Thick Positive Electrode Mesh Binder for Low-DCR Li-Ion Batteries
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face an increase in direct current resistance (DCR) when the positive electrode material mixture layer is thick, leading to reduced current collection efficiency and capacity.
Innovation Solution
A positive electrode with a nickel-based composite oxide and a polymer binder having a three-dimensional mesh structure, applied in a thick layer to the current collector sheet, which improves conductive agent distribution and adhesion, reducing internal resistance and stress resistance during charge and discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the positive electrode material mixture layer is increased to achieve high capacity, then the capacity increases, but the direct current resistance (DCR) increases significantly due to reduced current collection efficiency
Solution Approach 1:
The patent applies local quality by creating a thick positive electrode material mixture layer (280 g/m2 or more) only where high capacity is needed, while maintaining optimal conductive agent distribution and binder structure locally within the thick layer to ensure low DCR. The three-dimensional mesh structure of the polymer binder and uniform conductive agent distribution are implemented locally throughout the thick layer to maintain electron conduction paths.
Solution Approach 2:
The patent uses composite materials by combining the positive electrode active material with a polymer binder having a three-dimensional mesh structure and a conductive agent in specific proportions. This composite structure allows the thick layer to maintain both high capacity and low DCR by ensuring proper material distribution and interaction within the layer.
2Productivity
If the amount of positive electrode slurry applied is increased to reduce the number of spiral windings, then the manufacturing efficiency improves, but the internal resistance of the positive electrode material mixture layer increases
Solution Approach 1:
The patent applies parameter changes by optimizing the composition parameters of the positive electrode material mixture layer, specifically setting the conductive agent content to 1 wt% or more and the polymer binder content to 3 wt% or more. These parameter adjustments ensure that even in a thick layer (280 g/m2 or more), the internal resistance remains low while maintaining high capacity.
Solution Approach 2:
The patent ensures uniform local distribution of conductive agent and polymer binder throughout the thick positive electrode material mixture layer. This local quality control prevents aggregation and ensures consistent electron conduction paths throughout the entire thick layer, maintaining low internal resistance even when the layer thickness is increased for high productivity.
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 suppresses the increase in DCR, enhances capacity, and improves cycle characteristics by maintaining high-quality electronic conduction paths and adhesion between the material mixture layer and the current collector sheet.
Implementation Method 1
the binder contains a polymer binder that has a three-dimensional mesh structure
Data Source
AI summary
Disclosed is a positive electrode for a non-aqueous electrolyte secondary battery including: a positive electrode current collector sheet; and a positive electrode material mixture layer supported on the positive electrode current collector sheet. The positive electrode material mixture layer contains a positive electrode active material, a binder, and a conductive agent. The positive electrode active material contains a composite oxide that has a layered rock-salt type crystal structure and contains lithium and an element A other than lithium. The element A contains at least nickel. The atomic ratio Ni/A of nickel relative to the element A is 0.8 or more and 1.0 or less. The binder contains a polymer binder that has a three-dimensioned mesh structure. The mass of the positive electrode material mixture layer supported per m2 of the positive electrode current collector sheet is 280 g or more.