Silicon-Based Negative Electrode Plate for Long-Cycle Fast Charging
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving high energy density and long cycle life due to the introduction of silicon oxide particles, which can lead to decreased cycling performance and uneven lithium intercalation, causing polarization and reduced charging time.
Innovation Solution
A negative electrode plate with a specific design incorporating silicon-based material particles, such as silicon oxide and silicon carbide, is developed, where the particles meet certain size and distribution criteria to enhance cycling stability and energy density, including a moderate particle size and shape to minimize stress and strain, and a controlled specific surface area to reduce side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon oxide particles are added to increase energy density, then the battery capacity increases, but the cycling performance deteriorates
Solution Approach 1:
The patent uses composite silicon oxide particles formed by sintering silicon fine particles with silicon oxide particles. This composite structure combines the high capacity of silicon oxide with the stability of sintered aggregates, achieving both high energy density and improved cycling performance. The sintered composite particles prevent excessive expansion while maintaining lithium insertion/extraction capabilities.
Solution Approach 2:
The patent controls the particle size distribution and composition ratio of silicon oxide particles. By adjusting the average particle size to 3-10 μm and controlling the sintering temperature and atmosphere, the patent optimizes the balance between capacity and cycling stability. The specific surface area is controlled to reduce side reactions while maintaining adequate reaction sites.
2Quantity of substance
If silicon oxide particles are added to increase gram capacity, then the energy density increases, but the uniformity of lithium intercalation deteriorates
Solution Approach 1:
The patent creates local quality variations by forming sintered composite particles with specific internal structures. The sintering process creates regions with different densities and lithium diffusion pathways within each particle, allowing uniform lithium intercalation across the entire electrode while maintaining high local capacity.
Solution Approach 2:
The patent segments the silicon oxide material into fine particles (3-10 μm) and further segments them into sintered aggregates. This segmentation reduces the overall surface area while maintaining adequate lithium diffusion paths, preventing concentration polarization and improving uniformity of lithium intercalation across the electrode.
3Productivity
If large rate charging is performed to reduce charging time, then the charging speed increases, but lithium deposition occurs
Solution Approach 1:
The patent changes the electrochemical parameters by using silicon oxide particles with specific particle size (3-10 μm) and surface area. These parameter changes shift the lithium intercalation potential to higher values, creating a larger potential difference between silicon oxide and graphite that prevents lithium deposition during fast charging while maintaining high charging speed.
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 lithium-ion battery with improved high energy density and long cycle life, along with enhanced fast charging performance and reduced risk of lithium deposition, maintaining performance under various charging conditions.
Implementation Method 1
silicon oxide particles have a relatively amorphous structure and have an alloy-type lithium storage mode
Implementation Method 2
silicon oxide particles have more lithium intercalation channels
Implementation Method 3
the negative electrode plate has a shorter liquid-phase lithium-ion diffusion path
Data Source
AI summary
Disclosed are a negative electrode plate and a lithium-ion battery including the negative electrode plate. The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is disposed on at least one surface of the negative electrode current collector, the negative electrode active material layer includes silicon-based material particles, and the silicon-based material particles include silicon oxide and/or silicon carbide; and the silicon-based material particles meet the following relationship: Di≤35 μm (I), di≤25 μm (II), 0.45≤(ΣEj2)/(ΣDi2)≤0.75 (III), and (ΣFk2)/(ΣDi2)≥0.37 (IV), and a mixing amount of the silicon-based material particles meets the following relationship: 0.05≤(ΣFk2)/S≤0.47 (V). The lithium-ion battery disclosed in the present disclosure has characteristics of high energy density and a long cycle life.