Hierarchical Porous Graphite Anode for Fast Lithium-Ion Charging
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Solution Overview
Problem
Existing methods for pore formation in graphite anode materials for lithium-ion batteries face challenges such as uneven dispersion, high costs, safety hazards, environmental pollution, and inefficient production processes, particularly when using metal oxides or salts as pore-forming agents.
Innovation Solution
A graphite anode material with a hierarchical porous structure comprising macroporous and mesoporous structures is developed, achieved through a preparation method involving a water-soluble pore-forming agent dispersed via mechanical force and heat-treated under a protective atmosphere, ensuring uniform pore distribution and reducing production costs and environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal oxides or micro-metal oxides are used as pore-forming agents, then pores can be formed on graphite surface, but the effective utilization rate is low due to uneven dispersion and loose contact with graphite, leading to high cost
Solution Approach 1:
The patent changes the physical state of the pore-forming agent from solid particles to liquid droplets through emulsification. This parameter change enables uniform dispersion in the carbon slurry and ensures consistent pore formation across the graphite surface, resolving both the uniformity and cost issues
Solution Approach 2:
The patent introduces an emulsifier as an intermediary substance that facilitates uniform distribution of the pore-forming agent throughout the carbon slurry. This intermediary ensures homogeneous contact between the pore-forming agent and graphite particles, achieving uniform pore formation without aggregation
2Manufacturing precision
If metal salts are used as pore-forming agents, then pores can be formed, but a large amount of organic solvents are required for dissolving, resulting in high energy consumption, low production efficiency, high production cost and large potential safety hazards during evaporation and drying
Solution Approach 1:
The patent changes the solvent system from organic solvents to water-based emulsion. This parameter change eliminates the need for high-energy evaporation and drying processes, significantly reducing energy consumption while maintaining effective pore formation through the emulsified pore-forming agent
Solution Approach 2:
The patent replaces expensive and hazardous organic solvents with water, which is inexpensive, non-flammable, and environmentally friendly. This substitution reduces both production costs and safety hazards while maintaining the pore-forming functionality
3Manufacturing precision
If metal oxides or transition metal salts are used as pore-forming agents, then pores can be formed, but the heat treatment must be carried out in oxygen or oxygen-containing atmosphere, creating potential safety hazards of dust explosion
Solution Approach 1:
The patent creates an inert water-based emulsion environment that prevents dust explosion hazards during heat treatment. The water-based system suppresses combustion risks while still allowing the pore-forming agent to decompose and form pores through controlled thermal decomposition
Solution Approach 2:
The patent converts the potential harm of heat treatment in oxygen-containing atmosphere (dust explosion risk) into a benefit by using water as the continuous phase. The water-based emulsion acts as a fire suppressant while still allowing the pore-forming agent to function through controlled decomposition
4Manufacturing precision
If metal oxides and metal salts are used as pore-forming agents, then pores can be formed, but the pore-forming agents can only be removed by acid pickling or high-temperature graphitization, resulting in high production costs and potential safety and environmental pollution hazards
Solution Approach 1:
The patent enables easy removal of the pore-forming agent through water washing after heat treatment. The emulsified pore-forming agent decomposes into water-soluble or easily removable residues, eliminating the need for complex acid pickling or high-temperature graphitization processes
Solution Approach 2:
The patent uses a pore-forming agent system that can be easily removed by simple water washing, replacing expensive and complex removal processes like acid pickling. This approach reduces production costs and eliminates environmental pollution hazards associated with acid waste
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 material enables fast charging performance by shortening lithium ion diffusion paths, with delithiation capacity exceeding 359.7 mAh/g and initial Coulombic efficiency over 93.8%, while being safe, environmentally friendly, and suitable for industrial production.
Implementation Method 1
dispersing a pore-forming agent solution on the surface of graphite through the action of mechanical force
Implementation Method 2
performing heat treatment under a protective atmosphere to obtain the graphite anode material
Implementation Method 3
the diffusion paths of lithium ions from the graphite surface to the core are shortened
Data Source
AI summary
A graphite negative electrode material, a preparation method therefor and an application thereof. The surface of the graphite negative electrode material is provided with a macroporous structure and a mesoporous structure. In the macroporous structure, the ratio R of depth H of the macropores to size D of the macropores satisfies 0<R<60, where R=H/D. In the mesoporous structure, the ratio r of depth h of the mesopores to size d of the mesopores satisfies 0<r<250, where r=h/d. The preparation method comprises: dispersing a pore-forming agent solution on the surface of graphite by means of a mechanical force, and carrying out heat treatment in a protective atmosphere to obtain the graphite negative electrode material. The pore-forming agent is water-soluble. The surface of the graphite negative electrode material is provided with a macroporous structure and a mesoporous structure at the same time. The hierarchical porous structure equips the base plane and the edge plane of the graphite material with channels capable of allowing lithium ions to quickly enter between graphite layers, and shorten the solid-phase diffusion path of lithium ions. Therefore, the charging rate of the graphite negative electrode material is improved, rapid charging is realized, the preparation process is safe and environment friendly, and the cost is low.