Analyze the Key Points of EV Battery Top Plate Covers Structure
Structural Parts: Key Materials for EV Power Batteries
Power battery precision structural parts include EV battery top plate covers, steel/aluminum casings, positive and negative soft connections, battery soft connections, etc. In a narrow sense, they mainly include cell shells and top covers. It has a direct impact on the safety, tightness and energy efficiency of lithium batteries.
According to different battery packaging technology routes, there are three main shapes: prismatic, cylindrical, and pouch cells. The corresponding structural parts are prismatic structural parts, cylindrical structural parts, and aluminum-plastic films. Overall, cylindrical and prismatic are collectively called hard shells, and their packaging structures are relatively similar, consisting of a shell and a cover. pouch cells is unique and is composed of aluminum-plastic film.
Process End: Precision Manufacturing
The main production processes of the ev battery top cover include stamping, welding, injection molding, etc. The production processes of the shell are mainly stamping and deep drawing. The main production processes of aluminum-plastic film include precision coating, lamination, etc.
In addition to essential technologies, many extension technologies have also been developed for structural parts, such as safety battery vents design, welding technology, etc., which are mainly used for the optimization and upgrading of cover structures. In addition, in order to meet the needs of large-scale precision manufacturing, the industry has generally introduced automation equipment, flexible production lines, etc.
Introduction to Structural Parts
Hardshells Continue to Reduce Costs and are Being Replaced by Domestic Products
The need for structural parts comes from battery packaging. The safety and service life of power batteries are affected by their packaging process. Different packaging technologies have various technical barriers. In addition to being able to withstand the physical impact of impact vibration and extrusion puncture, the packaging process design also needs to meet chemical performance requirements such as fire retardancy.
Hardshell Structural Parts: Caps and Battery Safety Vents are Keys
Hardshell structural parts include cylindrical and prismatic structural parts. Take a prismatic battery cover as an example, it is usually composed of a shell and a cover. Among them, the manufacturing process complexity of the cover is usually much higher than that of the casing.
EV Battery Top Plate Covers
The Main Functions of the Top Plate Covers
- Fixing/Sealing Function
The top cover and the aluminum shell are laser welded to wrap and fix the bare battery core and achieve sealing;
- Current Conduction Function (Pole)
In the battery, the top cover pole, adapter piece, and cell tab are welded and connected to ensure the conduction of the charging and discharging current of the cell. In the module, the top cover The poles and busbars are laser welded and bolted to form series/parallel connections;
- Pressure Relief Function (Battery Safety Vents)
When the battery has an abnormality and the internal air pressure increases to a specific value, the battery safety vents on the top cover will open to relieve the pressure and reduce the risk of explosion.
- Fuse protection function (Battery Flip Disc):
When the battery is abnormal, the internal pressure increases to a certain value, the flipping piece of the top cover lifts and contacts the negative riveting block, causing the positive and negative poles of the top cover to be directly short-circuited. At the same time, the aluminum connecting piece Fuse fuses to quickly cut off the current;
- Reduce Electrical Corrosion
The plastic on the positive electrode is made of conductive PPS to ensure a specific resistance between the positive electrode column and the top cover plate. Reduce the potential difference between the positive electrode column and the aluminum shell. Prevent the entire cover plate/aluminum shell from electrical corrosion.Thereby improve the product quality and longevity.
The Essential Components of the EV Battery Top Plate Covers
- Lithium Battery Ventings
Generally, the top cover of a lithium-ion phosphate system battery is designed with a single explosion-proof valve. And the opening pressure of the explosion-proof valve is generally 0.4~0.8MPa. When the internal pressure increases and exceeds the opening pressure of the battery safety vents, the ev battery ventings will rupture from the notch and open to relieve pressure;
- Flip plate
In addition to using an explosion-proof valve, the ternary system battery will also be superimposed on the SSD flip plate combination design. The ev battery vents opening pressure and SSD flipping pressure are generally 0.75~1.05MPa and 0.45~0.5MPa, respectively. When the internal pressure of the battery increases to the SSD flipping pressure, the flipping piece lifts up and quickly cuts off the current;
- Pole
It mainly plays the role of current conduction. Usually, the positive electrode uses an aluminum pole, and the negative electrode uses a copper-aluminum composite pole.
Standardization of Power Battery Size
Currently, there are many power battery sizes, shapes, capacities, and voltage specifications and models on the market. For vehicle companies, it increases the difficulty of matching and purchasing. For battery manufacturers, it hinders large-scale standardized production of power batteries and is not conducive to cost reduction of power batteries. 
About Hejustamping
Dongguan Heju Precision Electronic Technology Co., Ltd. is a professional precision stamping company with over 30yrs stamping experience. Specializing in the production of ev battey safety vents and top plate covers for new energy vehicles. It is one of the earliest companies in China to develop and produce ev battery vents. With many models and complete specifications. It has passed the three major certification systems: ISO9001, ISO14001, and IATF16949. We have continuously provided high-quality services to the top ten well-known domestic terminal customers with a daily output of millions to meet your production capacity needs.