Asymmetric Separator Bonding for Wound Battery Cores
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Solution Overview
Problem
Conventional energy storage devices with wound electrode assemblies face performance degradation due to difficulty in securely bonding separators with heat-resistant coatings, leading to gaps between electrodes during winding, which affects device performance, especially in high-temperature environments.
Innovation Solution
The use of separators with distinct thermal bonding properties, where one surface has superior bonding properties and the other surface has poor thermal bonding properties, allowing for secure bonding to a core and each other, preventing electrode gaps and maintaining insulation in high-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If separators with heat-resistant coated layers are used to maintain insulation in high-temperature environments, then thermal stability is improved, but thermal bonding properties deteriorate making it difficult to securely bond separators to the core
Solution Approach 1:
The separator is divided into two distinct surfaces: a first surface with poor thermal bonding properties (heat-resistant coated layer facing the core) and a second surface with good thermal bonding properties (heat-resistant coated layer facing the electrode). This segmentation allows each surface to perform its specialized function independently.
Solution Approach 2:
Different surfaces of the separator are given different thermal bonding properties. The first surface has poor bonding properties to prevent adhesion to the core, while the second surface has good bonding properties to ensure secure bonding to the electrode, creating local quality differentiation.
2Reliability
If separators with poor thermal bonding properties are used to prevent adhesion to core, then separation effectiveness is improved, but bonding reliability deteriorates leading to gaps between electrodes during winding
Solution Approach 1:
The separator's surfaces are segmented into two functional zones: the first surface provides separation effectiveness by preventing core adhesion, while the second surface ensures manufacturing precision through reliable electrode bonding.
Solution Approach 2:
The separator exhibits local quality differentiation where one surface is optimized for separation (poor bonding) and the other surface is optimized for precise winding (good bonding), resolving the contradiction between separation effectiveness and winding precision.
3Ease of manufacture
If uniform thermal bonding properties are applied to both surfaces of separator, then manufacturing simplicity is improved, but functional performance deteriorates due to inability to prevent core adhesion while ensuring electrode bonding
Solution Approach 1:
The separator employs local quality differentiation with distinct thermal bonding properties on each surface, where the first surface prevents core adhesion and the second surface ensures electrode bonding, achieving superior functional performance despite increased manufacturing complexity.
Solution Approach 2:
The separator design introduces asymmetry in thermal bonding properties between its two surfaces, breaking the uniformity to achieve differentiated functionality: one surface for core separation and the other for electrode bonding.
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 approach ensures secure winding of electrodes, prevents performance degradation, and maintains insulation and ionic conduction in energy storage devices, even in high-temperature environments by effectively bonding separators to the core and each other.
Implementation Method 1
thermal bonding is preferred as a fixing method in terms of durability within the internal environment of the battery and impact battery performance
Implementation Method 2
a separator provided with a layer having poor thermal bonding properties such as a heat resistant coated layer
Data Source
AI summary
An energy storage device includes: a core; and a wound body including, layered and wound around the core: a positive electrode, a negative electrode, and two separators, one of which is interposed between the positive electrode and the negative electrode and each having a first surface and a second surface. The first surface has thermal bonding properties superior to thermal bonding properties of the second surface, and at least one of the two separators is bonded to the core via the first surface thereof.