Charge and discharge profiles of repurposed LiFePO4 batteries based on the UL 1974 standard

Abstract

Owing to the popularization of electric vehicles worldwide and the development of renewable energy supply, Li-ion batteries are widely used from small-scale personal mobile products to large-scale energy storage systems. Recently, the number of retired power batteries has largely increased, causing environmental protection threats and waste of resources. Since most of the retired power batteries still possess about 80% of their initial capacity, their second use becomes a possible route to solve the emergent problem. Safety and performance are important when using these second-use repurposed batteries. Underwriters Laboratories (UL), a global safety certification company, published the standard for evaluating the safety and performance of repurposed batteries, i.e., UL 1974. In this work, the test procedures are designed according to UL 1974, and the charge and discharge profile datasets of the LiFePO₄ repurposed batteries are provided. Researchers and engineers can use the characteristic curves to evaluate the quality of the repurposed batteries. Furthermore, the profile datasets can be applied in the model-based engineering of repurposed batteries, e.g., fitting the variables of an empirical model or validating the results of a theoretical model.