•Provided direct visualization information for the SEI film formation from aqueous solution for the first time.•SEI film form from aqueous solution mainly composed of Li2CO3 and LiF.•Young’s modulus ...of 4–6 nm thick SEI layer is 30 ± 10 GPa.
The structure and chemical composition of solid electrolyte interphase (SEI) play a critical role in the performance of Li-ion batteries. However, the complexity of SEI layer and lack of relevant and efficient characterization techniques limit understanding of SEI formation mechanism and associated properties. Moreover, compared with organic electrolyte-based SEI, few studies have focused on aqueous electrolyte-based solid-electrolyte interphase (A-SEI). Herein, we present in-situ AFM images to demonstrate the morphological evolution of SEI in the presence of 21 M lithium bis(trifluoromethane sulfonyl) imide (LiTFSI) aqueous electrolyte. Moreover, a combination of electrochemical-controlled atomic force microscopy (EC-AFM) and ex-situ X-ray photoelectron spectroscopy (XPS) is utilized to unveil the mechanism of SEI formation and identify its components. The results reveal that A-SEI layer is unevenly distributed and the inner and outer layers are mainly composed of Li2CO3 and LiF, respectively. The Young’s modulus of 4–6 nm thick SEI layer is found to be 30 ± 10 GPa. The current study provides novel insights into the formation of A-SEI by using in-situ AFM and provides a baseline for the future development of aqueous electrolytes for Li-ion batteries.
Lithium (Li) metal is a key anode material for constructing next generation high energy density batteries. However, dendritic Li deposition and unstable solid electrolyte interphase (SEI) layers ...still prevent practical application of Li metal anodes. In this work, it is demonstrated that an uniform Li coating can be achieved in a lithium fluoride (LiF) decorated layered structure of stacked graphene (SG), leading to the formation of an SEI‐functionalized membrane that retards electron transfer by three orders of magnitude to avoid undesirable Li deposition on the top surface, and ameliorates Li+ ion migration to enable uniform and dendrite‐free Li deposition beneath such an interlayer. Surface chemistry analysis and density functional theory calculations demonstrate that these beneficial features arise from the formation of C–Fx surface components on the SG sheets during the Li coating process. Based on such an SEI‐functionalized membrane, stable cycling at high current densities up to 3 mA cm−2 and Li plating capacities up to 4 mAh cm−2 can be realized in LiPF6/carbonate electrolytes. This work elucidates the promising strategy of modifying Li plating behavior through the SEI‐functionalized carbon structure, with significantly improved cycling stability of rechargeable Li metal anodes.
A surface conversion of LiF into C–Fx components on a defective carbon sheet can be achieved during Li plating to provide a solid electrolyte interphase (SEI)‐functionalization of a layered carbon structure. Uniform Li deposition with dendrite‐free features can be realized beneath the SEI‐functionalized layer for significantly improved cycling stability of Li metal anodes.
Silicon as the potential anode material for lithium-ion batteries suffers from huge volume change (up to 400%) during charging/discharging processes. Poor electrical conductivity of silicon also ...hinders its long-term cycling performance. Herein, we report a two-step ball milling method to prepare nanostructured P-doped Si/graphite composite. Both P-doped Si and coated graphite improved the conductivity by providing significant transport channels for lithium ions and electrons. The graphite skin is able to depress the volume expansion of Si by forming a stable SEI film. The as-prepared composite anode having 50% P-doped Si and 50% graphite exhibits outstanding cyclability with a specific capacity of 883.4 mAh/g after 200 cycles at the current density of 200 mA/g. The cost-effective materials and scalable preparation method make it feasible for large-scale application of the P-doped Si/graphite composite as anode for Li-ion batteries.
Improving the cyclic stability of lithium metal anodes is of particular importance for developing high-energy-density batteries. In this work, a remarkable finding shows that the control of lithium ...bis(fluorosulfonyl)imide (LiFSI) concentrations in electrolytes significantly alters the thickness and modulus of the related SEI layers, leading to varied cycling performances of Li metal anodes. In an electrolyte containing 2 M LiFSI, an SEI layer of ∼70 nm that is obviously thicker than those obtained in other concentrations is observed through in situ atomic force microscopy (AFM). In addition to the decomposition of FSI– anions that generates rigid lithium fluoride (LiF) as an SEI component, the modulus of this thick SEI layer with a high LiF content could be significantly strengthened to 10.7 GPa. Such a huge variation in SEI modulus, much higher than the threshold value of Li dendrite penetration, provides excellent performances of Li metal anodes with Coulombic efficiency higher than 99%. Our approach demonstrates that the FSI– anions with appropriate concentration can significantly alter the SEI quality, establishing a meaningful guideline for designing electrolyte formulation for stable lithium metal batteries.
The use of metal organic frameworks (MOFs) as new promising electrode materials in lithium-ion batteries (LIBs) has attracted significant attention. However, the low electrical conductivity of MOFs ...has resulted in the poor cycle performance of LIBs. Here, we report a facile synthesis route of Fe-MOF/reduced graphene oxide (RGO) composites using a solvothermal method. When used as anode materials for LIBs, the synthesized Fe-MOF/RGO (5%) composite shows superior Li storage with a reversible capacity of 1010.3 mA h g
−1
after 200 cycles and an excellent rate performance. The improved electrochemical performance may be attributed to the synergistic effect of MOFs with high theoretical capacities and RGO with high electrical conductivity.
