Positive Electrode Composition with Carbon Black-CNT Conductive Network
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving low internal resistance and excellent discharge rate characteristics due to poor electrical conductivity of positive electrode active materials, which leads to insufficient contact and utilization of the active material, resulting in decreased discharge capacity and shorter battery life.
Innovation Solution
A method for producing a positive electrode composition involving the use of carbon black and carbon nanotubes, where the carbon black forms particle groups with specific volume-based particle size distributions and ratios, combined with a controlled mixing process, to enhance electrical conductivity and form conductive paths between active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon black is added to positive electrode paste to impart electrical conductivity, then electrical conductivity is improved, but internal resistance increases and discharge rate characteristics deteriorate
Solution Approach 1:
The patent combines carbon black and carbon nanotubes in a specific ratio (0.1-5 mass% carbon black and 0.01-1 mass% carbon nanotubes) to create a composite conductive network. This composite structure leverages the high conductivity of carbon black and the excellent electron transport properties of carbon nanotubes, achieving both low internal resistance and superior discharge rate characteristics that neither material can achieve alone.
Solution Approach 2:
The patent optimizes the particle size distribution of carbon black (D50: 0.3-0.9 μm, D50/(D90-D10): 0.2-0.8) and controls the mixing sequence and conditions to achieve uniform dispersion. These parameter optimizations ensure maximum conductivity enhancement while minimizing internal resistance, resolving the contradiction between conductivity improvement and power performance.
2Stability of the object's composition
If carbon black particle size is reduced to improve dispersion, then homogeneity is improved, but electrical conductivity decreases
Solution Approach 1:
The patent uses a composite system where carbon nanotubes (0.01-1 mass%) form a conductive backbone that compensates for the reduced conductivity of fine carbon black particles. The carbon nanotubes create continuous conductive pathways that maintain electrical conductivity even when carbon black is finely dispersed (D50: 0.3-0.9 μm) for optimal homogeneity.
Solution Approach 2:
The patent creates different functional zones: carbon nanotubes provide long-range electron transport and structural integrity, while finely dispersed carbon black particles provide local conductivity enhancement and uniform distribution. This local quality differentiation allows simultaneous achievement of homogeneity and conductivity.
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 method results in a positive electrode with low internal resistance and excellent discharge rate characteristics, optimizing the distribution and interaction of carbon black and carbon nanotubes to improve battery performance.
Implementation Method 1
carbon black forms particle groups with specific volume-based particle size distributions and ratios, combined with a controlled mixing process, to enhance electrical conductivity and form conductive paths between active materials
Implementation Method 2
optimizing the distribution and interaction of carbon black and carbon nanotubes to improve battery performance
Data Source
AI summary
A method for producing a positive electrode composition, the method including: a preparation step of preparing a first slurry containing carbon black and a first liquid medium; and a mixing step of obtaining a positive electrode composition by mixing the first slurry, a binding material, carbon nanotubes, and an active material, wherein in a volume-based particle size distribution of a particle group combining secondary particles of the carbon black and a tertiary particle obtained by aggregation of the secondary particles in the first slurry, D50 is 0.3 µm or more and 0.9 µm or less, and a ratio (D50/(D90 - D10)) of D50 to the difference between D10 and D90 is 0.2 or more and 0.8 or less.