Characterization of the Particle-Polymer Interface in Dual-Phase Electrolytes by Kelvin Probe Force Microscopy

In this study, the possibility to characterize the electrochemical characteristics of the particle-polymer interface in dual-phase electrolytes by measuring the contact potential difference with high local resolution is demonstrated. Two different polymer electrolytes, polyethylene oxide (PEO) and poly[bis-2-(2-methoxyethoxy)-ethoxyphosphazene] (MEEP), were investigated in combination with lithium ion conductive Li7La3Zr2O12 (LLZ) particles and two different mixed ionic-electronic conductive ceramic particles: uncoated and carbon coated LiFePO4 (LFP) as typical cathode material and uncoated Li4Ti5O12 as typical anode material. A distinct Volta potential gradient between the particles and the polymer was observable in all cases, except when no lithium salt was present within the polymer matrix. The measured potential gradients can be explained in terms of a contact potential between the polymer electrolyte and the ceramic electrolyte. A more negatively charged space charge layer around LFP particles in PEO matrix and around LLZ particles in MEEP can be explained by enrichment of salt anions in direct vicinity of the particle.Electrochemical characterization with impedance spectroscopy showed an increased conductivity for addition of LFP for PEO while the addition of various particles in different concentrations showed no effect on the conductivity of MEEP. The lithium transference number was unaffected by particle addition for all samples

Polycarbonate-Based Lithium Salt-Containing Electrolytes: New Insights into Thermal Stability

For investigation of the thermal stability of polycarbonate-based lithium salt-containing electrolytes, polycarbonate–salt mixtures [polyethylene carbonate (PEC) and polypropylene carbonate (PPC) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)] were heated to 100 °C and the conductivity was monitored with electrochemical impedance spectroscopy for at least 24 h. At a constant high temperature, the observed rise in conductivity can be correlated to degradation of long-chain polymer units to small-chain polymer units as the viscosity decreases with a shorter chain length. In both cases, degradation can be observed. With PEC–LiTFSI, it takes ≈9 h until total degradation; with PPC–LiTFSI, the process is slower. Additionally, we repeated the experiments with PEC and other Li salts such as lithium trifluoromethanesulfonate (LiOTf), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), and lithium difluoro(oxalato)borate (LiDFOB). These experiments resulted in the degradation being dependent on the electrophilic activation by the lithium salt. With different Li-free salts such as sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), potassium bis(trifluoromethanesulfonyl)imide (KTFSI), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr14TFSI), no degradation of the polymer is observable. As a degradation mechanism, we anticipate a depolymerization of PEC at the α-carbon of the carbonate group in the polymer chain in the presence of a lithium salt with a weakly coordinating anion

Electrochemical Proton Intercalation in Vanadium Pentoxide Thin Films and its Electrochromic Behavior in the near‐IR Region

This work examines the proton intercalation in vanadium pentoxide (V2O5) thin films and its optical properties in the near‐infrared (near‐IR) region. Samples were prepared via direct current magnetron sputter deposition and cyclic voltammetry was used to characterize the insertion and extraction behavior of protons in V2O5 in a trifluoroacetic acid containing electrolyte. With the same setup chronopotentiometry was done to intercalate a well‐defined number of protons in the HxV2O5 system in the range of x=0 and x=1. These films were characterized with optical reflectometry in the near‐IR region (between 700 and 1700 nm wavelength) and the refractive index n and extinction coefficient k were determined using Cauchy’s dispersion model. The results show a clear correlation between proton concentration and n and k

Electrochemical Proton Intercalation in Vanadium Pentoxide Thin Films and its Electrochromic Behavior in the near‐IR Region

Abstract This work examines the proton intercalation in vanadium pentoxide (V2O5) thin films and its optical properties in the near‐infrared (near‐IR) region. Samples were prepared via direct current magnetron sputter deposition and cyclic voltammetry was used to characterize the insertion and extraction behavior of protons in V2O5 in a trifluoroacetic acid containing electrolyte. With the same setup chronopotentiometry was done to intercalate a well‐defined number of protons in the HxV2O5 system in the range of x=0 and x=1. These films were characterized with optical reflectometry in the near‐IR region (between 700 and 1700 nm wavelength) and the refractive index n and extinction coefficient k were determined using Cauchy’s dispersion model. The results show a clear correlation between proton concentration and n and k

Absolute Local Quantification of Li as Function of State-of-Charge in All-Solid-State Li Batteries via 2D MeV Ion-Beam Analysis

