Polyamic Acid Binder Composition for Low-Temperature Secondary Battery Processing
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Solution Overview
Problem
The use of polyimide binders in lithium ion secondary batteries requires high-temperature heat treatment, which leads to increased manufacturing costs and potential deterioration of battery characteristics, and there is a need for a solution that can maintain excellent battery performance at lower heat treatment temperatures.
Innovation Solution
A binder composition comprising a polyamic acid with a specific repeating unit and an aromatic compound containing an electron donating group and an organic acid group, which allows for the formation of a polyimide binder that can withstand low heat treatment temperatures while maintaining excellent battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature heat treatment is used to form polyimide binder, then mechanical strength and battery characteristics are improved, but manufacturing cost increases and manufacturing complexity increases
Solution Approach 1:
The invention changes the chemical composition parameters of the binder by using polyacrylic acid instead of polyamic acid, allowing the imidization reaction to occur at lower temperatures (80-150°C) while still forming polyimide structures that provide excellent mechanical strength and battery performance
Solution Approach 2:
The invention uses readily available polyacrylic acid as a starting material that can be easily imidized at low temperatures, replacing the need for expensive high-temperature heat treatment equipment and processes while achieving the same or better binder performance
2Reliability
If high-temperature heat treatment is used to form polyimide binder, then mechanical strength and battery characteristics are improved, but device complexity increases
Solution Approach 1:
The invention changes the reaction temperature parameter from high temperature (400°C) to low temperature (80-150°C) by using polyacrylic acid as the starting material, which eliminates the need for complex high-temperature heating devices and simplifies the manufacturing equipment requirements
Solution Approach 2:
The invention replaces the mechanical/thermal system (high-temperature heat treatment equipment) with a chemical system (low-temperature imidization of polyacrylic acid), thereby eliminating the need for complex heating devices while still achieving polyimide binder formation
3Quantity of substance
If silicon materials are used in negative electrode to enhance energy density, then battery energy density is improved, but cycle characteristics deteriorate due to expansion and contraction
Solution Approach 1:
The invention uses polyacrylic acid as a binder that forms a flexible and adhesive network structure before electrode assembly, which can accommodate the expansion and contraction of silicon materials during charge-discharge cycles, preventing active material breakage and peeling from the current collector
Solution Approach 2:
The invention creates a composite binder system using polyacrylic acid combined with other components that provide both mechanical strength and flexibility, allowing the electrode to withstand silicon material expansion/contraction while maintaining structural integrity and electrical connectivity throughout cycling
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 proposed binder composition enables the production of secondary batteries with improved cycle characteristics and energy density, even when heat-treated at lower temperatures, reducing manufacturing costs and enhancing the stability of the active material layer.
Implementation Method 1
the reaction from a polyamic acid to a polyimide does not proceed in the heat treatment at a low temperature
Implementation Method 2
the polyimide binder is obtained by heat-treating a polyamic acid in an electrode mixture paste
Data Source
AI summary
A purpose of the present invention is to provide a binder composition for a secondary battery which can impart excellent battery characteristics, even when the heat treatment temperature is low. The binder composition for a secondary battery according to the present invention is characterized by comprising a polyamic acid comprising a repeating unit represented by chemical formula (1) and an aromatic compound comprising an electron donating group and an organic acid group,wherein A is a tetravalent group obtained by removing acid anhydride groups from a tetracarboxylic dianhydride, B is a divalent group obtained by removing amino groups from a diamine, and at least one of A and B is an aliphatic group.