Intermediate Layer Flame Retardant for Battery Safety
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face challenges in suppressing heat generation during internal short-circuiting events, such as nail penetration, while maintaining output characteristics and safety, as existing solutions like adding flame retardants to the positive electrode mix layer degrade battery performance.
Innovation Solution
Incorporating a highly heat-conductive intermediate layer with a flame retardant between the positive electrode current collector and mix layer, which efficiently diffuses and releases heat, reducing exothermic reactions without degrading output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame retardant is added to a positive electrode mix layer to suppress thermal runaway reactions, then safety is improved, but output characteristics are degraded
Solution Approach 1:
An intermediate layer is introduced between the positive electrode current collector and the positive electrode mix layer. This intermediate layer contains the flame retardant and acts as a mediator that suppresses thermal runaway reactions without requiring the flame retardant to be present in the mix layer itself, thereby maintaining output characteristics while improving safety
Solution Approach 2:
The positive electrode is segmented into distinct layers: a current collector, an intermediate layer containing the flame retardant, and a mix layer. This segmentation allows the flame retardant to be isolated in the intermediate layer, preventing its negative impact on output characteristics while still providing safety benefits
2Object-affected harmful factors
If an intermediate layer containing flame retardant is added between current collector and mix layer, then heat generation is suppressed during internal short-circuiting, but device complexity increases
Solution Approach 1:
The intermediate layer serves as a mediator that specifically addresses heat generation during internal short-circuiting events. By placing the flame retardant in this intermediate layer rather than throughout the entire electrode structure, the solution targets the specific harmful effect while minimizing the increase in device complexity
Solution Approach 2:
The flame retardant is localized to the intermediate layer rather than being distributed throughout the entire positive electrode. This local placement optimizes heat suppression during internal short-circuiting at the critical interface between the current collector and mix layer, while avoiding unnecessary complexity in other regions of the electrode
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 effectively suppresses heat generation during internal short-circuiting events, enhancing safety without compromising battery performance, and improves storage properties by using a small amount of flame retardant in the intermediate layer rather than the mix layer.
Implementation Method 1
the intermediate layer containing a flame retardant and a conductive material having a heat conductivity of 10 W/m·K or more
Implementation Method 2
the intermediate layer containing a flame retardant and a conductive material having a heat conductivity of 10 W/m·K or more
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode that includes a positive electrode current collector, an intermediate layer on the positive electrode current collector, and a positive electrode mix layer on the intermediate layer. The intermediate layer contains a flame retardant and a conductive material having a heat conductivity of 10 W/m·K or more.