State of charge influence on thermal reactions and abuse tests in commercial lithium-ion cells

Cycling stability and thermal runaway characteristics of four commercially available cylindrical cells based on LixFePO4 (LFP) and Li-x (Ni0.80Co0.15Al0.05)O-2 (NCA) cathode materials were investigated. The cells with different formats were cycled to three states of charge (SOC): 0, 50 and 100%, before adiabatic thermal analysis using an accelerating rate calorimeter (ARC). The charged cells experienced thermal runaway; the first rise in temperature due to the exothermic reaction and maximum cell temperature are discussed in detail for the different cells. Abuse testing (crush and nail penetration tests) was also performed at 100% SOC; the videos of the tests are available online as supplementary data. The LFP cathode exhibited superior cycling and thermal stability compared to NCA.