In recent years, LEV and hybrid has been gradually popularized due to the energy crisis and increasing environmental awareness. The prevalence of LEV is to use batteries to replace the power from the gasoline. Secondary lithium battery is a good option for LEV since it has the features of light weights, high power density, long life, low pollution, and works without memory effect. However, the safety is a concern for end-users with more and more recalls of lithium-ion batteries involving the explosions. The purpose of this research is to propose a systematic approach of battery safety device with an engineering design method. The analysis on the factors affecting the safety is prior to the objective of this study as to define the specification of the battery safety device. Then, substance-field analysis and standard is to improve the initial systematic model, and the solution is specified with the synthesis of morphological matrix. Under the safety test for batteries, the effectiveness and feasibility of protected device is eventually verified.