Silicon Anode Sheet Binder Particle Sizing for Cycle Stability
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Solution Overview
Problem
Lithium-ion batteries face challenges with severe volume expansion of silicon-based materials during cycling, leading to poor cycle performance and rate performance, which limits their commercial application in high-energy density applications.
Innovation Solution
A negative electrode sheet is designed with a silicon-based material and a binder having an average-volume particle diameter of 0.1-0.8 μm, which enhances binding force, suppresses volume expansion, and maintains stability, thereby improving energy density and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based material is used as negative electrode active material to improve energy density, then the theoretical specific capacity increases, but severe volume expansion occurs during cycling leading to poor cycle performance
Solution Approach 1:
The patent changes the particle size parameter of the binder to 0.1-0.8 μm (specifically 0.3-0.6 μm in some embodiments), which optimizes the binding force and suppresses volume expansion of silicon-based material during cycling, thereby improving cycle performance while maintaining high energy density
Solution Approach 2:
The patent creates a composite negative electrode film layer combining silicon-based active material with specifically sized binder particles, where the composite structure allows the binder to effectively bind silicon particles and suppress their volume expansion, achieving both high energy density and good cycle performance
2Device complexity
If conventional binder particle size is used, then the electrode structure is simple, but the binding force is insufficient to suppress severe volume expansion of silicon-based material
Solution Approach 1:
The patent optimizes the binder particle size parameter to 0.1-0.8 μm, which enhances the binding force between binder and silicon-based material, effectively suppressing volume expansion during cycling while maintaining a relatively simple electrode structure
3Reliability
If binder content is increased to improve binding force, then volume expansion is suppressed, but energy density decreases due to excessive binder use
Solution Approach 1:
The patent optimizes binder particle size to 0.1-0.8 μm, which enhances the specific binding efficiency, allowing sufficient binding force to suppress volume expansion while minimizing the total binder content required, thus maintaining high energy density and good cycle performance
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 solution results in a battery with high energy density, power, and good cycle performance by effectively binding the silicon-based material, reducing expansion, and maintaining electrical contact.
Implementation Method 1
A binder whose average-volume particle diameter Dv50 is 0.1-0.8 μm is added to the negative electrode film layer, to not only increase active binding sites, but also effectively fill and bind a large pore region of the electrode sheet
Data Source
AI summary
Disclosed are a negative electrode sheet, a battery cell, a battery, and an electric device. The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one side of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material and a binder, and the negative electrode active material includes a silicon-based material. An average-volume particle diameter Dv50 of the binder is 0.1-0.8 μm. The battery has relatively high energy density, power, and relatively good cycle performance.