Thermal Analysis and Rheology of Batteries Analyzing & Testing

THERMAL ANALYSIS AND RHEOLOGY OF BATTERIES Engineers often face challenges when designing lithium ion batteries. A thorough thermal management strategy is required to enhance performance, improve battery life, and to keep batteries from going into thermal runaway. Thermal management starts with careful characterizations of battery components for the development of inherently safer batteries. Design parameters, for intended use, manufacturing processes and operating conditions all have an effect upon battery temperature during use. Manufacturers of battery components must consistently deliver...

Cathode precursor & electrode materials Battery slurry Electrode and electrode coating Binder, additives Battery cell Material testing CriticalParameters Crystal phase ■ Viscosity ■ Thermal management (thermal diffusivity/ conductivity) ■ Specific heat capacity ■ Reactivity Performance changes ■ Thermal stability■ Degradation with air/moisture■ Performance changes ■ Thermal behavior ■ Specific heat capacity Dimensional change ■ Internal short tests Enthalpies Thermal conductivity ■ Gas production (quantitative and qualitative) ■ Kinetic model development ■ sotropic & parasitic reactions Compatibility...

Thermal Analysis & Rheology Characterizing each material, measuring compatibility between and among the different components can be achieved by DSC, TGA, STA, MMC and ARC. With this information battery components are engineered to be more thermally stable, produce less heat and react more slowly. The release of toxic, flammable or explosive gases during the decomposition reactions can be studied and mitigated using GC-MS, QMS and FT-IR coupled to the thermal analyzer. The performance of cells can also be measured to determine parameters such as efficiency over the expected operating temperatures...

PERFORMANCE & SAFETY STA 509 Jupiter® coupled to QMS 505 Aëolos Cell Design Life Cycle Kinexus Prime ultra+

Thermal Runaway Li-ion cells are relatively lightweight and have a high energy density. These performance benefits have made them invaluable to the portable energy market. These two benefits also makes them more likely to be involved in thermal runaway. Thermal runaway occurs when the self-heating of cell is greater than the amount of heat that can be removed from the cell. This stored heat in the cell causes the temperature to rise which results in even higher self-heating. Left unchecked, a thermal runaway can cause the cell temperatures to rise rapidly leading to the production of toxic gases,...

Where it may be possible to design battery management and safety systems to reduce the frequency and consequence from external sources, this is a bit harder to do when the source is an internal defect. The age, health and charge of a cell all play a role in how and when this self-heating can occur. Characterizing the pathways of thermal runaway can be done using dedicated testing equipment and methodologies. Integrating safety, compatibility and other advanced testing methods early in the development process can have enormous payback in reducing time-to-market and in the creation of inherently...

Like the human body, the operating temperature of a battery should always be monitored, protected and kept at an optimal level. If the ambient temperature is too low, it will not deliver its full power and reduce the lifetime of the cell. If the ambient temperature rises too high promote the increase of parasitic reactions, reducing efficiency and lifetime. The battery can even swell, catch fire, explode and release toxic gases. Proper battery thermal management ensures longer lifespan by keeping the cells within a limited temperature range during storage, operation and charging. The State-of-Charge(SOC)-State...

Laser Flash Analysis Thermal conductivity and diffusivity are the most important thermophysical parameters for the description of the heat transport properties of a material or a component. The Laser/Light Flash technique has proven itself a fast, versatile and absolute method for measurement of the thermal diffusivity. NETZSCH offers three models, covering the widest temperature range for the broadest spectrum of materials. For the investigation of electrodes, electrode coating, separators, the LFA 717 HyperFlash® is the right instrument. The patented ZoomOptics allows the detector’s field of...

Temperature changes the physical properties of materials. Lithiation/ Delithiation can also change physical properties. These changes can include dimensional and volumetric changes, changes in strength, flexibility and durability. In a cell, these changes are not uniform and can add mechanical stress and affect material performance. For example, polymer separators can shrink significantly at elevated temperatures which affects the battery performance. To predict the deformation and stresses in the separator in battery cells, it is necessary to measure the expansion/shrinkage behavior. Thermomechanical...

Temperature range: -150°C to 1600°C (5 interchangeable furnaces) Measurement of length change and corresponding force Vacuum-tight thermostatic measuring system Easily interchangeable sample holders made of fused silica or alumina Max. sample length 30 mm High resolution: 0.125 nm/digit Force range: 1mN to 4 N (only for Supreme, 3N for Select) Modulated force (for Select optional) Temperature range: -180°C to 2800°C, various furnaces Single or double dilatometer Measuring range: 25 mm/50 mm NanoEye Δl resolution: 1 nm/0.1 nm/digit Automatic sample length detection Controlled contact Force range:...

THERMAL STABILITY Designing Inherently Safer Batteries Which Meet Application Challenges Electrolytes are characterized by high conductivity, good electrochemical stability and the ability to perform at low temperatures. However, the thermal stability of many electrolyte solutions is restricted even at moderate temperatures where side reactions can begin to limit the lifetime and performance of cells. Thermal stability is one of several important criteria in battery design. The trick is to find the right design that meets the application criteria. For example, there is a positive correlation...