Low-Temperature Polyimide Binder for Silicon Li-Ion Anodes
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Solution Overview
Problem
The use of silicon-based materials in lithium-ion secondary batteries results in significant expansion and contraction during charging and discharging, leading to degradation of the current collector and deterioration of cycle characteristics when heat treatment for forming the negative electrode active material layer is conducted at lower temperatures.
Innovation Solution
A polyimide compound is developed using two specific aromatic diamine compounds as the diamine component, allowing the formation of the negative electrode active material layer at a relatively low temperature of around 200°C while maintaining heat resistance and mechanical properties, thereby improving cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If heat treatment temperature is reduced, then current collector protection is improved, but negative electrode active material layer formation quality deteriorates
Solution Approach 1:
The invention adjusts the chemical parameters of the polyimide binder to enable effective negative electrode active material layer formation at lower heat treatment temperatures. The specific aromatic diamine structure (Formulae 1 and 2) facilitates proper material layer development without requiring high temperatures that would damage thin current collectors
2Temperature
If conventional polyimide compounds are used, then heat resistance and mechanical properties are maintained, but cycle characteristics deteriorate at low heat treatment temperatures
Solution Approach 1:
The invention modifies the chemical composition parameters of the polyimide by incorporating aromatic diamine compounds with specific structures (Formulae 1 and 2). This parameter optimization maintains the inherent heat resistance of polyimide while enhancing cycle characteristics through improved binder-active material interaction at low processing temperatures
Solution Approach 2:
The invention introduces local structural features through specific aromatic diamine compounds (Formulae 1 and 2) that provide enhanced binding functionality at the interface between negative electrode active material and current collector. This localized quality improvement addresses cycle characteristics without compromising overall heat resistance
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 polyimide compound enables lithium-ion secondary batteries with excellent cycle characteristics and retains inherent properties such as heat resistance and mechanical properties even at reduced heat treatment temperatures.
Implementation Method 1
subjected to high-temperature heat treatment to form the negative electrode active material layer
Data Source
AI summary
A polyimide that can be cured at relatively low temperatures as Electrode material is provided. The polyimide used as an electrode material for lithium-ion secondary batteries, in which a diamine component contains aromatic diamine compounds represented by the following Formulae (1) and (2).