Lithium Battery Negative Electrode Particle Gradient for Ion Transport
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving long battery life due to inefficient lithium ion migration and uneven reactivity between the negative electrode and the electrolyte solution.
Innovation Solution
A negative electrode for lithium secondary batteries is designed with a current collector and a negative electrode active material layer, where the layer is divided into two regions with 50% thickness each, containing two or more types of negative electrode active materials with different D50 particle sizes, optimizing the pore structure and ensuring uniform particle size distribution across the layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single type of negative electrode active material is used in the negative electrode active material layer, then the manufacturing process is simple, but the pore structure cannot be optimized and lithium ion migration is inefficient
Solution Approach 1:
The negative electrode active material layer is divided into two distinct regions: a first region adjacent to the current collector and a second region adjacent to the electrolyte solution interface. Each region contains negative electrode active materials with different D50 particle sizes, creating optimized pore structures in each zone to enhance lithium ion migration efficiency throughout the layer.
Solution Approach 2:
Different regions of the negative electrode active material layer are assigned different material compositions tailored to their specific functions. The first region near the current collector uses materials with specific D50 values optimized for electron collection, while the second region near the electrolyte interface uses materials with different D50 values optimized for lithium ion insertion and reaction with the electrolyte solution.
2Reliability
If the negative electrode active material layer has uniform composition throughout, then the manufacturing process is simple, but the reactivity between the negative electrode and electrolyte solution is uneven
Solution Approach 1:
The negative electrode active material layer is segmented into two regions with different material compositions. The first region contains negative electrode active materials with specific D50 particle sizes optimized for structural stability and electron collection, while the second region contains materials with different D50 particle sizes optimized for high reactivity with the electrolyte solution, ensuring uniform and controlled reactions throughout the battery operation.
Solution Approach 2:
Each region of the negative electrode active material layer is given localized material properties suited to its functional requirements. The first region near the current collector focuses on electrical conductivity and structural integrity, while the second region near the electrolyte interface focuses on chemical reactivity and lithium ion exchange efficiency, achieving reliable and uniform battery performance.
3Quantity of substance
If larger particle size materials are used in the negative electrode active material layer, then the energy density is high, but the pore structure is poor and lithium ion migration is hindered
Solution Approach 1:
The negative electrode active material layer is divided into two regions with different particle size distributions. The first region contains materials with larger particle sizes that provide high energy density and structural stability, while the second region contains materials with smaller particle sizes that create optimized pore structures for efficient lithium ion migration, achieving both high capacity and fast ion transport.
Solution Approach 2:
Different particle size characteristics are assigned to different regions of the negative electrode active material layer. The first region near the current collector uses larger particle size materials optimized for energy storage capacity, while the second region near the electrolyte interface uses smaller particle size materials optimized for creating pore structures that facilitate rapid lithium ion migration and reaction efficiency.
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
This design enhances lithium ion migration and reactivity, leading to improved battery life and performance by maintaining high energy density and uniform reaction control within the negative electrode active material layer.
Implementation Method 1
optimizing the pore structure that serves as a material movement path in the negative electrode active material layer, it is possible to improve not only migration of lithium ions
Implementation Method 2
improve not only migration of lithium ions but also reactivity between the negative electrode and an electrolyte solution including lithium
Data Source
AI summary
A negative electrode for a secondary battery includes a current collector and a negative electrode active material layer provided on at least one surface of the current collector. The negative electrode active material layer includes a first region corresponding to 50% of a total thickness of the negative electrode active material layer from a surface facing the current collector and a second region corresponding to 50% of the total thickness of the negative electrode active material layer from a surface opposite to the surface facing the current collector. The negative electrode active material layer includes two or more types of negative electrode active materials having D50 different from each other and satisfies the Equations 1 and 2. A secondary battery including the negative electrode is also provided.