Dual-criteria framework for lithium plating assessment in graphite/lithium iron phosphate cells

Abstract

Lithium plating on graphite anodes remains a critical safety concern in lithium-ion batteries, yet its prediction is often unreliable due to reliance on single-criterion-based detection approaches. This work introduces a dual-criteria framework that integrates a thermodynamically based potential threshold with a kinetically based surface concentration limit to robustly assess plating risk. Application of the framework across temperatures (-10 to 30 °C), charging rates (1C to 5C), and N/P ratios reveals consistent and interpretable trends. Low temperature and high C-rate were found to increase plating risk by elevating activation and diffusion overpotentials, with total overpotential increasing by up to sixfold under the most severe conditions investigated, while low N/P ratios promote over-lithiation near end-of-charge, shifting plating to earlier SOCs. Importantly, the concentration criterion is observed to precede the potential trigger under specific conditions, demonstrating that single-indicator methods can systematically underpredict plating risk. Building on these findings, plating-free safe operating contour maps are developed across temperatures and C-rates for varying N/P ratios, establishing dual-criterion SOC thresholds that yield a significantly wider safe operating window compared to the single potential-criterion approach. When used alongside dQ/dV peak detection, this framework offers a step towards a science-based, practically implementable tool for real-time plating prevention in battery management systems (BMSs), enabling improved charging control and enhanced safety margins. The framework further provides a foundation for future extension to aged cells, large-format batteries, and alternative cathode chemistries.