Positive Electrode Composition Using Uniform-Length CNTs for Conductivity
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Solution Overview
Problem
Conventional lithium secondary batteries face challenges in achieving high energy density and conductivity due to the limited dispersibility of nano-sized conductive materials like carbon nanotubes, leading to poor electrical connections and reduced battery performance.
Innovation Solution
Incorporating multi-walled carbon nanotubes with an average length of 1-2 μm and a length standard deviation of 0.5 μm or less in the positive electrode active material layer, ensuring uniform dispersion and improved electrical connections, even with a reduced content of conductive material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of conductive material is increased to improve conductivity, then the conductivity is improved, but the amount of positive electrode active material is relatively decreased
Solution Approach 1:
The patent changes the physical parameters of the carbon nanotube conductive material, specifically controlling the average length to 1-2 μm and length standard deviation to 0.5 μm or less. This parameter optimization enables effective conductivity with reduced material content (0.1-1 wt%), resolving the contradiction between achieving high conductivity and maximizing active material content.
Solution Approach 2:
The patent creates a composite structure where optimized carbon nanotubes (with specific length parameters) are combined with positive electrode active material. This composite approach allows the nanotubes to form effective conductive networks at lower concentrations, enabling high conductivity while maintaining high active material content for energy density.
2Reliability
If nano-sized conductive material is used to improve conductivity with small amount, then the conductivity can be improved with less material, but the dispersibility in positive electrode slurry is poor
Solution Approach 1:
The patent optimizes the physical parameters of carbon nanotubes by controlling average length (1-2 μm) and length standard deviation (0.5 μm or less). This parameter control prevents excessive aggregation while maintaining conductive effectiveness, enabling both good dispersibility in slurry and high conductivity in the final electrode.
3Duration of action of stationary object
If the content of conductive material is drastically reduced to improve life-time characteristics, then the life-time characteristics are improved, but the conductivity may be insufficient
Solution Approach 1:
The patent uses carbon nanotubes with optimized length parameters (average 1-2 μm, standard deviation 0.5 μm or less) that form efficient conductive networks at very low concentrations (0.1-1 wt%). This allows drastic reduction of conductive material content compared to conventional solutions, improving life-time characteristics while maintaining sufficient conductivity through the high efficiency of the optimized nanotube structure.
Data Source
AI summary
A positive electrode and a secondary battery including the same are provided. The positive electrode includes a current collector and a positive electrode active material layer disposed on the current collector, wherein the positive active material layer includes a positive electrode active material, a binder, and a multi-walled carbon nanotube, wherein the multi-walled carbon nanotube has an average length of 1-2 μm and has a length standard deviation of 0.5 μm or less.