Dendrite evolution in flexible lithium metal batteries: Insights from electrochemical phase field modeling and in-situ experiments

Flexible lithium metal batteries have significant potential for use in wearable devices due to their high energy density and flexibility. However, they face challenges such as dendrite growth and cycling stability issues. In this study, an electrochemical phase-field model that accounts for Gaussian curvature is used in conjunction with in-situ observational experiments to investigate the dendrite growth behavior on the surface of flexible lithium metal. The effects of positive and negative curvature electrodes on lithium dendrite growth and dead lithium formation in lithium metal batteries are investigated. Through a comprehensive approach combining electrochemical measurements, schematic analysis, and experimental observations, it is shown that positive curvature electrodes result in a significant electric field concentration. This concentration subsequently leads to rapid dendrite growth and the formation of a significant amount of dead lithium. These phenomena contribute to a decrease in battery capacity, an increase in internal impedance , and a deterioration in cycling efficiency. Conversely, negative curvature electrodes exhibit the ability to disperse the local electric field, which facilitates more uniform lithium deposition, suppresses dendrite formation, and minimizes the formation of dead lithium. The results suggest that optimization of electrode design, particularly through the use of negative curvature structures, can significantly improve the safety, stability, and lifetime of flexible and wearable batteries. • Developed an advanced electrochemical phase-field model considering Gaussian curvature • Investigated the impact of electrode curvature by combining in-situ experiments with theoretical modeling • Positive curvature promotes dendrite growth and dead Li accumulation. • Negative curvature reduces dendrite growth and enhance Li deposition uniformity. • Optimizing electrode geometry can improve battery cycling efficiency and safety.