Lower Plastic Assembly Structure to Prevent Battery Warping

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Solution Overview

Problem

The lower plastic member in secondary batteries is prone to warping during assembly, especially during welding of the electrode post, leading to unevenness and potential structural issues.

Innovation Solution

A lower plastic assembly with a first and second lower plastic member, each having specific deformation portions and dimensions, stacked alongside an upper cover to provide insulation and structural support, with explosion-proof grids and gas channels to manage pressure and prevent warping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the lower plastic member is made of insulating plastic material, then electrical insulation is improved, but the member becomes prone to warping under compression during assembly and welding

Engineering Contradiction:
Improveelectrical insulationVSAvoiddimensional stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The lower plastic member incorporates a deformation portion with different structural properties (reduced rigidity, increased flexibility) compared to the main body. This local quality change allows the deformation portion to absorb compression stress during assembly and welding through elastic deformation, preventing warping of the entire member while maintaining the insulating properties of the main body.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the structural parameters of the lower plastic member by introducing a deformation portion with specific geometric characteristics (reduced thickness, altered cross-section). This parameter change modifies the mechanical properties locally, enabling the member to withstand compression forces without warping while preserving its electrical insulation function.

Inventive Principle:
Principle #35Parameter changes

2Force

If the lower plastic member is compressed excessively during welding of the electrode post, then the assembly force is improved, but the member warps causing unevenness of the secondary battery

Engineering Contradiction:
Improveassembly forceVSAvoidflatness uniformity
Core Design Contradiction:
ForceVSManufacturing precision

Solution Approach 1:

The deformation portion is pre-designed with specific geometric characteristics that enable it to undergo controlled elastic deformation before the actual welding process. This preliminary structural preparation allows the member to absorb compression forces during assembly and welding, maintaining flatness uniformity while providing sufficient assembly force.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The deformation portion acts as a built-in cushioning element that absorbs excess compression stress during assembly and welding operations. This beforehand cushioning prevents the transmission of damaging forces to the main body of the lower plastic member, thereby preventing warping and maintaining manufacturing precision.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If the lower plastic member structure is simplified, then the manufacturing cost is reduced, but the member becomes more prone to deformation under load

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidresistance to deformation
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The lower plastic member is segmented into functionally distinct portions: a main body providing structural support and insulation, and a deformation portion providing stress absorption. This segmentation allows each portion to be optimized for its specific function while maintaining overall manufacturing simplicity through integral forming where possible.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lower plastic member employs composite structural design combining rigid and flexible regions within the same component. The deformation portion has modified structural characteristics that provide flexibility and stress absorption, while the main body maintains rigidity for structural support, creating a composite structure that balances strength and deformation resistance.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4415114B1Lower plastic assembly, end cover assembly, energy-storage apparatus, and electronic device
Publication Date: 2025.10.08 HITHIUM TECH HK LTD
  • EP4415114B1 patent drawingFigure 1~2
  • EP4415114B1 patent drawingFigure 3
  • EP4415114B1 patent drawingFigure 4

AI summary

A lower plastic assembly, an end cover assembly, an energy-storage apparatus, and an electronic device are provided in the disclosure. The lower plastic assembly includes a first lower plastic member. The first lower plastic member comprises a first-lower-plastic-member body. The first-lower-plastic-member body has a first top surface and a first bottom surface opposite the first top surface, and further comprises a first part, a second part, and a first deformation portion. The first deformation portion is located between the first part and the second part in a length direction of the first-lower-plastic-member body. A ratio of a depth h1 of the first deformation portion to a height h2 of the first part ranges from 0.05 to 0.42 in a thickness direction of the first-lower-plastic-member body. A ratio of the depth h1 of the first deformation portion to a height h3 of the second part ranges from 0.16 to 0.6.