Against the backdrop of global energy transition and rapid development of new energy vehicles, the application of lithium batteries as core energy storage technology is becoming increasingly widespread. Especially in hard pack (or soft pack) PACK systems, square batteries have become one of the mainstream. Their high energy density, long cycle life, and high safety have made them widely used in fields such as electric vehicles (EVs), energy storage, and consumer electronics. However, with the increasing demand for applications, lithium batteries also face many technical challenges in production, use, and maintenance, especially in terms of solder joint protection and shell sealing.
Classification and challenges of lithium batteries
Lithium batteries can be mainly divided into the following types:
Cylindrical batteries: commonly found in consumer electronics and some small and medium-sized power tools. Its structure is simple, the production process is mature, and it can provide good stability.
Square battery: commonly used in electric vehicles (EVs) and energy storage devices. The advantages of square batteries are high energy density, customizable volume, and compact structure, making them suitable for large-scale battery pack applications.
Soft pack battery: It has a wide range of applications in the field of electric vehicles, especially in some high-end models. It adopts flexible packaging, which can improve the design flexibility of battery packs to a certain extent, reduce volume and weight.
Although square batteries perform well in many applications, they also face some technical challenges in practical use, mainly reflected in solder joint protection, aluminum shell packaging, and issues such as high temperature and vibration that the battery may encounter during use. If these challenges are not properly addressed, they may affect the safety, reliability, and lifespan of batteries.
Challenge: Protection of solder joints in square batteries
In the PACK design of square batteries, solder joints are important parts for connecting the various units inside the battery pack. These solder joints carry the current transmission of the battery. If the solder joints are not effectively protected, they will face the following problems:
Fatigue damage of solder joints: During battery use, the battery undergoes changes in thermal expansion and contraction as the charge discharge cycle progresses. This thermal cycle can cause fatigue of the solder joint material, leading to solder joint fracture or failure, and even causing battery short circuits.
Environmental corrosion: Environmental factors such as moisture and salt spray may accelerate the oxidation corrosion of solder joints, seriously affecting the conductivity of solder joints and thus affecting the working efficiency of batteries.
Safety hazards: Insufficient protection of solder joints may lead to battery short circuits or electrical failures, and even serious safety issues such as fires or explosions.
To address these issues, it is recommended to use EP 2025 FR adhesive, which has excellent properties such as rapid curing (5 minutes), certain toughness, and resistance to yellowing. EP 2025 FR not only effectively protects solder joints and extends their service life, but also prevents battery failures caused by solder joint aging.
Challenge: Sealing problem of blue film backing adhesive for square battery aluminum shell
The outer shell of square batteries is usually made of aluminum material, which not only protects the internal components of the battery, but also improves the mechanical strength of the battery. However, aluminum shell batteries also face sealing issues, especially in high temperature and high humidity environments. If the connection between the aluminum shell and the interior of the battery is not effectively sealed, it may lead to the following problems:
Moisture intrusion: Moisture may enter the interior of the battery, causing internal components to become damp, leading to short circuits or decreased battery performance.
Gas leakage: During the charging and discharging process, gas expansion may occur inside the battery, and poorly sealed batteries may cause gas leakage, thereby affecting the safety of the battery.
Mechanical damage: The aluminum shell may deform due to external vibrations or impacts, affecting the structural stability and safety of the battery.
To effectively address these issues, using EP 6212-2-4 adhesive material is a very good choice. This product has good toughness (Shore D 60) and supports both heating curing and room temperature curing, which can be selected according to actual application needs. EP 6212-2-4 not only has excellent sealing performance, but also maintains stability under extreme conditions such as high temperature and vibration, ensuring effective protection between the battery casing and internal components.
Tag: Square Battery Solder Joint Protection · Aluminum Shell Blue Film Back Adhesive
