Materials Science

Emerging chemical heterogeneities in a commercial 18650 Li-ion battery during early cycling

Authors

  • Dorota Matras The Faraday Institution, Quad One, Harwell Science and Innovation Campus, Didcot, OX11 0RA, United Kingdom & Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom ,
  • Thomas E. Ashton Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom ,
  • Hongyang Dong Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom ,
  • Marta Mirolo ESRF - The European Synchrotron, Grenoble 38000, France ,
  • Isaac Martens ESRF - The European Synchrotron, Grenoble 38000, France ,
  • Jakub Drnec ESRF - The European Synchrotron, Grenoble 38000, France ,
  • Jawwad A. Darr Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom ,
  • Paul D. Quinn Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom ,
  • Simon D.M. Jacques Finden Limited, Merchant House, 5 East St Helens Street, Abingdon, OX14 5EG, United Kingdom ,
  • Andrew M. Beale Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom & Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxon OX11 0FA, United Kingdom & Finden Limited, Merchant House, 5 East St Helens Street, Abingdon, OX14 5EG, United Kingdom ,
  • Antonis Vamvakeros Finden Limited, Merchant House, 5 East St Helens Street, Abingdon, OX14 5EG, United Kingdom

Abstract

Synchrotron X-ray diffraction computed tomography (XRD-CT) was employed to study a commercial 18650 cylindrical LiNi0.8Co0.15Al0.5O2 (NCA) battery under operating conditions and during seven cycles. Multiple chemical heterogeneities related to the lithium distribution were observed in both the cathode and the anode from the analysis of the spatially-resolved diffraction signals. It is shown that during the battery charging, the anode exhibits different degrees of activity regarding the lithiation process. Explicitly, the following three regions were identified: uniform/homogenous lithiation, delayed lithiation and inactive-to-lithiation regions. The inactive-to-lithiation anode region was a result of the specific cell geometry (i.e. due to lack of cathode tape opposite these anode areas) and throughout the cycling experiments remained present in the form of LiC30-30+. The delayed lithiation region was seen to have a direct impact on the properties of NCA in its close proximity during the battery discharging, preventing its full lithiation. Further to this, the aluminum tab negatively affected the NCA in direct contact with it, leading to different lattice parameter a and c evolution compared to the rest of the cathode.

Version notes

Further clarifications and additions in the main manuscript and supporting information

Content

Thumbnail image of NCA_chemrxiv.pdf

Supplementary material

Thumbnail image of NCA_chemrxiv_ESI.pdf
Supporting Information
Contains Figures, Tables and other supporting information to the main manuscript