Rapid determination of solid-state diffusion coefficients in Li-based batteries via intermittent current interruption method.

The galvanostatic intermittent titration technique (GITT) is considered the go-to method for determining the Li+ diffusion coefficients in insertion electrode materials. However, GITT-based methods are either time-consuming, prone to analysis pitfalls or require sophisticated interpretation models. Here, we propose the intermittent current interruption (ICI) method as a reliable, accurate and faster alternative to GITT-based methods. Using Fick's laws, we prove that the ICI method renders the same information as the GITT within a certain duration of time since the current interruption. Via experimental measurements, we also demonstrate that the results from ICI and GITT methods match where the assumption of semi-infinite diffusion applies. Moreover, the benefit of the non-disruptive ICI method to operando materials characterization is exhibited by correlating the continuously monitored diffusion coefficient of Li+ in a LiNi0.8Mn0.1Co0.1O2-based electrode to its structural changes captured by operando X-ray diffraction measurements.

A non-academic perspective on the future of lithium-based batteries.

In the field of lithium-based batteries, there is often a substantial divide between academic research and industrial market needs. This is in part driven by a lack of peer-reviewed publications from industry. Here we present a non-academic view on applied research in lithium-based batteries to sharpen the focus and help bridge the gap between academic and industrial research. We focus our discussion on key metrics and challenges to be considered when developing new technologies in this industry. We also explore the need to consider various performance aspects in unison when developing a new material/technology. Moreover, we also investigate the suitability of supply chains, sustainability of materials and the impact on system-level cost as factors that need to be accounted for when working on new technologies. With these considerations in mind, we then assess the latest developments in the lithium-based battery industry, providing our views on the challenges and prospects of various technologies.

Investigation of Water-Soluble Binders for LiNi0.5 Mn1.5 O4 -Based Full Cells.

Two water-soluble binders of carboxymethyl cellulose (CMC) and sodium alginate (SA) have been studied in comparison with N-methylpyrrolidone-soluble poly(vinylidene difluoride-co-hexafluoropropylene) (PVdF-HFP) to understand their effect on the electrochemical performance of a high-voltage lithium nickel manganese oxide (LNMO) cathode. The electrochemical performance has been investigated in full cells using a Li4 Ti5 O12 (LTO) anode. At room temperature, LNMO cathodes prepared with aqueous binders provided a similar electrochemical performance as those prepared with PVdF-HFP. However, at 55 °C, the full cells containing LNMO with the aqueous binders showed higher cycling stability. The results are supported by intermittent current interruption resistance measurements, wherein the electrodes with SA showed lower resistance. The surface layer formed on the electrodes after cycling has been characterized by X-ray photoelectron spectroscopy. The amount of transition metal dissolutions was comparable for all three cells. However, the amount of hydrogen fluoride (HF) content in the electrolyte cycled at 55 °C is lower in the cell with the SA binder. These results suggest that use of water-soluble binders could provide a practical and more sustainable alternative to PVdF-based binders for the fabrication of LNMO electrodes.

On the Durability of Protective Titania Coatings on High-Voltage Spinel Cathodes.

TiO2 -coating of LiNi0.5-x Mn1.5+x O4 (LNMO) by atomic layer deposition (ALD) has been studied as a strategy to stabilize the cathode/electrolyte interface and mitigate transition metal (TM) ion dissolution. The TiO2 coatings were found to be uniform, with thicknesses estimated to 0.2, 0.3, and 0.6 nm for the LNMO powders exposed to 5, 10, and 20 ALD cycles, respectively. While electrochemical characterization in half-cells revealed little to no improvement in the capacity retention neither at 20 nor at 50 °C, improved capacity retention and coulombic efficiencies were demonstrated for the TiO2 -coated LNMO in LNMO||graphite full-cells at 20 °C. This improvement in cycling stability could partly be attributed to thinner cathode electrolyte interphase on the TiO2 -coated samples. Additionally, energy-dispersive X-ray spectroscopy revealed a thinner solid electrolyte interphase on the graphite electrode cycled against TiO2 -coated LNMO, indicating retardation of TM dissolution by the TiO2 -coating.

Towards reliable three-electrode cells for lithium-sulfur batteries.

