User Benefits Application News Fig. 1 Structure of an Electrode Sheet  Apparatus Fig. 2 and Table 1 show the test apparatus, and Fig. 3 shows the specimen structure. The tests were conducted using a Precision Universal Testing Machine AGS -V, with 1 kN screw-type flat grips and a copper foil peeling test device mounted on it. The specimens consisted of rectangular metal plates covered with double-sided tape, which were then coated with cathode active materials. The specimens were set in the copper foil peeling test device. and the aluminum foil was gripped by the screw-type flat grip. The foil was always peeled off in a 90° direction relative to the specimen, ensuring that the center of the load coincides with the center of AGS-V.  Introduction Lithium-ion batteries play an important role in various electronic devices due to their high energy density and excellent charging efficiency. To improve battery performance, materials and processing methods are actively being developed, and strength measurement is one of the essential evaluation methods. This Application News focuses on the adhesion strength of the electrode sheets used as battery electrodes. Fig. 1 shows the structure of an electrode sheet. An electrode sheet consists of an electrode material that adheres to a current collector, through which electrons move. The electrode material is composed of a cathode active material such as lithium iron phosphate and an insulating material known as a binder. When the adhesion between the electrode material and the current collector is weak, the electrode material may delaminate from the current collector, preventing electrons from moving in the electrode sheet and increasing the electrical resistance. Therefore, evaluating the adhesion strength is important for improving battery performance. In this application, test equipment, test conditions, and results of the peel test for battery cathode materials are described. The temperature dependence of the adhesion strength of the electrode materials is also described.  A thermostatic chamber makes it possible to measure the adhesion force of cathode materials in actual temperature environments.  A copper foil peeling test device enables to conduct peel tests while maintaining a 90° angle in a thermostatic chamber.  By using a load cell with a wider accuracy guarantee range than a conventional one, it is possible to conduct high-accuracy tests even with small test forces. Peel Test for Cathode Materials of Lithium-Ion Batteries in a Thermostatic Chamber Tomoya Matsushita Precision Universal Testing Machines AGS -V Current collector Cathode active material Binder Electrode material Electron Delamination Fig. 2 Test Equipment AGS-V TCE-N300A Screw-type Flat Grips Specimen Copper Foil Peeling Test Device Cathode active material Aluminum foil Double-sided tape Metal plate Fig. 3 Specimen Structure Testing Machine: Precision Universal Testing Machine AGS-V Load Cell Capacity: 500 N Thermostatic Chamber: Compact Type Thermostatic Chamber TCE-N300A Software: TRAPEZIUM X-V (Single) Jigs: 1 kN Screw-type Flat Grip (Upper) Copper Foil Peeling Test Device (Lower) Table 1 Test Apparatus

Application News www.shimadzu.com/an/ Shimadzu Corporation © Shimadzu Corporation, 2025 For Research Use Only. Not for use in diagnostic procedures. This publication may contain references to products that are not available in your country. Please contact us to check the availability of these products in your country. The content of this publication shall not be reproduced, altered or sold for any commercial purpose without the written approval of Shimadzu. See http://www.shimadzu.com/about/trademarks/index.html for details. Third party trademarks and trade names may be used in this publication to refer to either the entities or their products/services, whether or not they are used with trademark symbol “TM” or “”. Shimadzu disclaims any proprietary interest in trademarks and trade names other than its own. The information contained herein is provided to you "as is" without warranty of any kind including without limitation warranties as to its accuracy or completeness. Shimadzu does not assume any responsibility or liability for any damage, whether direct or indirect, relating to the use of this publication. This publication is based upon the information available to Shimadzu on or before the date of publication, and subject to change without notice. 0 1 2 3 4 5 6 7 8 9 10 0 10 20 30 40 50 60 70 80 90 100 Force (N) Displacement (mm) Room Temperature 50℃ 70℃ First Edition: Jul. 2025 01-00944-EN AGS and TRAPEZIUM are trademarks of Shimadzu Corporation or its affiliated companies in Japan and/or other countries.  Test Results Fig. 4 shows the force-displacement curve. The dash-dotted curve is at room temperature, dotted curve is at 50 °C, and real curve is at 70 °C. The tests were conducted three times at each temperature whereas the shown curve is one representative specimen of the three. The average values of adhesion force are shown in Table 3. Adhesion forces were calculated from the average force between 20 mm and 80 mm of the displacement. These results show that when the temperature gets higher, adhesion force becomes larger.  Conclusion Peel tests in a thermostatic chamber were conducted using an AGS-V and TCE-N300A for Lithium iron phosphate used as cathode sheet of lithium-ion batteries. From the test results, it was confirmed that the adhesion force between the cathode active material and the aluminum foil increased as the temperature increased. This measurement can easily evaluate the temperature dependence of mechanical characteristics of battery cathodes. This method is expected to be applied to solve problems for improving battery performance. Fig. 4 Test Results Table 3 Adhesion Strength at each temperature (Average of n = 3) Temperature Adhesion Strength (N) Room Temperature 0.753 50 °C 0.903 70 °C 8.07 Range for calculating test force average Table 2 Test Conditions Cathode Active Material: Lithium Iron Phosphate Temperature: Room temp., 50 °C, 70 °C Test Speed: 5 mm/sec Disp. Origin: Force 0.05 N Target Value: Stroke 100 mm Number of Samples: 3  Test Conditions Table 2 shows test conditions. In this test, the force and its temperature dependence were evaluated. The temperature conditions included room temperature, 50 °C, and 70 °C. 50 °C 70 °C

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