Polyamideimide Binder with Carbodiimide for Hydrolysis Resistance
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Solution Overview
Problem
Lithium secondary batteries face rapid deterioration due to hydrolysis of imide groups in polyamideimide binders, leading to reduced adhesive power, strength, and stretchability, especially in applications requiring long service life like motor-driving batteries for automobiles.
Innovation Solution
Incorporating carbodiimide into the electrode active material layer to instantly react with water and bind with hydrolyzed imide groups, maintaining the binder's properties and extending the battery's service life by suppressing deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyamideimide is used as a binder for electrode active material, then adhesive power and stretchability are improved, but the binder deteriorates rapidly due to hydrolysis of imide groups when water is present
Solution Approach 1:
Carbodiimide is introduced as a protective intermediary substance that reacts with water to form urea compounds, preventing water from hydrolyzing the imide groups in polyamideimide. This intermediary mechanism preserves the binder's adhesive properties while eliminating the harmful hydrolysis reaction.
Solution Approach 2:
The carbodiimide converts the harmful effect of water (which causes hydrolysis) into a beneficial reaction by forming urea compounds. The water that would otherwise degrade the binder is instead utilized to react with carbodiimide, protecting the imide groups and maintaining binder performance.
2Adaptability or versatility
If polyamideimide is used as a binder, then stretchability to accommodate volume change is improved, but service life is reduced due to decomposition of imide groups
Solution Approach 1:
Carbodiimide serves as a protective intermediary that prevents water from attacking the imide groups in polyamideimide. By reacting with water to form urea compounds, it preserves the stretchability and adhesive properties of the binder throughout the battery's service life, preventing decomposition.
Solution Approach 2:
The carbodiimide is pre-introduced into the binder system before water can cause hydrolysis. This preliminary protective action ensures that when water is present during battery operation, the imide groups are already protected by the carbodiimide-water reaction products.
3Strength
If polyamideimide is used as a binder, then adhesive power is improved, but deterioration occurs when water is generated during repeated charging and discharging
Solution Approach 1:
The water generated during battery cycling, which would normally cause hydrolysis and deterioration, is converted into a protective mechanism. The carbodiimide reacts with this water to form urea compounds, transforming the harmful cycling-by-product into a protective element that maintains adhesive power.
Solution Approach 2:
Carbodiimide acts as a protective intermediary that intercepts water molecules generated during charging/discharging cycles, preventing them from reaching and hydrolyzing the imide groups in polyamideimide, thus maintaining cycle stability.
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 use of carbodiimide in the binder effectively retains adhesive power, strength, and stretchability, prolonging the service life of lithium secondary batteries even when water is generated during charging and discharging, enhancing their durability and performance.
Implementation Method 1
imide groups which are easily hydrolyzed, these imide groups are readily reacted with water and decomposed
Implementation Method 2
the carbodiimide is reacted instantly with water in cases where water is generated due to repeated charging/discharging to suppress hydrolysis of imide groups
Data Source
AI summary
Provided are an electrode binder for lithium secondary batteries, which is suppressed in deterioration in adhesive power, strength and stretchability caused by decomposition of imide groups by hydrolysis, said imide groups being contained in a polyamide-imide that is used as a binder for an electrode active material, and which is capable of prolonging the service life of a lithium secondary battery by suppressing deterioration of an electrode even in cases where water is generated due to repeated charging and discharging; a negative electrode for lithium secondary batteries; a lithium secondary battery; a method for manufacturing a lithium secondary battery having long service life, said lithium secondary battery being suppressed in deterioration of an electrode even in cases where water is generated due to repeated charging and discharging; a method for producing an electrode binder for lithium secondary batteries; and an automobile. This electrode binder for lithium secondary batteries contains a polyamideimide and a carbodiimide. A lithium secondary battery is manufactured by forming an electrode layer using a coating liquid that contains an electrode active material, a polyamideimide, a carbodiimide and a solvent.