Positive electrode mixture layer, conductive additive, positive electrode mixture, and lithium-ion secondary battery
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in achieving high rate characteristics at ordinary and low temperatures, as well as low internal resistance at low temperatures, which are essential for automotive applications.
Innovation Solution
A conductive additive comprising carbon black, a carbon nanotube with an average fiber diameter of 80 to 400 nm, and a carbon nanotube with an average fiber diameter of 0.4 to 3.0 nm, in specific mass content ratios, is used in the positive electrode mixture layer to enhance electron conductivity and electrolyte retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive additives (carbon black, graphite, carbon nanotubes) are used alone, then electron conductivity is provided to the electrode mixture layer, but rate characteristics at low temperatures and internal resistance remain insufficient
Solution Approach 1:
The patent uses a composite conductive additive system combining three distinct carbon materials: carbon black (acetylene black) as the base conductor, medium-diameter carbon nanotubes (80-400 nm) as structural bridges, and fine-diameter carbon nanotubes (0.4-3.0 nm) as surface fillers. This multi-component composite approach creates synergistic effects where each material type contributes unique properties that collectively improve low-temperature rate characteristics and reduce internal resistance beyond what any single material could achieve alone.
Solution Approach 2:
The patent applies different carbon nanotube diameter ranges to different functional zones within the conductive additive system. The medium-diameter nanotubes (80-400 nm) serve as primary conductive bridges between active material particles, while the fine-diameter nanotubes (0.4-3.0 nm) specifically target and fill gaps at particle surfaces and interfaces. This spatial and functional differentiation of material properties optimizes electron conduction pathways throughout the electrode structure.
2Reliability
If carbon nanotubes with specific diameter ranges are used, then electron conductivity and electrolyte retention improve, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise diameter ranges for different carbon nanotube populations: 80-400 nm for medium-diameter nanotubes and 0.4-3.0 nm for fine-diameter nanotubes. These parameter specifications optimize the balance between electron conductivity and electrolyte retention. The medium-diameter nanotubes provide robust conductive pathways, while the fine-diameter nanotubes enhance surface coverage and electrolyte access. Controlling these diameter parameters ensures consistent performance across production batches.
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
This configuration results in lithium-ion secondary batteries with improved rate characteristics and capacity retention at low temperatures, along with reduced internal resistance, thereby increasing energy density.
Implementation Method 1
conductive additive comprises carbon black, a carbon nanotube 1 having an average fiber diameter of 80 to 400 nm, and a carbon nanotube 2 having an average fiber diameter of 0.4 to 3.0 nm
Implementation Method 2
enhance electron conductivity and electrolyte retention
Data Source
AI summary
A positive electrode mixture layer for a lithium-ion secondary battery suitable for producing a lithium-ion secondary battery with high rate characteristics at an ordinary temperature and low temperatures and low internal resistance (DCR) at low temperatures, characterized by including a positive electrode active material, a binder, and a conductive additive, in which the conductive additive includes carbon black, a carbon nanotube (1) having an average fiber diameter of 80 to 400 nm, and a carbon nanotube (2) having an average fiber diameter of 0.4 to 3.0 nm, the content rates of the carbon black, the carbon nanotube (1), and the carbon nanotube (2) in the conductive additive are 40 to 80% by mass, 10 to 50% by mass, and 1 to 30% by mass, respectively, and the content rate of the conductive additive in the positive electrode mixed layer is 0.1 to 5.0% by mass.