Graphite Negative Electrode With SWCNTs for Thickness Stability
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Solution Overview
Problem
Conventional negative electrodes in secondary batteries face challenges in suppressing thickness changes during repetitive charge and discharge cycles and maintaining high-temperature storage characteristics, leading to potential battery case swelling and capacity deterioration.
Innovation Solution
A negative electrode configuration using graphite as the active material and single-wall carbon nanotubes as conductive material, with a mass proportion of 0.02% to 0.08% of single-wall carbon nanotubes, which helps in binding graphite particles and reducing lithium ion intercalation, thereby minimizing thickness changes and enhancing high-temperature storage resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional multi-wall carbon nanotubes are used as conductive material in negative electrode active material layer, then cycle characteristics are enhanced, but thickness change during charge/discharge and capacity deterioration at high temperature cannot be suppressed
Solution Approach 1:
The patent changes the critical parameter of carbon nanotube structure from multi-wall to single-wall configuration. This structural parameter change enables the conductive material to simultaneously achieve good cycle characteristics and suppress thickness change during charge/discharge cycles while improving high-temperature storage characteristics, resolving the technical contradiction between reliability and compositional stability.
Solution Approach 2:
The patent creates a composite material system combining single-wall carbon nanotubes with graphite particles and binder. This composite structure leverages the unique properties of single-wall carbon nanotubes (smaller diameter, different aspect ratio) to achieve both electrical conductivity and structural stability, preventing both thickness change during cycling and capacity deterioration at high temperatures while maintaining cycle characteristics.
2Object-affected harmful factors
If large dimensional change of electrode body occurs during charge/discharge, then battery characteristics are harmfully affected and battery case swelling occurs, but suppressing thickness change requires specific carbon nanotube configuration
Solution Approach 1:
The patent modifies the carbon nanotube structural parameters (single-wall configuration with specific diameter and aspect ratio) to achieve dimensional stability of the electrode body during charge/discharge. This parameter change suppresses thickness variation and prevents battery case swelling without requiring complex multi-component additives or elaborate structural designs.
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 configuration effectively suppresses negative electrode thickness changes during charge/discharge cycles and improves high-temperature storage characteristics by reducing capacity deterioration, ensuring better battery performance and stability.
Implementation Method 1
single-wall carbon nanotubes... helps in binding graphite particles and reducing lithium ion intercalation
Data Source
AI summary
Provided is a negative electrode using graphite as a negative electrode active material and using carbon nanotubes as a conductive material. The negative electrode can suppress a change in thickness of the negative electrode in repetitive charge and discharge of a secondary battery and provides the secondary battery with excellent high-temperature storage characteristics. The negative electrode disclosed here includes a negative electrode current collector and a negative electrode active material layer supported on the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material and single-wall carbon nanotubes. The negative electrode active material consists essentially of graphite. A mass proportion of the single-wall carbon nanotubes to the negative electrode active material is 0.02 mass % or more and 0.08 mass % or less.