Negative Electrode Active Material Layer Sphericity Control
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Solution Overview
Problem
Current secondary batteries face challenges in maintaining high adhesive strength between the negative electrode active material layer and the current collector while ensuring high battery capacity, as increasing binder or additive content reduces active material particle content.
Innovation Solution
A negative electrode comprising first particles with high sphericity and oxygen content, second particles with lower sphericity, and third particles, all with specific sphericity and oxygen shell thickness, are used in a controlled weight ratio to enhance electrode packing and adhesive strength, preventing deintercalation and improving battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If binder or additive content is increased to improve adhesive strength, then adhesive strength between active material and current collector is improved, but active material particle content decreases leading to reduced battery capacity
Solution Approach 1:
The invention changes the physical parameters of the active material particles by controlling sphericity (0.90-0.98) and oxygen content (0.5-2.0 mmol/g) to achieve both high adhesive strength and high active material content, eliminating the need for excessive binder or additive content
Solution Approach 2:
The invention creates a composite structure where graphite particles are coated with an oxygen-containing layer, combining the high capacity of graphite with the adhesive benefits of oxygen-containing groups, thereby achieving both strong adhesion and high active material content without requiring additional binders
2Manufacturing precision
If spherical particles with high sphericity are used to improve packing density, then electrode packing is improved, but particle shape uniformity increases which may reduce adhesive diversity
Solution Approach 1:
The invention applies local quality by maintaining uniform high sphericity (0.90-0.98) for overall packing density while introducing localized oxygen-containing groups on the particle surface to provide adhesive functionality, thus achieving both good packing and strong adhesion
Data Source
AI summary
A negative electrode according to one embodiment of the present invention includes a current collector and a negative electrode active material layer disposed on the current collector, wherein the negative electrode active material layer includes a first particle and a second particle, the first particle includes a first core including artificial graphite; and a first shell disposed on the first core and including an oxide of the artificial graphite, sphericity of the first particle measured through a particle shape analyzer is from 0.94 to 0.98, the second particle is artificial graphite having sphericity measured through the particle shape analyzer of 0.70 to 0.92, and a weight ratio of the first particle and the second particle is from 1:1 to 1:9.