Metallic Lithium Detection on Electrodes via Fluorescent Dye
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in detecting metallic lithium deposition on electrodes, which can occur during high charge currents or low temperature conditions, making it difficult to assess and quantify this deposition using conventional methods.
Innovation Solution
A method involving a lithium-reactive solution with an oxidized fluorescent dye is applied to the electrode, reduced, dried, and then exposed to ultraviolet radiation to detect and quantify metallic lithium, allowing for optical imaging and mapping of its location and amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detection methods are used, then the detection process is simple, but the ability to detect and quantify metallic lithium deposition is insufficient
Solution Approach 1:
The patent introduces a fluorescent dye as an intermediary substance that reacts with metallic lithium to produce a detectable signal. The dye acts as a mediator between the metallic lithium (target analyte) and the detection system (UV light source and imaging device), enabling indirect detection through fluorescence emission when the reduced dye is exposed to UV radiation.
Solution Approach 2:
The patent replaces conventional mechanical or electrochemical detection methods with an optical detection system. Instead of using physical measurement techniques, the invention uses UV light excitation and fluorescence emission to detect and quantify metallic lithium, substituting mechanical/electrical systems with optical fields for measurement.
2Productivity
If high charge currents or low temperature conditions are used, then battery charging speed increases, but metallic lithium deposition occurs on electrodes
Solution Approach 1:
The patent performs detection of metallic lithium deposition after charging operations have occurred. By applying the fluorescent dye and conducting UV imaging after the charging process, the system can identify and quantify lithium plating that has already formed, allowing for preventive measures to be taken before the deposition causes reliability issues.
Solution Approach 2:
The invention provides a detection feedback mechanism that quantifies metallic lithium deposition on electrodes. This feedback information about lithium plating conditions can be used to adjust charging parameters (current, temperature) in real-time or for subsequent cycles, preventing excessive deposition that would compromise electrode integrity and battery reliability.
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 method enables accurate and efficient detection, location, and quantification of metallic lithium on the electrode, providing a cost-effective and automatable solution for identifying metallic lithium deposition, which is otherwise difficult with traditional techniques.
Implementation Method 1
reducing the oxidized fluorescent dye to form a reduced dye and a plurality of lithium ions
Implementation Method 2
oxidizing the reduced dye to form the oxidized fluorescent dye
Implementation Method 3
exposing the oxidized fluorescent dye to ultraviolet electromagnetic radiation having a wavelength of from 100 nm to 500 nm to thereby illuminate and detect the metallic lithium
Data Source
AI summary
A method of detecting metallic lithium present on an electrode of a lithium ion secondary battery includes depositing a lithium-reactive solution including an oxidized fluorescent dye onto the electrode to form a coated electrode. Concurrent to depositing, the method includes reducing the oxidized fluorescent dye to form a reduced dye and a plurality of lithium ions. The method further includes, after reducing, drying the coated electrode to again form the oxidized fluorescent dye. After drying, the method includes exposing the oxidized fluorescent dye to ultraviolet radiation having a wavelength of from 100 nm to 500 nm to thereby illuminate and detect the metallic lithium. A lithium ion secondary battery system is also disclosed.