Ferroelectric-Coated Battery Separator for Dendrite Suppression
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Solution Overview
Problem
The growth of dendrites in batteries leads to internal short circuits, reducing reliability and coulombic efficiency, which is not effectively addressed by current separators.
Innovation Solution
A separator with a ferroelectric coating comprising an inorganic ferroelectric and a ferroelectric polymer, particularly β-phase polyvinylidene fluoride, is used to slow down dendrite growth perpendicular to the electrode plate, improving adhesion, wettability, and dielectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used, then the battery structure is simple and manufacturing is easy, but dendrites grow continuously perpendicular to the electrode plate causing internal short circuits
Solution Approach 1:
The separator employs a composite structure consisting of a porous substrate layer and a ferroelectric coating layer. The ferroelectric coating layer contains β-phase polyvinylidene fluoride with high dielectric constant (greater than 60), which creates an electric field that repels dendrite growth. This composite structure combines the mechanical support function of the substrate with the dendrite-inhibiting function of the ferroelectric coating, thereby improving battery reliability without excessive complexity
Solution Approach 2:
The invention changes the dielectric parameter of the separator by introducing a ferroelectric coating layer with high dielectric constant (εr > 60). This parameter change creates a strong electric field at the separator surface that actively repels dendrites, transforming the separator from a passive physical barrier to an active electrostatic deterrent, thus improving reliability
2Reliability
If the separator structure is simplified, then manufacturing is easier, but coulombic efficiency and rate capability are reduced due to dendrite growth
Solution Approach 1:
The separator uses a porous substrate as its base structure, which allows efficient ion transport while providing mechanical support. The porous structure maintains good electrolyte wettability and ion conductivity, ensuring high coulombic efficiency and rate capability. The porosity is optimized to balance ion transport efficiency with structural integrity
Solution Approach 2:
The ferroelectric coating is applied as a thin layer on the porous substrate, combining the ion-transport advantages of porous materials with the dendrite-repelling properties of ferroelectric materials. This composite approach achieves high coulombic efficiency without requiring complete restructuring of the separator manufacturing process
3Reliability
If a ferroelectric coating with high dielectric constant is applied, then dendrite growth is slowed down, but the separator structure becomes more complex
Solution Approach 1:
The invention focuses on optimizing the dielectric constant parameter of the coating layer by using β-phase polyvinylidene fluoride with εr > 60. This high dielectric constant creates a strong electric field that effectively repels dendrites. The phase structure and chemical composition are carefully controlled to maximize the dielectric parameter while maintaining coating integrity
Solution Approach 2:
The ferroelectric coating is applied selectively on the surface of the porous substrate that contacts the electrode, creating a localized functional zone where dendrite repulsion is most needed. This local application of the ferroelectric property reduces overall structural complexity while maintaining effectiveness
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 reduces internal short circuits and enhances coulombic efficiency and rate capability by slowing dendrite growth, improving battery reliability and performance.
Implementation Method 1
The ferroelectric coating includes a ferroelectric material, and the ferroelectric material includes an inorganic ferroelectric and a ferroelectric polymer... The ferroelectric polymer includes β-phase polyvinylidene fluoride
Implementation Method 2
The ferroelectric polymer not only can serve as a binder, but also can have a high dielectric constant εr and thereby enable the slowdown of continuous growth of dendrites
Data Source
AI summary
A separator, a battery cell, a battery, and an electric device are described. The separator comprises a porous base material and a ferroelectric coating located on at least one surface of the porous base material. The ferroelectric coating comprises a ferroelectric material. The ferroelectric material comprises an inorganic ferroelectric and a ferroelectric polymer. The ferroelectric polymer comprises polyvinylidene fluoride and a copolymer thereof, the ferroelectric polymer comprises β-phase polyvinylidene fluoride, and the content of the β-phase polyvinylidene fluoride in the ferroelectric polymer is greater than or equal to 60%. The separator can slow the continuous growth of dendrites in a direction perpendicular to an electrode sheet, reduce internal short circuits of the battery and improve the reliability of the battery, and can further improve the coulombic efficiency and rate performance of the battery.