Dry Electrode Master Batch for CNT Dispersion and Low Resistance
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Solution Overview
Problem
Existing methods for manufacturing dry electrodes face challenges in achieving homogeneous dispersion of conductive materials with large BET specific surface areas, leading to issues such as increased electrode resistance, reduced active material content, and poor mechanical properties.
Innovation Solution
A conductive material master batch comprising carbon nanotubes, a PVDF-based binder, and a PTFE binder is used, with specific surface areas and crystallization degrees optimized to improve dispersibility and reduce electrode resistance, while maintaining mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the BET specific surface area of the conductive material is increased to improve conductivity, then the dispersibility of the conductive material deteriorates
Solution Approach 1:
The conductive material is pre-dispersed in a binder to form a master batch before being mixed with the active material. This preliminary dispersion action ensures that high-surface-area conductive materials are evenly distributed in the binder matrix, preventing aggregation during subsequent mixing steps and maintaining both conductivity and dispersibility.
Solution Approach 2:
A binder serves as an intermediary medium between the conductive material and the active material. The binder facilitates uniform distribution of the conductive material by providing a compatible matrix that prevents direct contact and aggregation between conductive material particles, thereby maintaining dispersibility while enabling high conductivity.
2Reliability
If the content of the conductive material is increased to improve conductivity, then the content of the active material decreases
Solution Approach 1:
The electrode composition is segmented into distinct functional components: a conductive material master batch (containing conductive material pre-dispersed in binder) and active material. This segmentation allows the conductive material to be concentrated in the master batch at optimal levels while the active material content in the final electrode can be maximized, resolving the trade-off between conductivity and active material content.
Solution Approach 2:
The formulation approach changes from directly mixing conductive material with active material to using a master batch with controlled conductive material content (1-10 parts by weight per 100 parts binder). This parameter change in the mixing strategy allows optimization of both conductivity and active material content in the final electrode.
3Ease of operation
If a solvent is used in the electrode mixture to improve workability, then the generation of defects such as pinholes and cracks increases
Solution Approach 1:
The solvent is extracted/removed from the electrode formulation entirely. The invention uses a solvent-free electrode mixture where the binder provides sufficient workability without requiring volatile solvents. This elimination of solvent prevents the formation of pinholes and cracks that occur during solvent evaporation, achieving both ease of operation and high manufacturing precision.
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 enables the production of dry electrodes with reduced conductive material content, improved electrode resistance, and enhanced mechanical stability, facilitating mass production without solvent use.
Implementation Method 1
A conductive material master batch including a conductive material, a polyvinylidene fluoride (PVDF)-based binder, and a polytetrafluoroethylene (PTFE) binder
Implementation Method 2
a binder used for the binding of powder particles among themselves and the adhesion to a current collector
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A conductive material master batch including a conductive material, a polyvinylidene fluoride (PVDF)-based binder, and a polytetrafluoroethylene (PTFE) binder, in which the conductive material has a BET specific surface area of 80 m2/g or more, and each of the PVDF-based binder and the PTFE binder independently has a crystallization degree of 30% or less. Also provided is an electrode obtained using the conductive material master batch. The electrode obtained by using the conductive material master batch has an electrode resistance of 55 ohm·cm or less.