Fluorinated Carbon Coated Lithium Battery Cathode
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Solution Overview
Problem
Rechargeable lithium batteries face performance deterioration due to excessive formation of a passivation film on the positive electrode, which hinders lithium ion transfer and reduces battery efficiency.
Innovation Solution
A positive active material is developed with a core particle capable of reversible lithium intercalation and a carbon-fluorine (C—F) bond coating on its surface, preventing excessive passivation film formation by forming a LiF film that enhances lithium ion transmission and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation film is formed on the positive electrode through reduction reaction of electrolyte solution, then the electrode surface is protected, but lithium ion transfer is hindered and battery performance deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the electrode surface by introducing fluorinated carbon materials with specific C-F bond characteristics. This parameter change transforms the passivation film from a harmful barrier into a beneficial protective layer that maintains both surface protection and lithium ion conductivity.
Solution Approach 2:
The invention uses composite materials consisting of fluorinated carbon structures (such as fluorinated carbon nanotubes, fluorinated graphene, or fluorinated carbon black) combined with the positive active material. This composite structure provides both the protective function and the lithium ion transfer pathway, resolving the contradiction between surface protection and ion transfer.
2Reliability
If excessive passivation film is formed on the positive electrode, then surface protection is enhanced, but battery efficiency and cycle life are reduced
Solution Approach 1:
The invention applies preliminary anti-action by pre-forming a controlled fluorinated carbon coating on the positive electrode surface before battery operation. This pre-formed coating prevents excessive passivation film formation during cycling, thereby protecting the electrode while maintaining long-term battery performance and cycle 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
The solution effectively reduces resistance and maintains battery performance by preventing excessive passivation film formation, thereby improving the cycle life and efficiency of rechargeable lithium batteries.
Implementation Method 1
forming a coating layer on a surface of the lithium-containing compound, the coating layer including a coating material including a carbon-fluorine (C—F) bond
Implementation Method 2
a core particle including a lithium-containing compound configured to reversibly intercalate and deintercalate lithium
Implementation Method 3
the C—F bond of the fluorine-bonded carbon nanostructure may exhibit a peak in a range of about 950 cm−1 to about 1350 cm−1 as measured by FT-IR spectroscopy
Implementation Method 4
The LiF may exhibit a (111) peak at a 2θ value of about 39°, a (200) peak at a 2θ value of about 45° and a (220) peak at a 2θ value of about 63° as measured by X-ray diffraction (XRD) analysis
Data Source
AI summary
Disclosed are a positive active material that includes a core particle including a lithium-containing compound configured to reversibly intercalate and deintercalate lithium, and a coating layer on a surface of the core particle, the coating layer including a material including a carbon-fluorine (C—F) bond, a method of manufacturing the same, and a rechargeable lithium battery including the positive active material.