Dry PTFE Negative Electrode With Nitrogen Protection Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high energy density due to microstructure deterioration caused by binder migration during the drying process in wet electrode preparation, making it difficult to thicken the electrode.
Innovation Solution
A dry process is employed to prepare a negative electrode with a polytetrafluoroethylene binder that includes a nitrogen-containing protection layer, formed through fibrillation, compression, and vapor reaction, resulting in a thick negative active material layer on a current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wet procedure is used to prepare the electrode, then the electrode can be formed with binder, but binder migration occurs during drying which causes microstructure deterioration
Solution Approach 1:
The patent changes the fundamental parameter of the preparation process from wet to dry procedure. The dry procedure eliminates solvent and drying steps, preventing binder migration while maintaining electrode formation capability. This parameter change resolves the contradiction by avoiding the harmful drying phase entirely.
Solution Approach 2:
The patent replaces the chemical-wet bonding mechanism with a mechanical dry bonding mechanism. Instead of using binder molecules that require drying (which causes migration), the dry procedure uses mechanical compression and fibrillation to create direct physical bonds between active material particles and current collector, eliminating the binder migration problem.
2Quantity of substance
If the electrode is thickened to improve energy density, then higher capacity is achieved, but microstructure deterioration prevents sufficient thickening
Solution Approach 1:
By changing from wet to dry procedure, the patent enables electrode thickening without the microstructure deterioration that limits thickness in wet procedures. The dry procedure maintains microstructural integrity even at greater thicknesses, allowing higher energy density electrodes to be fabricated.
3Ease of manufacture
If polytetrafluoroethylene binder is used in dry process, then electrode formation is achieved, but side reactions occur reducing electrochemical performance
Solution Approach 1:
The patent introduces nitrogen-containing compounds as intermediary substances that mediate between the polytetrafluoroethylene binder and the electrochemical system. These compounds form protective layers on the binder surface, preventing direct side reactions while maintaining the binder's mechanical function in the dry procedure electrode.
Solution Approach 2:
The patent converts the harmful side reactions of polytetrafluoroethylene into a beneficial protective mechanism. By intentionally allowing controlled reaction with nitrogen-containing compounds, a protective layer forms that prevents further harmful side reactions, thus converting the potential harm into a protective benefit.
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 enhances the electrochemical performance of the battery with improved initial efficiency and cycle-life characteristics by preventing side reactions and maintaining mechanical strength.
Implementation Method 1
a nitrogen-containing protection layer is formed on the surface of the polytetrafluoroethylene binder
Implementation Method 2
subjecting the dry film to a vapor reaction to prepare a negative active material layer
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the negative electrode are provided. The negative electrode includes a dry negative active material layer including a negative active material and a polytetrafluoroethylene binder that includes a N-including protection layer.