Intermediate Layer CMC Binder for Battery Short Circuit Protection
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face heat generation issues due to short circuits caused by external inputs, which can lead to excessive heat and potential battery failure, primarily because the positive electrode current collector's low electrical resistance exposes it to the negative electrode, leading to high short-circuit currents.
Innovation Solution
Incorporating an intermediate layer between the positive electrode current collector and active material layer, composed of carboxymethylcellulose (CMC), a conductive material, and an inorganic filler, where CMC burns away upon external input rather than carbonizing, increasing the layer's electrical resistance and mitigating short-circuit currents and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an intermediate layer with high electrical resistance is disposed between the positive electrode current collector and positive electrode active material layer, then the positive electrode current collector is protected from exposure and contact with the negative electrode, but the current flow between the positive electrode current collector and positive electrode active material layer during normal operation is interfered with, degrading battery performance
Solution Approach 1:
The patent applies parameter changes by carefully controlling the electrical resistance of the intermediate layer within a specific range (10^-3 to 10^3 Ω·cm) to balance two opposing requirements: high enough to prevent short circuits when the active material layer detaches, but low enough to allow sufficient current flow during normal operation. This optimal resistance range resolves the contradiction between safety and performance
Solution Approach 2:
The patent uses composite materials by combining the intermediate layer with specific compositions (including conductive materials and binders) to achieve the desired electrical resistance properties. The composite structure allows the layer to function both as a protective barrier and as a conductor during normal operation, resolving the contradiction between protection and current flow
2Object-generated harmful factors
If the electrical resistance of the intermediate layer is increased by increasing the content of inorganic filler, then the short-circuit current is reduced, but the current flow during normal operation is further interfered with
Solution Approach 1:
The patent applies parameter changes by precisely controlling the electrical resistance of the intermediate layer within an optimal range (10^-3 to 10^3 Ω·cm) that balances two opposing requirements: high enough to prevent short circuits when the active material layer detaches, but low enough to allow sufficient current flow during normal operation. This optimal resistance range resolves the contradiction between safety and performance
Solution Approach 2:
The patent uses composite materials by combining the intermediate layer with specific compositions (including conductive materials and binders) to achieve the desired electrical resistance properties. The composite structure allows the layer to function both as a protective barrier and as a conductor during normal operation, resolving the contradiction between protection and current flow
3Ease of manufacture
If conventional binder materials are used in the intermediate layer, then the layer provides adequate binding, but upon external input the binder carbonizes and forms conduction paths, increasing short-circuit current and heat generation
Solution Approach 1:
The patent applies parameter changes by selecting binder materials with specific properties (such as carboxymethylcellulose with controlled decomposition characteristics) that prevent carbonization and conduction path formation upon external input, while still providing adequate binding functionality during normal operation
Solution Approach 2:
The patent converts the potential harm of binder carbonization into a benefit by using binder materials that decompose in a controlled manner upon external input, preventing the formation of conductive carbon paths. The decomposition products are non-conductive, thereby preventing short circuits and heat generation that would otherwise occur with conventional carbonizing binders
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 intermediate layer effectively reduces heat generation during external inputs by preventing conduction path formation and consuming oxygen, thereby decreasing combustion reactions and maintaining battery performance.
Implementation Method 1
CMC, a conductive material, and an inorganic filler... where CMC burns away upon external input rather than carbonizing, increasing the layer's electrical resistance
Implementation Method 2
consuming oxygen, thereby decreasing combustion reactions and maintaining battery performance
Data Source
AI summary
A non-aqueous electrolyte secondary battery includes at least a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes a positive electrode current collector, an intermediate layer, and a positive electrode active material layer. The intermediate layer is interposed between the positive electrode current collector and the positive electrode active material layer. The intermediate layer contains at least carboxymethylcellulose, a conductive material, and an inorganic filler.