Battery Case Insulating Coating Layout for Weld-Safe Isolation
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Solution Overview
Problem
Lithium-ion batteries face insulation failures due to damage from external substances and particles during production and operation, affecting safety and reliability, as existing insulation methods are prone to scratches and damage.
Innovation Solution
A secondary battery design featuring a case with a coated region and a non-coated region on its outer surface, where the coated region is treated with an insulating coating comprising 80-97 wt% insulating film-forming resin, 3-12 wt% auxiliary agents, and 0-8 wt% pigment, ensuring strong adhesion and insulation performance while avoiding high-temperature welding effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating film is stuck to the surface during battery assembly, then insulation requirements are implemented, but the insulating film is easily scratched or damaged by external substances and hard particles, resulting in insulation failure
Solution Approach 1:
The patent applies a composite coating system consisting of a primer layer and a topcoat layer. The primer layer provides adhesion to the metal case surface, while the topcoat layer provides enhanced mechanical protection and insulation. This composite structure combines the advantages of different materials to achieve both strong adhesion and high scratch resistance, resolving the contradiction between insulation performance and scratch resistance.
Solution Approach 2:
The patent uses a multi-layer coating film structure that flexes with the battery case during thermal expansion and contraction. The coating films are designed with appropriate thickness and elasticity to accommodate case deformation without cracking or delaminating, maintaining insulation performance while providing mechanical protection against scratches and particles.
2Reliability
If the entire outer surface is coated with insulating coating, then insulation performance is improved, but the coating may be affected by high-temperature welding processes
Solution Approach 1:
The patent applies insulating coating only to specific regions of the battery case where insulation is required, rather than coating the entire surface. The coated regions are strategically selected to provide necessary insulation while leaving uncoated areas that can withstand welding heat without degradation. This localized coating approach maintains insulation integrity in critical areas while avoiding welding heat damage in other areas.
Solution Approach 2:
The patent divides the battery case surface into coated regions and uncoated regions based on functional requirements. The coated regions provide insulation where needed, while uncoated regions remain exposed to handle welding operations. This segmentation allows the insulation system to protect against electrical hazards without being compromised by high-temperature welding processes.
3Reliability
If a thick insulating coating is applied, then insulation performance and protection are improved, but the coating thickness and material consumption increase
Solution Approach 1:
The patent uses a multi-layer composite coating structure where each layer has optimized thickness and specific function. The primer layer is thin but provides strong adhesion, while the topcoat layer is also thin but provides enhanced mechanical and electrical insulation properties. This composite approach achieves high insulation durability with minimal total material consumption by leveraging the synergistic effects of different materials in each layer.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides long-term safety and reliability by maintaining the insulation integrity of the battery case, preventing electrochemical corrosion and external short circuits, and ensuring the stability of the insulating coating during production and use.
Implementation Method 1
ensuring strong adhesion and insulation performance
Data Source
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AI summary
Embodiments of the present application provide a case, a secondary battery, a battery pack, a vehicle, and a method for manufacturing a secondary battery. The case includes a bottom wall and a side wall, the bottom wall and the side wall defining an accommodating cavity with an opening at one end for accommodating an electrode assembly of the secondary battery; wherein, an outer surface of the side wall includes a coated region coated with an insulating coating, and the coated region extends, in a height direction of the side wall, from a side of the side wall that is close to the bottom wall to a position near an edge of a side of the side wall that is close to the opening, so as to reserve a non-coated region with a preset height on the outer surface of the side wall that is near an edge of the opening. During the production and use of the case, the insulating coating can be well bonded to the coated region for a long term, achieving a better long-term safety and reliability of the case.