Periodic Reporting for period 1 - SENSIBAT (Cell-integrated SENSIing functionalities for smart BATtery systems with improved performance and safety)
Berichtszeitraum: 2020-09-01 bis 2022-02-28
SENSIBAT’s overall objective is to develop a sensing technology for Li-ion batteries that measures in real-time the internal battery cell temperature, pressure (e.g. mechanical strain, gas evolution) conductivity and impedance (separately for the anode, cathode and electrolyte).
The improved understanding about the nature and timing of unwanted internal battery processes enables faster and more accurate control of the individual cells in a battery system during operation. More control can stretch the possibilities of fast charging, increases the usable battery capacity in as example adverse weather conditions and gives a detailed usage history which allows for better battery state forecasting, resulting in more economical use during the 1st and 2nd life of the battery. In summary, improving the monitoring to understand the changes within a battery cell under various operation conditions is key to mass introduction of this technology in high demanding applications.
Our ambition is to provide data and insights from these new sensing technologies, to improve state estimator functions based on an improved understanding of how, where and when degradation and failure mechanisms occur to have more reliable batteries. The sophisticated lifetime prediction models also result in improved maintenance schemes.
Finally, the higher level of understanding in combination with the collected data will facilitate the discovery of future battery chemistries.
Overall, SENSIBAT will lead to an increase of the safety, performance, usability and lifetime of Li-ion batteries.
The improved understanding about the nature and timing of unwanted internal battery processes enables faster and more accurate control of the individual cells in a battery system during operation. More control can stretch the possibilities of fast charging, increases the usable battery capacity in as example adverse weather conditions and gives a detailed usage history which allows for better battery state forecasting, resulting in more economical use during the 1st and 2nd life of the battery. In summary, improving the monitoring to understand the changes within a battery cell under various operation conditions is key to mass introduction of this technology in high demanding applications.
Our ambition is to provide data and insights from these new sensing technologies, to improve state estimator functions based on an improved understanding of how, where and when degradation and failure mechanisms occur to have more reliable batteries. The sophisticated lifetime prediction models also result in improved maintenance schemes.
Finally, the higher level of understanding in combination with the collected data will facilitate the discovery of future battery chemistries.
Overall, SENSIBAT will lead to an increase of the safety, performance, usability and lifetime of Li-ion batteries.
During the first project period (18 months) there have been several steps taken towards the achievement of the project technical objectives:
• Specifications and requirements
In the initial phase of the project, SENSIBAT partners established the specifications and requirements of the new sensing technologies to be developed, facing the multiple challenges of integrating any element within a Li-ion battery.
• Baseline cells
Prototype pouch cells of 1Ah and 5Ah capacity have been made. These cells will serve as a baseline/reference for the cells with integrated Level 1 (1 Ah and 5 Ah cells) and integrated Level 2 sensors (1 Ah cells), all cells have a graphite anode and a NMC622 cathode.
• Temperature and pressure sensor (Level1):
The SENSIBAT Level 1 sensor matrix has been designed for 1 Ah battery cells. The matrix holds 12 resistive temperature sensors for cross-point array addressing as well as 12 capacitive pressure sensors in common rail configuration.
• Impedance sensor (Level2):
Printed auxiliary electrodes based on graphene have been developed on battery separators, and the validation of their electrochemical performances is ongoing.
• BMS master
The BMS master HW (hardware) concept is finalized, and the PCB is developed and in the process of being built. The concept version exists and is used for the SW (software) development part. The interfacing with the BMS slave is in development with NXP and FHG.
• Dissemination activities
Several events have been organised also in connection with Battery2030+: e.g. a zeroing course, an Advisory Board workshop, etc. In addition, the project webpage is in place, together with 2 newsletters and 11 public deliverables.
• Specifications and requirements
In the initial phase of the project, SENSIBAT partners established the specifications and requirements of the new sensing technologies to be developed, facing the multiple challenges of integrating any element within a Li-ion battery.
• Baseline cells
Prototype pouch cells of 1Ah and 5Ah capacity have been made. These cells will serve as a baseline/reference for the cells with integrated Level 1 (1 Ah and 5 Ah cells) and integrated Level 2 sensors (1 Ah cells), all cells have a graphite anode and a NMC622 cathode.
• Temperature and pressure sensor (Level1):
The SENSIBAT Level 1 sensor matrix has been designed for 1 Ah battery cells. The matrix holds 12 resistive temperature sensors for cross-point array addressing as well as 12 capacitive pressure sensors in common rail configuration.
• Impedance sensor (Level2):
Printed auxiliary electrodes based on graphene have been developed on battery separators, and the validation of their electrochemical performances is ongoing.
• BMS master
The BMS master HW (hardware) concept is finalized, and the PCB is developed and in the process of being built. The concept version exists and is used for the SW (software) development part. The interfacing with the BMS slave is in development with NXP and FHG.
• Dissemination activities
Several events have been organised also in connection with Battery2030+: e.g. a zeroing course, an Advisory Board workshop, etc. In addition, the project webpage is in place, together with 2 newsletters and 11 public deliverables.
