Periodic Reporting for period 1 - BattMaxLife (Life-long health monitoring and assessment for lifetime maximization of Li-ion batteries)
Reporting period: 2023-09-01 to 2025-08-31
The ultimate goal of this fellowship project was to maximize the available lifetime of Li-ion batteries. The approach how this was pursued was using the concept of making battery impedance accessible for the battery BMS state-estimation algorithms in real time with a novel ternary-sequence on-board measurement. With impedance included in the state estimation algorithms, the BMS can better optimize the use of the battery to extend its first life by approximately 5-10% depending on the application. In addition, the safety of the battery is more likely to be guaranteed throughout the battery life. With adequate SOH information available at the end of its first life, the battery will become an attractive candidate for second-life application as reliable predictions can be made about the remaining lifetime, safety, and economic value of the battery. The main objectives of the project were:
OBJ 1 - Demonstration and validation of the concept’s on-board impedance measurements in the laboratory
OBJ 2 - Achieve and validate the targeted 5-10% lifetime improvement for the battery first life with the more accurate state-estimation algorithms provided in the concept.
OBJ 3 - Validate the feasibility of the concept for providing comprehensive battery health information throughout the battery life to make it feasible for second-life use, and to gain the targeted 30-50% of additional lifetime improvement.
OBJ 1 - Demonstration and validation of the concept’s on-board impedance measurements in the laboratory
OBJ 2 - Achieve and validate the targeted 5-10% lifetime improvement for the battery first life with the more accurate state-estimation algorithms provided in the concept.
OBJ 3 - Validate the feasibility of the concept for providing comprehensive battery health information throughout the battery life to make it feasible for second-life use, and to gain the targeted 30-50% of additional lifetime improvement.
In particular, the first part of the project focused on building and implementing a customized setup that emulates the battery impedance ternary sequence measurements for a a small battery pack comprised of series connected cells. Onwards the project, this setup was used to monitor the impedance of selected battery cells which were subjected to aging in a separate battery cycler. It was verified that the impedance provides unique information about the health of the battery but also about the temperature. Moreover, it was shown that computationally light feature-based models may be sufficient to be applied in the algorithms but that data-driven methods would also benefit of the inclusion of the impedance.
Later on in the project, it was discovered that some of the applied ternary sequences have very unique properties that allow the sequences to be applied for non-steady-state system measurements. In the context of battery impedance measurements, this implies that the impedance can be measured while the battery is being used by the application, being highly beneficial in the real-time monitoring of the impedance. This, along with the briefly derived theoretical framework in why the sequences works as they do, can be considered as the main achievement of the whole project which can further facilitate the reaching of the objectives 2 and 3 of the project. However, the actual verification of the technology applicability in real BMS af a battery pack prototype and further validation of the obtained lifetime increase was something that was not possible in the project. This was because of lacking laboratory equipment that prevented lifetime tests with such a battery pack prototype. However, because of other findings regarding the mentioned discovery of real-time monitoring capabilities of specific ternary sequences, these objectives have actually better technological grounds in succeeding in future research activities. Moreover, surprising discovery in the project was that the impedance measurement technology and state monitoring concept is also applicable to hydrogen technology.
Later on in the project, it was discovered that some of the applied ternary sequences have very unique properties that allow the sequences to be applied for non-steady-state system measurements. In the context of battery impedance measurements, this implies that the impedance can be measured while the battery is being used by the application, being highly beneficial in the real-time monitoring of the impedance. This, along with the briefly derived theoretical framework in why the sequences works as they do, can be considered as the main achievement of the whole project which can further facilitate the reaching of the objectives 2 and 3 of the project. However, the actual verification of the technology applicability in real BMS af a battery pack prototype and further validation of the obtained lifetime increase was something that was not possible in the project. This was because of lacking laboratory equipment that prevented lifetime tests with such a battery pack prototype. However, because of other findings regarding the mentioned discovery of real-time monitoring capabilities of specific ternary sequences, these objectives have actually better technological grounds in succeeding in future research activities. Moreover, surprising discovery in the project was that the impedance measurement technology and state monitoring concept is also applicable to hydrogen technology.
The discovery of the unique properties of specific ternary sequences has significant scientific impact and also potential in having further exploitation possibilities. These possibilities will be investigated in the future and some of the planned activities for this purpose are provided in the communication, dissemination and exploitation plan available as a project deliverable.