Graphene-Active Material Composite via Siloxane Bonding
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Solution Overview
Problem
Current methods for enhancing electron conductivity in lithium ion battery positive electrodes, such as using graphene oxide or carbon black, often result in weak bonds and reduced conductivity due to physical adhesion or limited surface contact, restricting the use of active materials and leading to increased surface resistance.
Innovation Solution
The development of graphene/positive electrode active material composite particles with a siloxane bond, where graphene forms a strong chemical bond with the active material, enhancing electron and ion conductivity through surface contact and coating, particularly effective with granulated active materials and specific surface area optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphene oxide or carbon black is used as conductive additive with physical adhesion, then electron conductivity is improved, but bond strength is weak and surface resistance increases
Solution Approach 1:
The patent uses silane coupling agent as an intermediary substance that chemically bonds to both the positive electrode active material surface and graphene. This mediator creates a strong chemical bridge between the two materials, replacing weak physical adhesion with robust chemical bonds, thereby maintaining low surface resistance and high electron conductivity while significantly improving bond strength.
Solution Approach 2:
The patent changes the bonding parameter from physical adhesion to chemical bonding by introducing silane coupling agents. This parameter change transforms the interaction mechanism between graphene and active material, creating strong covalent bonds that maintain excellent electrical conductivity while providing mechanical strength.
2Reliability
If conventional conductive additives are used, then electron conductivity is enhanced, but active material selection is restricted and surface resistance increases
Solution Approach 1:
The silane coupling agent provides universal applicability across different positive electrode active materials (lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, etc.). The coupling agent's ability to chemically bond with various metal oxide surfaces enables broad material selection freedom while maintaining low surface resistance and high electron conductivity, making the conductive network universally effective.
3Ease of manufacture
If physical adhesion methods are used for graphene coating, then manufacturing is simple, but conductivity network stability is poor
Solution Approach 1:
The silane coupling agent serves as a mediator that enables stable chemical bonding between graphene and active material while maintaining manufacturing simplicity. The coupling agent naturally forms chemical bonds during the coating process, providing stable conductive network composition without complicating the manufacturing procedure.
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 a lithium ion battery with improved electron and ion conductivity, leading to higher capacity and output, as demonstrated by the formation of a stable conductive network and effective dispersion of graphene.
Implementation Method 1
graphene/positive electrode active material composite particles with a siloxane bond, where graphene forms a strong chemical bond with the active material
Data Source
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Figure 3
AI summary
An object of the present invention is to improve the electron conductivity and ion conductivity of the surface of a positive electrode active material to provide a lithium ion battery having high capacity and high output. The present invention relates to a positive electrode for a lithium ion secondary battery, including a mixture layer containing a positive electrode active material for a lithium ion secondary battery and graphene, wherein the mixture layer has a percentage of abundance of silicon composing a siloxane bond in total elements of 0.4 atomic% or more as measured by X-ray photoelectron spectroscopy.