Lithium Battery Separator Silane Bonding
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Solution Overview
Problem
Non-aqueous lithium secondary batteries face issues with deterioration due to repetitive contraction and expansion of electrodes during charge and discharge cycles, leading to potential overcharge, internal or external short circuits, and rapid temperature increases that can cause separator fusion and destruction, compromising safety.
Innovation Solution
A lithium secondary battery design featuring a separator with a coating layer comprising an inorganic compound, a polymer, and an organic/inorganic bonding silane compound with reactive functional groups, which forms a chemical bond with the electrode binder, enhancing adherence and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous polyethylene separator is used, then shutdown characteristics and low cost are improved, but heat resistance deteriorates causing separator fusion at high temperatures
Solution Approach 1:
The patent applies composite materials by combining polyethylene separator with heat-resistant polymers (polyimide, polyamideimide, or aramid) to create a multi-layered separator structure. This composite approach maintains the shutdown characteristics of polyethylene while adding high-temperature stability from the heat-resistant polymer layers, preventing separator fusion at elevated temperatures.
2Ease of manufacture
If conventional binder is used in electrode, then ease of manufacture is improved, but adhesion strength to separator deteriorates leading to detachment during cycling
Solution Approach 1:
The patent modifies the chemical parameters of the binder by incorporating functional groups (carboxyl, hydroxyl, or amine groups) into the binder composition. This chemical modification enables reactive bonding with the separator coating layer, significantly improving adhesion strength while maintaining ease of manufacture through standard electrode fabrication processes.
3Temperature
If separator coating layer is applied to improve heat resistance, then temperature stability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the separator into distinct functional layers: a base polyethylene layer for shutdown characteristics and additional heat-resistant polymer layers for temperature stability. This segmented structure allows each layer to perform its specific function independently, achieving temperature stability without excessive overall complexity.
4Strength
If reactive functional groups are introduced to enhance bonding, then adhesion strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies preliminary action by pre-introducing reactive functional groups into the binder composition during electrode fabrication, before assembly with the separator. This advance preparation ensures that when the electrode contacts the separator coating layer, chemical bonding occurs automatically through the pre-positioned functional groups, reducing the need for precise control during final assembly.
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 solution improves cycle-life characteristics, strength, and high-temperature stability of the battery, reducing the risk of short circuits and enhancing safety by increasing the adhesion strength between the separator and electrodes.
Implementation Method 1
the first reactive functional group is able to react with the second reactive functional group, thereby forming a chemical bond
Implementation Method 2
improving the heat resistance of the separator and in particular, by improving the safety even when the separator is sharply contracted or destroyed
Data Source
AI summary
Disclosed is a lithium secondary battery (100) which comprises a separator (112) comprising a substrate and a coating layer, the coating layer comprising an inorganic compound, a polymer and an organic/inorganic bonding silane compound having a first reactive functional group; and an electrode (113, 114) having contact with the coating layer, the electrode comprising an active material and a binder having a second reactive functional group, wherein the first reactive functional group is able to react with the second reactive functional group thereby forming a chemical bond. Also disclosed is a lithium secondary battery (100) in which the chemical reaction has occurred.