Positive Electrode Active Material Layer Composition for Battery Reliability
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high output and long-life characteristics, particularly at high temperatures, due to inadequate adhesion between the positive electrode active material layer and the current collector, and poor lithium ion mobility, when using carbon nanotubes and binders in the positive electrode.
Innovation Solution
A positive electrode with a specific composition of Li(Nix1Mny1Coz1)O2 and Li(Nix2Mny2Coz2) active materials, combined with carbon nanotubes and a binder, where the positive electrode active material layer satisfies specific relationships between the loading amount and the total content of remaining components, ensuring appropriate adhesion and lithium ion mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of conductive material is increased to improve conductivity, then the conductivity is improved, but the amount of positive electrode active material is relatively decreased, and accordingly, output and durability of the battery are deteriorated
Solution Approach 1:
The patent changes the physical form of the conductive material from dot-type (carbon black) to linear-type (carbon nanotube), which fundamentally alters the conductivity mechanism. This parameter change allows achieving the same or better conductivity with much lower content (0.1-5 wt%) compared to conventional dot-type conductive materials, thereby resolving the contradiction between conductivity improvement and active material quantity preservation
Solution Approach 2:
The patent creates a composite structure where linear conductive material (carbon nanotube) forms a three-dimensional conductive network within the positive electrode. This composite approach enables efficient electron transport pathways while minimizing the amount of conductive material needed, thus maintaining high active material content and preserving output and durability characteristics
2Reliability
If adhesion between the positive electrode active material layer and current collector is not ensured, then the life-time characteristics at high temperature are deteriorated
Solution Approach 1:
The patent optimizes the binder content parameter within a specific range (0.5-5 wt% of total electrode weight) to achieve optimal adhesion strength. This parameter optimization ensures sufficient bonding between the active material layer and current collector, preventing delamination at high temperatures and maintaining long-term reliability without excessive binder usage that would reduce active material content
3Reliability
If adhesion between the positive electrode active material layer and current collector is not ensured, then the mobility of lithium ions is deteriorated
Solution Approach 1:
The patent carefully controls the binder content parameter (0.5-5 wt%) to achieve a balance between adhesion and ion mobility. The optimized binder amount provides sufficient mechanical adhesion to maintain structural integrity while preserving adequate porosity and electrolyte access for lithium ion transport, thus preventing deterioration of ion mobility
4Quantity of substance
If the positive electrode requires a high energy density, then the capacity is increased, but the adhesion and lithium ion mobility are not ensured, thereby deteriorating the life-time characteristics and output characteristics
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: conductive material content (0.1-5 wt%), binder content (0.5-5 wt%), and active material loading amount. This multi-parameter optimization ensures that high energy density is achieved while maintaining sufficient adhesion and lithium ion mobility, thereby preserving life-time and output characteristics without compromise
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
This configuration enhances the high output and life-time characteristics of the secondary battery at high temperatures by optimizing the balance between the active material loading and the content of other components in the positive electrode active material layer.
Implementation Method 1
a positive electrode active material capable of intercalating/deintercalating lithium ions
Implementation Method 2
a method for using a linear conductive material such as a carbon nanotube has been introduced. Since the carbon nanotube has a relatively longer length than the particle-type conductive material, the conductivity may be improved
Data Source
AI summary
A positive electrode includes a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder, wherein the positive electrode active material contains any one among Li(Nix1Mny1Coz1)O2 (0.55<x1<0.69, 0.15<y1<0.29, 0.15<z1<0.29, x1+y1+z1=1) and Li(Nix2Mny2Coz2)O2 (0.75<x2<0.89, 0.05<y2<0.19, 0.05<z2<0.19, x2+y2+z2=1) and the conductive material contains a carbon nanotube, and when the positive electrode active material is Li(Nix2Mny2Coz2)O2, the positive electrode active material layer satisfies Relation 1 and when the positive electrode active material is Li(Nix2Mny2Coz2)O2, the positive electrode active material layer satisfies Relation 2:0.0020×a<b<0.0050×a [Relation 1]0.0015×a<b<0.0044×a [Relation 2]wherein a is a loading amount (mg/25 cm2) of the positive electrode and b is a total content (wt %) of the remaining components excluding the positive active material in the positive electrode material.