Metal organic frameworks (MOFs) and reduced graphene oxide (RGO) composite were used as anode materials in lithium-ion batteries (LIBs).
The lithium–air battery is one of the most promising technologies among various electrochemical energy storage systems. We demonstrate that a novel air electrode consisting of an unusual hierarchical ...arrangement of functionalized graphene sheets (with no catalyst) delivers an exceptionally high capacity of 15000 mAh/g in lithium–O2 batteries which is the highest value ever reported in this field. This excellent performance is attributed to the unique bimodal porous structure of the electrode which consists of microporous channels facilitating rapid O2 diffusion while the highly connected nanoscale pores provide a high density of reactive sites for Li–O2 reactions. Further, we show that the defects and functional groups on graphene favor the formation of isolated nanosized Li2O2 particles and help prevent air blocking in the air electrode. The hierarchically ordered porous structure in bulk graphene enables its practical applications by promoting accessibility to most graphene sheets in this structure.
Demoralization is common in older adult homebound breast cancer patients, seriously affecting their quality of life. This study aimed to investigate the demoralization of older adult homebound breast ...cancer patients and to analyse the mediating effects of social support between self-disclosure and demoralization.
The study enrolled 368 older adult homebound breast cancer patients reviewed in outpatient clinics of three hospitals from January 2022 to August 2023. A questionnaire survey was conducted using the general information questionnaire, the distress disclosure index (DDI), the social support revalued scale (SSRS), and the demoralization scale (DS). Path analysis was conducted to test the hypothesised serial mediation model.
The total scores of self-disclosure, social support, and demoralization were 37 (25-42), 34 (19-48.75), and 46.5 (35-68), respectively. The results indicated a positive correlation between self-disclosure and social support (
< 0.01). In contrast, a statistically significant negative correlation was observed between self-disclosure, social support, and various demoralization dimensions (
< 0.01). Social support played a partial mediation effects between self-disclosure and demoralization, indirect effect =0.6362, SE = -0.591, 95% CI (-0.785 ~ -0.415); Self-disclosure direct effect demoralization, direct effect =0.3638, SE = -0.337, 95% CI (-0.525 ~ -0.144); total effect, SE = -0.929, 95% CI (-0.945 ~ -0.904).
Social support a partial mediated between self-disclosure and demoralization in Chinese older adult homebound breast cancer patients. Clinical staff should focus on developing a social support system for Chinese older adult homebound breast cancer patients, encouraging patients to reveal their minds, and providing psychological counselling to enhance self-confidence and rebirth from adversity.
The effects of carbon microstructure and carbon loading on the performance of Li/air batteries were investigated. The active carbons from various sources were compared, and a dry rolling method was ...optimized to prepare air electrodes with high mesopore volume. It is found that the capacities of air electrodes improve significantly when the mesopore volume of the carbon source is high. However, for carbons with low mesopore volumes, other factors such as surface activity also play an important role in determining the electrochemical performances of the Li/air batteries. A practical criterion, area-specific capacity, was used to optimize the carbon loading for air electrode. The best area-specific capacity of 13.1 mAh/cm2 was obtained at a carbon loading of 15.1 mg/cm2. Further increasing or decreasing the carbon loading led to a reduced area- specific capacity. Finally, at fixed carbon loading and discharge rates, electrolyte amount was another key factor governing cell performance. A spring mechanism is proposed to explain the formation of the tri-phase regions in air electrodes. After optimizing the parameters listed above, a high capacity of 1,756 mAh/g carbon corresponding to a specific energy of 4,614 Wh/kg carbon was obtained for Li/air batteries operated in a dry air environment.
Based on the official data modeling, this paper studies the transmission process of the Corona Virus Disease 2019 (COVID-19). The error between the model and the official data curve is quite small. ...At the same time, it realized forward prediction and backward inference of the epidemic situation, and the relevant analysis help relevant countries to make decisions.
The possible reasons and key factors on gas generation of Li4Ti5O12 (LTO) cells are investigated by the accelerating measurement baking at 80 °C for 120 h. It is found that the chemically catalytic ...reaction related to moisture makes a minor contribution to cell swelling. Our LTO-based 383450 cells (∼10 mL) before pre-charge (i.e. formation) only produce ∼1.5 mL gas during baking test and CO2, instead of H2, is the dominant species in EC/DMC electrolyte. By contrast, the swelling ratio of the charged LTO cells, which are re-sealed after formation, is kept at ∼97% regardless of states of charge. This severe decomposition of carbonates at elevated temperature should be dominated by the anode potential, rather than catalysis of LTO, since graphite/NMC cells show a similar swelling behavior at over-discharge state, where graphite anode shares the same potential as LTO. On the other hand, the electrolyte stability is also dependent on the type of solvent. Among the investigated systems, the mixture of PC + DMC (1:1) exhibits the best behavior to suppress the cell swelling. The swelling ratio diminishes from ∼100% of other electrolytes to 50%. This improvement probably roots in the high quality of protective films formed during solvents' decomposition.
•The key factors of gassing in Li4Ti5O12 cells are investigated by the accelerating measurement.•The chemically catalytic reaction related to moisture makes a minor contribution to Li4Ti5O12 cell gassing.•Graphite cells show a similar swelling behavior at over-discharge state as Li4Ti5O12 cells.•Electrolyte decomposition at elevated temperature should be dominated by the anode potential.
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