Transoral Excision of an Intracordal Schwannoma: A Case Report and Review.

We discuss a novel approach to resecting a large 1.5 cm intracordal schwannoma via direct laryngoscopy with combined endoscopic and microlaryngoscopic techniques. Removing relatively bulky masses within the vocal cord soft tissue can be challenging secondary to difficult visualization of the operative field during direct laryngoscopy. We describe a case where a bulky atypical spindle cell schwannoma was removed via direct laryngoscopy via combined endoscopic and microlaryngoscopic techniques. The tumor obstructed 40% of the visual field of the laryngoscope. In this case, a 44-year-old female presented to the head and neck surgery clinic with 1.5 years of progressive hoarseness. On fiberoptic laryngoscopy, a mass was noted medializing the right true vocal cord. The patient was taken to surgery and after intubation and suspension with a Dedo laryngoscope, the mass was removed trans-orally through the laryngoscope with visualization using a combination of rigid and flexible endoscopy as well as with a microscope. Although visualization can sometimes be reduced using direct laryngoscopy, surgical excision of relatively large laryngeal masses can be performed in selected cases without the need to approach the masses trans-cervically.

Toward solid-state Limetal-air batteries; an SOFC perspective of solid 3D architectures, heterogeneous interfaces, and oxygen exchange kinetics.

The full electrification of transportation will require batteries with both 3-5× higher energy densities and a lower cost than what is available in the market today. Energy densities of >1000 W h kg-1 will enable electrification of air transport and are among the very few technologies capable of achieving this energy density. Limetal-O2 or Limetal-air are theoretically able to achieve this energy density and are also capable of reducing the cost of batteries by replacing expensive supply chain constrained cathode materials with "free" air. However, the utilization of liquid electrolytes in the Limetal-O2/Limetal-air battery has presented many obstacles to the optimum performance of this battery including oxidation of the liquid electrolyte and the Limetal anode. In this paper a path towards the development of a Limetal-air battery using a cubic garnet Li7La3Zr2O12 (LLZ) solid-state ceramic electrolyte in a 3D architecture is described including initial cycling results of a Limetal-O2 battery using a recently developed mixed ionic and electronic (MIEC) LLZ in that 3D architecture. This 3D architecture with porous MIEC structures for the O2/air cathode is essentially the same as a solid oxide fuel cell (SOFC) indicating the importance of leveraging SOFC technology in the development of solid-state Limetal-O2/air batteries.

The use of MRI for the imaging of metastatic bone lesions.

Skeletal metastatic disease accounts for significant overall morbidity in cancer patients. Accurate and accessible imaging forms an integral part of the investigation for patients with suspected or known skeletal metastatic disease; it is considered indispensable in making appropriate oncological treatment decisions. Magnetic resonance imaging (MRI) is a contemporary imaging modality that provides excellent spatial and contrast resolution for bone and soft tissues. Therefore, it is particularly useful for imaging patients suffering from metastatic skeletal disease. This review provides a fundamental overview of the physics and image generation of MRI. The most commonly used MRI sequences in the investigation of metastatic skeletal disease are also discussed. Additionally, a review of the pathophysiological basis of metastatic bone disease is presented, along with an introduction to the interpretation of MRI sequences obtained for metastatic bone disease. Finally, the strengths and drawbacks of MRI are considered in comparison to alternative imaging modalities for the investigation of this common and important oncological complication.

Presence of Preoperative Neurodegeneration Biofluid Markers in Patients with Postoperative Delirium.

