A Novel Measurement Technique for Parallel-Connected Lithium-Ion Cells with Controllable Interconnection Resistance

Due to the broad use of parallel-connected cells across a wide variety applications, it is essential understand current distribution between them. Variations in resistance, temperature and capacity can lead an inhomogeneous have deleterious influence on ageing safety. It therefore crucial investigate within such systems. Many researchers designed distinct test-benches measure distribution. In any test-bench, known unknown resistances caused by wiring, interconnections measurement equipment adversely affect The aim this work design low-complexity test apparatus that does not itself measurement. This describes novel technique [1] analyse without complex custom-made benches. While are physically connected conventional benches, proposed utilizes software commercially available battery cycler connect parallel. Because replaces parallel junction equations, approach called “virtual connection“. Each cell individually each voltage or be controlled separately. pulse used determine reference cell, control unit imposes same cell. Therefore, benefits from 4-wire cycler, which generates no additional interconnection resistances. For reason, only Open Circuit Voltage (OCV), resistance itself, as well its relationship other Additionally, desired connection chosen adding drop equation cycler. Connecting virtually has many advantages, ability decouple for check-ups recouple them cycling ever touching physically, independent location scaling n-parallel constellations, low assembly effort test-bench defined contact addition, different formats investigated with effort. work, virtual will first demonstrated, validated discussed constant current-, voltage- rest phases using bench [2] two NMC cells. Next, cells, studies were carried out varied 0 5 mΩ. study investigates increase one paths. Subsequently, second examines homogeneous both conclusion height local minima maxima mainly dependent ratio legs. divide relative combined pathway. contrast, neither measured at various cumulative charge throughputs, nor intersection points affected Meanwhile, OCV interactions shape Differential Analysis (DVA) showed correlations Some appear almost region DVA. By assigning peaks half-cell profiles DVA anode cathode, currents expected these characteristic peaks. References Jocher, P.; Steinhardt, M.; Ludwig, S.; Schindler, Martin, J.; Jossen, A.: A lithium-ion controllable In: Journal Power Sources 503 ( 1) , S. 230030. (2021). doi: https:/ / doi.org/ 10.1016/ j.jpowsour.2021.230030 Hofmann, M.H.: Current 1. Auflage, Verlag Dr. Hut, München. (2020), ISBN: 978-3-8439-4614-8