Olefin Separator Battery Design for Low-Resistance Carbon Anodes
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Solution Overview
Problem
Cellulose-based separators in electrochemical devices tend to contain water, leading to degradation of the negative electrode and increased internal resistance.
Innovation Solution
The use of an olefin-based separator with a negative electrode active material that includes hardly graphitized carbon and a specific surface area of 10 m2/g or more, and 70 m2/g or less, to suppress degradation and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cellulose-based separators are used, then the device is inexpensive and easy to manufacture, but water content increases causing negative electrode degradation and increased internal resistance
Solution Approach 1:
The patent changes the material parameter of the separator from cellulose-based to olefin-based resin, which fundamentally alters the water content characteristics. Olefin-based separators inherently contain less water than cellulose-based separators, thereby preventing negative electrode degradation and maintaining low internal resistance while remaining cost-effective and easy to manufacture.
2Ease of manufacture
If cellulose-based separators are used, then manufacturing cost is reduced, but internal resistance increases due to negative electrode degradation
Solution Approach 1:
The patent changes the separator material parameter from cellulose-based to olefin-based resin, which reduces water content and prevents negative electrode degradation. This parameter change maintains manufacturing cost effectiveness while eliminating the harmful increase in internal resistance that would otherwise occur.
3Quantity of substance
If high surface area negative electrode material is used, then capacity increases, but water sensitivity and degradation risk increase
Solution Approach 1:
The olefin-based separator acts as an intermediary protective layer between the high-surface-area negative electrode material and water. This mediator prevents water from reaching and degrading the sensitive negative electrode, allowing the device to utilize high-capacity materials without suffering from water-induced degradation.
Solution Approach 2:
The patent changes the separator material parameter to olefin-based resin, which has inherent water-repellent properties. This parameter change protects the high-surface-area negative electrode from water exposure, enabling high capacity utilization while preventing degradation.
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 olefin-based separator reduces water content, stabilizes the electrolyte, and maintains low internal resistance over time, enhancing the reliability of the electrochemical device.
Implementation Method 1
the separator includes an olefin-based resin
Implementation Method 2
the negative electrode mixture layer includes a negative electrode active material into which lithium ions are reversibly doped
Implementation Method 3
the positive electrode includes a positive electrode active material into which anions are reversibly doped
Implementation Method 4
a lithium ion-conductive electrolyte
Data Source
AI summary
An electrochemical device includes a positive electrode, a negative electrode, a separator and a lithium ion-conductive electrolyte. The positive electrode includes a positive electrode active material into which anions are reversibly doped. The negative electrode includes a negative electrode current collector, and a negative electrode mixture layer supported on the negative electrode current collector, the negative electrode mixture layer includes a negative electrode active material into which lithium ions are reversibly doped, and the negative electrode active material includes hardly graphitized carbon. The negative electrode mixture layer has a specific surface area of 10 m2/g or more, and 70 m2/g or less. The separator includes an olefin-based resin.