BACKGROUND: The pathophysiology of delirium is incompletely understood, including what molecular pathways are involved in brain vulnerability to delirium. This study examined whether preoperative plasma neurodegeneration markers were elevated in patients who subsequently developed postoperative delirium through a retrospective case-control study. METHODS: Inclusion criteria were patients of 65 yr of age or older, undergoing elective noncardiac surgery with a hospital stay of 2 days or more. Concentrations of preoperative plasma P-Tau181, neurofilament light chain, amyloid ß1-42 (Aß42), and glial fibrillary acidic protein were measured with a digital immunoassay platform. The primary outcome was postoperative delirium measured by the Confusion Assessment Method. The study included propensity score matching by age and sex with nearest neighbor, such that each patient in the delirium group was matched by age and sex with a patient in the no-delirium group. RESULTS: The initial cohort consists of 189 patients with no delirium and 102 patients who developed postoperative delirium. Of 291 patients aged 72.5 ± 5.8 yr, 50.5% were women, and 102 (35%) developed postoperative delirium. The final cohort in the analysis consisted of a no-delirium group (n = 102) and a delirium group (n = 102) matched by age and sex using the propensity score method. Of the four biomarkers assayed, the median value for neurofilament light chain was 32.05 pg/ml for the delirium group versus 23.7 pg/ml in the no-delirium group. The distribution of biomarker values significantly differed between the delirium and no-delirium groups (P = 0.02 by the Kolmogorov-Smirnov test) with the largest cumulative probability difference appearing at the biomarker value of 32.05 pg/ml. CONCLUSIONS: These results suggest that patients who subsequently developed delirium are more likely to be experiencing clinically silent neurodegenerative changes before surgery, reflected by changes in plasma neurofilament light chain biomarker concentrations, which may identify individuals with a preoperative vulnerability to subsequent cognitive decline.

Microwave-Assisted Fabrication of High Energy Density Binary Metal Sulfides for Enhanced Performance in Battery Applications.

Nanomaterials have found use in a number of relevant energy applications. In particular, nanoscale motifs of binary metal sulfides can function as conversion materials, similar to that of analogous metal oxides, nitrides, or phosphides, and are characterized by their high theoretical capacity and correspondingly low cost. This review focuses on structure-composition-property relationships of specific relevance to battery applications, emanating from systematic attempts to either (1) vary and alter the dimension of nanoscale architectures or (2) introduce conductive carbon-based entities, such as carbon nanotubes and graphene-derived species. In this study, we will primarily concern ourselves with probing metal sulfide nanostructures generated by a microwave-mediated synthetic approach, which we have explored extensively in recent years. This particular fabrication protocol represents a relatively facile, flexible, and effective means with which to simultaneously control both chemical composition and physical morphology within these systems to tailor them for energy storage applications.

Ultrasound-guided supraclavicular block versus Bier block for emergency reduction of upper limb injuries: a protocol for an open-label, non-inferiority, randomised controlled trial.

BACKGROUND: Closed reduction of upper limb fractures and/or dislocations are common in the emergency department (ED), which involves physically re-aligning the injured part prior to immobilisation. As this is painful, numerous techniques are available to provide regional anaesthesia to ensure patient tolerance. A Bier block (BB) is typically performed as part of routine care. An alternative technique gaining interest in the ED is ultrasound-guided supraclavicular block (UGSCB), which involves injecting local anaesthetic around the brachial plexus at the supraclavicular fossa under ultrasound guidance. It is unclear whether UGSCB is effective and safe when performed in the ED. METHODS: SUPERB (SUPraclavicular block for Emergency Reduction versus Bier block) is a prospective open-label, non-inferiority randomised controlled trial that compares the effectiveness of UGSCB versus BB for closed reduction of upper limb fractures and/or dislocations. Adult patients presenting with an upper limb fracture and/or dislocation that requires emergent closed reduction in the ED will be eligible. After screening, participants will be randomised to either UGSCB or BB. Once regional anaesthesia is obtained, closed reduction of the injured part will be performed and appropriately immobilised. The primary outcome is maximal pain experienced during closed reduction measured via a visual analogue scale (VAS). Secondary outcomes include baseline and post-reduction pain, patient satisfaction, total opioid requirement in ED, ED length of stay, adverse events and regional anaesthesia failure. DISCUSSION: Existing evidence suggests UGSCB is effective when performed in the operating theatre by trained anaesthetists. SUPERB will be the first randomised controlled trial to elucidate the effectiveness and safety of UGSCB in the ED. The findings have the potential to provide an alternative safe and effective option for the management of upper extremity emergencies in the ED. TRIAL REGISTRATION: This trial has been registered on 21 October 2022 with Australia and New Zealand Clinical Trials Registry (ACTRN12622001356752).

