Battery Separator Coating for Ion Flow and Thermal Stability
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Solution Overview
Problem
Secondary batteries face challenges in achieving high energy density while maintaining both good cycling performance and safety performance, as increasing energy density often compromises dynamic, electrochemical, or safety performance.
Innovation Solution
A separator for secondary batteries is developed with a substrate coated with a layer of inorganic and organic particles, where the organic particles form protrusions on the surface, optimizing their size and coverage to enhance ion transmission and thermal management, comprising specific polymers and inorganic materials like boehmite and aluminum oxide, to create a non-uniform pore structure that balances energy density and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the energy density of secondary batteries is increased, then the battery capacity and energy storage are improved, but the cycling performance, electrochemical performance, and safety performance deteriorate
Solution Approach 1:
The separator uses a porous structure with controlled pore size distribution to maintain ion transmission pathways. The porous coating layer allows efficient ion transport while the pore structure provides thermal management capabilities, resolving the contradiction between high energy density and safety performance.
Solution Approach 2:
The separator employs a composite structure combining organic polymer matrix with inorganic particles (such as aluminum oxide and boehmite). This composite material provides both mechanical integrity for cycling stability and thermal conductivity for safety, enabling high energy density without compromising reliability.
2Reliability
If the coating layer is made denser to improve safety, then thermal management is enhanced, but ion transmission efficiency deteriorates
Solution Approach 1:
The coating layer exhibits local quality variations with different pore size distributions in different regions. The surface layer has smaller pores for safety while the bulk maintains larger pores for ion transmission, allowing simultaneous optimization of safety performance and ion transmission efficiency.
Solution Approach 2:
The separator utilizes temperature-dependent parameter changes where the pore structure and material properties vary with temperature. At normal operating temperatures, the structure maintains high ion transmission, while at elevated temperatures, thermal contraction and phase changes enhance safety by blocking ion transport.
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 separator effectively combines high energy density with improved cycling and safety performance by controlling the area coverage and size of organic particles, ensuring efficient ion transmission and thermal management, thereby extending battery life and safety under various operating conditions.
Implementation Method 1
a non-uniform pore structure that balances energy density and safety
Implementation Method 2
optimizing their size and coverage to enhance ion transmission
Implementation Method 3
ensuring efficient ion transmission and thermal management
Data Source
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AI summary
The present application relates to a separator in the electrochemical field and a preparation method therefor, and to a secondary battery comprising the separator, a device comprising the secondary battery. The separator of the present application is prepared by a simple process and has excellent heat resistance performance. Moreover, the secondary batteries and devices comprising the separator of the present application have good safety performance and cycling performance.