Composite Separator Coating for Sodium Battery Side-Reaction Control
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Solution Overview
Problem
The side reactions between the electrode plate and the electrolyte solution in secondary batteries affect the stability and performance of the battery, leading to decreased electrochemical and safety performance, which is not suitable for modern energy storage systems.
Innovation Solution
A composite separator with a polymer coating on one side, containing polymers with sodium carboxylate and/or sodium sulfonate groups, is used to reduce the contact between the metal and electrolyte solution, enhancing sodium ion conductivity and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer coating is added to the separator substrate, then the protection of sodium metal phase and reduction of side reactions is improved, but the device complexity increases
Solution Approach 1:
The patent uses a composite separator structure combining a separator substrate with a polymer coating layer. The polymer coating contains polymers with sodium carboxylate groups and/or sodium sulfonate groups that provide high sodium ion conductivity while protecting the sodium metal phase from side reactions with the electrolyte solution.
Solution Approach 2:
The polymer coating acts as an intermediary layer between the sodium metal phase and the electrolyte solution. It facilitates sodium ion transport while preventing direct contact between the metal and electrolyte, thereby reducing side reactions without completely blocking ion transport.
2Reliability
If the polymer coating thickness is increased, then the protection effect is improved, but the sodium ion conductivity decreases
Solution Approach 1:
The patent optimizes the thickness of the polymer coating to balance protection效果 and ion conductivity. The coating thickness is controlled within a specific range to ensure sufficient protection while maintaining adequate sodium ion transport capability.
Solution Approach 2:
The polymer coating is applied selectively on one side of the separator substrate, creating a localized protective layer where it is most needed (at the sodium metal phase interface) while leaving the rest of the separator structure optimized for 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 polymer coating improves cycling and storage performance by minimizing side reactions and protecting the sodium metal phase, thereby increasing the battery's stability and efficiency.
Implementation Method 1
the polymer coating with high sodium ion conductivity can effectively change the transport mode of sodium ions between the electrolyte solution and the electrode plate, and reduce the free electrolyte solution solvent on the surface of the electrode plate through solid phase transport
Implementation Method 2
the polymer coating covers the surface of the electrode plate through elastic compression during the battery assembly process, and under the action of mechanical force, it further reduces the contact between the sodium metal phase in the negative electrode plate and the electrolyte solution
Implementation Method 3
by changing the solvation structure of sodium ions in the electrolyte solution, the free electrolyte solution solvent on the interface between the sodium metal and the separator is reduced
Data Source
AI summary
The present application provides a composite separator, a secondary battery and an electrical apparatus. The composite separator comprises a separator substrate and a polymer coating located on one side of the separator substrate, and the sodium ion conductivity of the composite separator is 0.3 mS/cm to 1 mS/cm. The polymer coating is beneficial to reducing the contact between the metal deposited on the current collector and the electrolyte solution, thereby reducing the side reaction between the metal and the electrolyte solution and improving the cycling performance and storage performance of the battery.