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GHz nanoscale electrical and dielectric measurements of the solid-electrolyte interface and applications in the battery manufacturing line

Periodic Reporting for period 1 - NanoBat (GHz nanoscale electrical and dielectric measurements of the solid-electrolyte interface and applications in the battery manufacturing line)

Reporting period: 2020-04-01 to 2021-09-30

NanoBat aims to develop new broad-band frequency and nanoscale methods for measuring the electrical impedance and electrochemistry of batteries, that are significantly faster, more sensitive, and more accurately calibrated than existing methods. As such, battery compartments and interface layers including the nanoscale electrode SEI (solid electrolyte interface) can be measured and modelled, leading to an improved characterization speed and accuracy in manufacturing as demonstrated in pilot lines, open workshops, as well as high-throughput quality tests in industrial settings.
For the incoming battery quality tests, the new broad-band frequency and nanoscale methods improve the grading and classification efficiency, as well as the production efficiency. For Europe, green battery production is a strategic imperative for a clean energy transition and the competitiveness of its automotive sector and the battery production market. Thereby, NanoBat focuses on four thematic fields:
• Nanotech instrumentation and new broad-band frequency methods for studying the battery interface layers.
• Calibration, modelling, and data analytics of advanced metrological battery measurements.
• Tests in pilot lines and automotive batteries, as well as testing of new battery materials.
• Higher efficiency in battery production and open innovation objectives.
On the first action line – new nanotechnology instrumentation and new methods - results were published in three prominent scientific journals. Thereby, various scanning microscopy techniques are being adapted for battery research to investigate the nanoscale electrode interface across multi-scale dimensions from nano- to milli-meter. A new scanning microwave microscope for battery research has been assembled and tested in liquid to examine interface layers. Also, a scanning electrochemical microscopy was used inside an Argon-filled glovebox in combination with newly developed operating modes for the first time in the field of Lithium-ion batteries (LIBs).
The results of the second field - calibration, modelling, and data analytics – include an advanced metrological calibration method that has been developed for electrochemical impedance spectroscopy (EIS) and self-discharge measurements (SDM), both prominent methods to study the performance of batteries or their components. Moreover, a standard operating procedure was prepared under guidance of a national metrology institute. The calibration process has been applied for a large measurement station using test standards. The development of a dielectric resonator scanner designed and calibrated with electromagnetic simulations for studying battery layers has successfully entered the prototype stage. New electromagnetic models for batteries have been developed. This includes finite element modeling of battery cells based on multiphysics methods and equivalent electric circuit models. A paper has been published showing the application of modeling to connect nanotechnology and electronic measurements for the unambiguous assessment of ageing in LIBs.
Work on the third area – advanced materials and pilot lines – included the integration of a fast high-voltage quality test for battery separators and virtual quality gates in a pilot-line setting, also establishing a data communication link of the test device with the pilot line database.
Battery materials developments included graphene anode samples, and beyond lithium studies. For the latter, studies of the electrode interface layer formation and evolution during cycling on Mg-metal using advanced nanoscale techniques have been initiated.
On the fourth subject, an assessment of the environmental impact of efficient battery quality handling has been conducted, a case study of reduction of CO2 emissions by applying the new in-line test methods has been done, and the development of virtual quality gates for end-of-line testing of battery cells has been started. A measure station concept for high throughput measurements has been demonstrated by applying 256 cell measurements in parallel. The open innovation and dissemination objectives have been addressed in several aspects: An Open Innovation Environment (OIE) website has been created, including an open platform tools section. NanoBat-Modeler, an open platform GUI (graphical user interface) workbench, has been developed and uploaded on the OIE. Standardized characterization and modelling procedures were established and stored on our webpage. This is done in alignment with the EMCC (European Materials Characterization Council) and EMMC (European Materials Modelling Council).
Two scientific workshops were organized reaching 80+ and 130+ active participants for the first and the second workshop, respectively. In the workshops, renowned experts were invited to discuss progress in the field, and specific sessions were done for students with short video presentations from their labs. Presentations involved Early-Stage Researchers from two ongoing Marie Skłodowska-Curie training networks, POLYSTORAGE and SENTINEL.
Regular meetings with the Stakeholder group and Advisory Board members are conducted, three meetings have been held already, the Stakeholder group has grown to 20 partners now.
Progress beyond the state of the art is spanning three branches. Firstly, advanced nanoscale imaging tools were developed to study the crucial SEI layer, including broad-band frequency spectroscopy. Secondly, new calibration methods were developed for the EIS and SDM advanced electrical qualification routines of batteries, by making them more accurate and more repeatable. Thirdly, our OIE provides useful modelling and experimental workflows for the operation of the new methods, which impacts the larger measurement and modelling ecosystem. For instance, with one of the methods implemented in-line as quality gate, savings in the energy and material consumption, and consequently, environmental emissions, can be significantly reduced as shown in a life-cycle analysis. Because of the quality gate decision, partly finished cells will not continue to being transferred to the next production steps, thus saving materials and energy.
Regarding the expected results and potential impact until the end of the project, metrology grade calibrated in-line impedance spectroscopy will be implemented for in-line testing and evaluation of forming, aging, and cycling at battery pilot lines, including virtual quality gates, modelling and data analytics. Additionally, high-throughput test implementation is ongoing for module fabrication and cell sorting based on electrode interface layer properties, using fast qualification algorithms based on both real test data and modeling data.
Connecting Nanotech and EIS measurements