Spatiotemporal Resolution of Phase Formation in Thick Porous Sodium Vanadium Oxide (NaV3O8) Electrodes via Operando Energy Dispersive X-ray Diffraction.

Herein, zinc vanadium oxide (ZVO) and zinc hydroxy-sulfate (ZHS) formation as discharge products in sodium vanadium oxide (NVO) cathode materials of two distinct morphologies, NVO(300) and NVO(500), is studied with ex situ and operando X-ray diffraction methods. ZHS formation upon discharge is shown to be favored at higher current densities and reversible upon charge, while ZVO formation is found to be favored at lower current densities but persists throughout cycling. Operando synchrotron-based energy dispersive X-ray diffraction (EDXRD) reveals reversible expansion of the NVO lattice due to Zn2+ during discharge, spontaneous ZVO formation following cell assembly, and ZHS formation concomitant with H+ insertion at potentials less than ∼0.8 V vs Zn/Zn2+. With spatially resolved EDXRD, ZVO formation is show to occur near the separator region first, eventually moving to the current collector region as discharge depth increases. ZHS formation, however, is found to originate from the current collector side of the positive electrode and then propagate through the porous electrode network. This study highlights the special benefits of the EDXRD method to gain mechanistic insight into structural evolution within the electrode and at its interface.

Sleep Loss the night before surgery and incidence of postoperative delirium in adults 65-95 years of age.

STUDY OBJECTIVES: To describe the association between preoperative sleep disruption and postoperative delirium. METHODS: Prospective cohort study with six time points (3 nights pre-hospitalization and 3 nights post-surgery). The sample included 180 English-speaking patients ≥65 years old scheduled for major non-cardiac surgery and anticipated minimum hospital stay of 3 days. Six days of wrist actigraphy recorded continuous movement to estimate wake and sleep minutes during the night from 22:00 to 05:59. Postoperative delirium was measured by a structured interview using the Confusion Assessment Method. Sleep variables for patients with (n = 32) and without (n = 148) postoperative delirium were compared using multivariate logistic regression. RESULTS: Participants had a mean age of 72 ± 5 years (range 65-95 years). The incidence of postoperative delirium during any of the three postoperative days was 17.8%. Postoperative delirium was significantly associated with surgery duration (OR = 1.49, 95% CI 1.24-1.83) and sleep loss >15% on the night before surgery (OR = 2.64, 95% CI 1.10-6.62). Preoperative symptoms of pain, anxiety and depression were unrelated to preoperative sleep loss. CONCLUSIONS: In this study of adults ≥65 years of age, short sleep duration was more severe preoperatively in the patients who experienced postoperative delirium as evidenced by sleep loss >15% of their normal night's sleep. However, we were unable to identify potential reasons for this sleep loss. Further investigation should include additional factors that may be associated with preoperative sleep loss to inform potential intervention strategies to mitigate preoperative sleep loss and reduce risk of postoperative delirium.

Managing two-dose COVID-19 vaccine rollouts with limited supply: Operations strategies for distributing time-sensitive resources.