Three-electrode measurements are valuable to the understanding of the electrochemical processes in a battery system. However, their application in lithium-sulfur chemistry is difficult due to the complexity of the system and thus rarely reported. Here, we present a simple three-electrode cell format with relatively good life time and minimum interference with the cell operation.

Limitations of Ultrathin Al2O3 Coatings on LNMO Cathodes.

This study demonstrates the application of Al2O3 coatings for the high-voltage cathode material LiNi0.5-x Mn1.5+x O4-δ (LNMO) by atomic layer deposition. The ultrathin and uniform coatings (0.6-1.7 nm) were deposited on LNMO particles and characterized by scanning transmission electron microscopy, inductively coupled plasma mass spectrometry, and X-ray photoelectron spectroscopy. Galvanostatic charge discharge cycling in half cells revealed, in contrast to many published studies, that even coatings of a thickness of 1 nm were detrimental to the cycling performance of LNMO. The complete coverage of the LNMO particles by the Al2O3 coating can form a Li-ion diffusion barrier, which leads to high overpotentials and reduced reversible capacity. Several reports on Al2O3-coated LNMO using alternative coating methods, which would lead to a less homogeneous coating, revealed the superior electrochemical properties of the Al2O3-coated LNMO, suggesting that complete coverage of the particles might in fact be a disadvantage. We show that transition metal ion dissolution during prolonged cycling at 50 °C is not hindered by the coating, resulting in Ni and Mn deposits on the Li counter electrode. The Al2O3-coated LNMO particles showed severe signs of pitting dissolution, which may be attributed to HF attack caused by side reactions between the electrolyte and the Al2O3 coating, which can lead to additional HF formation. The pitting dissolution was most severe for the thickest coating (1.7 nm). The uniform coating coverage may lead to non-uniform conduction paths for Li, where the active sites are more susceptible to HF attack. Few benefits of applications of very thin, uniform, and amorphous Al2O3 coatings could thus be verified, and the coating is not offering long-term protection from HF attack.

Poly(Ethylene Glycol-block-2-Ethyl-2-Oxazoline) as Cathode Binder in Lithium-Sulfur Batteries.

Functional binders constitute a strategy to overcome several challenges that lithium-sulfur (Li-S) batteries are facing due to soluble reaction intermediates in the positive electrode. Poly (ethylene oxide) (PEO) and poly (vinylpyrrolidone) (PVP) are in this context a previously well-explored binder mixture. Their ether and amide groups possess affinity to the dissolved sulfur species, which enhances the sulfur utilization and mitigates the parasitic redox shuttle. However, the immiscibility of PEO and PVP is a concern for electrode stability. Copolymers comprising ether and amide groups are thus promising candidates to improve the stability the system. Here, a series of poly (ethylene glycol-block-2-ethyl-2-oxazoline) with various block lengths is synthesized and explored as binders in S/C composite electrodes in Li-S cells. While the electrochemical analyses show that although the sulfur utilization and capacity retention of the tested electrodes are similar, the integrity of the as-cast electrodes can play a key role for power capability.

Prospective Experience of Pulmonary Embolism Management and Outcomes.

OBJECTIVE: We sought to evaluate the impact of pulmonary embolism (PE) response teams (PERTs) on all consecutive patients with PE. BACKGROUND: Multidisciplinary PERTs have been promoted for the management and treatment of (PE); however, the impact of PERTs on clinical outcomes has not been prospectively evaluated. METHODS: We prospectively studied 220 patients with computed tomography (CT)-confirmed PE between January, 2019 and August, 2019. Baseline characteristics, as well as medical, interventional, and operational care, were captured. The total population was divided into 2 groups, ie, those with PERT activation and those without PERT activation. PERT activation was left at the discretion of the primary team. Our primary outcome was 90-day composite endpoint (rate of readmission, major bleeds, and mortality). Using 2:1 propensity-matched and multivariable-adjusted Cox proportional hazard analyses, we examined the impact of PERT activation on primary outcome, treatment approach, and length of stay. RESULTS: Of the total 220 patients, PERT was activated in 47 (21.4%). The PERT cohort, as compared with the non-PERT cohort, was more likely to present with dyspnea, syncope, lower systolic blood pressure, higher heart rate, higher respiratory rate, lower oxygen saturation, higher troponin levels, and higher right ventricular to left ventricular ratio. PERT activation was associated with increased use of advanced therapies (36.2% vs 1.2%; P<.001) and catheter-directed inventions (25.5% vs 0.6%; P<.001). In multivariable-adjusted analysis of propensity-matched cohorts, PERT activation was associated with lower 90-day outcomes (hazard ratio, 0.40; 95% confidence interval, 0.21-0.75; P<.01). CONCLUSION: At our institution, PERT had a clinically significant impact on therapeutic strategies and 90-day outcomes in patients with PE.

