News & Events

Outline of the applied methodology of using fast X-ray tomography on a CO2 electrolyzer in operation.

Unraveling degradation processes in a bipolar membrane CO2 electrolyzer by time-resolved X-ray tomographic microscopy

Employing a bipolar ion conducting membrane (BPM) in forward bias is a convenient solution for the biggest issues in the more common anion exchange membrane (AEM) CO2 co-electrolysis: the degradation of the performance caused by carbonate salt precipitation at the cathode and the decrease of net CO2 conversion caused by the crossover of this molecule from cathode to anode also requiring energy for downstream gas separation. However, the performance and stability of this device remain largely insufficient when using such a BPM configuration. To understand the reasons for this, we performed time-resolved X-ray tomographic microscopy of an operating BPM CO2 electrolyzer. The imaging method reveals partly unexpected degradation processes that result in design recommendations for improvement.

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In situ and operando X-ray spectroscopy enables a better understanding of the enhanced oxygen evolution reaction activity of CoOx nanocatalysts coupled with CeO2.

Insights into the superior oxygen evolution reaction activity of CoOx/CeO2 composite electrocatalyst

CeO2 significantly enhances the oxygen evolution reaction (OER) activity of CoOx, although the mechanism behind this synergy is still unclear. Here, operando hard X-ray absorption spectroscopy (hXAS) is applied to monitor the Co-K edge and Ce L3 edge in CoOx/CeO2 to shed light on the evolution of Co and Ce oxidation states during OER. In addition, ex situ soft XAS (sXAS) characterizations provide information on the irreversible surface-specific transformations of the Co L3 edge as well as the O K edge.

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Scheme of the combined SAXS measurement and simulation approach

Quantification of PEFC Catalyst Layer Saturation via Small-Angle X‑ray Scattering

The complex nature of liquid water saturation in polymer electrolyte fuel cell (PEFC) catalyst layers (CLs) greatly affects the device performance. To investigate this problem, a method to quantify the presence of liquid water in a PEFC CL using small-angle X-ray scattering (SAXS) was developed in a collaboration of researchers of the Federal Institute for Materials Research and Testing (BAM, Berlin, Germany), the Photon Science Division and the Electrochemistry Laboratory of PSI. The method leverages the differences in electron densities between the solid catalyst matrix and the CL-pores filled with liquid water under dry and wet conditions, respectively.

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Operando XAS and XRD

Understanding the (de-)lithiation mechanism of nano-sized LiMn2O4 allows achieving long-term cycling stability

We report an in-depth investigation of the local atomic geometry, electronic and crystallographic structure evolution of nano-sized LiMn2O4 using operando XAS and XRD to shed light on (de-)lithiation mechanism when cycled in wide voltage range of 2.0 to 4.3 V vs Li+/Li. Leveraging on these findings, a novel electrochemical cycling protocol, with periodic deep discharge, yields superior electrochemical performance cycled in the range of 3.3 to 4.3 V exhibiting an excellent structure cyclability and an unprecedented increase in the specific capacity upon long cycling.

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Left: benzyl-type quaternary ammonium model compounds mimicking the chemistry of anion exchange membranes. All compounds contain perchlorate as counter anion. NBTM = 3-nitro-benzyltrimethylammonium, BTM = bennzyltrimethylammonium, BMP = N-benzyl-N-methyl-piperidiunium, MBTM = 3-methoxy-benzyltrimethylammonium. Degradation of compounds (1 mM) after exposure in the 60Co gamma cell to a dose of 1’200 Gy, corresponding to 0.75 mM of radicals. Comparison between inert atmosphere and air, which leads to different

Insights into radical induced degradation of anion exchange membrane constituents

Electrochemical energy conversion devices, such as fuel cells and electrolyzers, using an anion exchange membrane (AEM) operating in the alkaline regime offer the prospect of the use of non-noble metal electrocatalysts and lower-cost cell construction materials. The wide-spread application of electrochemical cells with AEMs has been largely limited by the low chemical stability of the material. AEM degradation is triggered by i) nucleophilic attack by OH, and ii) by reaction with free radicals formed during cell operation. Whereas the alkaline stability of AEMs has been greatly increased over the last 10 years, the understanding of mechanisms of radical induced degradation is limited. In this study, we have addressed this topic for the first time.

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How can cobalt be reduced in EV batteries?

Energy and Climate ESI Platform Energy transition

The electrification of transport is increasing. This means, more batteries are needed. However, some of these batteries contain an extremely problematic raw material: cobalt. PSI is researching alternatives.

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Crystal structure of the investigated cobalt-based oxides.

Improving the oxygen evolution reaction activity of Co-based oxides by phosphate functionalization

Our findings disclose that P-functionalization successfully enhances the oxygen evolution reaction (OER) activity of different cobalt-based catalysts (namely, La0.2Sr0.8CoO3–δ, La0.2Sr0.8Co0.8Fe0.2O3–δ, and CoOx) at near-neutral pHs and that both phosphate ion assistance in the OER mechanism and catalyst Co oxidation state can play a role in the enhanced OER activity.


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a) Linear dependency of cycle number on electrolyte to electroactive material loading. b) Identical performance of the cells when electroactive materials loading is unified and the only difference between cells is the nature of the binder.

Importance of Identifying Key Experimental Parameters for the Li-ion Battery Performance Testing

The mass loading of Si-graphite electrodes is often considered as a parameter of secondary importance when testing their performance. However, if a sacrificial additive is present in the electrolyte, the electrode loading becomes the battery cycle-life-determining factor. 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.

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