8.3 Advanced Dual Terahertz Sensor Inspection for Battery Coating Quality
The global surge in demand for lithium-ion batteries, primarily driven by electric vehicle expansion and renewable energy storage, is challenging existing manufacturing capabilities. Battery electrodes, featuring complex multilayer coatings on double-sided current collectors, require precise control of coating thickness, density, uniformity, and conductivity to ensure safety, longevity, and performance. Traditional inspection methods, including X-ray, laser profilometry, and ultrasound, face limitations related to safety, calibration frequency, and parameter coverage, impeding their effectiveness for real-time, high-throughput industrial use.
This research introduces an advanced, non-contact, inline measurement solution leveraging dual terahertz time-domain spectroscopy (THz-TDS) sensors integrated within a gantry system. The system facilitates simultaneous inspection of both sides of double-sided battery electrodes during production, allowing comprehensive characterization of critical parameters with micron-scale spatial resolution. By analysing time-resolved terahertz pulse reflections from multilayer coatings, the method extracts coating thickness, loading density, electrical conductivity, and detects defects such as delamination and contamination, providing a more complete and robust profile than conventional single-parameter techniques.
The dual-sensor gantry system accelerates data acquisition and enhances manufacturing yield by enabling closed-loop process control through real-time feedback, thereby reducing scrap rates and improving product reliability. Its modular design, flexible optical fibre sensor positioning, and seamless communication with plant automation infrastructure demonstrate practical adaptability to giga-scale battery production lines.
By transferring terahertz imaging principles successfully applied in pharmaceutical tablet coating inspection to battery electrode measurement, this technology bridges a critical gap in functional coatings quality control. The results contribute to advancing coating production technology by offering scalable, safe, and precise inline monitoring essential for meeting the rigorous specifications of next-generation electrochemical energy storage systems.