Over-heating triggered thermal runaway behavior for lithium-ion battery with high nickel content in positive electrode

The thermal abuse of high specific energy NCM811 lithium-ion power battery in the process of use or safety test was simulated by winding resistance wire heating method, and local heating and uniform heating were carried out to trigger a thermal runaway. When thermal runaway triggered by uniform heating, the safety valve is opened timely and only open flame occurred without explosion, it did not cause the internal short circuit, and the safety valve was not damaged. However, when thermal runaway triggered by the local heating method, it caused a serious internal short circuit, the released electrolyte and other material burned violently and exploded, and the safety valve was completely damaged. In this process, a thin film heat flux sensor is also used to quantify the surface heat flux during thermal runaway, which could provide the test method and calculation basis for the thermal management design. The experimental results were also compared with those of NCM111, NCM 532 and NCM 622 batteries, the results revealed that increase of nickel content in positive electrode would also increase the degree of damage when a TR triggered by local heating method. • The internal structure of the battery is relatively intact when TR was triggered by uniform heating. • The internal structure became debris when TR was triggered by local heating, but shell was intact. • Ncm 811 produced higher temperature and stronger destructiveness when TR happened. • The heat flux density was quantified by a heat flux sensor for TR triggered by local heating.