Distributing scarce resources such as COVID-19 vaccines is often a highly time-sensitive and mission-critical operation. Our research was prompted by a significant obstacle that the United States and other nations encountered during the early months of the COVID-19 vaccination campaign: Most COVID-19 vaccines require two doses given 3 or 4 weeks apart. Given the severely limited supply and mounting pressure on many countries to reduce hospitalizations and mortality, how to effectively roll out two-dose vaccines was a critical policy decision. In this paper, we first model and analyze inventory dynamics of the rollout process under three rollout strategies: (1) holding back second doses, (2) releasing second doses, and (3) stretching the lead time between doses. Then we develop an SEIR (susceptible, exposed, infectious, recovered) model that incorporates COVID-19 asymptomatic and symptomatic infections to evaluate these strategies in terms of infections, hospitalizations, and mortality. Among our findings, we show releasing second doses reduces infections but creates uneven vaccination patterns. In addition, to ensure second doses are given on time without holding back inventory, strictly less than half of the supply can be allocated to first-dose appointments. Stretching the between-dose lead time flattens the infection curve and reduces both hospitalizations and mortality compared with the strategy of releasing second doses. We also consider an alternative single-dose vaccine with lower efficacy and show that the vaccine can be more effective than its two-dose counterparts in reducing infections and mortality. We conduct extensive sensitivity analyses related to age composition, risk-based prioritization, supply disruptions, and disease transmissibility. Our paper provides important implications for policymakers to develop effective vaccine rollout strategies in developed and developing countries alike. More broadly, our paper sheds light on how to develop effective operations strategies for distributing time-sensitive resources in times of crisis.

Chondrolaryngoplasty.

Chondrolaryngoplasty is a well-described surgical procedure most commonly performed as part of facial feminization surgery for transgender patients with a diagnosis of gender dysphoria. A complete understanding of relevant neck anatomy and laryngeal function is critical to optimizing surgical outcomes. The overall goal of the procedure is to maximally reduce the thyroid cartilage prominence while preserving laryngeal integrity and minimizing the risk of external scarring. Among available approaches, the bronchoscopic-assisted technique with intraoperative needle localization has been demonstrated to reliably lead to safe and effective surgical outcomes while minimizing the risk of postoperative complications.

KIBRA, MTNR1B, and FKBP5 genotypes are associated with decreased odds of incident delirium in elderly post-surgical patients.

Despite the association between cognitive impairment and delirium, little is known about whether genetic differences that confer cognitive resilience also confer resistance to delirium. To investigate whether older adults without postoperative delirium, compared with those with postoperative delirium, are more likely to have specific single nucleotide polymorphisms (SNPs) in the FKBP5, KIBRA, KLOTHO, MTNR1B, and SIRT1 genes known to be associated with cognition or delirium. This prospective nested matched exploratory case-control study included 94 older adults who underwent orthopedic surgery and screened for postoperative delirium. Forty-seven subjects had incident delirium, and 47 age-matched controls were not delirious. The primary study outcome was genotype frequency for the five SNPs. Compared with participants with delirium, those without delirium had higher adjusted odds of KIBRA SNP rs17070145 CT/TT [vs. CC; adjusted odds ratio (aOR) 2.80, 95% confidence interval (CI) 1.03, 7.54; p = 0.04] and MTNR1B SNP rs10830963 CG/GG (vs. CC; aOR 4.14, 95% CI 1.36, 12.59; p = 0.01). FKBP5 SNP rs1360780 CT/TT (vs. CC) demonstrated borderline increased adjusted odds of not developing delirium (aOR 2.51, 95% CI 1.00, 7.34; p = 0.05). Our results highlight the relevance of KIBRA, MTNR1B, and FKBP5 in understanding the complex relationship between delirium, cognition, and sleep, which warrant further study in larger, more diverse populations.

The Impact of Surgery duration and Surgery End Time on Postoperative Sleep in Older Adults.

