Positive Electrode Composition for Stable Thick Battery Coatings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-aqueous electrolytic solution secondary batteries face challenges in forming a positive electrode active material layer with a desired shape due to partial collapse during manufacturing, especially when increasing the content of positive electrode active material and reducing the binder content or thickness, which affects the battery's capacity and formability.
Innovation Solution
A composition for the positive electrode using a specific particle size distribution of large and small particles with controlled surface tensions, allowing for a positive electrode active material layer with enhanced shape stability and capacity, achieved by using a positive electrode active material comprising large particles with a diameter of 5.0 μm or more and small particles with a diameter of less than 5.0 μm, where the small particles have a surface tension of 15.0 to 40.0 mN/m and the large particles have a surface tension of 15.0 to 25.0 mN/m.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the content of positive electrode active material is increased and binder content is reduced, then battery capacity is improved, but the positive electrode active material layer collapses during manufacturing and cannot maintain desired shape
Solution Approach 1:
The invention changes the surface tension parameter of the positive electrode active material particles by controlling the particle size distribution. Specifically, it uses a mixture of particles with D50 of 3 μm or less and D50 of more than 3 μm, where the ratio of their number-based frequencies is 0.05 to 2.0. This parameter change in particle size distribution directly affects the surface tension, enabling the material to maintain shape stability even with reduced binder content while preserving battery capacity.
Solution Approach 2:
The invention creates a composite particle system by combining positive electrode active material particles of different size ranges. The composite consists of fine particles (D50 ≤ 3 μm) and coarse particles (D50 > 3 μm) in a specific ratio range. This composite structure provides both the capacity enhancement from high active material content and the shape stability from optimized surface tension characteristics.
2Quantity of substance
If the thickness of positive electrode active material layer is increased, then battery capacity is improved, but the layer becomes difficult to form with desired shape
Solution Approach 1:
The invention modifies the surface tension parameter through controlled particle size distribution to enable the formation of thick positive electrode active material layers with desired shapes. The specific particle size ratio (0.05 to 2.0 between fine and coarse particles) optimizes surface tension to prevent collapse during manufacturing, making it easier to manufacture thick layers that maintain structural integrity.
3Use of energy by moving object
If binder content is reduced, then energy density is improved, but the positive electrode active material layer peels and slides
Solution Approach 1:
The invention changes the surface tension parameter of the positive electrode active material by optimizing particle size distribution. This parameter change enhances the inherent adhesion properties of the material, allowing the layer to maintain reliability and resist peeling and sliding even when binder content is reduced to improve energy density.
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 composition enables the formation of a positive electrode active material layer with improved shape stability and increased capacity, resulting in a non-aqueous electrolytic solution secondary battery with enhanced performance.
Implementation Method 1
the small particles have a surface tension of 15.0 to 40.0 mN/m and the large particles have a surface tension of 15.0 to 25.0 mN/m
Data Source
AI summary
Provided are a composition for a positive electrode containing a positive electrode active material consisting of a large particle group A having a particle diameter of 5.0 μm or more and a small particle group B having a particle diameter of less than 5.0 μm, in which, in a number-based particle size distribution of the positive electrode active material, in a case where the total frequency is set to 100%, a frequency of the large particle group A is 60% or more and a frequency of the small particle group B is 40% or less, and a surface tension γB (mN/m) of the small particle group B with respect to N-methylpyrrolidone satisfies an expression B1: 15.0≤γB≤40.0; a positive electrode sheet including a positive electrode active material layer formed of the composition for a positive electrode; and a non-aqueous electrolytic solution secondary battery using the positive electrode sheet.