Lithium Battery Electrode Orientation and Additive Design
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in optimizing the orientation of negative active materials, leading to increased DC internal resistance, reduced rate capabilities, and deteriorated cycle-life characteristics due to inadequate lithium ion conductivity and concentration overvoltage issues.
Innovation Solution
A rechargeable lithium battery design featuring a negative electrode with a Degree of Divergence (DD) value of 19 to 60, achieved through controlled magnetic field orientation of carbon-based negative active materials, and a positive electrode with a porous structured additive, such as activated carbon, to enhance lithium ion conductivity and balance overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional negative active materials are used without controlled orientation, then manufacturing is simpler, but DC internal resistance increases and rate capabilities are reduced
Solution Approach 1:
The patent applies parameter changes by controlling the Degree of Divergence (DD) value of the negative active material orientation within a specific range (19-60). This quantitative parameter control optimizes lithium ion conductivity and reduces DC internal resistance while maintaining manufacturability through controlled magnetic field application during electrode fabrication.
Solution Approach 2:
The patent replaces conventional mechanical mixing and coating methods with a magnetic field-based orientation system. By applying a magnetic field during the electrode fabrication process, the negative active materials are oriented in a controlled manner to achieve the desired DD value, substituting mechanical randomness with magnetic field-directed alignment.
2Reliability
If negative active materials are highly oriented, then lithium ion conductivity improves, but concentration overvoltage increases and cycle-life deteriorates
Solution Approach 1:
The patent optimizes the DD value parameter within the range of 19-60 to balance lithium ion conductivity and cycle-life characteristics. This parameter optimization prevents excessive orientation that would cause concentration overvoltage, while maintaining sufficient orientation for good ionic conductivity, thereby extending battery cycle life.
Solution Approach 2:
The patent applies local quality by creating specific orientation zones within the negative electrode structure. The controlled DD value ensures that orientation is optimized locally at the particle level while maintaining overall electrode homogeneity, preventing localized concentration gradients that would accelerate degradation.
3Use of energy by moving object
If porous structured additive is added to positive electrode, then energy density and rate capability improve, but device complexity increases
Solution Approach 1:
The patent uses composite materials by combining the positive active material with a porous structured additive in specific weight ratios (0.01-2 wt%). This composite structure enhances energy density and rate capability by providing additional pathways for lithium ion transport while maintaining structural integrity through the porous network.
Solution Approach 2:
The patent incorporates porous materials as structured additives in the positive electrode. These porous structures provide increased surface area and improved electrolyte penetration, enhancing lithium ion conductivity and energy density while the controlled quantity (0.01-2 wt%) prevents excessive complexity in the electrode composition.
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 solution improves lithium ion conductivity, reduces DC internal resistance, and enhances cycle-life characteristics and energy density by optimizing the orientation of negative active materials and incorporating a porous structured additive in the positive electrode.
Implementation Method 1
a porous layer between the positive current collector and the positive active material layer and including a porous structured additive
Implementation Method 2
improves lithium ion conductivity
Implementation Method 3
achieved through controlled magnetic field orientation of carbon-based negative active materials
Data Source
AI summary
A rechargeable lithium battery includes an electrolyte, a negative electrode, and a positive electrode. The negative electrode includes a negative active material layer on a negative current collector, and includes a carbon-based negative active material. The negative electrode having a Degree of Divergence (DD) value of about 19 to about 60. The positive electrode includes a positive active material layer and a positive current collector, and includes a positive active material and a porous structured additive. The content of the porous structured additive is about 0.01 wt % to about 2 wt % based on 100 wt % of the positive active material layer.