Parametrisation of the influence of different cycling conditions on the capacity fade and the internal resistance increase for lithium nickel manganese cobalt oxide/graphite cells

摘要

Here we provide a detailed study of the capacity fade and the internal resistance increase for 40 mAh LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2/graphite cells under different cycling conditions. The effects of temperature (20 °C, 30 °C, 40 °C, 60°C）, power (72 mW, 216 mW, 432 mW), average state of charge (30%, 50%, 70%）and depth of charge/discharge (used capacity: 1.6 mAh, 8 mAh, or 20 mAh) are investigated. The ageing properties are compared with reference measurements of 40 Ah commercial cells. The cycling tests were carried out for up to 9000 h or until a state of initial capacity of 70% was reached. The results identify different ageing mechanisms and reveal which one is dominant under certain cycling conditions. In addition, the results determine how strong a certain ageing mechanism is contributing to the overall ageing of the battery. Furthermore, guidelines on how to set up the cycling tests parametrisation for optimal output per experiment and per time are given.