Negative Electrode Binder Complexation for Lithium Ion Mobility
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Solution Overview
Problem
Lithium ion batteries with polyvinylidene fluoride as a negative electrode binder face challenges in achieving high input and output characteristics due to limited lithium ion mobility and diffusion, leading to poor cycle characteristics and difficulty in increasing active material layer thickness or volume density, especially when ceramic particles with large primary sizes are used.
Innovation Solution
Incorporating nano ceramic particles with a primary particle size of not more than 100 nm into the negative electrode active material layer, where the binder and ceramic particles are complexed, enhances lithium ion mobility and electron conduction, improving the battery's input and output density and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If polyvinylidene fluoride is used as a negative electrode binder to enhance lithium ion mobility, then input and output characteristics are improved, but when the negative electrode is highly filled and discharged at larger current, metallic lithium deposits on the negative electrode, lowering cycle characteristics
Solution Approach 1:
The patent uses a composite binder system combining polyvinylidene fluoride with polyacrylonitrile in a specific weight ratio (0.1 to 10 parts by weight of polyacrylonitrile per 100 parts by weight of polyvinylidene fluoride). This composite structure leverages the high lithium ion mobility of polyvinylidene fluoride while using polyacrylonitrile to provide structural stability and prevent excessive lithium deposition, thereby resolving the contradiction between power output and cycle reliability
Solution Approach 2:
The patent optimizes the weight ratio parameters of the binder components, specifically setting polyacrylonitrile at 0.1 to 10 parts by weight per 100 parts by weight of polyvinylidene fluoride. This parameter optimization balances the lithium ion conductivity enhancement from polyvinylidene fluoride with the structural stability provided by polyacrylonitrile, preventing metallic lithium deposition while maintaining high input and output characteristics
2Quantity of substance
If the thickness of the active material layer is increased to increase volume density, then energy density is improved, but lithium ion diffusion becomes slower, impairing input and output characteristics
Solution Approach 1:
The composite binder system of polyvinylidene fluoride and polyacrylonitrile creates a dual-function matrix that maintains high lithium ion conductivity throughout the electrode thickness. Polyvinylidene fluoride provides rapid lithium ion transport pathways that penetrate through thicker active material layers, while polyacrylonitrile ensures structural integrity, enabling increased volume density without sacrificing lithium ion diffusion speed
3Power
If ceramic particles are added to enhance lithium diffusibility and reduce internal resistance, then input and output characteristics are improved, but if the primary particle size is too large, ion diffusion is inhibited and electron conduction is blocked
Solution Approach 1:
The patent specifies that ceramic particles must have a primary particle size of not more than 10 μm to ensure they can be properly dispersed within the binder matrix and active material layer. This size constraint ensures that ceramic particles provide localized lithium ion diffusion enhancement without creating large barriers that would inhibit overall ion transport or block electron conduction pathways, maintaining both power characteristics and cycle reliability
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 complexation of nano ceramic particles with the binder in the negative electrode active material layer increases lithium ion mobility, enabling high input and output densities and excellent cycle characteristics, even at high current levels, by optimizing ion diffusion and electron conduction.
Implementation Method 1
the binder and the nano ceramic particle are complexed
Implementation Method 2
enhances the diffusibility of a lithium ion, thereby reducing an internal resistance of the negative electrode
Implementation Method 3
electron conduction between active materials or conductive materials is inhibited
Data Source
AI summary
A non-aqueous electrolyte battery includes a positive electrode, a negative electrode having a negative electrode active material layer provided on a negative electrode collector and a non-aqueous electrolyte, wherein the negative electrode active material layer contains a polyvinylidene fluoride-containing binder and a nano ceramic particle having a primary particle size of not more than 100 nm; and the binder and the nano ceramic particle are complexed.