Nonaqueous Battery Negative Electrode Pore Distribution
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Solution Overview
Problem
Nonaqueous electrolyte batteries used in electric motor vehicles face challenges in achieving high energy density, efficient charging, and rapid discharge capabilities, particularly when subjected to large current inputs, which affects their performance and charge-discharge cycle life.
Innovation Solution
A nonaqueous electrolyte battery design featuring a negative electrode with a lithium ion insertion potential of 0.4V (vs. Li/Li+) or higher, and a pore diameter distribution where the median diameter is 1 μm or more and the mode diameter is no larger than 1/10 of the median diameter, measured by mercury porosimetry, combined with a suitable positive electrode active material like lithium-manganese-nickel composite oxide or lithium-phosphorus composite oxide for improved impregnation and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the negative electrode uses conventional porous structures, then the battery achieves reasonable energy density, but the internal impedance increases under large current conditions
Solution Approach 1:
The negative electrode employs a porous carbon material with a specific pore diameter distribution (median diameter ≥1 μm and mode diameter ≤1/10 of median diameter) to optimize electrolyte retention and ion transport. This porous structure increases the electrode-electrolyte contact area, reduces internal impedance under large currents, and maintains structural stability during charge-discharge cycles, thereby improving both power output and cycle life.
2Quantity of substance
If the battery is designed for high energy density, then the discharge capacity per unit weight increases, but the charging efficiency under large current input deteriorates
Solution Approach 1:
The invention optimizes the pore diameter distribution parameters of the negative electrode, specifically setting the median diameter to 1 μm or more and the mode diameter to 1/10 of the median diameter or less. This parameter optimization enables the electrode to maintain high energy density while facilitating efficient electrolyte penetration and ion transport, thereby achieving both high discharge capacity and efficient charging under large current conditions.
3Quantity of substance
If the negative electrode active material has high lithium ion insertion capacity, then the battery capacity increases, but the thermal stability decreases
Solution Approach 1:
The negative electrode uses a composite structure combining porous carbon material with specific pore characteristics and lithium ion insertion materials. The porous carbon matrix provides thermal stability and structural integrity, while the embedded lithium ion insertion material delivers high capacity. This composite approach allows the battery to achieve high capacity without sacrificing thermal stability.
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 enhances the battery's ability to retain the nonaqueous electrolyte, reduces internal impedance, and improves input-output performance under large currents while maintaining high density, leading to extended charge-discharge cycle life and thermal stability.
Implementation Method 1
a pore diameter distribution in which a median diameter is not smaller than 1 μm and a mode diameter is not larger than 1/10 of the median diameter
Data Source
AI summary
A nonaqueous electrolyte battery includes a positive electrode, a negative electrode and a nonaqueous electrolyte. The negative electrode contains a negative electrode active material. The negative electrode active material has a lithium ion insertion potential of 0.4V (vs. Li/Li+) or higher and a pore diameter distribution in which a median diameter is not smaller than 1 μm and a mode diameter is not larger than 1/10 of the median diameter. The pore diameter distribution is measured by mercury porosimetry.