Polyimide Binders for Lithium-Ion Battery Anodes
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Solution Overview
Problem
Conventional polymer binders used in lithium-ion batteries are mechanically weak and thermally unstable, limiting their compatibility with new high-temperature manufacturing processes and pre-lithiation processes.
Innovation Solution
Development of a water-soluble polyamic precursor that can be converted to a polyimide binder with exceptional thermal stability and mechanical flexibility, suitable for high-temperature processes, using amic acid groups and imide functionalities, which can be partially or fully reacted with lithium salts and converted to imide through thermal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional polymer binders (PVDF, PEO, PAA, PVA) are used, then the electrode components are held together, but the binders are mechanically weak and thermally unstable at higher temperatures
Solution Approach 1:
The invention changes the chemical parameters of the binder by introducing imide functionalities and amic acid groups into the polymer backbone. This chemical modification transforms conventional polymers into thermally stable polyimide-based binders that maintain mechanical strength at high temperatures, directly resolving the contradiction between mechanical strength and thermal stability.
Solution Approach 2:
The invention creates a composite binder system combining polyimide backbone with amic acid functional groups. This composite structure integrates the thermal stability of polyimide with the reactivity and binding capability of amic acid groups, achieving both mechanical strength and thermal resistance simultaneously.
2Ease of manufacture
If conventional polymer binders are used, then the electrodes can be manufactured, but they are not compatible with new high temperature manufacturing processes
Solution Approach 1:
The invention modifies the thermal parameter threshold of the binder by incorporating imide functionalities that are stable at high temperatures. This allows the binder to withstand high temperature manufacturing processes (such as hot pressing at 100-200°C or higher) without degradation, enabling compatibility with advanced manufacturing techniques while maintaining ease of manufacture.
Solution Approach 2:
The polyimide binder is designed to be thermally stable before the manufacturing process occurs, providing preliminary thermal protection to the electrode structure during high temperature processing. This preliminary thermal stability ensures the binder maintains its integrity and binding function throughout the manufacturing process.
3Temperature
If polymer binders with improved thermal stability are developed, then high temperature processes become compatible, but the binders need complex chemical structures with imide functionalities
Solution Approach 1:
The polyimide binder structure serves multiple functions simultaneously: the imide functionalities provide thermal stability, while the amic acid groups provide binding capability and potential lithium salt reactivity. This multi-functionality reduces the need for additional separate components, effectively managing chemical structure complexity while achieving desired performance.
Solution Approach 2:
The invention merges the thermal stability function (imide functionality) with the binding function (amic acid groups) into a single polymer backbone structure. This consolidation integrates multiple required properties into one chemical system, avoiding the need for complex multi-component systems and simplifying the overall chemical structure while maintaining functionality.
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 resulting composite electrodes demonstrate improved chemical, mechanical, and electrochemical performance, tolerating high temperatures and mechanical bending, and are compatible with various battery types, including lithium-ion, metal-ion, and metal-air batteries.
Implementation Method 1
The amic acid groups can be partially or fully converted to imide by a thermal process. Conversion of polyamic to polyimide can happen concurrently with a high temperature processes.
Implementation Method 2
Synthetic polymer binders have been widely utilized in lithium-ion batteries to hold electrode components, for example, active material, carbon black, etc., together.
Implementation Method 3
The amic acid groups can be partially or fully reacted with lithium salts for water or organic based process.
Data Source
AI summary
Polyimide binders and their polyamic precursors to be used for forming electrode structures are provided. The designed polyamic binder precursors are water-soluble, and the resulting polyimide binders are mechanically strong, electrochemically and thermally stable. The properties of polyimide binders have led to significant improvement in electrode compatibility towards new manufactural processes.