• The introduction of sensors into pouch cells is currently not done on an industrial scale. Beyond the state of the art, SENSIBAT is currently under demostration process of the following issues that can occur due to the introduction of sensors:
i) incompatibility of the sensors with the pouch cell assembly process:
SENSIBAT project demostrated that the Level 1 sensors are be compatible during the pouch cell assembly as they are chosen and designed to be as thin as possible. The level 2 sensors will be printed on the cell separator and therefore it is expected that they will not influence the assembling process.
ii) intervention of sensors during the transport or transfer of lithium ions between anode and cathode electrodes:
The SENSIBAT Level 1 sensors are attached to one side of the stacked battery electrode inside the cell where there is minimum flow of lithium ions, the level 2 sensors will be printed on the separator and the work done up to know demostrated that will be possible to minimaze the impact of the L2 sensor on the lithium ions transfer.
iii) sensors may react to produce by-products or dissolve in the electrolyte used
During the development of Level 1 sensor some difficulties on the the sensor encapsulation were found due to the exposure of the sensor to the electrolyte. This issue was overcomed adopting material choice and integrating a tempering step in the sensor encapsulation process.
• SENSIBAT project demostrated that it is possible to introduce the developed Level 1 sensors inside pouch-type lithium-ion cells, in the next project period it will be studied how these sensors are useful to maximise the performance, functionality and safety of a complete battery system over its entire lifetime (increase QRL), including forecasting the remaining lifetime under different use cases, especially the suitability for possible "second life" usage.
• SENSIBAT will analize the impact on the electrochemical behaviour and lifetime of cells of the SENSIBAT L1 integrated sensors. Once cell results are demonstrated, the developed sensing technology can be used without significant modifications in a pouch type NMC/graphite battery.
• The battery cells with integrated L1 sensors will be used to develop a 24V battery module with integrated sensors.
i) A complete battery module based on six prototype cells connected in series, with integrated sensors connected to the multicell monitoring IC (aic) and slave BMS will be developed.
ii) A master BMS connected to the slave BMS and programmed with advanced state estimation algorithms will be also developed.
• Finally, by making use of the data from the internal sensing technologies, robust and advanced state estimation functions are under developemet. Commonly used state estimation algorithms are been improved and novel safety concepts are under study.
i) This will allow to develop faster charge protocols based on temperature and pressure measurements inside the cell.
ii) In addition, safety limits are more accurately measured and understood leading to safer battery operation and use of full battery capacity.
iii) in the same way, better battery maintenance with the improved ability to detect, repair or replace defective cell components will be possible.
v) Finally, using detailed data, more sophisticated lifetime prediction models will be developed and this will allow improved preventive maintenance measurements to prolong its lifetime.
i) incompatibility of the sensors with the pouch cell assembly process:
SENSIBAT project demostrated that the Level 1 sensors are be compatible during the pouch cell assembly as they are chosen and designed to be as thin as possible. The level 2 sensors will be printed on the cell separator and therefore it is expected that they will not influence the assembling process.
ii) intervention of sensors during the transport or transfer of lithium ions between anode and cathode electrodes:
The SENSIBAT Level 1 sensors are attached to one side of the stacked battery electrode inside the cell where there is minimum flow of lithium ions, the level 2 sensors will be printed on the separator and the work done up to know demostrated that will be possible to minimaze the impact of the L2 sensor on the lithium ions transfer.
iii) sensors may react to produce by-products or dissolve in the electrolyte used
During the development of Level 1 sensor some difficulties on the the sensor encapsulation were found due to the exposure of the sensor to the electrolyte. This issue was overcomed adopting material choice and integrating a tempering step in the sensor encapsulation process.
• SENSIBAT project demostrated that it is possible to introduce the developed Level 1 sensors inside pouch-type lithium-ion cells, in the next project period it will be studied how these sensors are useful to maximise the performance, functionality and safety of a complete battery system over its entire lifetime (increase QRL), including forecasting the remaining lifetime under different use cases, especially the suitability for possible "second life" usage.
• SENSIBAT will analize the impact on the electrochemical behaviour and lifetime of cells of the SENSIBAT L1 integrated sensors. Once cell results are demonstrated, the developed sensing technology can be used without significant modifications in a pouch type NMC/graphite battery.
• The battery cells with integrated L1 sensors will be used to develop a 24V battery module with integrated sensors.
i) A complete battery module based on six prototype cells connected in series, with integrated sensors connected to the multicell monitoring IC (aic) and slave BMS will be developed.
ii) A master BMS connected to the slave BMS and programmed with advanced state estimation algorithms will be also developed.
• Finally, by making use of the data from the internal sensing technologies, robust and advanced state estimation functions are under developemet. Commonly used state estimation algorithms are been improved and novel safety concepts are under study.
i) This will allow to develop faster charge protocols based on temperature and pressure measurements inside the cell.
ii) In addition, safety limits are more accurately measured and understood leading to safer battery operation and use of full battery capacity.
iii) in the same way, better battery maintenance with the improved ability to detect, repair or replace defective cell components will be possible.
v) Finally, using detailed data, more sophisticated lifetime prediction models will be developed and this will allow improved preventive maintenance measurements to prolong its lifetime.