Aging mechanisms of NMC811/Si-Graphite Li-ion batteries

Thumbnail Image
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Degree programme
Journal of Power Sources, Volume 599
Electrode degradation processes at various Li-ion batteries’ state-of-health (SoH 100 %, 80 %, 50 %, and 30 %) and cycling temperatures (5 °C, 23 °C, and 45 °C) were investigated. For this purpose, the standard format of Li-ion cylindrical 18,650 batteries with Si-Graphite negative and LiNi0·8Co0·1Mn0·1O2 (NMC811) positive electrodes were cycled with registering battery parameters and the electrochemical impedance spectrum were recorded after every 200 cycles. Once reaching their end-of-life, electrodes from cycled batteries were subjected to post-mortem analysis. NMC811 positive electrode was observed to crack during the charge and discharge processes, suffered by irreversible phase transition, transition metal dissolution, cathode electrolyte interphase growth, and cation mixing. The Si-Graphite negative electrode material was also affected by crack formation, layer exfoliation, solid electrolyte interphase (SEI) recompositing, Li dendrite growth, transition metal contamination, and Si dissolution. Degradation of components leads to an increase of the contact resistance, Li+ diffusion limitations, reduction of active materials participating in Li-ion storage and, as a result, capacity fade that finally rendered the battery utilization unfeasible. Degradation processes can be detected by capacity fade and impedance growth of the full battery. High temperature accelerates electrode degradation processes when low temperature leads to SEI and Li dendrite growth.
Publisher Copyright: © 2024 The Authors
Ageing, Degradation, Electrochemical impedance spectroscopy, Lithium-ion battery, NMC, Post-mortem study, State-of-health
Other note
Laakso, E, Efimova, S, Colalongo, M, Kauranen, P, Lahtinen, K, Napolitano, E, Ruiz, V, Moškon, J, Gaberšček, M, Park, J, Seitz, S & Kallio, T 2024, ' Aging mechanisms of NMC811/Si-Graphite Li-ion batteries ', Journal of Power Sources, vol. 599, 234159 .