Design techniques for the fixation method of lithium battery packs

As a core component of energy storage, the lithium battery pack's fixation method directly affects the safety, reliability and service life of the equipment. Fixed design needs to comprehensively consider vibration suppression, thermal management, modular assembly and long-term stability. The following is an analysis from the core design principles, technical key points and typical application scenarios.

First, core design principles

Vibration and shock suppression

Lithium battery packs may be subject to high-frequency vibrations (such as bumpy road conditions of electric vehicles) or instantaneous impacts (such as the fall of unmanned aerial vehicles) during transportation or operation. The fixed structure needs to absorb energy through shock-absorbing materials or elastic connectors to prevent relative displacement between battery cells, which may cause short circuits or structural fatigue.

Thermal expansion adaptability

During the charging and discharging process of the battery pack, temperature changes may cause the casing to expand and contract due to temperature changes. The fixing method should reserve a certain deformation space to avoid material cracking or connection failure caused by stress concentration.

Modularity and maintainability

The fixed structure should support quick disassembly and assembly to facilitate the replacement or maintenance of the battery pack. For example, when using snap-on or bolt fixation, it is necessary to ensure that the operating tools are easily accessible and the disassembly and assembly process is simple.

Lightweight and space utilization

In portable devices (such as unmanned aerial vehicles), fixed structures need to minimize weight and volume occupation as much as possible while ensuring structural strength. For example, weight reduction can be achieved by optimizing the shape of the support or adopting a hollow design.

Second, classification of fixed methods and key points of design

Mechanical fixation method

Bolt fixation

Design points: Bolts should be evenly distributed to disperse stress and prevent excessive local pressure from causing deformation of the casing. For example, reinforcing ribs are set at the four corners of the square battery pack and fixed with bolts.

Applicable scenarios: Heavy equipment (such as energy storage power stations) or scenarios with high requirements for fixed strength.

Fixed by clips/slots

Design highlights: The snap fastener should have elastic recovery capability to ensure that it can maintain its fastening force after multiple disassemblies and reassemblies. For example, dovetail grooves or raised structures are designed on the plastic shell to achieve self-locking.

Applicable scenarios: Consumer electronic devices or scenarios that require frequent maintenance.

Bracket/frame fixed

Design points: The bracket needs to fit the shape of the battery pack to avoid vibration transmission caused by gaps. For example, in cylindrical battery packs, honeycomb-shaped brackets are used to fix individual battery cells.

Applicable scenarios: Modular battery packs or scenarios requiring high-precision positioning.

2. Adhesive fixation method

Structural adhesive bonding

Design key points: The adhesive layer should be uniform and the thickness controllable to avoid bonding failure due to insufficient adhesive amount. For instance, thermal conductive structural adhesive is applied to the bottom of the battery pack to achieve both fixation and heat dissipation functions simultaneously.

Applicable scenarios: Scenarios with strict space requirements (such as mobile phone batteries) or those that need shock absorption.

Double-sided tape fixation

Design points: The tape should have high adhesion and heat resistance to prevent delamination in high-temperature environments. For example, VHB (Very High Bond) tape is used to fix wiring harnesses or sensors in the battery pack of electric vehicles.

Applicable scenarios: Temporary fixation or connection of lightweight components.

3. Mixed fixation method

Mechanical fixation + bonding

Design highlights: Mechanical fixation provides the main strength, while bonding fills the gap and suppresses vibration. For example, bolt fixing points are set at the edge of the battery pack, and the middle area is filled with structural adhesive.

Applicable scenarios: High-vibration environments (such as construction machinery) or scenarios with extremely high reliability requirements.

Elastic connection + rigid support

Design highlights: Elastic connectors (such as rubber pads) absorb vibrations, and rigid brackets provide positioning. For example, silicone pads are used in the battery pack of unmanned aerial vehicles to buffer vibrations, and the overall structure is fixed by aluminum alloy brackets at the same time.

Applicable scenarios: Scenarios where shock absorption and positioning accuracy need to be taken into account.

Third, typical application scenarios and design optimization

Electric vehicle battery pack

Design difficulty: It needs to withstand the vibration and collision impact of complex road conditions.

Optimization plan: A combination of bolt fixation and elastic buffer pads is adopted. The bracket is designed in a honeycomb shape to disperse stress, while reserving a thermal expansion gap.

Unmanned aerial vehicle battery pack

Design difficulty: It needs to be lightweight and resistant to high G-value impact.

Optimization plan: Carbon fiber brackets and structural adhesives are adopted for fixation. The battery pack and the unmanned aerial vehicle body are connected through elastic clips to avoid rigid collisions.

Battery cabinet for energy storage power station

Design difficulty: It needs to be modularly assembled and easy to maintain.

Optimization plan: The battery module is connected to the cabinet through a quick-plug interface, and the bracket is designed to be adjustable to accommodate battery packs of different sizes.

Fourth, key design verification and testing

Vibration test

Simulate the vibration frequency and amplitude under actual working conditions to verify whether the fixed structure has loosened or deformed. For example, in the test of battery packs for electric vehicles, it is necessary to pass the GB/T 31467.3 vibration standard.

Impact test

Simulate drop or collision scenarios to verify whether the fixed structure remains intact. For example, in the battery pack test of unmanned aerial vehicles, a drop test from a height of 1.5 meters is required.

Thermal cycling test

Cyclic tests were conducted within the temperature range of -40℃ to 85℃ to verify whether the fixed structure failed due to thermal expansion. For instance, in the battery cabinet testing of energy storage power stations, 100 thermal cycle tests are required.