Secondary Battery Case with Liquid Insulation for Nail Test Safety
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Solution Overview
Problem
Secondary batteries experience short circuits and ignition during nail tests due to the penetration of a nail through the pouch, causing electrical contact between the positive and negative electrodes.
Innovation Solution
A secondary battery design incorporating a case with an external polyethylene terephthalate layer, an internal polypropylene layer, and a short-circuit prevention layer of insulation oil, along with an aluminum layer for durability and adhesion, to prevent electrical contact between the electrodes during a nail test.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pouch structure without liquid-phase short-circuit prevention layer is used, then the device complexity is reduced, but short circuit occurs between positive and negative electrodes during nail test
Solution Approach 1:
The patent introduces a liquid-phase short-circuit prevention layer as an intermediary substance between the positive and negative electrodes. This layer comprises insulating oil and optionally thickening agents, forming a physical barrier that prevents direct contact between electrodes during nail penetration tests while maintaining battery functionality.
Solution Approach 2:
The patent utilizes the hydraulic properties of liquid insulating oil to create a flexible, self-adjusting short-circuit prevention mechanism. The liquid layer can flow and redistribute in response to external forces such as nail penetration, maintaining its protective function while adapting to structural changes in the battery during abuse conditions.
2Reliability
If a multi-layer case structure with short-circuit prevention layer is implemented, then safety during nail test is improved, but manufacturing complexity increases
Solution Approach 1:
The patent controls the viscosity and composition parameters of the liquid short-circuit prevention layer to optimize both safety performance and manufacturability. By adjusting the ratio of insulating oil to thickening agents and selecting appropriate viscosity ranges, the invention achieves effective short-circuit prevention while maintaining ease of filling and assembly during manufacturing.
3Reliability
If insulation oil is used as short-circuit prevention layer, then electrical insulation between electrodes is improved, but oil leakage risk increases
Solution Approach 1:
The patent creates a composite system combining insulating oil with thickening agents and encapsulating structures. The thickening agents increase viscosity to reduce leakage tendency, while the outer pouch structure provides mechanical containment. This composite approach maintains the electrical insulation properties of oil while mitigating its leakage risks through material modification and structural integration.
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 effectively prevents short circuits and minimizes the risk of ignition during nail tests by ensuring the insulation oil flows and isolates the electrodes, enhancing safety and durability.
Implementation Method 1
ensuring the insulation oil flows and isolates the electrodes
Implementation Method 2
a short-circuit prevention layer provided in a liquid phase between the external layer and the internal layer... an oil layer containing an oil... The oil may include an insulation oil
Data Source
AI summary
The present invention relates to a secondary battery that is capable of preventing short circuit from occurring when a nail test is performed.Also, the secondary battery includes a case accommodating an electrolyte and an electrode assembly therein, and the case includes an external layer exposed to the outside, an internal layer disposed in the case, and a short-circuit prevention layer provided in a liquid phase between the external layer and the internal layer.