Dual-Separator Electrode Assembly for Battery Cycle and Safety Balance
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Solution Overview
Problem
Existing secondary batteries, particularly lithium-ion batteries, face challenges in concurrently improving cycle performance and safety performance due to the limitations of current separators.
Innovation Solution
The use of a dual separator system comprising a first separator with high ionic conductivity and low bonding performance, and a second separator with high bonding and puncture resistance, along with ceramic coating layers to enhance electrolyte retention and interface stability, is employed in the electrode assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single separator with high bonding performance is used, then safety performance is improved, but cycle performance deteriorates due to electrolyte depletion
Solution Approach 1:
The separator is divided into two distinct separators: a first separator with high bonding performance and puncture resistance for safety, and a second separator with high ionic conductivity for cycle performance. This segmentation allows each separator to specialize in one function, resolving the contradiction between safety and cycle life
Solution Approach 2:
The battery employs a composite separator system combining two different separator materials with complementary properties. The first separator (high bonding) and second separator (high ionic conductivity) work together as a composite structure, achieving both safety and cycle performance that neither separator could provide alone
2Duration of action of moving object
If a single separator with high ionic conductivity is used, then cycle performance is improved, but safety performance deteriorates due to low bonding and puncture resistance
Solution Approach 1:
The separator function is segmented into two separate components: the first separator handles safety functions (bonding and puncture resistance), while the second separator handles ionic conductivity. This functional segmentation resolves the contradiction by assigning each property to the appropriate separator
Solution Approach 2:
Different regions of the separator system have different properties optimized for their specific functions. The first separator is designed with high bonding performance for safety, while the second separator is designed with high ionic conductivity for performance, creating local quality optimization throughout the separator system
3Strength
If separator bonding performance is increased, then mechanical strength is improved, but electrolyte retention and ionic conductivity deteriorate
Solution Approach 1:
The separator system is segmented so that the first separator provides mechanical strength and bonding, while the second separator provides electrolyte retention and ionic conductivity. This segmentation allows each separator to optimize for its primary function without compromise
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 configuration enhances both cycle performance by reducing electrolyte depletion and safety performance by improving mechanical strength and preventing short circuits, thereby achieving concurrent improvements in battery performance.
Implementation Method 1
The first separator has a good ionic conductivity and relatively low bonding performance, which is conducive to reducing the problem of a lack of electrolyte solution that occurs in a later stage of cycling of the secondary battery
Implementation Method 2
The second separator has good bonding performance and a high puncture resisting capacity, which is conducive to improving the safety performance of the secondary battery
Data Source
Figure 1~2
Figure 3~4
AI summary
A secondary battery includes an electrode assembly (100). The electrode assembly (100) is of a wound structure and includes a positive electrode plate (40), a negative electrode plate (30), a first separator (10), and a second separator (20). The negative electrode plate (30) is provided between the first separator (10) and the second separator (20). The first separator (10) includes an aqueous bonding layer (12), and the second separator (20) includes an oily bonding layer (22). The aqueous bonding layer (12) includes a first binder, and the oily bonding layer (22) includes a second binder.