Simultaneous Monitoring of Crystalline Active Materials and Resistance Evolution in Lithium-Sulfur Batteries.

Operando X-ray diffraction (XRD) is a valuable tool for studying secondary battery materials as it allows for the direct correlation of electrochemical behavior with structural changes of crystalline active materials. This is especially true for the lithium-sulfur chemistry, in which energy storage capability depends on the complex growth and dissolution kinetics of lithium sulfide (Li2S) and sulfur (S8) during discharge and charge, respectively. In this work, we present a novel development of this method through combining operando XRD with simultaneous and continuous resistance measurement using an intermittent current interruption (ICI) method. We show that a coefficient of diffusion resistance, which reflects the transport properties in the sulfur/carbon composite electrode, can be determined from analysis of each current interruption. Its relationship to the established Warburg impedance model is validated theoretically and experimentally. We also demonstrate for an optimized electrode formulation and cell construction that the diffusion resistance increases sharply at the discharge end point, which is consistent with the blocking of pores in the carbon host matrix. The combination of XRD with ICI allows for a direct correlation of structural changes with not only electrochemical properties but also energy loss processes at a nonequilibrium state and, therefore, is a valuable technique for the study of a wide range of energy storage chemistries.

Coronary Embolism: A Systematic Review.

BACKGROUND: Coronary embolism is a rare and potentially fatal phenomenon that occurs primarily in patients with valvular heart disease and atrial fibrillation. There is a lack of consensus regarding the diagnosis, treatment, and management of coronary embolism, leaving management at the discretion of the treating physician. Through this review, we aim to establish a better understanding of coronary embolism, and to identify treatment options - invasive and non-invasive - that may be used to manage coronary embolism. METHODS AND RESULTS: Our systematic review included 147 documented cases of coronary embolism from case reports and case series. The average age of our population was 54.2 ±â€¯17.6 years. The most common causes of coronary embolism included infective endocarditis (22.4%), atrial fibrillation (17.0%), and prosthetic heart valve thrombosis (16.3%). Initial presentation was indistinguishable from an acute coronary syndrome (ACS) due to coronary atherosclerosis, and the diagnosis required a high level of suspicion and evaluation with angiography. Treatment strategies included, but were not limited to, thrombectomy, thrombolysis, balloon angioplasty and stent placement. Myocardial dysfunction on echocardiography was observed in over 80% of patients following coronary embolism. "Good outcomes" were reported in 68.7% of case reports and case series, with a mortality rate of 12.9%. CONCLUSION: Coronary embolism is an under-recognized etiology of myocardial infarction with the potential for significant morbidity and mortality. To improve outcomes, physicians should strive for early diagnosis and intervention based on the underlying etiology. Thrombectomy may be considered with the goal of rapid restoration of coronary flow.

Operando EQCM-D with Simultaneous in Situ EIS: New Insights into Interphase Formation in Li Ion Batteries.

An operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) with simultaneous in situ electrochemical impedance spectroscopy (EIS) has been developed and applied to study the solid electrolyte interphase (SEI) formation on copper current collectors in Li ion batteries. The findings are backed by EIS simulations and complementary analytical techniques, such as online electrochemical mass spectrometry (OEMS) and X-ray photoelectron spectroscopy (XPS). The evolution of mass and the mechanical properties of the SEI are directly correlated to the electrode impedance. Electrolyte reduction at the anode carbon active material initiates dissolution, diffusion, and deposition of reaction side products throughout the cell and increases electrolyte viscosity and the ohmic cell resistance as a result. On Cu the reduction of CuO x and HF occurs at >1.5 V and forms an initial LiF-rich interphase while electrolyte solvent reduction at <0.8 V vs Li+/Li adds a second, less rigid layer on top. Both the shear storage modulus and viscosity of the SEI generally increase upon cycling but-along with the SEI Li+ diffusion coefficient-also respond reversibly to electrode potential, likely as a result of Li+/EC interfacial concentration changes. Combined EIS-EQCM-D provides unique prospects for further studies of the highly dynamic structure-function relationships of electrode interphases in Li ion batteries.

