Positive Electrode Pore Distribution for Overcharge Safety
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, face challenges in effectively preventing overcharging defects and maintaining high reaction rates of overcharge additives, which can lead to reduced safety and performance.
Innovation Solution
A non-aqueous electrolyte secondary battery with a positive electrode material layer having a specific pore size distribution curve, characterized by two peaks in the 0.05 μm to 2 μm range, where the ratio of the differential pore volumes between these peaks is optimized to enhance the reaction of overcharge additives, increasing gas generation and polymer formation during overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of overcharge additive is increased to enhance gas generation and polymer formation, then the safety and reaction efficiency improve, but the battery properties deteriorate due to excess additive
Solution Approach 1:
The patent applies porous materials principle by optimizing the pore size distribution of the positive electrode material layer. The pore size distribution curve shows two peaks: peak A at 0.2-2.0 μm providing electrolyte supply pathways, and peak B at 0.05-0.5 μm providing reaction sites for overcharge additive. This porous structure increases the reaction efficiency of overcharge additive, allowing safer operation with reduced additive quantity.
Solution Approach 2:
The patent applies parameter changes principle by precisely controlling the pore size distribution parameters of the positive electrode material. The differential pore volume ratio (XC/XL ≥ 0.6) and peak position parameters are optimized to enhance overcharge additive reaction. This parameter optimization improves the reaction efficiency, enabling reduced additive content while maintaining safety.
2Productivity
If the pore size distribution is optimized to enhance overcharge additive reaction, then the gas generation and polymer formation increase, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes principle by defining specific pore size distribution parameters (two peaks at defined positions, differential pore volume ratio ≥ 0.6). These parameter specifications provide clear manufacturing targets, enabling controlled production of electrodes with optimized pore structures through adjustments in slurry composition, coating conditions, and drying/pressing parameters.
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 increases the amount of gas generated and polymer formed from overcharge additives, improving the battery's safety and reaction efficiency while minimizing the need for excess overcharge additives, thus maintaining high battery properties.
Implementation Method 1
the overcharge additive undergoes a reaction to form gas... the overcharge additive undergoes a reaction to generate gas while undergoing self-polymerization
Implementation Method 2
the polymer formed from the overcharge additive is allowed to precipitate out on the positive electrode surface to form a membrane
Data Source
AI summary
The present invention provides a non-aqueous electrode secondary battery supplied with a non-aqueous electrolyte comprising an overcharge additive. The positive electrode material layer constituting the positive electrode in the non-aqueous electrolyte secondary battery is characterized by having a differential pore volume peak A as well as a peak B located on the smaller pore diameter side than the peak A in a pore diameter range of 0.05 μm to 2 μm in a pore size distribution curve measured by a mercury porosimeter, wherein the pore size distribution curve has a minimum C corresponding to a minimum differential pore volume between the peak A and the peak B, such that a ratio (XC/XL) of the minimum C's differential pore volume XC to a differential pore volume XL, which is the larger between the peak A's differential pore volume XA and the peak B's differential pore volume XB is 0.6 or larger.