Conventional Approach versus State-of-Charge Feedback for Lithium Titanate Battery Cell Charging – A Comparative Simulation Study

Lithium-titanate currently represents state-of-the-art technology in lithium secondary batteries that is characterized by exceptional thermal stability and operational safety levels. This makes them particularly interesting for highly demanding stationary energy storage applications. In practical field operations, minimizing the recharging time from a partially discharged state is often crucial, while still adhering to technological constraints such as battery terminal voltage and continuous charging current. To address this, the present work outlines the design of a dynamic battery charging system, leveraging state-of-charge estimation obtained from a nonlinear state estimator, specifically an extended Kalman filter (EKF). The above approach is used to enhance the conventional constant-current/constant-voltage charging system, which traditionally relies solely on battery voltage feedback. To evaluate the novel charging system performance, a comparative analysis is conducted through extensive simulations employing the nonlinear equivalent circuit model of the lithium titanate battery cell. The presented mathematical model can be successfully used in the design of digital twins of battery systems to augment the related charging strategies for electric vehicles (EVs) through straightforward retrofitting.