Porous Graphite Anode Material for Faster Li-Ion Diffusion
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Solution Overview
Problem
Graphite anode materials face limitations in lithium ion diffusion rates and safety issues due to their layered structure, leading to poor rate performance and potential safety hazards like short circuits and thermal runaway, despite efforts to optimize pore volume and specific surface area.
Innovation Solution
A method involving controlled mixing of carbon-based raw materials, pore-forming agents, and binders, followed by specific heat treatments, to create an anode material with optimized pore volume, specific surface area, and tap density within the range of 2≤V*S/T≤10, enhancing lithium ion diffusion pathways and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite anode materials use a layered structure, then wide sources and stable electrochemical performance are achieved, but lithium ion diffusion rate is low and rate performance is poor
Solution Approach 1:
The patent introduces a porous structure into the graphite anode material, creating interconnected pores that serve as additional diffusion pathways for lithium ions. This porous architecture allows lithium ions to bypass the limitations of the layered structure and achieve faster diffusion rates while maintaining the stable electrochemical performance characteristic of graphite.
Solution Approach 2:
The patent transitions from a two-dimensional layered structure to a three-dimensional porous network structure. By adding the pore dimension, lithium ions gain additional pathways for diffusion that are not constrained by the planar limitations of the layered graphite structure, thereby improving rate performance while preserving electrochemical stability.
2Speed
If pore volume and specific surface area are increased to enhance lithium ion diffusion, then rate performance improves, but structural integrity deteriorates and safety problems occur
Solution Approach 1:
The patent optimizes specific parameters including pore volume (0.03-0.15 mL/g), specific surface area (0.5-2.5 m²/g), and average pore diameter (50-200 nm) to achieve the best balance between lithium ion diffusion rate and structural integrity. By precisely controlling these parameters, the material maintains sufficient structural strength while providing adequate diffusion pathways.
Solution Approach 2:
The patent creates a composite structure combining graphite particles with a porous network formed by pore-forming agents. This composite architecture integrates the stable electrochemical properties of graphite with the enhanced diffusion capabilities of the porous structure, while the controlled pore distribution maintains overall structural integrity and prevents safety issues.
3Speed
If pore structure is optimized for lithium ion diffusion, then rate performance improves, but manufacturing complexity increases
Solution Approach 1:
The patent uses pore-forming agents as intermediaries to create the desired porous structure during the sintering process. These agents (such as starch, cellulose, or sugar) are mixed with graphite powder and then decompose during heating, leaving behind controlled pores. This intermediary approach simplifies manufacturing by using a straightforward mixing and sintering process rather than requiring complex pore formation techniques.
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 method improves the rate performance and processability of graphite anode materials, ensuring stable electrochemical reactions and safety by creating uniform pore structures and maintaining structural integrity during cycling.
Implementation Method 1
an interior and/or a surface of the graphite have a pore, and a pore volume V (cm3/kg), a specific surface area S (m2/g), and a tap density T (g/cc) of the anode material satisfy: 2≤V*S/T≤10
Data Source
AI summary
An anode material and a battery. The anode material includes graphite, an interior and/or a surface of the graphite has pores, a pore volume of the anode material is V (cm3/kg), a specific surface area is S (m2/g), a tap density is T (g/cc), wherein, 2≤V*S/T≤10. By constructing the ratio relationship of the specific surface area of the anode material, the pore volume and the tap density of the anode material, the overall distribution condition of defects such as pore pathways, crystal lattices and micro cracks in the graphite particles can be reflected. Within the limited range, when the anode material is made into an electrode to be applied to a battery, the defect distribution in the anode material is uniform.