Positive Electrode Composition for Low-Porosity Battery Rolling
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving high energy density due to the damage of active materials during electrode rolling, which increases porosity and reduces rolling density, particularly when using carbon nanotubes as conductive materials.
Innovation Solution
A positive electrode comprising a combination of single particle-type active materials and point-type conductive materials, such as carbon black, with specific properties to minimize porosity and enhance rolling density, as defined by a rolling index equation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon nanotubes are used as conductive material and linearly positioned between active materials, then conductivity is achieved with small amount of conductive material, but active material is damaged during electrode rolling and porosity increases
Solution Approach 1:
The patent extracts the harmful linear carbon nanotube structure and replaces it with point-type conductive materials (carbon black, acetylene black, Ketjen black). This removes the source of damage while maintaining conductivity function through a different mechanism - point contact rather than linear bridging.
Solution Approach 2:
The patent changes the physical form parameter of the conductive material from linear (carbon nanotubes) to point-type (carbon black particles). This parameter change fundamentally alters how the conductive material interacts with active material particles during rolling, preventing damage while maintaining electrical connectivity.
2Manufacturing precision
If rolling pressure is reduced to create space for linear CNTs, then active material damage is prevented, but electrode thickness increases and energy density decreases
Solution Approach 1:
The patent removes the requirement for reduced rolling pressure by extracting the harmful linear CNT structure. This allows normal rolling pressure to be applied, achieving both high particle integrity and high energy density without the trade-off that existed with carbon nanotubes.
Solution Approach 2:
The patent uses point-type conductive materials that can withstand the rolling process without requiring special protection measures. These materials accept the rolling pressure and maintain their function, unlike linear CNTs that required reduced pressure to prevent damage.
3Manufacturing precision
If point-type conductive material with large specific surface area is used, then porosity is reduced and rolling density is increased, but manufacturing complexity increases
Solution Approach 1:
The patent uses conventional point-type conductive materials (carbon black, acetylene black, Ketjen black) that are already widely available and well-understood in battery manufacturing. These materials require no special handling or processing, maintaining simple manufacturing processes while achieving the desired porosity and rolling density improvements.
Data Source
AI summary
The present invention relates to a positive electrode having a positive electrode mixture layer, including a single particle-type positive electrode active material and a point-type conductive material, disposed on a current collector, and having a rolling index, with single particle formation degree of a single particle-type lithium nickel-based oxide, and bulk density, BET specific surface area, and oil absorption number of a point-type conductive material as a factor, of 0.01 to 1.00, and the positive electrode exhibits a low porosity and a high rolling density, enabling a lithium secondary battery having excellent energy density.