An mechanical/thermal analytical model for prismatic lithium-ion cells with silicon‑carbon electrodes in charge/discharge cycles

Conventional lithium-ion cell state analysis methods face challenges in applicability, efficiency, and convergence for online state evaluation of cells with silicon‑carbon electrodes. This paper proposes a mechanical/thermal analytical model for prismatic cells with silicon‑carbon electrodes to evaluate cell stress and electrode deformation during charging/discharging. A dual-layer mechanical sub-model is proposed to obtain the electrode deformations under the volumetric loads of the SOC-dependent and thermal expansions. A viscoelastic constitutive model for electrode materials is developed to capture the mechanical hysteresis effects in a constrained space. A thermal circuit sub-model is created to assess the cell temperature distribution, providing boundary conditions for calculating electrode thermal expansion. The analytical model contains a small number of input parameters and first-order differential equations. The results cover the temperature, stress, elastic and viscoelastic deformations of the electrodes. The performance of the proposed approach was validated through numerical and experimental results on two commercial cells during constant current and abrupt current cycles. The second-level efficiency, robust convergence, and refined results exhibit an excellent prospect in energy storage and vehicle power applications.