Lithium-ion batteries have been widely used as excellent energy storage devices for many applications, recently in development of electric vehicles (EVs). Challenges in both material and mechanical stability inside battery cells/packs have to be overcome to meet an expected EV lifetime of 10-15 years, which requires up to 3000 deep cycles for battery cells and packs, in addition to the safety requirements.^[1] Here we present the results from a systematic investigation combining experimental and modeling approaches to compare mechanical integrity of fresh and aged cell components. Samples were collected from two identical commercial cells containing graphite anode and lithium-nickel-cobalt-manganese oxide cathode, with and without 3000 1C/1C cycles at 45 ^oC. Mechanical response was measured for the anode, cathode and separator using tensile and compression tests. This data set was used to extract constitutive properties of the individual layers, using an approach we published recently.^[2] Implications for electrochemical performance of the cell will be discussed.

References:

1. T. Nagaura, K. Tozawa, Progress in Batteries and Solar Cells 9 (1990) 209-217.

2. C. Zhang, S. Santhanagopalan, M.A. Sprague, A. Pesaran, J. Power Sources 290 (2015) 102-113.