Polymer-Coated Battery Separator for Stronger Electrode Bonding
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Solution Overview
Problem
The current cycle performance of battery cells is poor and needs to be improved due to issues such as liquid shortage and increased spacing between electrode plates during the charge and discharge cycles, which deteriorate the battery's cycle life.
Innovation Solution
A separator with a polymer layer containing a liquid-retaining polymer is applied, which forms a three-dimensional connection network with the electrolyte solution, enhancing the bonding force between the separator and electrode plates, thereby improving stability and ion transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional separator is used, then the structure is simple, but the bonding force between separator and electrode plates is insufficient, leading to increased spacing during cycling
Solution Approach 1:
The separator is constructed as a composite material consisting of a base separator and a polymer layer coating. The polymer layer contains liquid-retaining polymers that form three-dimensional connection networks, creating a composite structure that enhances bonding force between the separator and electrode plates while maintaining structural simplicity.
Solution Approach 2:
The polymer layer in the separator incorporates porous structures that allow electrolyte penetration while maintaining mechanical strength. The liquid-retaining polymers form a three-dimensional network with controlled porosity, enabling both strong bonding and ion transport functionality.
2Reliability
If the gap between electrode plates increases during cycling, then the battery can accommodate expansion, but liquid shortage occurs and cycle performance deteriorates
Solution Approach 1:
The polymer layer undergoes parameter changes in response to electrolyte concentration and temperature variations. The liquid-retaining polymers adjust their swelling and binding characteristics based on electrolyte conditions, maintaining optimal bonding force and electrolyte retention throughout battery cycling to prevent liquid shortage.
Solution Approach 2:
The liquid-retaining polymers in the polymer layer automatically absorb and retain electrolyte solution through their inherent affinity, without requiring external intervention. This self-service mechanism ensures continuous electrolyte availability at the electrode-separator interface during cycling, preventing liquid shortage and maintaining reliable ion transport.
3Strength
If the polymer layer is added to improve bonding, then the bonding force increases, but the manufacturing process becomes more complex
Solution Approach 1:
The polymer layer is pre-formed with liquid-retaining polymers and three-dimensional connection networks before being applied to the separator. This preliminary preparation allows the polymer layer to be optimized for bonding performance independently, simplifying the overall manufacturing process by separating the bonding function development from the final assembly step.
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's three-dimensional connection network locks electrolyte solution, maintains ion transmission, and reduces the risk of liquid shortage, enhancing the battery cell's cycle performance and stability.
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 electrolyte solution can diffuse between the molecular chains, the polymer molecular chains swell and adsorb
Data Source
AI summary
A 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.