Lithium Ion Capacitor Negative Electrode Density Control
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Solution Overview
Problem
Lithium ion capacitors face challenges in achieving higher capacity, lower resistance, and greater reliability to meet the demands for improved performance in electric vehicles and hybrid vehicles.
Innovation Solution
The development of an electrical storage device with a negative electrode active material layer containing a fluorine-containing acrylic binder, specifically a polymer composition with a fluorine-containing polymer and an acrylic polymer, which forms a particulate seed and outer shell structure, and includes active materials like graphites and polyacene-based organic semiconductors, optimizing the density and composition for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a fluorine-modified acrylic binder is used in the positive electrode, then output characteristics are improved, but resistance remains high and capacity is limited
Solution Approach 1:
The invention changes the physical parameters of the negative electrode active material layer by controlling its density to be 0.70 g/cc or more. This parameter change optimizes the packing density and contact between particles, thereby reducing resistance and improving both output characteristics and capacity simultaneously
Solution Approach 2:
The invention uses a composite binder system comprising both a fluorine-containing polymer and an acrylic polymer in specific proportions (fluorine-containing polymer: 1-20 mass%, acrylic polymer: 80-99 mass%). This composite material approach combines the advantages of both polymers to achieve low resistance and high capacity
2Quantity of substance
If the negative electrode active material layer density is increased, then capacity and energy density are improved, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The invention establishes a specific parameter range for density (0.70 g/cc or more) that balances capacity enhancement with manufacturing feasibility. This parameter optimization ensures high energy density while maintaining controllable manufacturing precision through proper slurry preparation and coating process control
3Power
If the fluorine-containing polymer content is increased, then output characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The invention optimizes the fluorine-containing polymer content to a specific range (1-20 mass%) that provides sufficient output improvement while avoiding excessive manufacturing complexity. This parameter optimization balances performance enhancement with industrial manufacturability
Solution Approach 2:
The invention uses a composite binder system where the fluorine-containing polymer (1-20 mass%) works synergistically with the acrylic polymer (80-99 mass%). This composite approach distributes the functional requirements between two materials, simplifying the overall manufacturing process while achieving high output characteristics
Data Source
AI summary
An electrical storage device includes a positive electrode, and a negative electrode having a negative electrode active material layer containing a fluorine-containing acrylic binder, the negative electrode active material layer having a density of not less than 0.75 g/cc and not more than 1.10 g/cc.