Effect of cold welding on the inconsistencies and thermal safety of battery modules based on a constructed discharge model

Abstract

The thermal safety of battery systems is a common and key technical problem restricting industrial development. Welding is one of the most important electrical connection methods for lithium-ion battery groups, and the quality of welding directly determines the thermal safety of battery modules. In this research, the inconsistencies and thermal safety of cylindrical lithium-ion battery modules are studied based on cold welding technology. Secondly, the electrochemical characteristics and thermal runaway characteristics of the battery were experimentally studied. Finally, the battery (Table-Based) module launched by the SIMULINK tool of MATLAB software in 2018 was used to build a battery pack model simulating the discharge process to simulate and analyze the battery electrical characteristics. The relevant data show that the temperature difference between the batteries is less than 4 °C and the maximum battery temperature is less than 60 °C when the cold welded module is discharged at a current ratio(C) of 3 high rate, which has good temperature equalization and thermal safety. The output power is higher and the discharge energy increase by 3 % ~ 5 % when the cold-welded module is discharged at different rates. The results for heat abuse conditions show that the overall temperature rise of the cold-welded module is lower, the maximum temperature of the single battery is reduced by 10.7 %, and the maximum temperature rise rate is reduced by 41.2 %. The simulation results show that the current difference between the cells in the hot welding module is large, and there is an obvious overdischarge phenomenon in the late discharge period. The maximum SOC difference between the single battery of the cold-welded module is less than 0.02 when discharging at 3C. The requirements for SOC estimation are met. The above research results confirm that the relevant research will provide new ideas and theoretical value for the research of the consistency improvement of power battery packs, and solve the problem of the electrical/thermal balance difference of the existing resistance thermal welding process from another dimension based on the cold welding strategy.