Battery Pack Frame and Film Composite Case
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Solution Overview
Problem
Existing battery pack designs face challenges in achieving slimness and lightweight while ensuring safety and strength, particularly with the assembly type outer case made of steel, which is heavy, prone to short circuits, and has a complex manufacturing process.
Innovation Solution
A battery pack design combining a hard frame with a thin, flexible film to form a case structure, where the frame is made of plastic or steel and the film is made of polycarbonate, polyethylene, or polyvinylchloride, allowing for a thinner and lighter battery pack with improved safety and strength, and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an assembly type outer case made of steel is used, then safety and strength are improved, but weight increases and slimness is compromised
Solution Approach 1:
The patent uses a composite structure combining a steel frame (for strength) with a plastic outer case (for weight reduction). The frame provides the necessary mechanical strength and safety, while the plastic casing reduces overall weight and enables slimness. This composite approach resolves the contradiction between strength and weight by distributing functions across different materials.
2Strength
If an assembly type outer case made of steel is used, then safety and strength are improved, but the battery pack thickness cannot be reduced below a certain limit
Solution Approach 1:
The combination of steel frame and plastic case allows the outer case to be made thinner than conventional steel cases while maintaining strength. The steel frame provides structural integrity, enabling the plastic outer case to be reduced in thickness below the conventional 0.4 mm limit, thus achieving slimness while preserving safety and strength.
3Strength
If an assembly type outer case made of steel is used, then safety and strength are improved, but the manufacturing process becomes complicated
Solution Approach 1:
The battery pack case is segmented into two separate components: a steel frame and a plastic outer case. This segmentation allows each component to be manufactured independently using optimized processes for each material, then assembled together. This reduces manufacturing complexity compared to attempting to manufacture a complete steel case with all required features in a single process.
4Strength
If an assembly type outer case made of steel is used, then safety and strength are improved, but the risk of short circuit increases
Solution Approach 1:
The plastic outer case acts as an insulating layer between the steel frame and the battery cell, preventing direct contact that could cause short circuits. This composite structure maintains the electrical insulation benefits of plastic while retaining the mechanical strength of steel, thereby improving reliability without sacrificing strength.
Data Source
AI summary
A secondary battery comprises a case which includes a frame and a film covering an opening of the frame to form a space inside the frame, and a unit battery cell placed in the space inside the case. The frame has a higher hardness than the film. The frame can be formed with plastic or steel, and the film can be formed of polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), or polyvinylchloride (PVC). The thickness of the film is maintained within 0.03 to 0.3 mm, and a mark can be formed on the film. A contact terminal is formed on the case, and the contact terminal is electrically connected to a unit battery cell so as to connect the battery pack to an applied device. The frame can be formed in a divided manner, and the film can be bound to one surface placed adjacent to the opening of the frame, or on the latter surface and an outer circumferential surface of the frame. The frame can be formed as one body, and the film can be bound to a surface placed adjacent to the frame.