Graphitized Carbon Anode with Carbide Surface for Lithium-Ion Batteries
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Solution Overview
Problem
Current anode materials for lithium-ion batteries, particularly those using graphite, face challenges in achieving high specific capacity and initial coulombic efficiency while being cost-effective due to complex production processes and high solvent usage, especially when requiring a protective coating to prevent electrolyte decomposition.
Innovation Solution
The development of anode materials with a surface comprising carbide or nitride compounds formed on graphitized petroleum coke particles, which protects the underlying graphite structure from electrolyte interaction, allowing for efficient lithium ion intercalation without the need for additional coatings, using nucleating agents like boron and graphitizing in inert atmospheres to create a stable surface layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If graphite particles are used as anode material to achieve high specific capacity, then the battery energy density is improved, but the initial coulombic efficiency deteriorates due to electrolyte decomposition
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where graphite particles are coated with a carbonaceous layer containing heteroatoms (nitrogen, boron, or sulfur). The core graphite provides high specific capacity while the shell layer protects against electrolyte decomposition, achieving both high energy density and good initial coulombic efficiency. This composite approach combines the advantages of graphite with the protective benefits of heteroatom-containing carbon.
Solution Approach 2:
The patent changes the chemical composition parameters of the coating layer by incorporating heteroatoms (nitrogen, boron, or sulfur) into the carbonaceous material. This compositional modification alters the surface properties of the graphite particles, making them more resistant to electrolyte decomposition while maintaining lithium ion intercalation capability, thus improving initial coulombic efficiency without sacrificing specific capacity.
2Reliability
If a protective coating is applied to graphite particles to prevent electrolyte decomposition, then the initial coulombic efficiency is improved, but the manufacturing complexity increases due to multiple processing steps
Solution Approach 1:
The patent merges the coating application and graphitization steps into a single integrated process. The carbonaceous coating containing heteroatoms is applied to the graphite particles and then both the coating and core are graphitized together in one heat treatment step at 2000-3000°C. This consolidation eliminates separate coating and stabilization steps, reducing manufacturing complexity while maintaining the protective function.
Solution Approach 2:
The patent employs self-service by allowing the carbonaceous coating to be formed and stabilized through the same graphitization process that treats the core graphite particles. The heteroatom-containing carbon material undergoes graphitization under the same conditions as the graphite core, creating a self-consistent protective layer without requiring external stabilization treatments or multiple atmospheric changes.
3Reliability
If multiple heat treatments in different atmospheres are used to create protective coating, then the coulombic efficiency is improved, but the production cost increases
Solution Approach 1:
The patent uses an inert atmosphere (nitrogen or argon) for the graphitization process that simultaneously forms and stabilizes the protective coating. This single inert atmosphere treatment replaces multiple atmospheric treatments (oxidizing, then inert), reducing the number of process steps and associated costs while achieving the same protective effect against electrolyte decomposition.
4Use of energy by moving object
If the particle size is reduced to increase surface area for lithium ion intercalation, then the specific capacity is improved, but the susceptibility to electrolyte decomposition increases
Solution Approach 1:
The patent applies local quality by creating a heterogeneous structure where the surface layer has different composition and properties from the core. The carbonaceous coating containing heteroatoms (nitrogen, boron, or sulfur) provides localized protection at the particle surface where electrolyte contact occurs, while the interior graphite core maintains its high lithium ion intercalation capability. This local differentiation allows small particle size without sacrificing to electrolyte decomposition.
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 anode materials with enhanced specific capacity and coulombic efficiency, reducing the decay of graphite structures and simplifying the manufacturing process, leading to more cost-effective and high-performance lithium-ion battery electrodes.
Implementation Method 1
a surface comprising at least one carbide compound and a core comprising graphite
Implementation Method 2
lithium ions are able to easily pass through the coating and intercalate into the more organized graphite sheets
Data Source
AI summary
The disclosure relates to a carbon-based electrode material that has been graphitized to hold ions in the electrode of a battery and more particularly include carbide or carbide and nitride surfaces that protect the graphite core. The preferred batteries include metal ion such as lithium ion batteries where the carbon-based electrode is the anode although the carbon-based electrode may also serve in dual ion batteries where both electrodes may comprise the graphitized carbon-based electrodes. The electrodes are more amorphous than conventional graphite electrodes and include a carbide or nitride containing surface treatment.