Exploring 3D microstructural evolution in Li-Sulfur battery electrodes using in-situ X-ray tomography

Lithium sulfur (Li-S) batteries offer higher theoretical specific capacity, lower cost and enhanced safety compared to current Li-ion battery technology. However, the multiple reactions and phase changes in the sulfur conversion cathode result in highly complex phenomena that significantly impact cycling life. For the first time to the authors’ knowledge, a multi-scale 3D in-situ tomography approach is used to characterize morphological parameters and track microstructural evolution of the sulfur cathode across multiple charge cycles. Here we show the uneven distribution of the sulfur phase fraction within the electrode thickness as a function of charge cycles, suggesting significant mass transport limitations within thick-film sulfur cathodes. Furthermore, we report a shift towards larger particle sizes and a decrease in volume specific surface area with cycling, suggesting sulfur agglomeration. Finally, we demonstrate the nano-scopic length-scale required for the features of the carbon binder domain to become discernible, confirming the need for future work on in-situ nano-tomography. We anticipate that X-ray tomography will be a powerful tool for optimization of electrode structures for Li-S batteries

High power Nb-doped LiFePO₄ Li-ion battery cathodes; pilot-scale synthesis and electrochemical properties

AbstractHigh power, phase-pure Nb-doped LiFePO4 (LFP) nanoparticles are synthesised using a pilot-scale continuous hydrothermal flow synthesis process (production rate of 6 kg per day) in the range 0.01–2.00 at% Nb with respect to total transition metal content. EDS analysis suggests that Nb is homogeneously distributed throughout the structure. The addition of fructose as a reagent in the hydrothermal flow process, followed by a post synthesis heat-treatment, affords a continuous graphitic carbon coating on the particle surfaces. Electrochemical testing reveals that cycling performance improves with increasing dopant concentration, up to a maximum of 1.0 at% Nb, for which point a specific capacity of 110 mAh g−1 is obtained at 10 C (6 min for the charge or discharge). This is an excellent result for a high power cathode LFP based material, particularly when considering the synthesis was performed on a large pilot-scale apparatus

An optimal condition based maintenance scheduling for metal structures based on a multidisciplinary research approach

Latest research findings show that the deterioration of metal coatings results due to complex combination of material and meteorological parameters. The classical maintenance scheduling do not consider complex interface of materials and meteorological parameters to determine optimal maintenance framework. The cost of recoating can be optimised through appropriate selection of coating specifications and maintenance strategy. This research provides a multidisciplinary algorithmic approach to determine cost-effective solutions for recoating. The specifications of red oxide primer coating and structural steel substrate system are considered for simulation analysis. The results show that the appropriate selection of 10% increase in coating thickness based on coating-substrate system specifications resulted in 20-25% reduction in annual patch failures which reduces 5-6 % cost of recoating. Furthermore, the proposed model also simulated to compare Patch recoating and Part recoating strategy and algorithm show that the Part recoating is cost-effective as compared to Patch recoating if number of annual patch failure is greater than ‘2’ and area of the part is ‘2x’times larger than the area of the patch. Contrary, the Patch recoating results in low cost if the part area is ‘10x’ times larger than patch area and number of annual patch failures are less than ‘7’

Exploring 3D microstructural evolution in Li-Sulfur battery electrodes using in-situ X-ray tomography

Lithium sulfur (Li-S) batteries offer higher theoretical specific capacity, lower cost and enhanced safety compared to current Li-ion battery technology. However, the multiple reactions and phase changes in the sulfur conversion cathode result in highly complex phenomena that significantly impact cycling life. For the first time to the authors’ knowledge, a multi-scale 3D in-situ tomography approach is used to characterize morphological parameters and track microstructural evolution of the sulfur cathode across multiple charge cycles. Here we show the uneven distribution of the sulfur phase fraction within the electrode thickness as a function of charge cycles, suggesting significant mass transport limitations within thick-film sulfur cathodes. Furthermore, we report a shift towards larger particle sizes and a decrease in volume specific surface area with cycling, suggesting sulfur agglomeration. Finally, we demonstrate the nano-scopic length-scale required for the features of the carbon binder domain to become discernible, confirming the need for future work on in-situ nano-tomography. We anticipate that X-ray tomography will be a powerful tool for optimization of electrode structures for Li-S batteries

Continuous Hydrothermal Synthesis of Metal Germanates (M₂GeO₄ ; M = Co, Mn, Zn) for High Capacity Negative Electrodes in Li‐ion Batteries

