Positive Electrode Activated Carbon Composition for Slurry Stability
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Solution Overview
Problem
Existing electrochemical elements, such as lithium ion secondary batteries, face challenges with high electrode resistance, low lithium utilization efficiency, and gelation issues in the slurry, which affect battery capacity and coatability, particularly due to the properties of activated carbon and fluorine-based binders.
Innovation Solution
An additive for the positive electrode comprising activated carbon with specific surface area, pore volume, and ash content, along with a slurry stabilizer, is used to improve conductivity, reduce resistance, and prevent gelation, enhancing lithium utilization and battery characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If activated carbon is added to improve conductivity and lithium utilization, then electrode resistance decreases and lithium utilization efficiency improves, but slurry gelation occurs and coatability deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pore volume of activated carbon (0.20-0.40 mL/g) and its particle size distribution (D10-D90 range of 3-15 μm). These parameter optimizations allow the activated carbon to provide sufficient conductivity improvement while minimizing slurry gelation, thus resolving the contradiction between electrode resistance reduction and coatability maintenance.
Solution Approach 2:
The patent uses composite materials by combining activated carbon with specific binders (polyvinylidene fluoride or carboxymethyl cellulose sodium salt) and conductive agents (acetylene black) in optimized ratios. This composite approach ensures that the slurry maintains proper flow characteristics for coating while the activated carbon delivers the desired conductivity enhancement.
2Productivity
If pore volume of activated carbon is increased to enhance ion transfer, then lithium utilization efficiency improves, but slurry stability deteriorates due to gelation
Solution Approach 1:
The patent applies parameter changes by optimizing the pore volume of activated carbon to a specific range (0.20-0.40 mL/g) and controlling its particle size distribution (D10-D90 of 3-15 μm). These parameter optimizations enable the activated carbon to provide sufficient porosity for lithium ion transfer while maintaining slurry stability and preventing gelation during the coating process.
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 effectively reduces electrode resistance, improves lithium utilization efficiency, and stabilizes the slurry, resulting in enhanced battery performance and coatability, with the activated carbon's tailored properties ensuring effective ion transfer and reduced risks of short circuits.
Implementation Method 1
the activated carbon has a pore volume of pores having a diameter of 2 nm or more of 0.20 mL/g to 0.40 mL/g, contributes to its effectiveness in improving conductivity and lithium utilization
Data Source
AI summary
The present invention relates to an additive for an electrochemical element positive electrode comprising an activated carbon, wherein the activated carbon has a specific surface area in accordance with BET method of 1300-2500 m2/g, a pore volume of pores having a diameter of 2 nm or more of 0.35 cm3/g or less, a pore volume of pores having a diameter less than 2 nm of 0.5 cm3/g or more, and an ash content of 0.5% by weight or less.