Lithium Battery Electrode Conducting Agent Gradient Distribution
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Solution Overview
Problem
Conducting agents in lithium secondary batteries have low density, leading to inadequate interfacial conductivity between the electrode and the active material layer, with the conducting agent often being more concentrated in the upper region of the active material layer and less near the current collector.
Innovation Solution
Incorporating a first conducting agent with an average particle diameter of 10 to 1×10^3 nm and a second conducting agent, which is an agglomerate of the first conducting agent and a fluorine-based polymer, with an average particle diameter greater than 1×10^3 to 4×10^5 nm, to create a concentration gradient in the active material layer, improving distribution and interfacial conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conducting agent with low density is used, then the electrode composition can be formed, but the conducting agent concentrates in the upper region and depletes near the current collector, resulting in insufficient interfacial conductivity
Solution Approach 1:
The patent applies parameter changes by introducing a concentration gradient of the second conducting agent in the active material layer, where the concentration decreases from the current collector toward the upper region. This gradient distribution optimizes interfacial conductivity at the current collector while maintaining adequate conductivity throughout the layer, resolving the contradiction between interfacial conductivity and compositional uniformity.
Solution Approach 2:
The patent implements local quality by creating different conducting agent concentrations at different positions within the active material layer. The second conducting agent is concentrated near the current collector to enhance interfacial conductivity, while its concentration gradually decreases toward the upper region, allowing each zone to have the appropriate conducting agent density for its specific function.
2Reliability
If conducting agents are added to increase conductivity, then the electrode conductivity improves, but the low density of conducting agents causes them to be present more in the upper region and less near the current collector
Solution Approach 1:
The patent uses parameter changes by establishing a concentration gradient for the second conducting agent that decreases from the current collector toward the upper region. This gradient ensures adequate conducting agent presence at the current collector interface while maintaining overall electrode conductivity, thus resolving the contradiction between improving conductivity and achieving uniform spatial distribution.
Solution Approach 2:
The patent employs composite materials by combining two types of conducting agents with different properties: a first conducting agent (fine particles, 10-1×10³ nm) that can be uniformly distributed, and a second conducting agent (coarse particles, 1×10³-4×10⁵ nm) that forms an agglomerate structure and concentrates near the current collector. This composite approach allows simultaneous optimization of both overall conductivity and interfacial conductivity.
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 use of a second conducting agent with a larger particle diameter enhances the distribution of conducting agents near the current collector, reducing interfacial resistance and improving the overall conductivity and binding force of the electrode.
Implementation Method 1
the second conducting agent is an agglomerate of a conducting material having an average particle diameter of about to about 1×10³ nm and a fluorine-based polymer
Implementation Method 2
mixing and thermally treating a composition that contains a conducting material having an average particle diameter of about 10 to about 1×10³ nm and a fluorine-based polymer to produce an aggregate
Implementation Method 3
the second conducting agent has a concentration gradient in a region of the active material layer adjacent to the current collector, such that the concentration of the second conducting agent decreases in a direction through the active material layer away from the current collector
Data Source
AI summary
An electrode composition containing a first conducting agent and a second conducting agent, an electrode for lithium secondary batteries, a method of manufacturing the electrode, and a lithium secondary battery including the electrode. The second conducting agent is an agglomerate formed of a conducting material and a fluorine-based polymer.