Secondary Battery Negative Electrode Insulating Layer Formation
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Solution Overview
Problem
Conventional methods for forming ceramic layers on negative electrodes in secondary batteries create gaps that are blocked by ceramic particles, disrupting ion movement paths and compromising insulating reliability.
Innovation Solution
A method where an active material mixture slurry and an insulating layer dispersion liquid are concurrently applied to the electrode foil, forming a mixture layer and an insulating layer with plate-shaped ceramic particles that maintain ion movement paths by ensuring the particle size of the mixture particles is larger than the ceramic particles, preventing blockage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ceramic layer is formed on the negative electrode mixture layer through sequential steps, then insulating reliability is improved, but ion movement paths are blocked by ceramic particles entering the gaps between mixture particles
Solution Approach 1:
The patent combines the formation of the active material mixture layer and the insulating layer into a single concurrent coating step. The slurry for the active material mixture layer and the dispersion liquid for the insulating layer are applied simultaneously to the electrode foil, ensuring that insulating particles are distributed on the surface without penetrating into the gaps between active material particles, thus maintaining ion movement paths while providing insulation.
Solution Approach 2:
The patent uses plate-shaped insulating particles with a specific aspect ratio (a/d ≥ 2.0) that are applied in advance to form an insulating layer on the surface of the active material mixture layer. The preliminary selection of particle shape and size prevents ceramic particles from entering the gaps between mixture particles during the coating process, thereby preserving ion movement paths while establishing insulation.
2Reliability
If ceramic particles are used to form an insulating layer, then short-circuit prevention is improved, but the performance of the active material mixture layer is degraded due to blockage of ion movement paths
Solution Approach 1:
The patent applies insulating particles with specific local characteristics (plate shape, aspect ratio ≥ 2.0, size smaller than active material particles) to the surface of the active material mixture layer. This localized application ensures that insulation is provided only where needed for short-circuit prevention, while the gaps between active material particles remain open for ion transport, thus maintaining power output characteristics.
Solution Approach 2:
The patent changes the physical parameters of the insulating particles, specifically using plate-shaped particles with an aspect ratio (a/d) of 2.0 or more. This parameter change ensures that the insulating particles lie flat on the surface of the active material mixture layer rather than penetrating into the gaps between particles, thereby preventing short-circuits while maintaining ion movement paths and output characteristics.
3Reliability
If conventional sequential coating method is used, then insulating layer formation is achieved, but manufacturing complexity increases and productivity decreases
Solution Approach 1:
The patent merges the coating processes for the active material mixture layer and the insulating layer into a single concurrent operation. Both layers are formed in one step by simultaneously applying the slurry and dispersion liquid, eliminating the need for separate coating and drying steps, thus simplifying the manufacturing process and improving productivity while ensuring proper insulating layer formation.
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 approach enhances insulating reliability and maintains electrode performance by securing ion movement paths for lithium ions, improving output characteristics and reducing the risk of short-circuits.
Implementation Method 1
each insulating particle has a plate shape, and provided that the thickness of each insulating particle is d and the length of the long side of each insulating particle is a, the aspect ratio a/d of each insulating particle is greater than or equal to 2.0 and less than or equal to 5.0, and the particle size of each of mixture particles forming the active material mixture is greater than the length of the long side of each insulating particle
Implementation Method 2
concurrently applying to the electrode foil an active material mixture slurry containing an active material mixture to form the active material mixture layer, and an insulating layer dispersion liquid containing insulating particles to form the insulating layer
Data Source
AI summary
An object of the present invention is to provide a method for manufacturing a secondary battery with enhanced insulating reliability without degrading the performance of an active material mixture layer formed on an electrode. The present invention provides a method for manufacturing a prismatic secondary battery (100) including a negative electrode (41) having a negative electrode current-collecting foil (411), a negative electrode mixture layer (412) formed thereon, and an insulating layer (413) formed on the negative electrode mixture layer (412). The method of the present invention includes a step of forming the negative electrode mixture layer (412) and the insulating layer (413) by concurrently applying an active material mixture slurry and an insulating layer dispersion liquid to the negative electrode current-collecting foil (411). Each ceramic particle (413a) has a plate shape with an aspect ratio greater than or equal to 2.0 and less than or equal to 5.0. The particle size of each mixture particle (412a) is greater than the length of the long side of each ceramic particle (413a).