Negative Electrode Coatability via Ceramic Particle Aspect Ratio
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Solution Overview
Problem
The production of lithium ion secondary battery negative electrodes faces challenges in achieving satisfactory coatability of the paste and high peel strength and hardness of the active material layer, which affects the mechanical strength and cycle characteristics of the battery.
Innovation Solution
A method involving coating a negative electrode paste containing a negative electrode active material and ceramic particles with an aspect ratio of 1.5 or more and 20 or less on a current collector, followed by drying and pressing, where the ceramic particles are present in 3% to 20% by mass, ensuring improved coatability and increased peel strength and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ceramic particles are added to improve peel strength and hardness, then the mechanical strength and cycle characteristics are improved, but the paste coatability deteriorates due to increased viscosity
Solution Approach 1:
The patent applies parameter changes by precisely controlling the aspect ratio of ceramic particles (within 1.05 to 5.0) and their content (3-20 mass%). By optimizing these parameters, the invention achieves a balance where ceramic particles provide sufficient mechanical reinforcement without causing excessive viscosity increase that would impair paste coatability
Solution Approach 2:
The patent creates a composite material system by combining negative electrode active material with ceramic particles having specific aspect ratios. This composite structure allows the ceramic particles to effectively fill gaps and reinforce the electrode layer while maintaining compatibility with the paste formulation for satisfactory coatability
2Strength
If ceramic particles with high aspect ratio are used to increase peel strength, then the hardness is improved, but the paste viscosity increases excessively reducing coatability
Solution Approach 1:
The patent applies parameter changes by setting specific bounds for the aspect ratio of ceramic particles (1.05 to 5.0) and their content (3-20 mass%). This parameter optimization ensures that the ceramic particles provide sufficient hardness enhancement without causing excessive viscosity increase that would impair paste coatability
Data Source
AI summary
Provided is a method for producing a negative electrode by using a negative electrode active material and ceramic particles, the method ensuring satisfactory coatability of the paste and high peel strength and hardness of the obtained negative electrode active material layer. The method for producing a negative electrode disclosed herein includes a step of coating a negative electrode paste including a negative electrode active material and ceramic particles on a negative electrode current collector; a step of drying the coated negative electrode paste to form a negative electrode active material layer; and a step of pressing the negative electrode active material layer. The ceramic particles have an aspect ratio of 1.5 or more and 20 or less. The ceramic particles have a short side length of ⅕ or less of an average particle diameter of the negative electrode active material. In the negative electrode paste, the ceramic particles are contained in an amount of 3% by mass to 20% by mass based on a total solid content of the negative electrode paste.