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. An analytical approach for prismatic cells with silicon‑carbon electrodes is proposed, including a dual-layer mechanical and a thermal circuit sub-models. It can evaluate the state distribution and evolution in temperature, stress, elastic and viscoelastic deformations of positive and negative electrodes. [Display omitted] •A mechanical/thermal analytical model is proposed for the cells with silicon‑carbon electrodes.•A viscoelastic constitutive model and parameter identification method are developed for electrode materials.•The SOC-dependent and thermal expansions are incorporated as volumetric loads.•The mechanical hysteresis responses and deformation differences of the electrodes are captured.•The experiments of constant and abrupt constant cycles are performed to verify performances.