Mixed Modes Fracture and Fatigue Evaluation for Lithium-Ion Batteries

Lithium ion batteries have become a widely known commodity for satisfying the world’s mobile energy storage needs. But these needs are becoming increasingly important, especially in the transportation industry, as concern for rising oil prices and environmental impact from fossil fuels are pushing for deployment of more electric vehicles (EV) or plug in hybrid-electric vehicles (PHEV) and renewable energy sources. The objective of this research is to obtain a fundamental understanding of degradation mechanisms and rate-capacity loss in lithium-ion batteries through fracture mechanics and fatigue analysis approaches. In this study we follow empirical observations that mechanical stresses accumulate on electrode materials during the cycling process. Crack induced fracturing will then follow in the material which electrical contact surface area is degraded and over capacitance of the battery reduces. A fatigue analysis simulation is applied using ANSYS finite element software coupled with analytical models to alleviate these parameters that play the most pivotal roles in affecting the rate-capacity and cycle life of the lithium-ion battery. Our results have potential to provide new models and simulation tools for clarifying the interplay of structure mechanics and electrochemistry while offering an increased understanding of fatigue degradation mechanisms in rechargeable battery materials. These models can aid manufacturers in the optimization of battery materials to ensure longer electrochemical cycling life with high-rate capacity for improved consumer electronics, electric vehicles, and many other military or space applications.