Positive Electrode Composition for High-Density Rolling
Find Innovative SolutionsGenerate Solutions
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 conductive materials like carbon nanotubes.
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 defined by a rolling index equation, to minimize damage and enhance rolling density and reduce porosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbon nanotubes are used as conductive material to maximize active material loading, then conductivity is achieved with small amount of conductive material, but the CNTs damage the active material during electrode rolling
Solution Approach 1:
The patent replaces expensive carbon nanotubes with carbon black particles, which are cheaper and function effectively as conductive material. The carbon black particles serve their conductive purpose without causing damage to active material during rolling, resolving the contradiction between maximizing active material loading and maintaining active material integrity.
Solution Approach 2:
The patent changes the physical form of conductive material from linear carbon nanotubes to particulate carbon black. This parameter change in the conductive material's morphology eliminates the damaging effect on active material during rolling while maintaining conductivity, allowing higher active material loading without compromising structural integrity.
2Strength
If rolling density is reduced to create space for linear CNTs between active materials, then damage to active material is prevented, but the electrode becomes thicker with higher porosity
Solution Approach 1:
By substituting carbon nanotubes with carbon black particles, the patent eliminates the need to reduce rolling density to accommodate linear CNTs. The particulate carbon black fits between active material particles without requiring reduced rolling density, thus preventing active material damage while maintaining compact electrode thickness and low porosity.
Solution Approach 2:
The patent changes the conductive material from linear form (CNTs) to particulate form (carbon black). This parameter change allows the conductive material to occupy minimal space between active material particles, eliminating the trade-off between protecting active material and maintaining electrode compactness.
3Volume of stationary object
If rolling pressure is applied to achieve high rolling density, then energy density increases, but the active material particles are damaged
Solution Approach 1:
The patent uses carbon black particles instead of carbon nanotubes as conductive material. This substitution allows application of high rolling pressure to achieve high rolling density without damaging active material particles, as the particulate carbon black does not create the same mechanical stress concentrations as linear CNTs during rolling.
Solution Approach 2:
The patent changes the conductive material morphology from linear to particulate. This parameter change enables the application of high rolling pressure to achieve high rolling density and energy density while maintaining the structural stability of active material particles, as the particulate structure distributes rolling stress more uniformly.
Data Source
AI summary
A positive electrode having a mixture layer includes a single particle-type positive electrode active material and a point-type conductive material, disposed on a current collector. The positive electrode having the mixture layer also includes a rolling index ranging from 0.01 to 1.00. The rolling index is determined using a single particle formation degree of a single particle-type lithium nickel-based oxide, a bulk density, a BET specific surface area, and an oil absorption number of a point-type conductive material. The positive electrode exhibits a low porosity and a high rolling density. Also provided is a lithium secondary battery including the same having excellent energy density.