Physics-Informed Design of Hybrid Pulse Power Characterization Tests for Rechargeable Batteries

Abstract

Industry-standard diagnostic methods for rechargeable batteries, such as hybrid pulse power characterization (HPPC) tests for hybrid electric vehicles, provide some indications of state of health (SoH), but lack a physical basis to guide protocol design and identify degradation mechanisms. We develop a physics-based theoretical framework for HPPC tests, which are able to accurately determine specific mechanisms for battery degradation in porous electrode simulations. We show that voltage pulses are generally preferable to current pulses, because voltage-resolved linearization more rapidly quantifies degradation without sacrificing accuracy or allowing significant state changes during the measurement. In addition, asymmetric amounts of information gain between charge/discharge pulses are found from differences in electrode kinetic scales. We demonstrate our approach of physics-informed HPPC on simulated Li-ion batteries with nickel-rich cathodes and graphite anodes. Multivariable optimization by physics-informed HPPC rapidly determines kinetic parameters that correlate with degradation phenomena at the anode, such as solid-electrolyte interphase growth and lithium plating, as well as at the cathode, such as oxidation-induced cation disorder. If validated experimentally, standardized voltage protocols for HPPC tests could play a pivotal role in expediting battery SoH assessment and accelerating materials design by providing new electrochemical features for interpretable machine learning of battery degradation.

Optimum Model-Based Design of Diagnostics Experiments (DOE) with Hybrid Pulse Power Characterization (HPPC) for Lithium-Ion Batteries

“…This section displays the results for the Pareto front and MCMC simulations when our framework for optimizing the HPPC protocol is applied to an NCA-graphite full-cell electrode 20 with the CIET reaction model. It should be noted that the same framework can be applied to any kind of electrode combination and kinetic reaction models.…”

“…Information dependency on kinetic parameters.-The impact of the overpotential balance based on kinetic properties 20 on the Pareto front is investigated in Fig. 2b.…”

“…19 The lack of physical modeling included in these methods, however, causes a significant loss of useful information since these systems are heavily reliant on physical mechanisms. In recent work, 20 we have shown through electrochemical simulations that pulse diagnostics can accurately extract dominant degradation mechanisms with modified Hybrid Pulse Power Characterization (HPPC) methods. However, a large amount of time is still spent performing diagnostics in these protocols.…”

“…In this work, single-particle models are adopted for both electrodes as in Ref. 20. Commonly, either voltage constraints or current constraints are applied to a cell to extract electrochemical power.…”

“…As derived in Ref. 20, the fitness response of the kth pulse for the full-cell, W k , can be expressed as…”