TY - CONF A1 - Scharpmann, Philippa T1 - Exploring the effects of accelerated ageing on lithium- and sodium-ion cells N2 - Lithium-iron-phosphate (LFP) and sodium-ion batteries (SIBs) offer safe and cost-effective options for energy storage. In this study, the effects of continuous electrical stress, including high current loads and overdischarge, during cyclic ageing are investigated by tracing capacity loss and Coulombic efficiency during cycling of both cell types. Additionally, differential voltage analysis of pseudo open-circuit voltage discharges is utilised for degradation mode analysis. The results show that electrical stress accelerates degradation in both LFPs and SIBs, with high current rates potentially triggering plating or even cell failure in SIBs. Overdischarging primarily intensifies ageing by promoting accelerated solid electrolyte interphase growth. T2 - Doktorandenseminar der Technischen Universität Berlin CY - Berlin, Germany DA - 29.09.2025 KW - Lithium-ion -batteries KW - Sodium-ion-batteries KW - Electrical stress KW - Differential voltage analysis KW - Plating PY - 2025 AN - OPUS4-65057 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scharpmann, Philippa A1 - Leonhardt, Robert A1 - Schmidt, Anita A1 - Kowal, Julia A1 - Tichter, Tim A1 - Krug von Nidda, Jonas T1 - Exploring restrictive overdischarge cycling as a method to accelerate characteristic ageing in lithium-ion cells N2 - This study presents a test protocol that greatly accelerates the ageing process of lithium-ion battery cells comprising a positive electrode of nickel manganese cobalt oxide while preserving their characteristic degradation upon cyclic ageing. Applying a repetitive restricted overdischarge, resulting in a depth of discharge larger than 100%, a capacity loss of 20% is achieved over five times faster compared to conventional cycling. The well-known overdischarge degradation phenomenon of copper current collector dissolution is deliberately prevented by setting a discharge cutoff voltage above the theoretical threshold of copper oxidation. Hence, the accelerated degradation can be primarily connected to solid electrolyte interphase growth. A comparative assessment of the ageing dynamics using electrochemical impedance spectroscopy and differential voltage analysis hints towards similar, characteristic degradation processes during accelerated and conventional ageing. A post-ageing examination of the electrical behaviour (i.e., coulombic and energy efficiency, capacity fade) under reference conditions reveals very little to no lasting damages caused by overdischarging. Additionally, post-mortem analysis discloses no increased copper dissolution when comparing cells subjected to accelerated and conventional ageing. Generally, the developed ageing method appears suitable for providing cells with a defined state of health at a reasonable timescale without altering the main degradation mechanisms significantly. KW - Lithium-ion cell KW - Accelerated ageing KW - Overdischarge KW - Degradation processes KW - Differential voltage analysis KW - Electrochemical impedance spectroscopy PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-650917 DO - https://doi.org/10.1016/j.jpowsour.2025.239072 SN - 0378-7753 VL - 665 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-65091 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -