Insulation Materials in Ternary Lithium Batteries and LiFePO4 Batteries: A Safety Perspective

Lithium iron phosphate (LiFePO4) and ternary lithium batteries are two commonly used battery types in the new energy vehicle industry. These batteries utilize different material solutions to enhance fire insulation and thermal safety protection. 

Thermal Runaway Risk:

Ternary Lithium Batteries: Due to their chemical composition and higher energy density, ternary lithium batteries pose an increased risk of thermal runaway under abnormal conditions such as overcharging, over-discharging, or high temperatures. This can lead to an elevated risk of fire incidents.

LiFePO4 Batteries: LiFePO4 batteries are comparatively safer, displaying robust tolerance towards high temperatures, overcharging, and over-discharging. Consequently, the demand for fire protection and thermal insulation is relatively lower for LiFePO4 batteries.

Insulation Materials:

Ternary Lithium Batteries: To mitigate the potential risks associated with thermal runaway, ternary lithium batteries typically require higher-grade insulation materials during their design and manufacturing processes. These materials may include high-temperature fire-resistant insulation, insulation tape, insulation gaskets, and similar components.

LiFePO4 Batteries: Due to their inherent safety and high temperature tolerance, LiFePO4 batteries generally require standard insulation materials and designs to fulfill fire protection and thermal insulation requirements.

Fire Protection and Heat Insulation Solutions for LiFePO4 Batteries:

Microporous Polypropylene (MPP): Microporous polypropylene is widely employed as a fireproof and heat-insulating layer in LiFePO4 batteries. This material exhibits excellent thermal and electrical insulation properties, reducing heat loss and enhancing the battery's thermal efficiency. Key properties of MPP include:

Exceptional isolation performance: The microscopic pore structure of MPP effectively isolates the positive and negative electrodes within the battery module, preventing electrolyte penetration. It can be used as a battery separator, ensuring the safe operation of the battery system by avoiding short circuits and current leakage.

Ceramic Silicone Rubber: Ceramic silicone rubber is commonly utilized as a safety protective layer in LiFePO4 batteries. To further enhance fire resistance, a layer of fiberglass is often applied on top of the ceramicized silicone rubber. In the event of a fire, the ceramic silicone rubber transforms into a hard ceramic block, preventing fire spread. It effectively isolates and withstands the high temperatures generated by the battery, protecting the battery system from heat damage.

Silicon Foam: Silicon foam, a flexible and soft material, is frequently used to fill gaps between LiFePO4 battery modules. It offers excellent thermal insulation and buffering effects, reducing heat transfer and vibrations while improving the battery's thermal management performance. Key features of silicon foam include:

Superior thermal insulation performance: Silicon foam possesses low thermal conductivity, effectively isolating heat conduction within the battery module and minimizing heat loss. This enhances the battery system's energy efficiency and extends the battery's cycle life.

High-temperature resistance: Silicon foam maintains its structural and performance stability in high-temperature environments, which is crucial for battery systems. It effectively isolates and withstands the impact of high temperatures generated by the battery.

Fire and Heat Insulation Solutions for Ternary Lithium Batteries:

Aerogel: Aerogel, a highly porous material with exceptional thermal insulation properties, is widely used as the thermal insulation layer in ternary lithium batteries. Key features of aerogel include:

Low thermal conductivity: Aerogel exhibits an extremely low thermal conductivity, effectively isolating heat conduction within the battery and minimizing heat loss. This improves the battery's thermal management and mitigates the risk of overheating.

High porosity: The highly open pore structure of aerogel provides a larger surface area, enhancing insulation and preventing heat transfer and current leakage between internal battery components. This contributes to improved battery safety.

Lightweight and flexible: Aerogel is lightweight and can be molded to fit various battery module shapes and sizes without adding significant weight.

Mica Board: Mica board, known for its excellent high-temperature resistance, is frequently used as a thermal isolation gasket between ternary lithium battery modules or cells. It prevents heat transfer and reduces the risk of short circuits. Key properties of mica board include:

Excellent insulating properties: Mica sheets exhibit outstanding insulation performance.

High-temperature resistance: Mica boards maintain stability in high-temperature environments, ensuring durability within new energy vehicle batteries that generate high temperatures during operation. The mica board withstands the elevated temperatures within the battery module, protecting surrounding components from heat-related damage.

In conclusion, lithium iron phosphate batteries and ternary lithium batteries employ different material solutions for fire protection and thermal insulation safety measures. LiFePO4 batteries often utilize microporous polypropylene materials,