Lithium plating is one of the most critical aging mechanisms that is harmful to the performance and safety of batteries. During fast charging, metallic lithium may be deposited on the Li-ion negative electrode when the surface overpotential drops below 0 V vs Li/Li+ under these conditions. This plating subsequently increases the rate of capacity fade (cyclable Li loss) and in extreme cases can result in dendrite growth through the separator. Experiments have shown that thermal and mechanical constraints could have significant effects on the performance and safety of lithium-ion batteries, including lithium plating [1-2].In this work, two models are used to study the thermal and mechanical effects on lithium plating in a NCM811/graphite cell. One is a 1D modified DualFoil model that solves the electrochemical equations and takes into account the mechanical effects caused by lithium intercalation and external pressure. The other one is a 3D electro-chemo-thermo-mechanical coupled model that couples the 1D modified DualFoil model with a 3D thermomechanical finite element model [3-5]. Our 1D results show that a lower temperature and mechanical deformation can both accelerate the occurrence of lithium plating, and that mechanical deformation is as important as thermal evolution. The 3D model is capable of capturing the inhomogeneity of temperature and mechanical environment in a cell during operation. Our 3D simulation results show that because of the mechanical constraints from the housing materials, localized tensile stress will appear in certain parts of the jellyrolls, and lithium plating is more likely to occur in these parts. We demonstrate that it is necessary to consider mechanical deformation during cell design, and show that our models can provide guidance for battery reliability.[1] John Cannarella, Craig B. Arnold, Stress evolution and capacity fade in constrained lithium-ion pouch cells, J. Power Source 245, 745-751 (2014).[2] Mathias Petzl, Michael Kasper, Michael A. Danzer, Lithium plating in a commercial lithium-ion battery – A low-temperature aging study, J. Power Source 275, 799-807 (2015).[3] Jake Christensen, David Cook, Paul Albertus, An Efficient Parallelizable 3D Thermoelectrochemical Model of a Li-Ion Cell, J. Electrochem. Soc. 160 (11), A2258-A2267 (2013).[4] Xiaoxuan Zhang, Markus Klinsmann, Sergei Chumakov, and et al., A Modified Electrochemical Model to Account for Mechanical Effects Due to Lithium Intercalation and External Pressure, J. Electrochem. Soc. 168, 020533 (2021).[5] Xiaoxuan Zhang, Sergei Chumakov, Xiaobai Li, and et al., An Electro-chemo-thermo-mechanical Coupled Three-dimensional Computational Framework for Lithium-ion Batteries, J. Electrochem. Soc. 167, 160542 (2020).