Negative Electrode Pore Distribution for Battery Output
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Solution Overview
Problem
Nonaqueous electrolyte batteries using lithium compounds as negative electrode active materials face challenges in achieving high output performance due to particle coagulation and uneven distribution during electrode production, leading to variations in output characteristics and reduced cycle life.
Innovation Solution
A nonaqueous electrolyte battery design with a negative electrode that has a specific pore size diameter distribution, measured by mercury porosimetry, with a peak in the range of 0.03 to 0.2 μm and a high ratio of small pore volume, improving impregnation and uniformity, and using lithium compounds like lithium titanate with a spinel structure for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If microparticles of lithium compound are used as negative electrode active material to achieve high power, then power output is improved, but particle coagulation occurs during electrode production causing large variation in output characteristics
Solution Approach 1:
The patent applies porous materials by controlling the pore size distribution of the negative electrode to have a peak in the range of 0.03 to 0.2 μm. This porous structure prevents particle coagulation while maintaining high surface area for lithium ion insertion, thus achieving high power output with consistent performance across different production batches.
Solution Approach 2:
The patent changes physical parameters by specifying the pore size diameter distribution (peak at 0.03-0.2 μm) and the ratio of small pore volume (20% or more). These parameter changes optimize the balance between preventing particle coagulation and maintaining high power output, resolving the contradiction between power improvement and output consistency.
2Stability of the object's composition
If lithium compound particles are strongly stirred during negative electrode manufacture to reduce coagulation, then particle distribution is improved, but edges of particles are scraped away reducing filling density
Solution Approach 1:
The patent utilizes porous materials with controlled pore size distribution (peak at 0.03-0.2 μm) that allows gentle particle arrangement during electrode formation. The porous structure provides space for particles to settle uniformly without requiring strong stirring, thus maintaining both distribution uniformity and high filling density.
Solution Approach 2:
The patent changes the physical state by controlling pore size distribution and small pore volume ratio, which fundamentally alters how particles are arranged during electrode manufacture. This eliminates the need for strong stirring that causes particle edge damage, simultaneously achieving uniform distribution and high filling density.
3Stability of the object's composition
If pore size diameter is reduced to improve active material distribution uniformity, then distribution uniformity is improved, but DC resistance increases reducing output performance
Solution Approach 1:
The patent applies porous materials with an optimized pore size distribution where the peak is at 0.03 to 0.2 μm and small pores (≤0.05 μm) constitute 20% or more of total pore volume. This specific porous structure provides sufficient surface area for uniform active material distribution while maintaining adequate ion transport pathways to prevent excessive DC resistance, thus balancing distribution uniformity with output performance.
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 battery achieves improved output performance and cycle life by reducing DC resistance and ensuring uniform active material distribution, while preventing detachment of the active material from the current collector, thus maintaining mechanical integrity and efficiency during charging and discharging.
Implementation Method 1
a negative electrode containing a lithium compound
Implementation Method 2
a lithium compound having a small ionic diffusibility in a solid
Implementation Method 3
a nonaqueous electrolyte
Data Source
AI summary
A nonaqueous electrolyte battery includes a positive electrode, a negative electrode and a nonaqueous electrolyte. The negative electrode contains a lithium compound and a negative electrode current collector supporting the lithium compound. A log differential intrusion curve obtained when a pore size diameter of the negative electrode is measured by mercury porosimetry has a peak in a pore size diameter range of 0.03 to 0.2 μm and attenuates with a decrease in pore size diameter from an apex of the peak. A specific surface area (excluding a weight of the negative electrode current collector) of pores of the negative electrode found by mercury porosimetry is 6 to 100 m2/g. A ratio of a volume of pores having a pore size diameter of 0.05 μm or less to a total pore volume is 20% or more.