Heated Rolling of Lithium Nickel Composite Oxide Electrodes
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Solution Overview
Problem
Lithium-containing composite oxide particles with nickel in non-aqueous electrolyte secondary batteries have weak binding forces, leading to particle cracking during rolling, which causes oxidation reactions and battery expansion, especially at high temperatures or during charge/discharge cycles.
Innovation Solution
A method for producing a positive electrode with a lithium-containing composite oxide active material, including secondary particles with an average diameter of 5 μm or more, using a slurry applied onto a core material and rolled while heating to reduce pressure and enhance binder deformation, resulting in improved binding characteristics and reduced particle cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the positive electrode precursor is rolled without heating, then the rolling process is simple and fast, but the active material particles crack due to weak binding force
Solution Approach 1:
The patent applies heating during the rolling process to change the temperature parameter, which enhances binder deformation and improves binding characteristics between active material particles, thereby preventing particle cracking while maintaining production efficiency
Solution Approach 2:
The patent performs heating as a preliminary action before the rolling process to soften the binder, making it more deformable and capable of providing stronger binding force during subsequent rolling, thus preventing particle cracks
2Reliability
If the binding force of active material particles is increased, then particle cracks are suppressed, but the battery density decreases
Solution Approach 1:
The patent changes the temperature parameter during rolling to enhance binder deformation and binding force, achieving particle crack suppression without requiring increased material quantity, thus maintaining high battery density
3Strength
If the rolling pressure is increased to improve binding characteristics, then particle cracks are reduced, but the active material particles still crack due to weak inherent binding force
Solution Approach 1:
The patent introduces temperature as an additional parameter to modify the binder's physical state, making it more deformable and effective at lower rolling pressures, thus achieving strong binding characteristics without excessive pressure that would cause particle cracking
Solution Approach 2:
The patent creates a composite structure where the binder and active material particles form a strongly bound composite through enhanced binder deformation, improving overall particle integrity without relying solely on high rolling pressure
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 method achieves excellent charge/discharge cycle characteristics and high-temperature storage performance by maintaining the average particle diameter and increasing the active material density, suppressing gas generation and battery expansion.
Implementation Method 1
rolling while heating the positive electrode precursor to produce a positive electrode in which 3.5 g or more of said positive electrode active material is included per 1 cm3 of the positive electrode material mixture layer, and the positive electrode active material includes secondary particles having an average particle diameter of 5 μm or more
Data Source
AI summary
A method for producing a positive electrode for non-aqueous electrolyte secondary battery of the present invention includes the steps of: (1) producing a positive electrode precursor by applying a positive electrode slurry including a positive electrode active material comprising a lithium-containing composite oxide including nickel, a binder, and a conductive agent on a positive electrode core material, the positive electrode active material including secondary particles having an average particle diameter of 8 μm or more, and then drying the positive electrode slurry to form a positive electrode material mixture layer; and (2) rolling while heating the positive electrode precursor to produce a positive electrode in which 3.5 g or more of the positive electrode active material is included per 1 cm3 of the positive electrode material mixture layer, and the positive electrode active material includes secondary particles having an average particle diameter of 5 μm or more.