Two-Layer Silicon-Carbon Anode Orientation for Fast Charging
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Solution Overview
Problem
Conventional lithium secondary batteries face limitations in energy density, rapid charging performance, and lifespan due to the use of graphite-based negative electrode materials, which have low capacity and slow lithium insertion rates, leading to prolonged charging times and reduced efficiency.
Innovation Solution
A negative electrode comprising a two-layer structure with a first carbon-based active layer and a second layer containing a silicon-based active material, optimized through specific orientation indices and controlled particle sizes, along with a magnetic field application to enhance lithium mobility and adhesion, is developed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based negative electrode active material is used to increase charge and discharge capacity, then the capacity is improved, but the lifespan and rapid discharge efficiency deteriorate due to large volume changes and poor high-rate discharge characteristics
Solution Approach 1:
The patent uses a composite structure combining silicon-based negative electrode active material with carbon-based negative electrode active material. The silicon-based material (e.g., silicon, silicon oxide, silicon carbide) provides high capacity, while the carbon-based material (e.g., graphite, amorphous carbon) provides structural stability and conductivity. This composite approach allows the electrode to achieve high charge and discharge capacity while maintaining good lifespan and rapid discharge characteristics through the synergistic effects of the two materials.
2Reliability
If graphite-based negative electrode active material is used, then the structure is stable, but the energy density and rapid charging performance are limited due to low capacity and slow lithium insertion rates
Solution Approach 1:
The patent combines graphite-based carbon material with silicon-based material to create a composite negative electrode. The graphite provides structural stability and good lithium insertion/extraction characteristics, while the silicon-based material contributes high capacity and enables rapid charging. This composite structure overcomes the limitations of pure graphite by incorporating silicon's high capacity while maintaining graphite's structural advantages.
Solution Approach 2:
The patent applies local quality by creating a heterogeneous structure where different materials are distributed in specific regions of the negative electrode. The silicon-based material is dispersed within the carbon-based matrix, allowing local areas to provide high capacity while the overall structure maintains stability. This local optimization enables both high energy density and structural reliability.
3Speed
If the negative electrode active layer is designed to improve rapid charging performance, then the charging speed is improved, but the charge and discharge capacity may be reduced
Solution Approach 1:
The patent uses a composite of silicon-based and carbon-based materials where silicon provides rapid lithium insertion/extraction capabilities for fast charging, while the carbon-based material ensures sufficient capacity. The synergistic combination allows the electrode to achieve both rapid charging performance and high charge and discharge capacity simultaneously.
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 electrode achieves high charge and discharge capacity, rapid charging capabilities, and improved lifespan characteristics, enabling charging in a short time with enhanced safety and efficiency.
Implementation Method 1
applying magnetic field to the applied negative electrode slurry
Data Source
AI summary
A negative electrode may include a two-layer structure negative electrode active layer on a negative electrode current collector. The second negative electrode active layer may be an upper layer, may include a carbon-based negative electrode active material and a silicon-based negative electrode active material in a predetermined content ratio, and may have a high charge and discharge capacity by adjusting an orientation index (O.I) of the first negative electrode active layer., The first negative electrode active layer may be a lower layer and may have a ratio (O.I1st/O.I2nd) of the first negative electrode active layer and the second negative electrode active layer to a predetermined range. In addition, a lithium secondary battery comprising the same may have the advantage of having excellent output characteristics and can be charged in a short time even at a 1C-rate.