Rolling forming behavior of ultra-thin lithium metal for battery anode

Abstract

A comprehensive understanding of lithium metal’s mechanical deformation behavior during roll forming is crucial for producing thin lithium strips suitable for high-energy-density battery systems. However, there is currently a lack of comprehensive studies on the adequacy of the lithium metal constitutive model in the roll-forming process. The lithium metal true stress-strain is investigated via different strain rates of uniaxial tensile tests conducted at room temperature. The Johnson-Cook (J-C) model was modified to accurately describe lithium metal’s stress-strain relationship, determining its constitutive parameters, and the micro-mechanism of strain rate’s impact on plasticity was analyzed using SEM. Subsequently, the validity of the modified J-C model was conducted by employing statistical analyses such as Average Absolute Relative Error (AARE) and Root Mean Square Error (RMSE), along with numerical simulations of uniaxial tensile tests in ABAQUS. The improved J-C model is employed in numerical simulations of roll-forming thin lithium metal strips and compared with the roll-pressing experiment of lithium metal foil. The results indicate a positive correlation between the flow stress of lithium metal and the strain rate. The fitted curve of the modified J-C model closely matches the test tensile curve. Additionally, the simulation results of the modified model in the finite element simulation of roll forming are consistent with the roll-pressing experimental findings, further validating its feasibility.