Multi-layered Battery Electrode with High Crystallinity Binder
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Solution Overview
Problem
Rechargeable batteries, particularly lithium batteries, face stability issues due to rapid heat generation and potential ignition or explosion from needle-shaped penetration, which is exacerbated by local short-circuits and high energy density, leading to safety concerns and increased costs with existing solutions.
Innovation Solution
A multi-layered electrode structure is developed using a binder with high crystallinity (≥58%) in the first layer and a lower crystallinity binder in the second layer, reducing the elongation percentage and short-circuit area, thereby enhancing safety without additional materials or processes, by adjusting the drying temperature of the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a material having high heat conductivity or fire-proof material is adhered to a pouch to prevent overheating or ignition, then battery stability is improved, but manufacturing complexity and cost increase, and battery volume increases
Solution Approach 1:
The invention merges the safety function into the electrode structure itself by creating a multi-layered electrode where the second electrode composite layer acts as an intrinsic safety barrier. This eliminates the need for separate fire-proof materials adhered to the pouch, as the electrode layers themselves provide the penetration resistance and thermal management functionality.
Solution Approach 2:
The electrode structure provides its own safety function through the multi-layered configuration. The second electrode composite layer with different binder crystallinity self-regulates the penetration process, creating resistance to needle-shaped objects and preventing direct contact with the current collector without requiring external safety components or additional manufacturing processes.
2Reliability
If a material having high heat conductivity or fire-proof material is adhered to a pouch to prevent overheating or ignition, then battery stability is improved, but battery volume increases and capacity per unit volume decreases
Solution Approach 1:
The safety functionality is merged into the existing electrode structure rather than being added as a separate component. The multi-layered electrode configuration uses the electrode layers themselves to provide penetration resistance and thermal management, eliminating the need for additional volume-consuming fire-proof materials.
3Reliability
If the binder crystallinity is increased to reduce elongation percentage and short-circuit area, then battery stability is improved, but electrode flexibility and output characteristics may deteriorate
Solution Approach 1:
The invention applies local quality by using binders with different crystallinity values in different layers of the electrode. The first electrode composite layer uses a binder with crystallinity of 40-55% to maintain flexibility and output characteristics, while the second electrode composite layer uses a binder with crystallinity of 55-70% to provide penetration resistance and reduce elongation. This spatial differentiation of material properties allows the electrode to simultaneously achieve both flexibility and stability.
Solution Approach 2:
The multi-layered electrode structure combines materials with different binder crystallinity values to create a composite system that exhibits both the flexibility needed for electrode operation and the resistance needed for safety. The combination of PVdF-based binder (lower crystallinity) and CMC-based binder (higher crystallinity) in different layers creates a composite structure that balances opposing requirements.
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 multi-layered electrode design effectively reduces the short-circuit area and heat generation during needle-shaped penetration, enhancing the safety of rechargeable batteries while maintaining output characteristics, and is manufactured using existing materials and processes, thus improving safety and efficiency.
Implementation Method 1
a first binder, and a second binder, wherein crystallinity of the first binder is 58 or greater
Implementation Method 2
the local short-circuit causes an excessive current to flow, and the current causes heat generation
Data Source
AI summary
An electrode for a rechargeable battery in which a current collector is coated with an electrode mixture including an electrode active material and a binder includes a first electrode composite layer including PVdF as a first binder and an electrode active material and applied on a current collector; and a second electrode composite layer including a second binder and an electrode active material and applied on the first electrode composite layer, wherein crystallinity of the first binder is 58 or greater.