Cathode Active Material Powder for High-Capacity Electrode Coatability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium ion secondary batteries face challenges in achieving high energy density and stable coatability due to insufficient binder dispersion, leading to electrode cracking and peeling, despite efforts to control oil absorption amounts and powder physical properties.
Innovation Solution
A lithium transition metal composite oxide powder with a specific composition and structure, characterized by a formula Li1+aNibCocMdXeO2+α, is used, with an oil absorption amount of 19 to 30 mL/100 g and a sphericity ratio of 0.88≤A/B≤1.0, along with a powder filling density of 1.65 to 2.20 Mg/m3, to enhance coatability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the binder amount is increased to improve coatability and prevent electrode cracking, then the binding force is improved, but the energy density of the positive electrode decreases
Solution Approach 1:
The invention changes the physical parameters of the positive electrode active material powder by controlling particle size (5-20 μm), specific surface area (0.1-0.6 m²/g), and oil absorption amount (15-30 mL/100g). These parameter changes improve coatability and binder dispersion without requiring increased binder amounts, thus maintaining energy density.
2Manufacturing precision
If pressure molding is repeated to improve electrode density, then the electrode density is improved, but the manufacturing complexity and time increase
Solution Approach 1:
The invention performs preliminary action by pre-optimizing the positive electrode active material powder characteristics (particle size, specific surface area, oil absorption amount) before electrode manufacturing. This preliminary preparation of the active material ensures good coatability and binder dispersion from the start, reducing the need for repeated pressure molding operations and simplifying the manufacturing process.
3Strength
If the specific surface area is increased to improve binder contact, then the binding force is improved, but the agglomeration tendency increases and coatability worsens
Solution Approach 1:
The invention optimizes the balance between specific surface area (0.1-0.6 m²/g) and particle size (5-20 μm) to achieve adequate binder contact while preventing excessive agglomeration. The controlled oil absorption amount (15-30 mL/100g) further regulates binder interaction, ensuring good coatability and binding force simultaneously.
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 provides a positive electrode active material with high capacity and exceptional coatability, ensuring stable electrode manufacturing and improved energy density by controlling the oil absorption amount and powder physical properties.
Implementation Method 1
an oil absorption amount, based on JIS K5101-13-1, of N-methyl-2-pyrrolidone (NMP) per 100 g of the lithium transition metal composite oxide powder is 19 to 30 mL/100 g
Data Source
AI summary
A positive electrode active material for a lithium ion secondary battery, the positive electrode active material having high capacity and exceptional coatability due to comprising both an oil absorption amount and powder physical properties suitable therefor. This positive electrode active material for a lithium ion secondary battery comprises a lithium transition metal composite oxide powder represented by compositional formula (1), having primary particles and secondary particles in which the primary particles are aggregated. In the positive electrode active material for a lithium ion secondary battery, the oil absorption amount, based on JIS K5101-13-1, of NMP (N-methyl-2-pyrrolidone) per 100 g of the lithium transition metal composite oxide powder is 19-30 mL/100 g, and the sphericity represented by the ratio AB of the short axis A and the long axis B of the secondary particles measured from an SEM image is 0.88≤A/B≤1.0. Compositional formula (1): Li1+aNibCocMdXeO2+α