Nuclear Magnetic Resonance with Low Magnetic Fields
A tiny component which amplifies measurement signals and suppresses noise is presented by Jülich and Aachen researchers in the current issue of Nature Physics. They developed it for nuclear magnetic resonance measurements in battery research. The method is typically used for imaging techniques in medicine (MRI) or the analysis of molecular structures in biology and chemistry (NMR). The receiver permits high sensitivity at low frequencies – without the extremely strong and expensive magnets which are usually required for precise measurements.
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Operando electron paramagnetic resonance spectroscopy – formation of mossy lithium on lithium anodes during charge–discharge cycling
The formation of mossy lithium and lithium dendrites so far prevents the use of lithium metal anodes in lithium ion batteries. To develop solutions for this problem (e.g., electrolyte additives), operando measurement techniques are required to monitor mossy lithium and dendrite formation during electrochemical cycling. Here we present a novel battery cell design that enables operando electron paramagnetic resonance (EPR) spectroscopy. It is shown that time-resolved operando EPR spectroscopy during electrochemical cycling of a lithium-metal/LiFePO4 (LFP) cell provides unique insights into the lithium plating/dissolution mechanisms, which are consistent with ex situ scanning electron microscopy (SEM) analysis. To demonstrate the viability of the operando EPR method, two cells using different electrolytes were studied. When using an electrolyte containing fluoroethylene carbonate (FEC) additive, a higher reversibility of the lithium anode and reduced formation of micro-structured (mossy/dendritic) lithium were observed.
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Joint European Summer School on Fuel Cell, Electrolyser, and BatteryTechnologies JESS 2015