State-of-health prognostics of electrochemical energy systems

Principal investigator:

Dr. Pavle Boškoski


March 1, 2016 – February 28, 2019


ARRS - Slovenian Research Agency, L2-7663 (C), co-financed by INEA d.o.o.


Electrochemical energy system (EES) is a joint label for electrochemical storage devices (i.e., batteries) and electrochemical conversion devices (i.e., fuel cells, electrolyzers). EESs are the key components in a range of priority areas like clean and efficient energy, green transport, smart buildings and many more segments of everyday life. Enormous effort across many disciplines, particularly in the development of new materials has been aimed to reach higher storage capacity, efficiency, reliability and longevity of EESs. Despite the progress, degradation phenomena still significantly affect EES safety and reduce the overall exploitation efficiency.

The aim of this project is the development of online, accurate and computationally efficient prognostics and health management (PHM) approaches thus ensuring reliable EES operation. Such approaches provide information about the current condition indices and their degradation rate, which in the context of EES are referred to as State-Of-Health (SOH) and remaining useful life (RUL). These approaches are the heart of so-called PHM systems, which perform data acquisition and execute the PHM methods. PHM systems provide the end-user or the high-level control system with information required for conducting actions that mitigate the degradation effects. In particular, the PROG-EES project addresses the PHM issues for Lithium-based batteries and PEM fuel cells. Although these two EESs belong to two different groups, from the data analysis standpoint, they can be treated in a similar manner, thus justifying the joint study of both EES types within the same project.

Two main issues limit the performance of the contemporary PHM systems for EES. The first is the usage of suboptimal signal processing methods and oversimplified models. Although detailed first principle electrochemical models are available, their complexity restricts the applicability for online PHM tasks. The second is the hardware implementation that either has limited capabilities or is dedicated solely to laboratory usage. In laboratory context, PHM tasks are conducted in dedicated diagnostic cycles that disrupt the normal EES operation, which is unacceptable in real world installations.

Overcoming the aforementioned deficiencies requires advances in several segments:

  • Tailored stochastic excitation signals coupled with effectual signal processing techniques. Such a combination will allow timely EES characterisation even in the low frequency band, which can be directly related to its SOH.
  • Information fusion techniques for merging the information into SOH estimate. By taking into account the EES's nonlinearity, the complete approach will be sufficiently robust to changes in the operating set-point.
  • Statistical degradation models. Based on the available electrochemical models, such degradation models will offer simplified yet sufficiently accurate framework applicable for online RUL estimation.
  • Hardware implementation. Implementing the PHM system as a part of the power-conditioning unit (e.g., DC/DC converter) will enable seamless integration of online PHM without influencing nominal EES operation.
  • The final result will be a cost-efficient online embedded PHM system for EESs.
  • The feasibility of PROG-EES project is guaranteed by the interdisciplinary team of the project's partners with leading experts in modelling, statistics, PHM method development and electronics design.

The expected impacts of the project results are far-reaching. The proposed PHM system will be applicable throughout the EES's operational life-time. More importantly, the methodological improvements will enable the development of SOH estimation devices required for next-generation EES recycling. Besides the obvious ecological impact, the project's co-financier, INEA d.o.o., will be among the first companies addressing the emerging EES refurbishing/repurposing market niche with estimated global worth of $3-billion-a-year by 2035.

Project partners: