11.03.2025 by Aileen Sammler
Understanding the Role of Tar Materials in Anode Production by Means of NETZSCH Analysis Instruments
Tar plays a key role in the production of high-performance battery grade graphite anode materials. During PyrolysisPyrolysis is the thermal decomposition of organic compounds in an inert atmosphere.pyrolysis at elevated temperatures, tar carbonizes and helps form the anode particles. The softening point of the tar determines the temperature range at which the material will sufficiently liquefy to ensure homogeneous distribution in the composite.
The Importance of Tar in Graphite Anode Manufacturing
Tar plays a key role in the production of high-performance battery grade graphite anode materials. During PyrolysisPyrolysis is the thermal decomposition of organic compounds in an inert atmosphere.pyrolysis at elevated temperatures, tar carbonizes and helps form the anode particles. The softening point of the tar determines the temperature range at which the material will sufficiently liquefy to ensure homogeneous distribution in the composite. A higher softening point results in a more uniform coating, which is critical for anode performance. After thermal treatment, the carbonaceous residue remains structurally stable and retains its essential thermal and chemical resistance, a key factor in high-temperature applications.
NETZSCH’s Thermal Analysis methods such as Thermogravimetry (TG or thermogravimetric analysis, TGA) and Differential Scanning Calorimetry (DSC) can be used to assess the suitability of different tar types for anode production.
Experimental Approach: Thermal Analysis of Tar Materials
Four different types of tar were analyzed using the NETZSCH TG 309 Libra® for thermogravimetric measurements and the NETZSCH DSC 300 Caliris® for Phase TransitionsThe term phase transition (or phase change) is most commonly used to describe transitions between the solid, liquid and gaseous states.phase transition and softening point determination. The TGA experiments were performed under inert conditions up to 900°C and then in an oxidative atmosphere up to 1100°C. DSC measurements were performed to evaluate the 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 temperatures and other caloric effects of the tar samples.
Key Findings from the Analysis
- Thermogravimetric Analysis (TGA):
- The PyrolysisPyrolysis is the thermal decomposition of organic compounds in an inert atmosphere.pyrolysis process of the tar samples showed mass losses ranging from 47.5% to 65.5%, indicating varying levels of organic content.
- The transition to an oxidizing atmosphere initiated carbon combustion, with the carbon content of the samples varying between 34.4% and 52.4%.
- The residual Ash ContentThe ash is a measure of the mineral oxide content on a weight basis. Thermogravimetric analysis (TGA) in an oxidative atmosphere is a well-proven method to determine the inorganic residue, commonly referred to ash, in organic materials such as polymers, rubbers, etc. Therefore, the TGA measurement will identify if a material is filled and calculates the total filler content.ash content showed little variation among the samples.
- Sample A had the highest 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, while sample B had the lowest.
Key Findings from the Analysis
2. Differential Scanning Calorimetry (DSC):
- EndothermicA sample transition or a reaction is endothermic if heat is needed for the conversion.Endothermic peaks were observed during the first heating cycle for samples B, C, and D, while sample A showed an ExothermicA sample transition or a reaction is exothermic if heat is generated.exothermic response.
- These EndothermicA sample transition or a reaction is endothermic if heat is needed for the conversion.endothermic effects are due to RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation and provide insight into the thermal history of the material.
- The 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 temperatures varied among the samples, with sample A having the highest 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 at 147°C.
Implications for Anode Material Selection
The combination of TGA and DSC analysis provides a comprehensive evaluation of tar materials, allowing manufacturers to determine their 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, carbon yield, and 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 behavior. This information is essential for selecting the most appropriate raw materials, optimizing formulations, and ensuring consistency in anode production. By carefully evaluating tar properties, manufacturers can improve battery efficiency and longevity, leading to improved performance in high-temperature applications.
Watch also our webinar “Introduction to Battery Testing by Thermal Analysis”:
Learn more about the NETZSCH DSC 300 Caliris® and TG 309 Libra®
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