A novel reduced-order electrochemical model of lithium-ion batteries with both high fidelity and real-time applicability

Physics-based lithium-ion battery model is rarely used in real-time applications due to its complexity, restricting the development of next-generation refined battery management systems. Fidelity and computation efficiency are still challenging to coordinate for existing Model Order Reduction (MOR) methods, especially in solving either electrochemical reaction rate distribution or coupled multi-physics fields. This paper proposes a novel reduced-order electrochemical model called the Triple Region Transmission-Line Model (TRTLM), aiming at a win-win situation for both fidelity and real-time applicability. The TRTLM stands on a simple triple region transmission-line circuit topology, concisely depicting the inhomogeneous distribution of the electric field. Current and potential distribution are obtained considering the effect of the reaction distribution and concentration field. Two different linearized MIMO state-space models are then established to solve liquid and solid phase concentration fields continuously based on Padé Approximation techniques, achieving less distortion with limited discretization of the electric field. Convenient parameterized governing equations and extreme computation efficiency are both realized. Coupling of electric and concentration field is implemented by solving them alternatively and iteratively. A comparison study of the TRTLM with a Full-Order Model (FOM) and other representative MOR is conducted. The result shows less than 10 mV maximum distortion is reached by the TRTLM, even in extreme conditions, mainly through increasing the fidelity of reaction overpotential and liquid phase polarization. Moreover, hardware validation of the TRTLM is executed under different computation periods (down to 0.01s) based on the dSPACE platform, intuitively proving the real-time applicability of the model.