Aluminum Current Collector Protective Layer for Battery Heat Management
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Solution Overview
Problem
Existing positive electrodes for nonaqueous electrolyte secondary batteries face issues with heat generation due to redox reactions between the aluminum current collector and lithium-containing transition metal oxide active materials, which cannot be adequately prevented by existing technologies, and this leads to deterioration in current collecting properties.
Innovation Solution
A positive electrode design featuring a protective layer with a thickness of 1 to 5 μm, containing an electroconductive material and an inorganic compound with lower oxidation power than the lithium-containing transition metal oxide, is applied between the aluminum current collector and the positive electrode mixture layer to prevent redox reactions and maintain satisfactory current collecting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the aluminum oxide coating film is increased to prevent redox reactions and heat generation, then the heat generation due to redox reaction is reduced, but the current collecting properties deteriorate significantly because the coating film cannot be sufficiently broken during pressing
Solution Approach 1:
The protective coating is divided into two distinct layers: a first protective layer (1-5 μm thick) containing inorganic compound particles and electroconductive material that provides both protection and conductivity, and a second protective layer (0.1-10 μm thick) containing inorganic compound particles that provides additional protection. This segmentation allows each layer to perform its specific function optimally while working together to resolve the contradiction between heat prevention and current collection.
Solution Approach 2:
The protective coating uses composite materials combining inorganic compounds (such as aluminum oxide, aluminum hydroxide, titanium oxide, silicon oxide, or boron nitride) with electroconductive materials (such as acetylene black, Ketjen black, graphite, or metal powder). This composite structure provides both the protective barrier function to prevent redox reactions and the electroconductive function to maintain current collecting properties, resolving the technical contradiction.
2Object-affected harmful factors
If a protective layer is added to prevent redox reactions, then heat generation is reduced, but the device complexity increases
Solution Approach 1:
The protective coating is designed to perform multiple functions simultaneously: it acts as a physical barrier to prevent redox reactions between the aluminum current collector and lithium-containing transition metal oxide, provides electroconductive pathways to maintain current collection, and offers thermal stability. By integrating these multiple functions into a single coating structure, the invention reduces device complexity while still preventing heat generation.
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 from redox reactions while maintaining battery performance by preventing contact between the aluminum current collector and the lithium-containing transition metal oxide, ensuring both heat management and current collection efficiency.
Implementation Method 1
an internal short circuit in a battery or exposure of a battery to high temperature may cause a redox reaction between a positive electrode active material and an aluminum current collector to cause large heat generation
Data Source
AI summary
A positive electrode for a nonaqueous electrolyte secondary battery according to an embodiment of the present disclosure includes a positive electrode current collector mainly composed of aluminum (Al), a protective layer disposed on the positive electrode current collector, and a positive electrode mixture layer containing a lithium-containing transition metal oxide and disposed on the protective layer. The protective layer has a thickness of 1 to 5 μm and contains an electroconductive material and an inorganic compound having an oxidation power lower than that of the lithium-containing transition metal oxide.