Effect of Partial Cycling of NCA/Graphite Cylindrical Cells in Different SOC IntervalsShow others and affiliations
2020 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 167, no 4, article id 040529Article in journal (Refereed) Published
Abstract [en]
A quasi-realistic aging test of NCA/graphite lithium-ion 18650 cylindrical cells is performed during a long-term low c-rate cycling and using a new protocol for testing and studying the aging. This to emulate a characteristic charge/discharge profile of off-grid PV-battery systems. The cells were partially cycled at four different cut-off voltages and two state of charge ranges (ΔSOC) for 1000 and 700 cycles over 24 months. Differential voltage analysis shows that a combination of loss of active material (LAM) and loss of lithium inventory (LLI) are the causes of capacity loss. Cells cycled with high cut-off voltages and wide ΔSOC (20% to 95%) were severely affected by material degradation and electrode shift. High cut-off voltage and narrow ΔSOC (65% to 95%) caused greater electrode degradation but negligible cell unbalance. Cell impedance is observed to increase in both cells. Cells cycled with middle to low cut-off voltages and narrow ΔSOC (35%-65% and 20% to 50%) had comparable degradation rates to calendar-aged cells. Cycling NCA/graphite cells with low c-rate and high cut-off voltages will degrade the electrode in the same way high c-rate would do. However, low c-rate at low and middle cut-off voltages greatly decrease cell degradation compared to similar conditions at middle to high c-rate, therefore increasing battery lifetime. © 2020 The Author(s).
Place, publisher, year, edition, pages
Institute of Physics Publishing , 2020. Vol. 167, no 4, article id 040529
Keywords [en]
Degradation, Electrodes, Lithium, Lithium-ion batteries, Testing, Battery lifetime, Cell degradations, Charge/discharge, Cut-off voltages, Cylindrical cells, Differential voltage, Electrode degradation, Material degradation, Charging (batteries)
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:ri:diva-44793DOI: 10.1149/1945-7111/ab78fdScopus ID: 2-s2.0-85083529460OAI: oai:DiVA.org:ri-44793DiVA, id: diva2:1436495
Note
Export Date: 5 May 2020; Article; CODEN: JESOA
2020-06-082020-06-082020-12-01Bibliographically approved