TY - JOUR
T1 - Relaxation Effects in Self-Discharge Measurements of Lithium-Ion Batteries
AU - Roth, Thomas
AU - Streck, Luiza
AU - Graule, Andreas
AU - Niehoff, Philipp
AU - Jossen, Andreas
N1 - Publisher Copyright:
© 2023 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.
PY - 2023/2
Y1 - 2023/2
N2 - In order to determine the quality of newly produced lithium-ion cells, self-discharge measurements are performed after manufacturing during the so-called aging step. The aging step is a time-consuming and cost-intensive process due to relaxation effects disturbing the self-discharge measuremtens. Relaxation effects are mainly attributed to voltage relaxation and anode overhang equalization. In this work, different methods for electrical self-discharge measurement, such as the voltage decay method, the voltage hold method, and the capacity loss method, were investigated using commercial Samsung INR21700-50E cylindrical cells (NCA/silicon-graphite) and non-commercial pouch-cells (NMC622/graphite). Various preconditioning methods allowed a distinction to be made between undisturbed, short-term, and long-term disturbed cells. While short-term disturbances subsided after several hours, long-term disturbances due to anode overhang were found to significantly disturb all electrical self-discharge measurements for several weeks. A theoretical explanation was introduced, describing the lithium inventory change due to anode and coupled side reactions being measured differently by voltage- and capacity-based methods. Experimental results confirmed this notion and showed that voltage-based self-discharge measurements underestimated the anode overhang equalization. A comparison to the initial cell aging data indicated that the self-discharge measurement performed shortly after cell formation was disturbed by the anode overhang equalization.
AB - In order to determine the quality of newly produced lithium-ion cells, self-discharge measurements are performed after manufacturing during the so-called aging step. The aging step is a time-consuming and cost-intensive process due to relaxation effects disturbing the self-discharge measuremtens. Relaxation effects are mainly attributed to voltage relaxation and anode overhang equalization. In this work, different methods for electrical self-discharge measurement, such as the voltage decay method, the voltage hold method, and the capacity loss method, were investigated using commercial Samsung INR21700-50E cylindrical cells (NCA/silicon-graphite) and non-commercial pouch-cells (NMC622/graphite). Various preconditioning methods allowed a distinction to be made between undisturbed, short-term, and long-term disturbed cells. While short-term disturbances subsided after several hours, long-term disturbances due to anode overhang were found to significantly disturb all electrical self-discharge measurements for several weeks. A theoretical explanation was introduced, describing the lithium inventory change due to anode and coupled side reactions being measured differently by voltage- and capacity-based methods. Experimental results confirmed this notion and showed that voltage-based self-discharge measurements underestimated the anode overhang equalization. A comparison to the initial cell aging data indicated that the self-discharge measurement performed shortly after cell formation was disturbed by the anode overhang equalization.
UR - http://www.scopus.com/inward/record.url?scp=85147792980&partnerID=8YFLogxK
U2 - 10.1149/1945-7111/acb669
DO - 10.1149/1945-7111/acb669
M3 - Article
AN - SCOPUS:85147792980
SN - 0013-4651
VL - 170
JO - Journal of the Electrochemical Society
JF - Journal of the Electrochemical Society
IS - 2
M1 - 020502
ER -