OBJECTIVES/BACKGROUND: Sleep disruption is prevalent in older patients. No previous studies have considered the impact of surgery duration or surgery end time of day on postoperative sleep disruption. Accordingly, we examined the duration of surgery and surgery end times for associations with postoperative sleep disruption. METHODS: Inclusion criteria were patients ≥ 65 years of age undergoing major, non-cardiac surgery. Sleep disruption was measured by wrist actigraphy and defined as wake after sleep onset (WASO) during the night, or inactivity/sleep time during the day. The sleep opportunity window was set from 22:00 to 06:00 which coincided with "lights off and on" in the hospital. WASO during this 8-hour period on the first postoperative day was categorized into one of three groups: ≤ 15%, 15-25%, and > 25%. Daytime sleep (inactivity) during the first postoperative day was categorized as ≤ 20%, 20-40%, and > 40%. Statistical analyses were conducted to test for associations between surgery duration, surgery end time and sleep disruption on the first postoperative day and following night. RESULTS: For this sample of 156 patients, surgery duration ≥ 6 hours and surgery end time after 19:00 were not associated with WASO groups (p = 0.17, p = 0.94, respectively). Furthermore, daytime sleep was also not affected by surgery duration or surgery end time (p = 0.07, p = 0.06 respectively). CONCLUSION: Our hypothesis that patients with longer duration or later-ending operations have increased postoperative sleep disruption was not supported. Our results suggest the pathophysiology of postoperative sleep disruption needs further investigation.

Obesity and perioperative outcomes in older surgical patients undergoing elective spine and major arthroplasty surgery.

STUDY OBJECTIVE: To determine whether obesity status is associated with perioperative complications, discharge outcomes and hospital length of stay in older surgical patients. DESIGN: Secondary analysis of five independent study cohorts (N = 1262). SETTING: An academic medical center between 2001 and 2017 in the United States. PATIENTS: Patients aged 65 years or older who were scheduled to undergo elective spine, knee, or hip surgery with an expected hospital stay of at least 2 days. MEASUREMENTS: Body mass index (BMI) was stratified as nonobese (BMI ≤ 30 kg/m2), obesity class 1 (30 kg/m2 ≤ BMI < 35 kg/m2) or obesity class 2-3 (BMI ≥ 35 kg/m2). Primary outcomes included predefined intraoperative and postoperative complications, hospital length of stay (LOS), and discharge location. Univariate and multivariate logistic regression was performed. MAIN RESULTS: Obesity status was not associated with intraoperative adverse events. However, obesity class 2-3 significantly increased the risk for postoperative complications (IRR 1.43, 95% CI 1.03-1.95, P = 0.03), hospital LOS (IRR 1.13, 95% CI 1.02-1.25, P = 0.02) and non-home discharge destination (OR 1.95, 95% CI 1.35-2.81, P < 0.001) after accounting for patient related factors and surgery type. CONCLUSIONS: Obesity class 2-3 status has prognostic value in predicting an increased incidence of postoperative complications, increased hospital LOS, and non-home discharge location. These results have important clinical implications for preoperative informed consent and provide areas to target for care improvement for the older obese individual.

Impact of sodium vanadium oxide (NaV3O8, NVO) material synthesis conditions on charge storage mechanism in Zn-ion aqueous batteries.

The electrochemical charge storage of sodium vanadate (NaV3O8 or NVO) cathodes in aqueous Zn-ion batteries has been hypothesized to be influenced by the inclusion of structural water for facilitating ion transfer in the material. Materials properties considered important (morphology, crystallite and particle size, surface area) are systematically studied herein through investigation of two NVO materials, NaV3O8·0.34H2O [NVO(300)] and NaV3O8·0.05H2O [NVO(500)], with different water content, acicular morphologies with different size and surface area achieved via post-synthesis heat treatment. The electrochemistry of the two materials was evaluated in aqueous Zn-ion cells with 2 M ZnSO4 electrolyte using cyclic voltammetry, galvanostatic cycling, and rate capability testing. The thinner NVO(300) nanobelts (0.13 µm) demonstrate greater specific capacities and higher effective diffusion coefficients relative to the thicker NVO(500) nanorods. Notably however, while cells containing NVO(500) deliver lower specific capacity, they demonstrate enhanced capacity retention with cycling. The structural changes accompanying oxidation and reduction are elucidated via ex situ X-ray diffraction, transmission electron microscopy, and operando V K-edge X-ray absorption spectroscopy (XAS), where NVO material properties are shown to influence the ion insertion. Operando XAS verified that electron transfer corresponds directly to change in vanadium oxidation state, affirming vanadium redox as the governing electrochemical process.

