UPS measurements. The graphitic phase decreases almost linearly for hydrogen and deuterium concentrations between 12% and 46% (at.), but abruptly decreases when the concentration reaches 53%. This vanishing of the graphitic phase is accompanied by a strong increase of SEY and the Tauc gap. These results suggest that the SEY is not dictated directly by the concentration of H/D, but by the fraction of the graphitic phase in the film. The results are supported by an original model used to calculate the SEY of films consisting of a mixture of graphitic and polymeric phases. Full article

Particle accelerators with superconducting magnets operating at cryogenic temperatures use a beam screen (BS) liner that extracts heat generated by the circulating bunched charge particle beam before it can reach the magnets. The BS surface, commonly made of high–conductivity copper, provides a low impedance for beam stability reasons, low secondary electron yield (SEY) to mitigate the electron–cloud (EC) effect, and low electron–stimulated desorption yield (ESD) to limit the dynamic pressure rise due to EC. Rare–earth barium copper oxide (REBCO) high–temperature superconductors (HTSs) recently reached technical maturity, are produced as coated conductor tapes (REBCO–CCs), and will be considered for application in future colliders to decrease the BS impedance and enable operation at around 50 K, consequently relaxing the cryogenic requirements. Aside from HTS properties, industry–grade REBCO–CCs also need qualification for EC and dynamic vacuum compatibility under accelerator–like conditions. Hence, we report the SEY and ESD measured at cryogenic temperatures of 12 K under low–energy electron irradiation of 0–1.4 keV. We also verify the sample compositions and morphologies using the XPS, SEM, and EDS methods. The energy and dose dependencies of ESD are comparable to those of technical–grade metals and one sample reached SEY${}_{MAX}$ = 1.2 after electron conditioning. Full article

The family of chalcogenide molybdenum clusters is well presented in the literature by a series of compounds of nuclearity ranging from binuclear to multinuclear articulating octahedral fragments. Clusters actively studied in the last decades were shown to be promising as components of superconducting, magnetic, and catalytic systems. Here, we report the synthesis and detailed characterization of new and unusual representatives of chalcogenide clusters: square pyramidal complexes [{Mo₅(μ₃-Se)ⁱ₄(μ₄-Se)ⁱ(μ-pz)ⁱ₄}(pzH)^t₅]^1+/2+ (pzH = pyrazole, i = inner, t = terminal). Individually obtained oxidized (2+) and reduced (1+) forms have very close geometry (proven by single-crystal X-ray diffraction analysis) and are able to reversibly transform into each other, which was confirmed by cyclic voltammetry. Comprehensive characterization of the complexes, both in solid and in solution, confirms the different charge state of molybdenum in clusters (XPS), magnetic properties (EPR), and so on. DFT calculations complement the diverse study of new complexes, expanding the chemistry of molybdenum chalcogenide clusters. Full article

The formation and evolution of the solid electrolyte interphase (SEI) layer as a function of electrolyte and electrolyte additives has been extensively studied on simple and model pure Si thin film or Si nanowire electrodes inversely to complex composite Si-based electrodes with binders and/or conductive carbon. It has been recently demonstrated that a binder-free Si@C-network electrode had superior electrochemical properties to the Si electrode with a xanthan gum binder (Si-XG-AB), which can be principally related to a reductive decomposition of electrolytes and formation of an SEI layer. Thus, here, the Si@C-network and Si-XG-AB electrodes have been used to elucidate the mechanism of SEI formation and evolution on Si-based electrodes with and without binder induced by lithiation and delithiation applying surface analytical techniques. The X-ray photoelectron spectroscopy and time-of-flight ion mass spectrometry results demonstrate that the SEI layer formed on the surface of the Si-XG-AB electrode during the discharge partially decomposes during the subsequent charging process, which results in a less stable SEI layer. Contrarily, on the surface of the Si@C-network electrode, the SEI shows less significant decomposition during the cycle, demonstrating its stability. For the Si@C-network electrode, initially, the inorganic and organic species are formed on the surface of the carbon shell and the silicon surface, respectively. These two parts of species in the SEI layer gradually grow and then fuse when the electrode is fully discharged. The behavior of the SEI layer on both electrodes corroborates with the electrochemical results. Full article