Carbon Nanofiber Electrode Composition for Lithium Ion Battery
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Solution Overview
Problem
Conventional methods for producing carbon nanofibers from carbon monoxide gas as a main component result in insufficient yield and activity, and the dispersibility of fine carbon fibers in electrode slurries is poor, leading to increased costs and decreased battery performance due to aggregation and surface oxidation issues.
Innovation Solution
A conductive composition for electrodes using carbon nanofibers with specific properties, including a median diameter of 0.1 to 8 μm, powder resistivity of 0.03 Ωcm or less, and D/G ratio of 0.5 to 1.3, produced using a catalyst with cobalt as the main active species supported on magnesium-containing oxide, and processed under controlled conditions to enhance conductivity and dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalytic vapor deposition is used to produce carbon nanofiber from carbon monoxide gas, then carbon nanofiber can be obtained, but the yield and catalytic activity are insufficient
Solution Approach 1:
The patent changes the physical and chemical parameters of the catalyst system by using cobalt as the active species supported on magnesium oxide with a specific surface area of 0.01 to 5 m²/g, and by controlling the carbon monoxide partial pressure (0.04 to 0.98 MPa) and reaction temperature (670 to 780°C), thereby achieving both high yield and high catalytic activity
Solution Approach 2:
The patent employs a composite catalyst structure consisting of cobalt active species supported on magnesium oxide carrier, creating a composite material system that enhances both the productivity and reliability of carbon nanofiber production through synergistic effects
2Reliability
If fine carbon fiber is used to improve conductivity, then electric conductivity increases, but dispersibility deteriorates due to fiber entanglement
Solution Approach 1:
The patent controls the physical parameters of carbon nanofiber including median diameter (0.1 to 8 μm), powder resistivity (0.03 Ωcm or less), and D/G ratio (0.5 to 1.3), optimizing these parameters to achieve both high conductivity and good dispersibility without fiber entanglement
Solution Approach 2:
The patent creates local quality optimization by ensuring uniform distribution of carbon nanofiber throughout the electrode slurry, with each local region having appropriate conductivity and dispersion characteristics, preventing aggregation while maintaining overall conductivity
3Ease of operation
If surface oxidation process is applied to improve dispersibility, then dispersibility increases, but conductivity decreases
Solution Approach 1:
The patent performs preliminary action by producing carbon nanofiber with optimized surface properties and structural parameters during the synthesis stage, using cobalt catalyst on magnesium oxide support, so that the nanofiber achieves good dispersibility without requiring subsequent oxidation treatment that would harm conductivity
4Reliability
If carbon nanofiber content is increased to maintain conductive agent performance, then conductivity is maintained, but active material content decreases
Solution Approach 1:
The patent changes the quality parameters of carbon nanofiber (median diameter, powder resistivity, D/G ratio) to achieve high conductive efficiency, allowing lower carbon nanofiber content (0.1 to 2 mass%) to maintain conductivity while preserving more active material in the electrode
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 improved carbon nanofiber composition achieves excellent conductivity and dispersibility, resulting in a low plate resistance and enhanced discharge rate characteristics for lithium ion secondary batteries.
Implementation Method 1
catalytic vapor deposition is considered to be most suitable as an industrial production method. In the catalytic vapor deposition, transition metal particles are used as a catalyst to make contact a raw material gas as a carbon source, such as acetylene and benzene, thereby growing CNF from catalyst particles
Implementation Method 2
adjacent carbon powder with excellent electronic conductivity, such as carbon black... CNF... high electric conductivity is obtained with relatively low conductive carbon material content
Implementation Method 3
there is another method of uniform dispersion in a solvent by surface oxidation process to CNF using concentrated nitric acid and concentrated sulfuric acid
Data Source
AI summary
A conductive composition for electrode is provided that is excellent in conductivity and dispersibility. Further, an electrode for lithium ion secondary battery with lower plate resistance and a lithium ion secondary battery excellent in rate characteristics are provided that use this conductive composition. A conductive composition for electrode, including: carbon nanofiber with a median diameter D50 value by volume from 0.1 to 8 pm; an active material; and a binder enables production of an electrode for lithium ion secondary battery with lower plate resistance and a lithium ion secondary battery excellent in rate characteristics.