Nanosized metal germanates (M2GeO4; M = Co, Mn, Zn) were synthesised using a continuous hydrothermal flow synthesis process for the first time. Phase‐pure rhombohedral Zn2GeO4 nanorods, cubic spinel Co2GeO4 nanoparticles, and orthorhombic Mn2GeO4 nanotubes/nanoparticles were obtained. The electrochemical properties of all samples as active materials for negative electrodes in Li‐ion half cells was explored. The galvanostatic and potentiodynamic testing was conducted in the potential range 3.00 to 0.05 V vs. Li/Li+. The results suggest that both alloying and conversion reactions associated with Ge contributed to the stored charge capacity; Zn2GeO4 showed a high specific capacity of 600 mAh g-1 (10 cycles at 0.1 A g -1) due to alloying and conversion reactions for both Ge and Zn. Mn2GeO4 was studied for the first time as a potential negative electrode material in a Li‐ion half‐cell; an excellent specific charge capacity of 510 mAh g-1 (10 cycles / 0.1 A g-1) was obtained with a significant contribution to charge arising from the conversion reaction of Mn to MnO upon delithiation. In contrast, Co2GeO4 only showed a specific capacity of 240 mAh g-1, after 10 cycles at the same current rate, which suggested that cobalt had little or no benefit for enhancing stored charge in the germanate

Tailoring the Charge/Discharge Potentials and Electrochemical Performance of SnO₂ Lithium‐Ion Anodes by Transition Metal Co‐Doping

It has been shown that the introduction of several transition metal (TM) dopants into SnO2 lithium‐ion battery anodes can overcome the issues associated with the irreversible capacity loss from the conversion reaction of SnO2 and the aggregation of the metallic Sn particles formed upon lithiation. As the choice of the single dopant, however, plays a decisive role for the achievable energy density – precisely its redox potential – we investigate herein TM co‐doped SnO2, prepared by using a readily scalable continuous hydrothermal flow synthesis (CHFS) process, to tailor the dis‐/charge profile and by this the energy density. It is shown that the judicious choice of different elemental doping combinations in samples made via CHFS simultaneously improves the cycling performance and the full‐cell energy density. To support these findings, we realized a lithium‐ion full‐cell incorporating the best performing co‐doped SnO2 as negative electrode and high‐voltage LiNi0.5Mn1.5O4 (LNMO) as positive electrode–to the best of our knowledge, the first full‐cell based on such anode material in combination with LNMO as cathode active material

TiO2/MoO2 nanocomposite as anode materials for high power Li-ion batteries with exceptional capacity

Nanoparticles of molybdenum(IV) oxide (MoO 2 ) and a TiO 2 /MoO 2 nanocomposite were synthesised via a continuous hydrothermal synthesis process. Both powders were analysed using XRD, XPS, TEM, and BET and evaluated as active materials in anodes for Li-ion half-cells. Cyclic voltammetry and galvanostatic charge/discharge measurements were carried out in the potential window of 0.1 to 3.0 V vs. Li/Li+. Specific capacities of ca. 350 mAh g -1 were obtained for both materials at low specific currents (0.1 A g -1 ); TiO 2 /MoO 2 composite electrodes showed superior rate behaviour & stability under cycling (compared to MoO 2 ), with stable specific capacities of ca. 265 mAh g -1 at a specific current of 0.5 A g -1 and ca. 150 mAh g -1 after 350 cycles at a specific current of 2.5 A g -1 . The improved performance of the composite material, compared to MoO 2 , was attributed to a smaller particle size, improved stability to volume changes (during cycling), and lower charge transfer resistance during cycling. Li-ion hybrid electrochemical capacitors using TiO 2 /MoO 2 composite anodes and activated carbon (AC) cathodes were evaluated and showed excellent performance with an energy density of 44 Wh kg -1 at a power density of 600 W kg -1

Risk factors and coronary angiographic profile in young STEMI patients: results from a tertiary care centre in south-central India

Background: Compared to older counterparts, a significant distinction has been found related to risk factors, clinical presentation, and prognosis of ST-segment elevation myocardial infarction (STEMI) in younger patients. To date, a lack of studies has been looked, specifically at-risk factors and angiographic profile of STEMI among younger patients; with this in mind, we conducted the present study.Methods: This hospital-based, cross-sectional, open-label study was carried out at Deccan College of Medical Sciences between April 2018 and December 2019. Patients under 40 years with the presentation of STEMI were included. All patients were subjected to electrocardiography, 2D echocardiography, and coronary angiogram. Baseline demographics, risk factors, and procedural characteristics were recorded.Results: Of 51 young STEMI patients, 41 (80.4%) were male and 10 (19.6%) were female. The most common risk factors associated with the development of STEMI in young patients were smoking (58.8%), followed by diabetes (45.1%), and dyslipidaemia (45.1%). Anterior wall MI was the most frequent presentation (84.3%). The left anterior descending artery was the most frequently (62.8%) involved vessel, followed by left circumflex artery (9.8%), and right coronary artery (5.9%).Conclusions: Insights gained from the study can aid in identifying clinical characteristics of STEMI in young patients, which may be beneficial to achieve appropriate and timely management. Further, the young population should be educated as to control modifiable risk factors and smoking cessation to prevent coronary artery disease since they belong to the highly productive group in the community