May/June_AMP_Digital

Three-point flexure test on lithium-ion cell. The LTM 5 electrodynamic testing machine is used to determine material and component fatigue-strength in the fatigue life and fatigue limit ranges. CHALLENGES FOR NEW MOBILITY Test solutions for electric- and hydrogen- powered drives aid industry. SPONSORED CONTENT For more information on high temperature materials testing systems, contact ZwickRoell at 770.420.6555 / www.zwickroell.com. F uel cell or battery electric vehi- cles: Which is the better technol- ogy for the future? This question commonly divides drivers and manufacturers. Both technologies prom- ise to support a more climate-friendly environment, and ZwickRoell provides manufacturers with intelligent testing solutions for research, development, and series production to ensure strongmarket entry and reliable long-term operation. From pure electric, to hybrid vari- ations, to hydrogen powered drives, the strategic approaches are diverse. However, as with combustion technol- ogy, materials and components testing, whether in R&D or QA, play an important role in making vehicles safe and reliable. Materials Testing on Lithium-Ion Battery Cells The lithium-ion battery is the core component of electric and hybrid vehi- cles and helps in determining its range Therefore, special attention is given to the battery cells during development and quality assurance. During operation, the materials used are exposed to electromechanical, thermal, and mechanical loads. Through- out the various steps in the manufac- turing process, they are subjected to different loads and must be designed accordingly. For example, tensile stress, buckling resistance, crack strength, shear strength, sealed seam strength, bond strength, puncture resistance, elasticity, tempera- ture stress or compressive strength, need to be determined. In addition, knowledge of themechanical cell deformation caused by swelling during the charging process plays an important role in the design of the battery cell environment. Tests are typically performed using universal testing machines in a force range of up to 10 kN. To determine accu- rate characteristic values, the specimen grips for tensile testing must be well aligned and able to securely hold very thin films (<30 µm) without damaging them. The test also requires the use of very accurate sensors (load cell, exten- someter). For the determination of strain values on very thin electrode films, it is important that there is no influence on the material characteristic values caused by contact-type extensometers. In this case, non-contact video or laser-based exten- someters are ideal. Testing of Lithium-Ion Battery Electrode Coating Next to the electrolyte and the separator, the electrodes are the most im- portant components in the development of lithium-ion batteries. During the charging cycles, lithium ions are deposited in the coatings of the anodes and cathodes. Over the service life of the battery, this interca- lation causes mechanical changes in the coatings, ultimately leading to a weaker battery. The bond strength of the electrode’s coating also changes with the age of the battery and therefore, its connection must be guaranteed for the long-term. For this test, a special Z peel test kit is ideal. Important characteristic elasticity values can be determined with utmost accuracy using the nanoindenter. Testing in a Hydrogen Atmosphere If hydrogen is to be used as a com- mercial source of energy in the future, it is essential to achieve maximum possi- ble specific energy density in the storage and distribution system. This is achieved by compressing gaseous hydrogen. Max- imum pressures up to more than 70 MPa are already attained in fuel tanks. Ma- terials used in this field are exposed to the effects of hydrogen, in addition to temperature and pressure stress- es. To ensure safe, reliable operation, components must be adequately dimen- sioned and the necessary specifications determined. A servohydraulic testing machine for test loads up to 100 kN is fitted with a hydrogen container designed for pres- sures up to 100 MPa. In this container, testing can be performed in a tempera- ture range of -85°C to +150°C. With this testing system, quasi-static tensile tests, fatigue tests and fracture mechanics tests are performed primarily on metal- lic materials.