Overview of lithium battery pack and frame

Lithium battery pack mainly consists of a load frame (lower frame, upper frame), lithium battery, high-voltage connection components (such as high-voltage connectors), low-voltage connection components (such as low-voltage connectors), etc.

The lithium battery frame not only serves as a carrier for various components, but also acts as a "bridge" connecting the entire vehicle. The lithium battery is assembled on the vehicle through the lithium battery frame mounting structure.

In order to facilitate installation and maintenance, the load-bearing frame is generally divided into an upper frame and a lower frame. The lower frame mainly carries components and bears more weight of the battery system; the upper frame generally plays a protective role and has a smaller load-bearing requirement;

Lower frame design

As the main load-bearing component of the battery system, the lower frame is relatively more complex to design. There are many considerations in the design process, mainly mechanical strength, sealing design, corrosion resistance, lightweight, etc. At present, the lower frame processes used in battery systems include sheet metal processing, cold stamping, extrusion molding, die casting, etc.

(1) Design based on vehicle envelope and lithium battery process

Different lithium battery types and processes are suitable for different frame design schemes.

Battery arrangement is carried out according to the selected battery type and its process. The arrangement scheme of the battery in the frame is called grouping technology. The pros and cons of the grouping scheme and whether the frame design meets the standards are important indicators. The grouping efficiency is the proportion of effective weight and effective space of the battery. The higher the effective proportion, the higher the grouping efficiency.

Battery frame design needs to consider the arrangement, fixing and thermal management of the battery in the frame.

prismatic batteries are mainly arranged vertically along the height

There are two main ways of fixing: bracket fixing, which is the traditional module solution, and bracket-free fixing, such as the CTP (Cell to Pack) solution, in which the battery cell is directly fixed to the frame with glue.

(2) Design based on power and energy density

Battery layout is carried out according to the power and voltage platform required by the vehicle. In this process, the size decomposition from envelope to battery can be preliminarily completed. According to the battery type and the decomposed battery size, the battery energy density, volume density, etc. can be estimated, and the selection and layout plan can be checked again to confirm whether this layout plan meets the current battery technology level of the industry.

Different battery systems have different battery voltage platforms, and the number of batteries required to be grouped in the system will also be different.

Upper frame design

The upper frame mainly cooperates with the lower frame to form a closed space to protect the internal components of the frame. The selection of the upper frame material mainly considers environmental adaptability, such as high temperature resistance and corrosion resistance; and has a certain strength to meet the structural strength requirements of the battery system. Currently, sheet metal materials and composite materials are mainly used.

With the promotion and application of the CTC solution, the upper frame will also be integrated into the chassis of the vehicle.

Other auxiliary designs

(1) Sealing design

The connection between the upper and lower frames needs to be sealed to achieve waterproof and dustproof functions.

(2) Air pressure balance design

There is a pressure difference between the inside and outside of the sealed frame, which is affected by temperature, altitude, etc. Excessive pressure difference will cause additional force on the frame, affect the frame structure, and even cause the frame to explode. Devices such as air pressure balance valves or breathable valves are often used to balance the internal and external pressure differences.

Another function of the air pressure balance design is to provide timely air release.

(3) Thermal management design

(4) Safety design

The frame design also needs to consider corresponding safety protection designs, such as electric shock protection design, extrusion protection, collision protection, thermal runaway protection design, etc.

(5) High and low pressure connection design

Bosa Energy

Bosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.

We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.

We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.

For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.

l Customized and Flexible

l High Delivery capacity

l Wide Applications

l Rich experience on Lithium battery pack