Battery Separator Polymer Coating for Stable Electrode Bonding
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Solution Overview
Problem
Current battery cells exhibit poor cycle performance due to increased spacing between electrode plates, leading to liquid shortage and bridge breakage, which deteriorates the cycle life and ion transmission efficiency.
Innovation Solution
A separator with a polymer layer containing a liquid-retaining polymer is applied, forming a three-dimensional connection network with the electrolyte solution, enhancing the bonding force between the separator and electrode plates, and maintaining electrolyte solution within the diaphragm structure to improve ion transmission and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the separator uses a conventional structure without polymer layer, then the manufacturing process is simple, but the bonding force between separator and electrode plate is insufficient, causing increased spacing and poor cycle performance
Solution Approach 1:
The separator is constructed as a composite structure consisting of a base separator and a polymer layer coated on its surface. The polymer layer contains liquid-retaining polymers that form three-dimensional connection networks, creating a multi-material system that combines the structural integrity of the base separator with the bonding and liquid-retaining properties of the polymer coating, thereby achieving enhanced bonding force while maintaining manufacturing feasibility
Solution Approach 2:
The polymer layer is applied locally on the surface of the separator rather than throughout the entire separator structure. This localized application concentrates the bonding-enhancing and liquid-retaining functions at the critical interface between separator and electrode plate, improving bonding force where it is most needed while minimizing additional complexity and material usage
2Reliability
If the separator and electrode plate are tightly bonded, then liquid shortage is alleviated and cycle performance improves, but the manufacturing precision requirements increase
Solution Approach 1:
The polymer layer acts as an intermediary substance between the separator and the electrode plate. It provides a compliant interface that accommodates thermal expansion and contraction during battery cycling, maintaining consistent contact and bonding without requiring extremely tight manufacturing tolerances. The liquid-retaining polymers in the polymer layer further mediate the interface by holding electrolyte to ensure continuous ionic contact
Solution Approach 2:
The polymer layer changes its physical parameters (such as viscosity and elasticity) in response to temperature and electrolyte content during battery operation. This dynamic parameter adjustment allows the separator to adapt to cycling conditions, maintaining reliable bonding and preventing liquid shortage without requiring the separator structure itself to have perfect manufacturing precision
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 layer improves the stability of the electrode plate and separator structure, reducing the risk of spacing increase, maintaining electrolyte solution, and enhancing ion transmission, thereby improving the cycle performance of the battery cell.
Implementation Method 1
the liquid-retaining polymer is in contact with an electrolyte solution, polymer molecular chains stretch and open, the electrolyte solution can diffuse between the molecular chains, the polymer molecular chains swell and adsorb
Implementation Method 2
the polymer molecular chains swell and adsorb, so as to construct and form a three-dimensional connection network between the separator and the electrolyte solution
Implementation Method 3
the separator has excellent bonding performance, so that the separator and an electrode plate are tightly bonded
Data Source
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AI summary
Provided in the present application are a separator, a battery cell, a battery, and an electrical apparatus. The separator comprises a separator body and a polymer layer disposed on at least one surface of the separator body, wherein the polymer layer comprises a liquid-retaining polymer. The liquid-retaining polymer is added to a first solvent at 70°C to form a polymer system, the polymer system is left to stand at 70°C for 8 h, and after standing at 25°C for more than or equal to 24 h, the polymer system is filtered by means of a 200-mesh filter screen, thereby leaving a first substance, wherein the mass of the liquid-retaining polymer is q, the unit thereof being g; the mass of the first substance is m, the unit thereof being g; and the liquid-retaining polymer and the first substance satisfy: 5≤m/q≤1000. The bonding force of the separator is greater than or equal to 10 N/m.