Positive Electrode Conductive Mix to Prevent Agglomeration
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Solution Overview
Problem
The agglomeration of linear conductive materials in positive electrodes leads to increased mixing energy consumption, uneven distribution, and cell resistance, resulting in decreased capacity and performance degradation in lithium secondary batteries.
Innovation Solution
A positive electrode using a lithium nickel-based oxide with 70 mol% or less nickel and a mixture of linear and dotted conductive materials, with controlled density and particle diameter ratios, to ensure uniform distribution and minimize agglomeration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If linear conductive material is applied to reduce conductive material content, then energy density is improved, but agglomeration occurs causing uneven distribution and increased cell resistance
Solution Approach 1:
The conductive material is segmented into two distinct types: linear conductive material (for reducing content and improving energy density) and dotted conductive material (for preventing agglomeration and ensuring uniform distribution). This segmentation allows each type to perform its specific function optimally while working together to resolve the contradiction between reducing conductive material content and maintaining reliable electrical conductivity.
Solution Approach 2:
The invention uses a composite conductive material system combining linear and dotted conductive materials with specific density relationships. The linear conductive material has higher density than the dotted conductive material, creating a composite structure where the lighter dotted material acts as a spacer to prevent agglomeration of the heavier linear material, thereby maintaining uniform distribution and low cell resistance while enabling reduced overall conductive material content.
2Quantity of substance
If linear conductive material is used, then mixing time is increased and energy consumption rises, but conductive material content is reduced
Solution Approach 1:
The invention changes the physical parameters of the conductive material system by introducing dotted conductive material with lower density than linear conductive material. This parameter change (density difference) fundamentally alters the mixing behavior, allowing the materials to self-distribute uniformly without requiring excessive mixing time or energy, thus resolving the contradiction between reducing conductive material content and minimizing mixing energy consumption.
3Quantity of substance
If linear conductive material is applied, then slurry viscosity increases, but coating properties deteriorate
Solution Approach 1:
The dotted conductive material acts as an intermediary substance between the linear conductive material and the slurry matrix. Due to its lower density and particulate form, it serves as a spacer that prevents linear conductive material from aggregating, thereby maintaining slurry fluidity and good coating properties while still achieving reduced conductive material content through the efficient linear component.
4Quantity of substance
If conductive material agglomeration occurs, then local deterioration happens causing lithium plating, but energy density can be increased
Solution Approach 1:
By segmenting the conductive material into linear and dotted types with specific density relationships, the invention prevents agglomeration that would cause local deterioration and lithium plating. This allows higher positive electrode active material content to be used for improved energy density while maintaining reliable cell capacity and resistance through uniform conductive material distribution.
Data Source
AI summary
The present disclosure relates to a positive electrode including a positive electrode active material, a positive electrode conductive material, and a positive electrode binder, wherein the positive electrode active material includes a lithium nickel-based oxide containing 70 mol % or less of nickel among all metals excluding lithium, wherein the lithium nickel-based oxide includes single particle-type particles, and the conductive material includes a linear conductive material and a dotted conductive material, and FCR defined by Equation (1) below satisfies 12 to 20:FCR=dc1×dc2×D50.a [Equation (1)]wherein, dc1 is the true density (unit: g/cm3) of the linear conductive material above, dc2 is the true density (unit: g/cm3) of the dotted conductive material above, and D50.a is the average particle diameter of the positive electrode active material (unit: μm).