Internal Precipitation of Molecular Oxygen and Electromechanical Failure of Zirconia Solid Electrolytes

Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side‑products. This is particularly important for bioelectronic devices which are designed to operate in biological systems. While redox‑active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side‑reactions with molecular oxygen during device operation. We show that this electrochemical side reaction yields hydrogen peroxide (H2O2), a reactive side‑product, which may be harmful to the local biological environment and may also accelerate device degradation. We report a design strategy for the development of redox-active organic semiconductors based on donor-acceptor copolymers that prevent the formation of H2O2 during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte‑gated devices in application-relevant environments.

Download Full-text

How Certain Are the Reported Ionic Conductivities of Thiophosphate-Based Solid Electrolytes? an Interlaboratory Study

10.26434/chemrxiv.11316497.v2 ◽

2020 ◽

Author(s):

Saneyuki Ohno ◽

Tim Bernges ◽

Johannes Buchheim ◽

Marc Duchardt ◽

Anna-Katharina Hatz ◽

...

Keyword(s):

Standard Deviation ◽

Ionic Conductivity ◽

Relative Standard Deviation ◽

Solid Electrolytes ◽

Ionic Conductivities ◽

Ionic Conductors ◽

Energy Storage Devices ◽

Activation Barriers ◽

Storage Devices ◽

Relative Standard

Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an interlaboratory reproducibility of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm-1 in the measured total ionic conductivity (1.3 – 5.8 mScm-1 for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.

Download Full-text

Optical Properties of Photodynamic Therapy Drugs in Different Environments: The Paradigmatic Case of Temoporfin

10.26434/chemrxiv.12118917.v2 ◽

2020 ◽

Author(s):

busenur Aslanoglu ◽

Ilya Yakavets ◽

Vladimir Zorin ◽

Henri-Pierre Lassalle ◽

Francesca Ingrosso ◽

...

Keyword(s):

Drug Delivery ◽

Optical Properties ◽

Photodynamic Therapy ◽

Minimally Invasive ◽

Visible Light ◽

Cancer Treatment ◽

Singlet Oxygen ◽

Tumor Cells ◽

Molecular Oxygen ◽

Computational Tools

Computational tools have been used to study the photophysical and photochemical features of photosensitizers in photodynamic therapy (PDT) –a minimally invasive, less aggressive alternative for cancer treatment. PDT is mainly based by the activation of molecular oxygen through the action of a photoexcited sensitizer (photosensitizer). Temoporfin, widely known as mTHPC, is a second-generation photosensitizer, which produces the cytotoxic singlet oxygen when irradiated with visible light and hence destroys tumor cells. However, the bioavailability of the mostly hydrophobic photosensitizer, and hence its incorporation into the cells, is fundamental to achieve the desired effect on malignant tissues by PDT. In this study, we focus on the optical properties of the temoporfin chromophore in different environments –in vacuo, in solution, encapsulated in drug delivery agents, namely cyclodextrin, and interacting with a lipid bilayer.

Download Full-text

A New Phase of the Na+ Ion Conductor Na3PS4

10.26434/chemrxiv.8003717.v1 ◽

2019 ◽

Author(s):

Theodosios Famprikis ◽

James Dawson ◽

François Fauth ◽

Emmanuelle Suard ◽

Benoit Fleutot ◽

...

Keyword(s):

Solid Electrolytes ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Orthorhombic Crystal ◽

Orthorhombic Crystal Structure ◽

Ion Conductor ◽

Solid State Batteries ◽

Density Analysis ◽

Two Phases ◽

Dynamics Simulations

<div> Solid electrolytes are crucial for next‑generation solid‑state batteries and Na3PS4 is one of the most promising Na+ conductors for such applications. At present, two phases of Na3PS4 have been identified and it had been thought to melt above 500 °C. In contrast, we show that it remains solid above this temperature and transforms into a third polymorph, γ, exhibiting superionic behavior. We propose an orthorhombic crystal structure for γ‑Na3PS4 based on scattering density analysis of diffraction data and density functional theory calculations. We show that the Na+ superionic behavior is associated with rotational motion of the thiophosphate polyanions pointing to a rotor phase, based on ab initio molecular dynamics simulations and supported by high‑temperature synchrotron and neutron diffraction, thermal analysis and impedance spectroscopy. These findings are of importance for the development of new polyanion‑based solid electrolytes. </div>

Download Full-text

Operando Visualization of Morphological Dynamics in All-Solid-State Batteries

10.26434/chemrxiv.8299406 ◽

2019 ◽

Author(s):

Xiaohan Wu ◽

Juliette Billaud ◽

Iwan Jerjen ◽

Federica Marone ◽

Yuya Ishihara ◽

...

Keyword(s):

Solid State ◽

Solid Electrolytes ◽

Rational Design ◽

Morphological Evolution ◽

Active Material ◽

Composite Layer ◽

Transference Number ◽

Thermal Stabilities ◽

Solid State Batteries ◽

All Solid State Batteries

<div> <div> <div> All-solid-state batteries are considered as attractive options for next-generation energy storage owing to the favourable properties (unit transference number and thermal stabilities) of solid electrolytes. However, there are also serious concerns about mechanical deformation of solid electrolytes leading to the degradation of the battery performance. Therefore, understanding the mechanism underlying the electro-mechanical properties in SSBs are essentially important. Here, we show three-dimensional and time-resolved measurements of an all-solid-state cell using synchrotron radiation x-ray tomographic microscopy. We could clearly observe the gradient of the electrochemical reaction and the morphological evolution in the composite layer. Volume expansion/compression of the active material (Sn) was strongly oriented along the thickness of the electrode. While this results in significant deformation (cracking) in the solid electrolyte region, we also find organized cracking patterns depending on the particle size and their arrangements. This study based on operando visualization therefore opens the door towards rational design of particles and electrode morphology for all-solid-state batteries. </div> </div> </div>

Download Full-text