Separator Design for Non-Aqueous Electrolyte Battery
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face the risk of electrical short circuits due to heat shrinkage of the separator in the width direction, leading to contact between positive and negative electrode plates, which existing solutions either require costly manufacturing processes or do not effectively prevent such contacts.
Innovation Solution
The electrode body design features a separator with thicker first and second ends that are folded back to prevent inward movement, ensuring the separator remains between the electrode plates, and these ends are either thermally shrunken or heat-welded to prevent further shrinkage, maintaining electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator is made wider than the electrode plates to prevent contact, then electrical insulation is improved, but the separator thermally shrinks in the width direction causing internal short circuit
Solution Approach 1:
The separator is divided into different regions with different thicknesses: a first region at the widthwise ends with a first thickness, and a second region in the intermediate portion with a second thickness. This segmentation allows the separator to maintain electrical insulation while managing thermal shrinkage behavior through localized thickness variations.
Solution Approach 2:
The separator exhibits non-uniform thickness distribution, with the first region at the widthwise ends having a greater thickness than the second region. This local quality variation ensures that the critical end portions maintain their dimensions during thermal shrinkage, preventing internal short circuits while preserving overall electrical insulation.
2Reliability
If insulating films with fine particles are attached to electrode plate ends to prevent short circuit, then electrical insulation is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts the insulating function from separate insulating films and integrates it directly into the separator structure itself. By making the separator ends thicker, the separator inherently provides electrical insulation without requiring additional insulating film layers, fine particles, or binder resins, thereby simplifying the manufacturing process.
Solution Approach 2:
The insulating function previously provided by separate insulating films is merged into the separator structure. The thicker first region of the separator simultaneously provides both mechanical separation and electrical insulation, eliminating the need for additional insulating components and reducing manufacturing complexity.
3Stability of the object's composition
If the separator ends are thermally shrunken beforehand to prevent shrinkage during battery operation, then dimensional stability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The separator undergoes preliminary thermal treatment during manufacturing to induce shrinkage in advance. This preliminary action ensures that the separator achieves its final dimensions before battery assembly, preventing further thermal shrinkage during battery operation and maintaining dimensional stability without requiring complex real-time control mechanisms.
Solution Approach 2:
The thermal history of the separator is changed during manufacturing by applying heat treatment. This parameter change (thermal exposure) permanently alters the separator's dimensional characteristics, causing it to shrink to its final stable dimensions before battery assembly, thereby preventing subsequent thermal shrinkage during operation.
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
This design effectively prevents electrical short circuits by keeping the separator in place between the positive and negative electrode plates, even during heat shrinkage, thus maintaining electrical insulation and preventing unwanted contacts.
Implementation Method 1
the first separator end being thermally shrunken by heating beforehand; and with respect to the width direction, the second separator end is located more interiorly than an other negative electrode end... the second separator end being thermally shrunken by heating beforehand
Implementation Method 2
the first separator end being heat-welded to a portion of the positive electrode plate which portion is opposed to the separator in its thickness direction; and with respect to the width direction, the second separator end is located more interiorly than an other negative electrode end... the second separator end being heat-welded to a portion of the negative electrode plate
Data Source
AI summary
In an electrode body for use in non-aqueous electrolyte secondary battery, a first end of a separator is located more interiorly than one positive electrode end of a positive electrode plate in a width direction, located more exteriorly than one end of a coated positive electrode portion of the positive electrode plate, and located more exteriorly than one end of a coated negative electrode portion of a negative electrode plate. The first end of the separator is thicker than an intermediate portion. A second end of the separator is located more interiorly than an other negative electrode end of the negative electrode plate in the width direction, located more exteriorly than the other end of the coated positive electrode portion of the positive electrode plate, and located more exteriorly than an other end of the coated negative electrode portion of the negative electrode plate. The second end of the separator is thicker than the intermediate portion.