Inside the electrode: Looking at cycling products in Li/O2 batteries
Journal article, Peer reviewed
Accepted version
Åpne
Permanent lenke
http://hdl.handle.net/11250/2637106Utgivelsesdato
2019Metadata
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- Institutt for materialteknologi [2663]
- Publikasjoner fra CRIStin - NTNU [39927]
Sammendrag
This work investigates the impact of electrochemical reactions and products on discharge capacity and cycling stability with electrolytes based on two common solvents – tetraethylene glycol dimethyl ether (TEGDME) and dimethyl sulfoxide (DMSO).
Although the DMSO-based electrolyte exhibits better initial electrochemical properties compared to that based on TEGDME, e.g., higher discharge capacity and potential, the use of TEGDME results in a significantly better cycling stability.
Scanning electron microscopy (SEM) and X-ray diffraction (XRD) investigations of the gas diffusion electrodes (GDE) after first discharge reveal a considerable difference in discharge product morphology. With DMSO as solvent one high-potential reduction process leads to the formation of crystalline lithium peroxide (Li2O2) particles on the cathode surface area. SEM imaging of GDE cross-sections depicts that the (non-crystalline) product film formation at lower potentials during discharge with the TEGDME-based electrolyte results in a GDE pore clogging close to the O2 inlet, so that gas transport is hindered and the discharge ends at an earlier point. The higher cycling stability with LiTFSI/TEGDME, however, is attributed to (i) the apparently complete recovery of the GDE active surface by recharge and (ii) different parasitic reactions resulting in the formation of side product particles rather than films.