Overcharge investigation of degradations and behaviors of large format lithium ion battery with Li(Ni0.6Co0.2Mn0.2)O2 cathode

Abstract

Abstract Overcharge is considered to be one of the most severity safety problems for large format lithium ion battery (LIB), understanding of correlation between overcharge states and associated degradations is still a challenging issue. Here overcharge features of 51Ah prismatic LIBs were studied by charging the LIBs to various state of charge (SOC). When the SOC reaches up to 125%, lithium plating and lithium involved side reactions have taken place accompanied by capacity fade, internal resistance increase and LIB swelling. Meanwhile, the interlayer spacing of graphite anode is enlarged as indicated by shift of (002) diffraction peak to lower angle. When the SOC reaches up to 140%, additional to above reactions aggravation, structural damage of cathode materials was found. With further increase of SOC, internal side reactions became more violent as indicated by obvious self-heating at 146% SOC. Moreover, effects of charging current and initial temperature on overcharge behaviors were also discussed. Large charging current (4C) can lead to more severity thermal runaway as supported by higher maximum surface temperature of 413.34 °C compared to that of 187.90 °C at 1C. LIB overcharged at initial low temperature shows quick temperature rise but lower maximum surface temperature of 143.15 °C at 160% SOC compared to that of 187.90 °C at 159% SOC for LIB overcharged under ambient temperature