TY - CONF A1 - Scharpmann, Philippa T1 - In-situ Quantification of the Ageing Dynamics in Lithium-Ion Cells up to Failure-Near Conditions N2 - Implementing end-of-life (EOL) lithium-ion batteries from automotive applications in stationary energy storages is of utmost relevance for a sustainable handling of scarce resources. Beneficial from an economic and ecological perspective, such second-life applications urgently require a guarantee for safe operation. Unlike the state of health (SOH), defined by classical performance indicators such as capacity and voltage, the state of safety (SOS) of an aged battery cannot be assessed straightforward. Its determination requires a plethora of cells to be tested which is a particular challenge for new technologies with limited access to EOL batteries. For providing cells with a defined SOH at a reasonable timescale, we herein propose a novel method of greatly accelerating the ageing process of lithium-ion batteries. In a preliminary test series, lithium-ion NMC pouch cells are exposed to incrementally increasing temperatures, current rates and/or states of charge (SOC), until thermal runaway is induced. In this manner, the critical state in proximity to cell failure is spotted for individual and combined stress parameters. Based on this knowledge, cell-specific test parameters for heavily accelerated ageing are developed. In this protocol, electrical abuse conditions are defined by over/under charging and high current rates. Typically, the cells are cycled utilizing a depth of discharge above 100 %. The accelerated aging dynamics under these critical conditions are monitored by systematic capacity, open circuit voltage and electrochemical impedance spectroscopy (EIS) measurements. This enables a comparative assessment of the electrical behaviour, following conventional vs. heavily accelerated ageing. Such knowledge will in turn help to define the threshold to which cyclic ageing can be accelerated without changing the characteristic degradation mechanisms of lithium-ion batteries. T2 - 244th ECS Meeting CY - Gothenburg, Sweden DA - 08.10.2023 KW - Lithium-Ion Battery KW - Safety KW - Ageing PY - 2023 AN - OPUS4-61490 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Scharpmann, Philippa T1 - Segregating the Degradation Mechanisms in Lithium-Ion Cells during Strongly Accelerated Ageing with Critically Extended Voltage Ranges N2 - Repurposing end-of-life (EOL) lithium-ion batteries from mobile applications, such as electric vehicles, is of utmost importance for a sustainable handling of scarce resources. For an economically and ecologically desirable reuse of aged batteries in second-life applications, a guarantee for safe and reliable operation is urgently required. However, the assessment of the state of safety (SOS) is not straightforward, as multiple abuse cases, variables and interactions need to be considered [1]. Therefore, defining safety parameters and test procedures, as well as determining the SOS requires a plethora of aged cells to be tested. In this study, a novel method of greatly accelerating the ageing process of lithium-ion batteries is proposed. Overcharging and overdischarging are embedded in cyclic ageing, continuously employing a depth of discharge larger than 100 %. Different electrical abuse conditions (overcharge, overdischarge, high current rates) are applied on lithium-ion NMC and LFP pouch cells in a preliminary test series. In this manner, the cells are stressed until a cell failure or a thermal runaway is induced. Thus, the critical state in proximity to a cell failure is spotted for individual and combined stress parameters. Based on this knowledge, a test protocol for strongly accelerated ageing with cell-specific, abusive electrical parameters is developed. The aging dynamics under these critical conditions are monitored by systematic capacity, open circuit voltage and electrochemical impedance spectroscopy (EIS) measurements. This enables an assessment of the degradation mechanisms induced by overdischarge and overcharge cycling. A special focus is set on the comparative assessment of the electrical behaviour, following conventional vs. greatly accelerated ageing. This novel method is suitable for providing cells with a defined SOH at a reasonable timescale. Furthermore, the results are of high relevance for the evaluation to which degree cyclic ageing can be accelerated without changing the characteristic degradation mechanisms of lithium-ion batteries. T2 - Advanced Battery Power Conference 2024 CY - Münster, Germany DA - 10.04.2024 KW - Lithium-Ion Battery KW - Safety KW - Ageing PY - 2024 AN - OPUS4-61492 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -