08.05.2023 by Aileen Sammler
The Importance of Plastics for the Energy Storage Function of Batteries
Plastics have been widely used in the automotive field for decades and are increasingly being employed in batteries as well: They have been used as housing, cables, and connectors right from the beginning, but with their increased utilization in energy storage, they are now a crucial element on the rise of e-mobility.
The Role of Plastics in Energy Storage
The materials and construction principles used in batteries primarily determine their energy storage function. Plastics play a significant role in this, even though they cannot be employed directly as electrical conductors. They are used in battery construction as insulators, separating materials, housings and electrolyte membranes, contributing to increased chemical stability and battery life, as well as ensuring safe and efficient performance.
One example are lithium-ion batteries, which are used in numerous applications such as smartphones, laptops, electric vehicles and energy storage systems. Cathodes and anodes of lithium-ion batteries are often coated with plastic to ensure insulation and long-term protection against unwanted chemical reactions and corrosion. In the mobility sector, requirements are also focused on Thermal StabilityA material is thermally stable if it does not decompose under the influence of temperature. One way to determine the thermal stability of a substance is to use a TGA (thermogravimetric analyzer). thermal stability.
There are various plastics employed in batteries, each fulfilling different storage functions. In the following, we are providing an overview of the most important plastics and their functions:
Thermal Analysis Devices and Rheometers by NETZSCH Help Determine the Ideal Properties of Plastics for Use in Batteries
Here are some examples:
Thermal analysis is used to characterize the thermal properties of plastics, such as Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting temperature, Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition temperature, CrystallizationCrystallization is the physical process of hardening during the formation and growth of crystals. During this process, heat of crystallization is released.crystallization and Thermal ConductivityThermal conductivity (λ with the unit W/(m•K)) describes the transport of energy – in the form of heat – through a body of mass as the result of a temperature gradient (see fig. 1). According to the second law of thermodynamics, heat always flows in the direction of the lower temperature.thermal conductivity. For example, the Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting temperature, which can be measured by means of differential scanning calorimetry (DSC), plays an important role in the development of battery separators. If the separator melts at high temperatures and the electrodes short-circuit, this can lead to a thermal reaction and an increase in the battery's operating temperature. An increase in operating temperature can affect battery performance and life by accelerating chemical reactions within the battery and accelerating electrolyte Decomposition reactionA decomposition reaction is a thermally induced reaction of a chemical compound forming solid and/or gaseous products. decomposition.
Thermogravimetric analysis (TGA) is used to test the stability of plastics at increased temperatures in their operating range.
Dynamic mechanical analysis (DMA) can be employed to predict long-term performance at room temperature or increased temperatures.
Rheological studies help determine the ideal properties of plastics for use in batteries. By analyzing the flow behavior of materials, viscosity, elasticity and plasticity of plastics can be characterized. For example, viscosity is essential in the development of coatings for electrodes, as it affects how evenly the coating is applied and how well it adheres.
Battery Applications by NETZSCH Analyzing & Testing
With a comprehensive product portfolio of thermal analysis instruments and rheometers by NETZSCH Analyzing and Testing, we support you in determining and selecting the perfect materials for use in your battery. Our experts have decades of experience and will work with you to find the right solution for your individual application.