Positive Electrode Hydrated Oxide Coating for Lower Battery Heat
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Solution Overview
Problem
Conventional non-aqueous electrolyte secondary batteries face heat generation issues due to external inputs, such as nail penetration, which can cause short circuits and increase battery resistance when using aluminum hydrated oxide films, as they may crack and expose the underlying aluminum foil, leading to excessive heat generation.
Innovation Solution
A positive electrode with an aluminum hydrated oxide film containing a mixture of boehmite and other aluminum hydrated oxides, such as diaspore, bayerite, and gibbsite, is used, with a thickness between 50 nm and 500 nm, and a boehmite ratio between 20 mol% and 80 mol%, to enhance flexibility and mitigate heat generation while minimizing battery resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aluminum hydrated oxide film is formed on the aluminum foil to improve adhesion and alkaline resistance, then the adhesion between current collector and active material layer is improved, but the film may crack under external impact and expose the aluminum foil, leading to increased heat generation
Solution Approach 1:
The patent applies composite materials by creating an aluminum hydrated oxide film containing multiple polymorphs (boehmite, diaspore, bayerite, gibbsite) in specific ratios. This composite structure provides both strong adhesion and crack resistance, preventing the film from breaking under external impact while maintaining its protective function.
Solution Approach 2:
The patent changes the compositional parameters of the aluminum hydrated oxide film by controlling the ratio of different polymorphs. Specifically, it specifies that boehmite should be 20-80 mol%, diaspore 10-50 mol%, bayerite 5-30 mol%, and gibbsite 5-20 mol%. This parameter optimization ensures the film has sufficient flexibility to prevent cracking while maintaining adhesion.
2Reliability
If the aluminum hydrated oxide film thickness is increased to improve crack resistance and prevent aluminum foil exposure, then the protective effect is enhanced, but the battery resistance increases
Solution Approach 1:
The patent optimizes the thickness parameter of the aluminum hydrated oxide film to be 1-10 μm. This specific thickness range provides sufficient crack resistance and protective function while minimizing the increase in battery resistance, achieving a balance between reliability and energy efficiency.
Solution Approach 2:
The composite structure of multiple aluminum hydrated oxide polymorphs provides enhanced mechanical properties and crack resistance within the optimized thickness range, allowing the film to be thin yet still effective at preventing aluminum foil exposure.
3Stability of the object's composition
If the boehmite ratio in the aluminum hydrated oxide film is increased to improve film stability, then the film structure is stabilized, but the flexibility decreases and the film becomes more prone to cracking
Solution Approach 1:
The patent creates a composite aluminum hydrated oxide film with multiple polymorphs in balanced ratios. The combination of different polymorphs (boehmite 20-80 mol%, diaspore 10-50 mol%, bayerite 5-30 mol%, gibbsite 5-20 mol%) provides both structural stability and flexibility, preventing cracking while maintaining film integrity.
Solution Approach 2:
The patent optimizes the compositional parameters by controlling the ratio of different aluminum hydrated oxide polymorphs. This parameter optimization ensures the film has sufficient flexibility to prevent cracking under external impact while maintaining structural stability and adhesion.
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 proposed solution effectively reduces heat generation during external inputs by increasing the flexibility of the aluminum hydrated oxide film, preventing direct contact between the aluminum foil and the negative electrode, thus minimizing battery resistance and heat generation.
Implementation Method 1
the electrical resistance of the Al hydrated oxide film is higher than that of the Al foil... the Al hydrated oxide film mitigates the Al foil from coming into direct contact with the negative electrode
Implementation Method 2
improving, among others, the adhesion between a positive electrode current collector and a positive electrode active material layer
Data Source
AI summary
A positive electrode includes at least a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is disposed on a surface of the positive electrode current collector. The positive electrode current collector includes an aluminum foil and an aluminum hydrated oxide film. The aluminum hydrated oxide film covers a surface of the aluminum foil. The aluminum hydrated oxide film has a thickness not smaller than 50 nm and not greater than 500 nm. The aluminum hydrated oxide film contains a plurality of types of aluminum hydrated oxides. The ratio of boehmite to the plurality of types of aluminum hydrated oxides is not lower than 20 mol % and not higher than 80 mol %.