Silicon Negative Electrode Binding Agent Expansion Control
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Solution Overview
Problem
Lithium ion secondary batteries using silicon-containing materials face challenges in suppressing negative electrode expansion, improving cycle characteristics, and ensuring process suitability due to limitations in binding agents used in existing technologies.
Innovation Solution
A negative electrode with a binding agent composition that includes a fluorine-containing resin and a polyacrylic acid metal salt, where the total amount of these components is between 10 to 30 parts by mass based on 100 parts by mass of the negative electrode active material, effectively addressing expansion and cycle characteristic issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-containing material is used as negative electrode active material to increase theoretical charging capacity, then energy density is improved, but negative electrode expansion occurs and cycle characteristics deteriorate
Solution Approach 1:
The patent uses a composite binding agent system combining fluorine-containing resin (5-20 parts by mass) and polyacrylic acid metal salt (5-20 parts by mass) to address the expansion issue of silicon-containing materials. This composite approach leverages the complementary properties of both materials: the fluorine-containing resin provides flexibility and expansion accommodation, while the polyacrylic acid metal salt provides strong adhesion and structural stability, thereby maintaining cycle characteristics while enabling high energy density
2Use of energy by moving object
If silicon-containing material is used as negative electrode active material to increase theoretical charging capacity, then energy density is improved, but negative electrode expansion occurs
Solution Approach 1:
The patent changes the chemical composition parameters of the binding agent by incorporating fluorine-containing resin and polyacrylic acid metal salt in specific proportions (each 5-20 parts by mass based on 100 parts by mass of active material). This parameter optimization allows the binding agent to accommodate the volume expansion of silicon during lithium insertion while maintaining electrode integrity, thus preventing negative electrode expansion issues
3Ease of manufacture
If conventional binding agents are used in negative electrode to maintain structural integrity, then process suitability is maintained, but cycle characteristics and expansion suppression are insufficient
Solution Approach 1:
The patent employs a composite binding agent system combining fluorine-containing resin and polyacrylic acid metal salt in specific proportions. This composite formulation maintains process suitability through proper slurry formulation and coating processes while significantly improving cycle characteristics through the synergistic effects of both binding agents - the fluorine-containing resin provides flexibility and the polyacrylic acid metal salt provides strong adhesion
Data Source
AI summary
Provided is a battery including a positive electrode, a negative electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material layer including a negative electrode active material and a binding agent. The negative electrode active material includes a silicon-containing material. The binding agent includes a fluorine-containing resin and a polyacrylic acid metal salt. A total amount of the fluorine-containing resin and the polyacrylic acid metal salt is 10 parts by mass to 30 parts by mass on the basis of 100 parts by mass of the negative electrode active material.