Evaluating Patient Benefit From Laryngochondroplasty.

OBJECTIVES/HYPOTHESIS: To elucidate and review current literature on the surgical technique for laryngochondroplasty in male-to-female transgender patients. To determine the degree of benefit afforded to male-to-female transgender patients by laryngochondroplasty using the Glasgow Benefit Inventory (GBI). STUDY DESIGN: Retrospective case series. METHODS: After institutional review board approval was obtained, the GBI survey was given to patients who underwent laryngochondroplasty by the author. Demographic information was analyzed including age, race, wait time to surgery, distance traveled, median zip code income, and concomitant gender-affirming surgeries such as vaginoplasty, breast augmentation, or facial feminization. RESULTS: From April 2016 to April 2020, 209 patients received laryngochondroplasty within the Kaiser Permanente Northern California Medical System. Of those, 91 received laryngochondroplasty with the author and were given the GBI, with 73 patients (80%) responding. Patients were on average 31.4 years old, traveled 45.4 miles to the surgical site, lived in a zip code with a median income of $86,793.61, and waited 95.7 days for surgery. Patients had a statistically significant improvement in all three subscores (general, social, and physical) of the GBI as well as in their overall score. CONCLUSIONS: Laryngochondroplasty is a safe and effective procedure to reduce thyroid cartilage prominence (Adam's apple) in male-to-female transgender patients. There was a statistically significant improvement in the overall score and all subscores of the GBI after laryngochondroplasty LEVEL OF EVIDENCE: 4 Laryngoscope, 130:S1-S14, 2020.

ADAPT-2: A Randomized Clinical Trial to Reduce Intraoperative EEG Suppression in Older Surgical Patients Undergoing Major Noncardiac Surgery.

BACKGROUND: Recent limited evidence suggests that the use of a processed electroencephalographic (EEG) monitor to guide anesthetic management may influence postoperative cognitive outcomes; however, the mechanism is unclear. METHODS: This exploratory, single-center, randomized clinical trial included patients who were ≥65 years of age undergoing elective noncardiac surgery. The study aimed to determine whether monitoring the brain using a processed EEG monitor reduced EEG suppression and subsequent postoperative delirium. The interventional group received processed EEG-guided anesthetic management to keep the Patient State Index (PSI) above 35 computed by the SEDline Brain Function Monitor (Masimo, Inc, Irvine, CA), while the standard care group was also monitored, but the EEG data were blinded from the clinicians. The primary outcome was intraoperative EEG suppression. A secondary outcome was incident postoperative delirium during the first 3 days after surgery. RESULTS: All outcomes were analyzed using the intention-to-treat paradigm. Two hundred and four patients with a mean age of 72 ± 5 years were studied. Minutes of EEG suppression adjusted by the length of surgery was found to be less for the interventional group than the standard care group (median [interquartile range], 1.4% [5.0%] and 2.5% [10.4%]; Hodges-Lehmann estimated median difference [95% confidence interval {CI}] of -0.8% [-2.1 to -0.000009]). The effect of the intervention on EEG suppression differed for those with and without preoperative cognitive impairment (interaction P = .01), with the estimated incidence rate ratio (95% CI) of 0.39 (0.33-0.44) for those with preoperative cognitive impairment and 0.48 (0.44-0.51) for those without preoperative cognitive impairment. The incidence of delirium was not found to be different between the interventional (17%) and the standard care groups (20%), risk ratio = 0.85 (95% CI, 0.47-1.5). CONCLUSIONS: The use of processed EEG to maintain the PSI >35 was associated with less time spent in intraoperative EEG suppression. Preoperative cognitive impairment was associated with a greater percent of surgical time spent in EEG suppression. A larger prospective cohort study to include more cognitively vulnerable patients is necessary to show whether an intervention to reduce EEG suppression is efficacious in reducing postoperative delirium.