ε-Caprolactone-based solid polymer electrolytes for lithium-ion batteries: synthesis, electrochemical characterization and mechanical stabilization by block copolymerization.

In this work, three types of polymers based on ε-caprolactone have been synthesized: poly(ε-caprolactone), polystyrene-poly(ε-caprolactone), and polystyrene-poly(ε-caprolactone-r-trimethylene carbonate) (SCT), where the polystyrene block was introduced to improve the electrochemical and mechanical performance of the material. Solid polymer electrolytes (SPEs) were produced by blending the polymers with 10-40 wt% lithium bis(trifluoromethane)sulfonimide (LiTFSI). Battery devices were thereafter constructed to evaluate the cycling performance. The best performing battery half-cell utilized an SPE consisting of SCT and 17 wt% LiTFSI as both binder and electrolyte; a Li|SPE|LiFePO4 cell that cycled at 40 °C gave a discharge capacity of about 140 mA h g-1 at C/5 for 100 cycles, which was superior to the other investigated electrolytes. Dynamic mechanical analysis (DMA) showed that the storage modulus E' was about 5 MPa for this electrolyte.

A Robust, Water-Based, Functional Binder Framework for High-Energy Lithium-Sulfur Batteries.

We report here a water-based functional binder framework for the lithium-sulfur battery systems, based on the general combination of a polyether and an amide-containing polymer. These binders are applied to positive electrodes optimised towards high-energy electrochemical performance based only on commercially available materials. Electrodes with up to 4 mAh cm-2 capacity and 97-98 % coulombic efficiency are achievable in electrodes with a 65 % total sulfur content and a poly(ethylene oxide):poly(vinylpyrrolidone) (PEO:PVP) binder system. Exchange of either binder component for a different polymer with similar functionality preserves the high capacity and coulombic efficiency. The improvement in coulombic efficiency from the inclusion of the coordinating amide group was also observed in electrodes where pyrrolidone moieties were covalently grafted to the carbon black, indicating the role of this functionality in facilitating polysulfide adsorption to the electrode surface. The mechanical properties of the electrodes appear not to significantly influence sulfur utilisation or coulombic efficiency in the short term but rather determine retention of these properties over extended cycling. These results demonstrate the robustness of this very straightforward approach, as well as the considerable scope for designing binder materials with targeted properties.

A stable graphite negative electrode for the lithium-sulfur battery.

Efficient, reversible lithium intercalation into graphite in ether-based electrolytes is enabled through a protective electrode binder, polyacrylic acid sodium salt (PAA-Na). In turn, this enables the creation of a stable "lithium-ion-sulfur" cell, using a lithiated graphite negative electrode with a sulfur positive electrode, using the common DME:DOL solvent system suited to the electrochemistry of the lithium-sulfur battery. Graphite-sulfur lithium-ion cells show average coulombic efficiencies of ∼99.5%, compared with <95% for lithium-sulfur cells, and significantly better capacity retention, taking into account cell balancing considerations. The high efficiency derives from the considerably better interfacial stability of the graphite electrode, which suppresses the polysulfide redox shuttle and self-discharge.

Visualising the problems with balancing lithium-sulfur batteries by "mapping" internal resistance.

Frequent and continuous determination of battery internal resistance by a simple current-interrupt method enables the visualisation of cell behaviour through the creation of resistance "maps", showing changes in resistance as a function of both capacity and cycle number. This new approach is applied here for the investigation of cell failure in the lithium-sulfur system with Li electrode excesses optimised towards practically relevant specifications.

Why PEO as a binder or polymer coating increases capacity in the Li-S system.

PEO, used either as a binder or a polymer coating, and PEGDME, used as an electrolyte additive, are shown to increase the reversible capacity of Li-S cells. The effect, in all three cases, is the same: an improved solvent system for the electrochemistry of sulfur species and suppression of cathode passivation on discharge. This constitutes a novel interpretation of the mechanistic behaviour of polyethers in the Li-S system, and sheds new light upon several previous studies.