9 research outputs found
Performance-Determining Factors for Si–Graphite Electrode Evaluation: The Role of Mass Loading and Amount of Electrolyte Additive
The mass loading of Si–graphite electrodes is often considered as a parameter of secondary importance when testing their electrochemical performance. However, if a sacrificial additive is present in the electrolyte to improve the electrochemical performance, the electrode loading becomes the battery cycle-life-determining factor. The correlation between mass-loading, electrolyte additive, and binder type was investigated by analyzing the cycling behavior of Si–graphite electrodes, prepared with water-based binders, with mass loading ranging from 3 to 9.5 mg cm and cycled with FEC electrolyte additive, while keeping electrolyte amount constant. A lower loading was obtained by keeping slurry preparation steps unchanged from binder to binder and resulted in a longer lifetime for some of the binders. When the final loading was kept constant instead, the performance became independent of the binder used. Since such results can lead to the misinterpretation of the influence of electrode components on the cycling stability (and to a preference of one binder over another in our case), we propose that a comparison of long-term electrochemical performance data of Si–graphite electrodes needs to be always collected by using the same mass-loading with the constant electrolyte and additive
Controlled Design of Functional Nano-Coatings: Reduction of Loss Mechanisms in Photoelectrochemical Water Splitting
Efficient water splitting
with photoelectrodes requires highly performing and stable photoactive
materials. Since there is no material known which fulfills all these
requirements because of various loss mechanisms, we present a strategy
for efficiency enhancement of photoanodes via deposition of functional
coatings in the nanometer range. Origins of performance losses in
particle-based oxynitride photoanodes were identified and specifically
designed coatings were deposited to address each loss mechanism individually.
Amorphous TiO<sub>2</sub> located at interparticle boundaries enables
high electron conductivity. A thin layer of amorphous Ta<sub>2</sub>O<sub>5</sub> can be used as protection layer for photoanodes because
of its hole conductivity and thermal and chemical stability. An amorphous
layer of NiO<sub><i>x</i></sub> and CoÂ(OH)<sub>2</sub> reduces
photocorrosion or increases water oxidation kinetics because they
act as a hole-capture material or water oxidation catalyst, respectively.
Crystalline CoO<sub><i>x</i></sub> nanoparticles increase
photocurrent and reduce the onset potential due to enhanced charge
separation. The combination of all coatings deposited by a scalable,
mild, and reproducible step-by-step approach leads to high-performance
oxynitride-based photoanodes providing a maximum photocurrent of 2.52
mA/cm<sup>2</sup> at 1.23 V<sub>RHE</sub> under AM1.5G illumination
High-Performance Amorphous Carbon Coated LiNi<sub>0.6</sub>Mn<sub>0.2</sub>Co<sub>0.2</sub>O<sub>2</sub> Cathode Material with Improved Capacity Retention for Lithium-Ion Batteries
Coating conducting polymers onto active cathode materials has been proven to mitigate issues at high current densities stemming from the limited conducting abilities of the metal-oxides. In the present study, a carbon coating was applied onto nickel-rich NMC622 via polymerisation of furfuryl alcohol, followed by calcination, for the first time. The formation of a uniform amorphous carbon layer was observed with scanning- and transmission-electron microscopy (SEM and TEM) and X-ray photoelectron spectroscopy (XPS). The stability of the coated active material was confirmed and the electrochemical behaviour as well as the cycling stability was evaluated. The impact of the heat treatment on the electrochemical performance was studied systematically and was shown to improve cycling and high current performance alike. In-depth investigations of polymer coated samples show that the improved performance can be correlated with the calcination temperatures. In particular, a heat treatment at 400 °C leads to enhanced reversibility and capacity retention even after 400 cycles. At 10C, the discharge capacity for carbon coated NMC increases by nearly 50% compared to uncoated samples. This study clearly shows for the first time the synergetic effects of a furfuryl polymer coating and subsequent calcination leading to improved electrochemical performance of nickel-rich NMC622
Perioperative and postoperative outcomes of perforated diverticulitis Hinchey II and III: Open Hartmann's procedure vs. laparoscopic lavage and drainage in the elderly
THE KPNO INTERNATIONAL SPECTROSCOPIC SURVEY. I. DESCRIPTION OF THE SURVEY
Accepted to the A.J. Preprint typeset using LATEX style emulateapj v. 04/03/9