Battery Electrode Body Particle Distribution for Lower Resistance
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Solution Overview
Problem
Non-aqueous electrolyte rechargeable batteries face challenges in reducing battery resistance and prolonging battery life, particularly in the negative electrode active material layer where carbon material particles of varying sizes are used, but existing configurations do not effectively optimize particle size distribution and separator surface roughness to achieve these goals.
Innovation Solution
The electrode body includes a negative electrode with an active material layer composed of carbon material particles with a specific volume distribution, featuring a first peak particle size of 7.0 μm to 9.0 μm and a second peak of 0.8 μm to 1.0 μm, along with a separator surface roughness of 1.54 μm or greater, and a peak ratio of 0.42 to 0.71, which enhances lithium ion movement and reduces side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If active material particles of varying sizes are used in the negative electrode, then the battery capacity increases, but the battery resistance increases and battery life decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters of active material particles. Specifically, it sets the volume average particle size to 3.0 μm or more and the span value to 1.6 or less, thereby optimizing the balance between battery capacity and battery resistance. This parameter optimization resolves the contradiction by finding the optimal range that maximizes capacity while minimizing resistance and extending life.
Solution Approach 2:
The patent uses composite material principles by combining active material particles with a specific size distribution profile. The controlled distribution creates a composite structure where particles are optimally arranged to provide both high capacity (through adequate volume) and low resistance (through uniform size distribution and reduced void spaces), thereby resolving the contradiction between capacity and reliability.
2Quantity of substance
If the span value of active material particles is increased to improve capacity, then more particle sizes are included, but the battery life is shortened
Solution Approach 1:
The patent resolves this contradiction by changing the span value parameter to 1.6 or less, which controls the width of the particle size distribution. This parameter setting ensures that while multiple particle sizes are present (providing good capacity), the distribution remains narrow enough to prevent excessive side reactions and maintain long battery life.
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 significantly reduces battery resistance and prolongs battery life by optimizing the particle size distribution and separator surface roughness, resulting in a DC resistance ratio of 98.69% or less and a battery capacity retention ratio of 97% or greater after ten days.
Implementation Method 1
The separator has a surface roughness of 1.54 μm or greater... significantly reduces battery resistance... enhances lithium ion movement
Implementation Method 2
The active material layer includes active material particles of different particle sizes formed from a carbon material... battery capacity retention ratio of 97% or greater
Data Source
AI summary
An electrode body of a non-aqueous electrolyte rechargeable battery includes a positive electrode, a negative electrode, and a separator. The negative electrode includes a current collector and an active material layer. The active material layer includes active material particles. The active material particles have a volume distribution including a first peak corresponding to a first particle size and a second peak corresponding to a second particle size smaller than the first particle size. The first particle size is in a range of 7.0 μm to 9.0 μm. The second particle size is in a range of 0.8 μm to 1.0 μm. The separator has a surface roughness of 1.54 μm or greater. A peak ratio of a volume of the active material particles of the second peak to a volume of the active material particles of the first peak is in a range of 0.42 to 0.71.