Multilayer Battery Anode Structure for Fast Charging and Adhesion
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Solution Overview
Problem
Existing lithium secondary batteries face limitations in achieving high output characteristics, rapid charging capabilities, and stable lifespan due to the use of graphite-based negative electrodes with low interlayer distance, limited lithium ion intercalation sites, and poor particle orientation, leading to decreased adhesion between the current collector and the negative electrode active material layer.
Innovation Solution
A negative electrode with a multilayer structure featuring a first and second active material layer, where the second layer comprises bimodal active material with smaller particles, enhancing adhesion and allowing for high rolling density without decreasing capacity, and incorporating silicon oxide-based active materials to maximize lithium ion chargeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite is used as negative electrode material, then cost and service lifespan are improved, but capacity is limited to 372 mAh/g due to small interlayer distance and few lithium ion intercalation sites
Solution Approach 1:
The patent uses a composite material structure combining graphite particles with silicon oxide-based active materials. The graphite provides structural stability and long service lifespan, while the silicon oxide-based materials contribute additional capacity, achieving a composite electrode that exceeds the 372 mAh/g limitation of pure graphite.
Solution Approach 2:
The patent applies local quality by creating a core-shell structure where graphite forms the outer layer providing structural integrity and silicon oxide-based materials are positioned in the inner layer providing high capacity. This spatial differentiation allows each material to发挥 its optimal properties locally.
2Ease of manufacture
If graphite with plate-like structure is used, then manufacturing is simplified, but intercalation rate of lithium ions is slow due to low packing density and poor particle orientation
Solution Approach 1:
The patent changes the particle size parameter of the active materials, using smaller particle sizes (D50: 3-15 μm) to increase packing density and improve particle orientation during electrode manufacturing. This parameter change enables both ease of manufacture and high intercalation rates by facilitating better particle arrangement and lithium ion access.
3Volume of stationary object
If high rolling density is achieved, then electrode density is improved, but adhesion between current collector and negative electrode active material layer decreases under rapid charging conditions
Solution Approach 1:
The patent applies local quality by using smaller particle sizes (D50: 3-15 μm) specifically in the region contacting the current collector, which improves adhesion through better surface contact and mechanical interlocking. The core-shell structure also positions materials optimally to maintain adhesion under rapid charging conditions while achieving high rolling density.
4Productivity
If particle size is reduced to improve adhesion and packing density, then rapid charging characteristics are improved, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent changes the particle size parameter to a specific range (D50: 3-15 μm) that balances rapid charging performance with manufacturability. This parameter optimization ensures fast lithium ion diffusion while maintaining reasonable manufacturing precision through controlled particle size distribution.
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 enables improved rapid charging characteristics and stable lifespan with increased capacity retention rates under high charging conditions, maintaining adhesion between the current collector and the negative electrode active material layer.
Implementation Method 1
a lithium secondary battery having a high energy density and voltage, a long cycle lifespan, and a low discharge rate has been widely used. The lithium secondary battery is a secondary battery that includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator, and an electrolyte and is charged and discharged by intercalation-desorption of lithium ions.
Data Source
AI summary
A negative electrode for a secondary battery includes: a current collector; a first negative electrode active material layer formed on the current collector and containing a first active material; and a second negative electrode active material layer formed on the first negative electrode active material layer and containing a second active material. The second active material is a bimodal active material including small particles and large particles having different particle sizes, a particle size (D2) of the second active material is smaller than a particle size (D1) of the first active material, and the particle size of the second active material is an average particle size of the small particles and the large particles.