Direct observation of the lithiation and de-lithiation in lithium batteries on the component and microstructural scale is still difficult. This work presents recent advances in MeV ion-beam analysis, enabling quantitative contact-free analysis of the spatially-resolved lithium content and state-of-charge (SoC) in all-solid-state lithium batteries via 3 MeV proton-based characteristic x-ray and gamma-ray emission analysis. The analysis is demonstrated on cross-sections of ceramic and polymer all-solid-state cells with LLZO and MEEP/LIBOB solid electrolytes. Different SoC are measured ex-situ and one polymer-based operando cell is charged at 333 K during analysis. The data unambiguously show the migration of lithium upon charging. Quantitative lithium concentrations are obtained by taking the physical and material aspects of the mixed cathodes into account. This quantitative lithium determination as a function of SoC gives insight into irreversible degradation phenomena of all-solid-state batteries during the first cycles and locations of immobile lithium. The determined SoC matches the electrochemical characterization within uncertainties. The presented analysis method thus opens up a completely new access to the SoC of battery cells not depending on electrochemical measurements. Automated beam scanning and data-analysis algorithms enable a 2D quantitative Li and SoC mapping on the μm-scale, not accessible with other methods

Absolute Local Quantification of Li as Function of State-of-Charge in All-Solid-State Li Batteries via 2D MeV Ion-Beam Analysis

Direct observation of the lithiation and de-lithiation in lithium batteries on the component and microstructural scale is still difficult. This work presents recent advances in MeV ion-beam analysis, enabling quantitative contact-free analysis of the spatially-resolved lithium content and state-of-charge (SoC) in all-solid-state lithium batteries via 3 MeV proton-based characteristic x-ray and gamma-ray emission analysis. The analysis is demonstrated on cross-sections of ceramic and polymer all-solid-state cells with LLZO and MEEP/LIBOB solid electrolytes. Different SoC are measured ex-situ and one polymer-based operando cell is charged at 333 K during analysis. The data unambiguously show the migration of lithium upon charging. Quantitative lithium concentrations are obtained by taking the physical and material aspects of the mixed cathodes into account. This quantitative lithium determination as a function of SoC gives insight into irreversible degradation phenomena of all-solid-state batteries during the first cycles and locations of immobile lithium. The determined SoC matches the electrochemical characterization within uncertainties. The presented analysis method thus opens up a completely new access to the state-of-charge of battery cells not depending on electrochemical measurements. Automated beam scanning and data-analysis algorithms enable a 2D quantitative Li and SoC mapping on the µm-scale, not accessible with other methods

Impact of elexacaftor/tezacaftor/ivacaftor on lung function, nutritional status, pulmonary exacerbation frequency and sweat chloride in people with cystic fibrosis: real-world evidence from the German CF RegistryResearch in context

Summary: Background: Treatment with elexacaftor/tezacaftor/ivacaftor (ETI) improves multiple clinical outcomes in people with cystic fibrosis (pwCF) with at least one F508del allele. This study evaluated the real-world impact of ETI on lung function, nutritional status, pulmonary exacerbation frequency, and sweat chloride concentrations in a large group of pwCF. Methods: This observational cohort study used data from the German CF Registry for pwCF who received ETI therapy and were followed up for a period of 12 months. Findings: The study included 2645 pwCF from 67 centres in Germany (mean age 28.0 ± 11.5 years). Over the first year after ETI was initiated, percent predicted forced expiratory volume in 1 s (ppFEV1) increased by 11.3% (95% confidence interval [CI] 10.8–11.8, p < 0.0001), body mass index (BMI) z-score increased by 0.3 (95% CI 0.3–0.4, p < 0.0001) in individuals aged 12 to <18 years and BMI in adults increased by 1.4 kg/m2 (95% CI 1.3–1.4, p < 0.0001), pulmonary exacerbations decreased by 75.9% (p < 0.0001) and mean sweat chloride concentration decreased by 50.9 mmol/L (95% CI –52.6, −49.3, p < 0.0001). Improvements in ppFEV1 over the first year of therapy were greater in pwCF who had not previously received cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy (12.6% [95% CI 11.9–13.4] vs. 9.7% [95% CI 9.0–10.5] in those with prior CFTR modulator treatment. Interpretation: These real-world data are consistent with the findings of randomised clinical trials, and support the use of ETI as a highly effective treatment option for pwCF who have at least one F508del allele. Funding: None