Positive Electrode with Reaction Inhibitor Gradient for Thermal Safety
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary battery technologies face issues with rapid temperature elevation due to internal short circuits, leading to reactions between the positive electrode active material and electrolyte, which deteriorate battery characteristics and safety, particularly when the flame retardant agent is not effectively positioned near the collector.
Innovation Solution
A positive electrode with a two-layer structure, where a first mixture layer containing a reaction inhibitor is positioned near the current collector and a second mixture layer without the inhibitor is on the surface, ensuring the inhibitor concentration is higher near the collector to suppress thermal reactions and maintain input-output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame retardant agent is blended in the positive electrode mixture to suppress rapid temperature elevation, then thermal reaction suppression is improved, but battery capacity and input-output characteristics deteriorate
Solution Approach 1:
The patent applies local quality by creating a two-layer positive electrode structure where the flame retardant agent is concentrated in the first mixture layer near the current collector, while the second mixture layer at the surface has reduced or no flame retardant agent. This localized distribution suppresses thermal reactions at the heat generation source (collector interface) while preserving battery capacity and input-output characteristics in the active material-rich surface layer.
2Object-affected harmful factors
If a flame retardant agent layer is disposed on the surface layer of the positive electrode or negative electrode, then surface combustion is suppressed, but thermal reaction near the collector is not suppressed
Solution Approach 1:
The patent introduces the first mixture layer containing the flame retardant agent as an intermediary layer positioned between the current collector and the second mixture layer. This intermediary layer acts as a thermal barrier and reaction suppressor at the critical collector interface, preventing direct thermal reactions between the active material and electrolyte in the high-heat region near the collector.
3Reliability
If the concentration of reaction inhibitor is increased throughout the positive electrode mixture layer, then thermal reaction suppression is improved, but input-output characteristics deteriorate
Solution Approach 1:
The patent implements local quality by creating a concentration gradient of the reaction inhibitor (flame retardant agent) within the positive electrode mixture layer. The first mixture layer near the current collector has high concentration for thermal protection, while the second mixture layer at the surface has low or zero concentration to maintain electrochemical performance and input-output characteristics.
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
This configuration effectively suppresses reactions between the positive electrode active material and non-aqueous electrolyte during internal short circuits, maintaining excellent input-output characteristics and reducing temperature elevation, thus enhancing battery safety and performance.
Implementation Method 1
a first mixture layer containing a positive electrode active material and a reaction inhibitor to suppress a thermal reaction between the positive electrode active material and a non-aqueous electrolyte
Implementation Method 2
a concentration of the reaction inhibitor contained in the positive electrode mixture layer near the positive electrode current collector is higher than that in a surface layer portion of the positive electrode mixture layer
Data Source
AI summary
A positive electrode for nonaqueous electrolyte secondary batteries having a positive electrode current collector and a positive electrode mixture layer that is formed on the positive electrode current collector. The positive electrode for nonaqueous electrolyte secondary batteries is: the positive electrode mixture layer comprises a first mixture layer that contains a positive electrode active material and a reaction inhibitor which inhibits a thermal reaction between the positive electrode active material and a nonaqueous electrolyte, and a second mixture layer that contains the positive electrode active material; the positive electrode is obtained by sequentially laminating the positive electrode current collector, the first and the second mixture layer in this order; and the concentration of the reaction inhibitor contained in the positive electrode mixture layer is high in the vicinity of the positive electrode current collector in comparison to that in the surface layer portion of the positive electrode mixture layer.