Summary of the context and overall objectives of the project (For the final period, include the conclusions of the action)

The increased use of batteries requires their improvement in terms of safety as well as quality, reliability and life (QRL). The EU-funded INSTABAT project aims to observe in operando essential parameters of a Li–ion battery cell to provide higher accuracy states of charge, health, power, energy and safety (SoX) cell indicators. The goal of INSTABAT is to improve the batteries’ safety and Quality, Reliability and Life (QRL). The project ambition is to develop a solution of smart sensing technologies and functionalities integrated into a battery cell. This solution is to be able to perform reliable monitoring of key parameters, correlate the evolution of these parameters to the physicochemical degradation phenomena taking place at the battery cell’s core and improve the battery’s functional performance and safety. This ambition is aligned to the Battery 2030+ roadmap.

To achieve this goal, INSTABAT was developing a proof of concept of smart sensing technologies and functionalities, integrated into a battery cell and capable of

      •          performing reliable in operando monitoring (time- and space-resolved) of key parameters (temperature and heat flow; pressure; strain; Li+ concentration and distribution; CO2 concentration; “absolute” impedance, potential and polarisation) by means of

             (i) four embedded physical sensors (optical fibers with Fiber Bragg Grating and luminescence probes, reference electrode and photo-acoustic gas sensors),

            (ii) two virtual sensors (based on reduced electro-chemical and thermal models),

      •          correlating the evolution of these parameters with the physico-chemical degradation phenomena occurring at the heart of the battery cell,

      •          improving the battery functional performance and safety, thanks to enhanced BMS algorithms providing in real-time higher accuracy SoX cell indicators (taking the measured and estimated parameters into consideration).

The main results of the project are: (1) a proof of concept of a multi-sensor platform (cell prototype equipped with physical/virtual sensors, and associated BMS algorithms providing SoX cell indicators in real time); (2) demonstration of higher accuracy for SoX cell indicators; (3) demonstration of improvement of cell functional performance and safety through two use cases for EV applications; (4) techno-economic feasibility study (manufacturability, adaptability to other cell technologies…).

INSTABAT smart cell concept aims to open up new horizons to improve cell use and performances (e.g. by reducing ageing, allowing the decrease of safety margins, triggering self-healing, facilitating second life, etc.).

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far (For the final period please include an overview of the results and their exploitation and dissemination)

During the INSTABAT project all the objectives were partially or fully achieved.

The requirements for smart batteries and the integration of the sensors into the cell were defined and compiled in deliverables D1.1 and D1.2.

During WP2, four out of five physical sensors were developed. These included two optical fibre sensors for temperature, one optical fibre sensor for pressure measurement, a photoacoustic sensor for PAS-CO2 measurement, and an embedded reference electrode. Additionally, a Li-ion luminescent probe was developed and validated for use on the electrolyte, paving the way for the development of a Li-ion sensor.

The physical sensors were validated for compatibility with the cell environment except for PAS-CO2. The insertion of fiber-optic and reference electrode sensors was successful. These sensors are capable of measuring the desired physical parameters inside the cell with a good accuracy. Only the FBG sensor, the OF-lumT sensor, and the reference electrode are sufficiently developed to be adapted to the battery environment without affecting electrochemical performance. However, the optical sensor and reference electrode do provide valuable information for understanding chemical degradation phenomena. Additionally, this approach has enabled long-term monitoring during WLTP cycling, which could potentially facilitate the use of EVs (refer to D3.3).

The electrochemical virtual sensor (E Base and T Base) has been developed and validated using experimental data from WP3. The model has also been adapted to different types of cells. These virtual sensors are fully customizable for varying resolutions. The accuracy of the virtual sensor was characterized with good results.

The demonstrator was developed by integrating all physical and virtual sensors with the SoX algorithm. The platform was tested under abuse conditions and cycling tests using multi-instrumented cells and standard cells without sensors.  These experiments demonstrated the functionality and operability of the INSTABAT lab-on-cell concept. However, due to time constraints and a limited number of samples, only a few experiments could be conducted.  Although the results are partial, we can conclude that the platform is functional and capable of achieving the project’s objectives. The results also demonstrate the platform’s versatility in integrating various types of sensors (physical and virtual) and advanced management functions. This platform also meets the objectives of the BATTERY 2030+ roadmap by integrating sensing and self-healing functions into the same tools.

Progress beyond the state of the art, expected results until the end of the project and potential impacts (including the socio-economic impact and the wider societal implications of the project so far)

We have developed new innovative sensors and demonstrated their capability to capture internal parameters of cells. We studied the effect of sensor integration on cell degradation and safety. The results showed no significant impact on cell performance, ageing, and safety upon the insertion of optical fibre sensors and reference electrode sensors.

The results of the ageing test demonstrate the sensors’ capability to monitor the key parameters of the cells. The correlation between the sensors’ signal and degradation phenomenon was achieved. These results were used to improve the development of cell models, virtual sensors, and the SoX algorithm integrated into the BMS. The correlation between the sensors’ signal and degradation also provided a much better understanding of the cell’s internal state during operation, opening up opportunities for innovation.

One of the major outcomes of INSTABAT is the development of the lab-on-cell concept and its associated platform. This platform has been used in various experiments, including ageing and abuse tests, and in collaboration with the BIG-Map project for multi-instrumented operando measurements at ESRF.  

INSTABAT contributed to improving performance and strongly encouraged the development of sustainable battery storage solutions for Li-ion batteries at a more competitive price. The project will use the “lab-on-a-cell” approach to develop a new generation of Li-ion and post-Li-ion batteries in the future, which aligns with the objectives of the Work Programme. The INSTABAT project’s results will aid in the widespread adoption of batteries for mobility, resulting in significant improvements and ultra-high performance. Finally, the progress made by INSTABAT is in line with the BATTERY 2030+ roadmap

J. Amici, et al. A Roadmap for Transforming Research to Invent the Batteries of the Future Designed within the European Large Scale Research Initiative BATTERY 2030+, Advanced Energy Materials, Volume 12, Issue 17 2102785

Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), France
Project coordinator: Program manager Dr Olivier Raccurt