Upper Insulating Plate Structure for Cylindrical Cell Gas Discharge
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Solution Overview
Problem
Secondary batteries face issues with internal pressure buildup due to gas generation, leading to potential short circuits and reduced lifespan, especially during the assembly process when conductive impurities are introduced into the main layer with pores or the cylindrical can.
Innovation Solution
A secondary battery design featuring an upper insulating plate with a main layer having a plurality of pores and an auxiliary layer bonded to it, where the auxiliary layer is partially melted by the electrolyte, preventing short circuits and facilitating gas discharge when internal pressure rises, and the auxiliary layer is made of materials like nylon, polystyrene, or oriented polystyrene to cover the main layer's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a main layer with pores is used to allow gas discharge, then gas can be easily discharged when internal pressure rises, but conductive impurities may be introduced into the pores or cylindrical can during assembly
Solution Approach 1:
An auxiliary insulating layer is introduced as an intermediary between the external environment and the main layer with pores. This auxiliary layer prevents conductive impurities from entering the pores or cylindrical can while still allowing gas to pass through, thus resolving the contradiction between gas discharge capability and short circuit prevention
Solution Approach 2:
The insulating plate is constructed as a composite structure combining a main layer with pores (for gas discharge) and an auxiliary insulating layer (for impurity prevention). This composite design integrates the benefits of both layers while mitigating their individual drawbacks
2Ease of manufacture
If the auxiliary layer is made thin to maintain flexibility, then it bonds well to the main layer, but it may not provide sufficient protection against conductive impurities
Solution Approach 1:
The thickness of the auxiliary layer is optimized within a specific range (5-25 μm) to balance bonding performance and protective function. This parameter optimization ensures sufficient protection against conductive impurities while maintaining flexibility and effective bonding to the main 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 design effectively prevents short circuits and extends the battery's lifespan by allowing easy discharge of gas and preventing the introduction of conductive impurities, ensuring reliable operation and improved energy storage density.
Implementation Method 1
an auxiliary layer adhered to at least one surface of the main layer and partially melted by the electrolyte
Implementation Method 2
The electrolyte may include LiPF6 dissolved in a solvent having EC, EMC, DEC, PC, and DMC mixed in equal volume ratios
Implementation Method 3
The auxiliary layer may be bonded to at least one of the upper and lower surfaces of the main layer by an acrylic adhesive
Data Source
AI summary
A secondary battery includes: a cylindrical can; an electrode assembly in the cylindrical can with an electrolyte, the electrode assembly including a cathode and an anode; a cap assembly coupled to a top of the cylindrical can; and a plate-shaped upper insulating plate between the electrode assembly and the cap assembly. The upper insulating plate includes: a main layer having a plurality of pores extending between an upper surface and a lower surface thereof; and an auxiliary layer adhered to at least one surface of the main layer and partially melted by the electrolyte.