The increasing pressure of air pollution and environmental protection has caused people to pay great attention to the development of energy-efficient energy sources. Governments of various countries have successively introduced measures and policies to promote the development of related industries. In terms of energy saving, electric vehicles have received strong support from the private sector and the government due to their advantages in pollution-free, low noise, and low energy consumption. In terms of electric vehicles, power batteries, as one of the key technologies, have become a barometer of the development of electric vehicles. On the road of industrialization of power batteries, people not only pay attention to the improvement of battery electrochemical performance, but also pay more attention to the reliability of safety performance. With the excellent performance of 50 Olympic buses loaded with lithium manganate power lithium ion batteries during the Olympics, people are full of hope and expectation for the wide application of power lithium batteries with spinel structure cathode materials. At the same time, CITIC Guoan Mengguli Company (MGL) has never stopped its work in improving safety performance. It has improved the thermal safety of the battery through various methods and process improvements, thereby ensuring that the battery’s safety performance test continues for 5 years. Passed the test of the Northern Automobile Quality Supervision and Inspection Institute (201 Institute).

　　1 Research status

　　The key factors that affect the thermal safety of the battery are the positive and negative electrode materials, the electrolyte type, the separator, and the design of the battery structure. Jin Huifen [1] et al. used ARC (Accelerated Calorimeter) to study the thermal stability characteristics of the commercial LiCoO2/graphite system. The results showed that the negative electrode began to emit heat at 60°C, and the positive electrode began to emit heat at 110°C. The increase in the internal pressure of the battery leads to thermal runaway; Tang Zhiyuan [2] et al. explained how these factors affect the thermal safety of the battery from the aspects of positive electrode material, negative electrode material, and electrolyte; the author Chil-HoonDoh [3] proposed In safety experiments (overcharge and acupuncture), the thermal and electrochemical performance of LiCoO2/C battery is mainly used to illustrate the safety of the battery through microscopic means. At the same time, the literature [4-6] applied finite element analysis and thermal simulation to the research of the overall battery and the heat dissipation performance of the battery pack to intuitively reflect the thermal safety of the battery.

　　There is no report on the macroscopic study of the thermal safety of spinel cathode materials for power lithium batteries. This article mainly conducts a macroscopic research on the thermal safety of single cells through methods such as thermal imaging and quantitative testing of safety performance.