Does postoperative delirium following elective noncardiac surgery predict long-term mortality?

OBJECTIVE: to determine whether incident postoperative delirium in elective older surgical patient was associated with increased risk for mortality, controlling for covariates of 5-year mortality. DESIGN: secondary analysis of prospective cohort studies. SETTING: academic Medical Center. SUBJECTS: patients ≥65 years of age undergoing elective non-cardiac surgery. OUTCOMES: postoperative assessments of delirium measured using the Confusion Assessment Method (CAM), mortality within 5 years of the index surgery was determined from National Death Index records. RESULTS: postoperative delirium occurred in 332/1,315 patients (25%). Five years after surgery, 175 patients (13.3%) were deceased. Older age was associated with an increased odds of mortality [odds ratio (OR) 1.90, 95% confidence interval (CI) 1.20-2.70] for those aged 70-79 years compared to those aged <70 years, and OR 3.29, 95% CI 2.14-5.06 for those aged >80 years. Other variables associated with 5-year mortality on bi-variate analyses were white race, self-rated functional status, lower preoperative cognitive status, higher risk score as measured by the American Society of Anesthesiologists (ASA) classification, higher surgical risk score, history of congestive heart failure, myocardial infarction, renal disease, cancer, peripheral vascular disease and postoperative delirium. However, postoperative delirium was not associated with 5-year mortality on multi-variate logistic regression (OR 1.18, 95% CI 0.85-1.65). CONCLUSIONS: our results showed that delirium was not associated with 5-year mortality in elective surgical patients after consideration of co-variates of mortality. Our results suggest the importance of accounting for known preoperative risks for mortality when investigating the relationship between delirium and long-term mortality.

Defect Control in the Synthesis of 2 D MoS2 Nanosheets: Polysulfide Trapping in Composite Sulfur Cathodes for Li-S Batteries.

One of the inherent challenges with Li-S batteries is polysulfide dissolution, in which soluble polysulfide species can contribute to the active material loss from the cathode and undergo shuttling reactions inhibiting the ability to effectively charge the battery. Prior theoretical studies have proposed the possible benefit of defective 2 D MoS2 materials as polysulfide trapping agents. Herein the synthesis and thorough characterization of hydrothermally prepared MoS2 nanosheets that vary in layer number, morphology, lateral size, and defect content are reported. The materials were incorporated into composite sulfur-based cathodes and studied in Li-S batteries with environmentally benign ether-based electrolytes. Through directed synthesis of the MoS2 additive, the relationship between synthetically induced defects in 2 D MoS2 materials and resultant electrochemistry was elucidated and described.

Insights into Reactivity of Silicon Negative Electrodes: Analysis Using Isothermal Microcalorimetry.

Silicon offers high theoretical capacity as a negative electrode material for lithium-ion batteries; however, high irreversible capacity upon initial cycling and poor cycle life have limited commercial adoption. Herein, we report an operando isothermal microcalorimetry (IMC) study of a model system containing lithium metal and silicon composite film electrodes during the first two cycles of (de)lithiation. The total heat flow data are analyzed in terms of polarization, entropic, and parasitic heat flow contributions to quantify and determine the onset of parasitic reactions. These parasitic reactions, which include solid-electrolyte interphase formation, contribute to electrochemical irreversibility. Cycle 1 lithiation demonstrates the highest thermal energy output at 1509 mWh/g, compared to cycle 1 delithiation and cycle 2. To complement the calorimetry, operando X-ray diffraction is used to track the phase evolution of silicon. During cycle 1 lithiation, crystalline Si undergoes transformation to amorphous lithiated silicon and ultimately to crystalline Li15Si4. The solid-state amorphization process is correlated to a decrease in entropic heat flow, suggesting that heat associated with the amorphization contributes significantly to the entropic heat flow term. This study effectively uses IMC to probe the parasitic reactions that occur during lithiation of a silicon electrode, demonstrating an approach that can be broadly applied to quantify parasitic reactions in other complex systems.