Non-Destructive Monitoring of Charge-Discharge Cycles on Lithium Ion Batteries using 7Li Stray-Field Imaging

Abstract

Magnetic resonance imaging provides a noninvasive method for in situ monitoring of electrochemical processes involved in charge/discharge cycling of batteries. Determining how the electrochemical processes become irreversible, ultimately resulting in degraded battery performance, will aid in developing new battery materials and designing better batteries. Here we introduce the use of an alternative in situ diagnostic tool to monitor the electrochemical processes. Utilizing a very large field-gradient in the fringe field of a magnet, stray-field-imaging (STRAFI) technique significantly improves the image resolution. These STRAFI images enable the real time monitoring of the electrodes at a micron level. It is demonstrated by two prototype half-cells, graphite∥Li and LiFePO4∥Li, that the high-resolution 7Li STRAFI profiles allow one to visualize in situ Li-ions transfer between the electrodes during charge/discharge cyclings as well as the formation and changes of irreversible microstructures of the Li components, and particularly reveal a non-uniform Li-ion distribution in the graphite.

Exklusiver π‐Einschluss leichter Alkalimetallkationen durch ein neutrales Molekül

“…Erst kürzlich gelang es,S chichten von Graphenoxid-Membranen zu entwickeln, welche selektiv Alkalimetallkationen durch Kation-p-Wechselwirkungen binden und in der Wasserentsalzung oder als Molekularsiebe eingesetzt werden. [16,17] Ein besseres Verständnis der Wechselwirkung von Li + -Ionen mit neutralen Kohlenstoffmaterialien ist deshalb erstrebenswert. [15] Die Interkalation von Lithiumionen in die Graphitschicht von üblichen (entladenen) Lithiumionenbatterien erfordert keine Kation-p-Wechselwirkung,d ad as Kohlenstoffmaterial negativ geladen vorliegt.…”

Investigating the evolving microstructure of lithium metal electrodes in 3D using X-ray computed tomography

“…However, most of these studies were performed ex-situ, thus requiring cell disassembly and removal of the lithium microstructures from their as grown environment. NMR and MRI investigations are non-invasive and have been successfully carried out in-situ to capture the formation of dendritic and electrodeposited lithium structures 2,3 ; however the resolution of MRI is limited, typically 100 µm 17 , and the presence of metals can introduce imaging artefacts 18 . There have also been reported attempts to theoretically model different electrodeposited Li growth with regards to their morphologies and feature size distributions [19][20][21][22] .…”

In situ methods for Li-ion battery research: A review of recent developments

“…The obtained spatial resolution is of the order of hundreds of mm. Tang et al [84] applied stray-field imaging, which makes use of a magnetic field with higher field gradients than that used for MRI to monitor the Li-ion transfer between the electrodes in Li-graphite and LieLiFePO 4 half-cells, obtaining a 1D distribution with a resolution of 39 mm.…”