Carbon-Coated Electrode Material for Li-Ion Battery Conductivity
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Solution Overview
Problem
Lithium ion battery electrode materials face challenges with insufficient electron conductivity, particle growth during high-temperature carbonization, and increased resistance due to excess carbonaceous carbide formation, which affects discharge capacity and cycle stability.
Innovation Solution
The use of an ionic organic substance as a carbon source in the carbon coating method prevents electrode active material particles from sintering and allows for a thin, efficient carbonaceous film coating, maintaining particle size and reducing excess carbon, thereby enhancing electron conductivity and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of conductive substance is used to improve electron conductivity, then electron conductivity is improved, but electrode density decreases
Solution Approach 1:
The invention applies conductive substance locally only at the surface of electrode active material particles through carbon coating, rather than uniformly throughout the electrode. This localized application provides necessary electron conductivity at the particle surface while minimizing the overall amount of conductive substance, thereby maintaining high electrode density.
Solution Approach 2:
The invention uses an organic substance as an intermediary carbon source that is carbonized to form a carbonaceous film on the particle surface. This intermediary approach allows for controlled, thin-film carbon deposition that provides conductivity without the excessive carbon accumulation that would reduce electrode density.
2Reliability
If high-temperature carbonization is used to carbonize organic substance, then carbon coating is achieved, but electrode active material particles sinter and grow
Solution Approach 1:
The invention changes the temperature parameter of the carbonization process, conducting it at a lower temperature range than conventional methods. This parameter modification allows sufficient carbonization of the organic substance to form a carbonaceous film while preventing the thermal energy from causing particle sintering and growth.
Solution Approach 2:
The invention performs preliminary mixing of the organic substance with electrode active material particles before carbonization, ensuring uniform distribution and adsorption. This preliminary action allows the organic substance to be positioned optimally on particle surfaces, enabling effective carbon coating at lower temperatures without requiring high-temperature processing that would cause sintering.
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 approach results in lithium ion batteries with improved discharge capacity, reduced resistance, and excellent cycle characteristics by preventing particle growth and excess carbon decomposition during charging and discharging.
Implementation Method 1
thermally treating the granulated substance obtained in the first step in a non-oxidative atmosphere at 600° C. or higher and 1,000° C. or lower
Implementation Method 2
an ionic organic substance which has an excellent adsorption capability to particle surfaces
Data Source
AI summary
An electrode material including a carbonaceous-coated electrode active material having primary particles of an electrode active material, secondary particles that are aggregates of the primary particles, and a carbonaceous film that coats the primary particles of the electrode active material and the secondary particles that are the aggregates of the primary particles, in which, in the electrode material, when ten random 180 nm×180 nm views are observed using an electron microscope at a magnification of 100,000 times, the number of free carbon aggregates is three or less, and the number of protrusions twice or more as thick as the carbonaceous film is three or less.